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TRANSCRIPT
N71-24586
LOW-WING-LOADING STOL STUDY FINAL REPORT
TRANSPORT RIDE SMOOTHING FEASIBILITY
The Boeing Company Wichita Kansas
January 1971
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NASA CZ1441
LOW-WING-LOADING STOL TRANSPORT RIDE SMOOTHING
FEASIBILITY STUDY
FINAL REPORT
D3-8514-2 Nii 5 6 _
(NSC R lx RAD NUMBER) (CATEGORY
JANUARY 1971 T ON OOMPANY
WICHITA DI]VISION WIQHITA KANSAS
IG710043
NATIONAL TECHNICALiINFORMATnoN -SEVICs t
1
THE COMPANYSOSA S WICHITA DIVISION - WICHITA KANSAS 67210
NUMBER D3-8514-2 REV LTR
INITIAL RELEASE DATE February 8 1971
-TITLE LOW-WING-LOADING STOL TRANSPORT RIDE SMOOTHING FEASIBILITY STUDY
FINAL REPORT
MODEL STOL Transport CONTRACT NASI-10410
APPROVED BY amp APPROVED By G 0 Thompson V RBHolloway
1cent
PROGRAM OBJECTIVE
This document presents results of an analytical study conducted by the Wichita Division of The Boeing Company for the Langley Research Center National Aeronautics and Space Administration under Contract NASI-104100 The primary objective of the study was to determine the feasibility of providing satisfactory ride qualities using modern controls technology on a high performance low-wing-loading STOL aircraft The aircraft configuration was designed to be competitive with present high speed jet aircraft economics and block times and to meet proposed noise requirements
Gust alleviation is not a new concept as indicated by the references shown in the bibliography During the late 1930s and 1940s NACA personnel conducted analyses wind tunnel tests and flight tests of gust alleviation systems and flight demonstrated acceleration reductions of up to 60 percent1
Advances in electronic and hydraulic actuation hardware indicate that mechanization of a satisfactory ride smoothing system is now a realizable goal with current technology This study was conducted to synthesize such a system for a high performance low-wing-loading STOL aircraft
1 Hunter Paul A Kraft Christopher C Jr and Alford William L AFlight Investigation of an Automatic Gust - Alleviation System in a Transport Airplane NACA TN D-532 dated 1961
2
PROGRAM OBJECTIVE
DETERMINE FEASIBILITY OF PROVIDING SATIS-
FACTORY RIDE QUALITIES USING MODERN CONTROLS
TECHNOLOGY ON A HIGH PERFORMANCE LOW-WING-
LOADING STOL AIRCRAFT
IG710043-21
3
PROGRAM SCHEDULE
A configuration was developed to provide a vehicle for the ride smoothing system synthesis Perforshymance analyses were conducted to assess significant airplane capabilities In addition operating costs noise application of advanced composite structure and Prop-Fan propulsion were assessed
4
PROGRAM SCHEDULE
1970 11971 OCT NOV DEC JAN
OCT 12 NOV 24 CONTRACT INITIATED INTERIM PRESENTATION
V V CONFIGURATION DEVELOPMENT
AIRPLANE PERFORMANCE
RIDE SMOOTHING AND HANDLING QUALITY SAS
OPERATING COST -
NOISE EVALUATION
ADVANCED TECHNOLOGY
JAN 18 FINAL PRESENTATION v
JAN 25 FINAL REPORT y
G710043-32
5
CONCLUSIONS
Within the limitations outlined in this document conclusions of this study are shown on this chart Principal limitations were rigid body dynamics linear aerodynamics and linear control systems analyses
6
CONCLUSIONS
A LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
IG710043-40
7
STOL DESIGN CONCEPTS
High cruise speeds have been a goal of most commercial STOL studies This requirement with a desire for high cruise efficiencies and passenger ride comfort has resulted in airplanes designed with high-wing-loadings To achieve STOL capability these configurations rely on complicated auidlishyary propulsive systems or augmented lift systems which must be carried throughout the mission for use on takeoff and landing only These designs are sensitive to propulsion system failures which affect safety of flight in most cases
The low-wing-loading concept relies on the flight control system to provide satisfactory ride and accepts some reduction in efficiency during high speed cruise This STOL capability is provided with simple flight proven aerodynamic concepts
8
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
NASA CZ1441
LOW-WING-LOADING STOL TRANSPORT RIDE SMOOTHING
FEASIBILITY STUDY
FINAL REPORT
D3-8514-2 Nii 5 6 _
(NSC R lx RAD NUMBER) (CATEGORY
JANUARY 1971 T ON OOMPANY
WICHITA DI]VISION WIQHITA KANSAS
IG710043
NATIONAL TECHNICALiINFORMATnoN -SEVICs t
1
THE COMPANYSOSA S WICHITA DIVISION - WICHITA KANSAS 67210
NUMBER D3-8514-2 REV LTR
INITIAL RELEASE DATE February 8 1971
-TITLE LOW-WING-LOADING STOL TRANSPORT RIDE SMOOTHING FEASIBILITY STUDY
FINAL REPORT
MODEL STOL Transport CONTRACT NASI-10410
APPROVED BY amp APPROVED By G 0 Thompson V RBHolloway
1cent
PROGRAM OBJECTIVE
This document presents results of an analytical study conducted by the Wichita Division of The Boeing Company for the Langley Research Center National Aeronautics and Space Administration under Contract NASI-104100 The primary objective of the study was to determine the feasibility of providing satisfactory ride qualities using modern controls technology on a high performance low-wing-loading STOL aircraft The aircraft configuration was designed to be competitive with present high speed jet aircraft economics and block times and to meet proposed noise requirements
Gust alleviation is not a new concept as indicated by the references shown in the bibliography During the late 1930s and 1940s NACA personnel conducted analyses wind tunnel tests and flight tests of gust alleviation systems and flight demonstrated acceleration reductions of up to 60 percent1
Advances in electronic and hydraulic actuation hardware indicate that mechanization of a satisfactory ride smoothing system is now a realizable goal with current technology This study was conducted to synthesize such a system for a high performance low-wing-loading STOL aircraft
1 Hunter Paul A Kraft Christopher C Jr and Alford William L AFlight Investigation of an Automatic Gust - Alleviation System in a Transport Airplane NACA TN D-532 dated 1961
2
PROGRAM OBJECTIVE
DETERMINE FEASIBILITY OF PROVIDING SATIS-
FACTORY RIDE QUALITIES USING MODERN CONTROLS
TECHNOLOGY ON A HIGH PERFORMANCE LOW-WING-
LOADING STOL AIRCRAFT
IG710043-21
3
PROGRAM SCHEDULE
A configuration was developed to provide a vehicle for the ride smoothing system synthesis Perforshymance analyses were conducted to assess significant airplane capabilities In addition operating costs noise application of advanced composite structure and Prop-Fan propulsion were assessed
4
PROGRAM SCHEDULE
1970 11971 OCT NOV DEC JAN
OCT 12 NOV 24 CONTRACT INITIATED INTERIM PRESENTATION
V V CONFIGURATION DEVELOPMENT
AIRPLANE PERFORMANCE
RIDE SMOOTHING AND HANDLING QUALITY SAS
OPERATING COST -
NOISE EVALUATION
ADVANCED TECHNOLOGY
JAN 18 FINAL PRESENTATION v
JAN 25 FINAL REPORT y
G710043-32
5
CONCLUSIONS
Within the limitations outlined in this document conclusions of this study are shown on this chart Principal limitations were rigid body dynamics linear aerodynamics and linear control systems analyses
6
CONCLUSIONS
A LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
IG710043-40
7
STOL DESIGN CONCEPTS
High cruise speeds have been a goal of most commercial STOL studies This requirement with a desire for high cruise efficiencies and passenger ride comfort has resulted in airplanes designed with high-wing-loadings To achieve STOL capability these configurations rely on complicated auidlishyary propulsive systems or augmented lift systems which must be carried throughout the mission for use on takeoff and landing only These designs are sensitive to propulsion system failures which affect safety of flight in most cases
The low-wing-loading concept relies on the flight control system to provide satisfactory ride and accepts some reduction in efficiency during high speed cruise This STOL capability is provided with simple flight proven aerodynamic concepts
8
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
THE COMPANYSOSA S WICHITA DIVISION - WICHITA KANSAS 67210
NUMBER D3-8514-2 REV LTR
INITIAL RELEASE DATE February 8 1971
-TITLE LOW-WING-LOADING STOL TRANSPORT RIDE SMOOTHING FEASIBILITY STUDY
FINAL REPORT
MODEL STOL Transport CONTRACT NASI-10410
APPROVED BY amp APPROVED By G 0 Thompson V RBHolloway
1cent
PROGRAM OBJECTIVE
This document presents results of an analytical study conducted by the Wichita Division of The Boeing Company for the Langley Research Center National Aeronautics and Space Administration under Contract NASI-104100 The primary objective of the study was to determine the feasibility of providing satisfactory ride qualities using modern controls technology on a high performance low-wing-loading STOL aircraft The aircraft configuration was designed to be competitive with present high speed jet aircraft economics and block times and to meet proposed noise requirements
Gust alleviation is not a new concept as indicated by the references shown in the bibliography During the late 1930s and 1940s NACA personnel conducted analyses wind tunnel tests and flight tests of gust alleviation systems and flight demonstrated acceleration reductions of up to 60 percent1
Advances in electronic and hydraulic actuation hardware indicate that mechanization of a satisfactory ride smoothing system is now a realizable goal with current technology This study was conducted to synthesize such a system for a high performance low-wing-loading STOL aircraft
1 Hunter Paul A Kraft Christopher C Jr and Alford William L AFlight Investigation of an Automatic Gust - Alleviation System in a Transport Airplane NACA TN D-532 dated 1961
2
PROGRAM OBJECTIVE
DETERMINE FEASIBILITY OF PROVIDING SATIS-
FACTORY RIDE QUALITIES USING MODERN CONTROLS
TECHNOLOGY ON A HIGH PERFORMANCE LOW-WING-
LOADING STOL AIRCRAFT
IG710043-21
3
PROGRAM SCHEDULE
A configuration was developed to provide a vehicle for the ride smoothing system synthesis Perforshymance analyses were conducted to assess significant airplane capabilities In addition operating costs noise application of advanced composite structure and Prop-Fan propulsion were assessed
4
PROGRAM SCHEDULE
1970 11971 OCT NOV DEC JAN
OCT 12 NOV 24 CONTRACT INITIATED INTERIM PRESENTATION
V V CONFIGURATION DEVELOPMENT
AIRPLANE PERFORMANCE
RIDE SMOOTHING AND HANDLING QUALITY SAS
OPERATING COST -
NOISE EVALUATION
ADVANCED TECHNOLOGY
JAN 18 FINAL PRESENTATION v
JAN 25 FINAL REPORT y
G710043-32
5
CONCLUSIONS
Within the limitations outlined in this document conclusions of this study are shown on this chart Principal limitations were rigid body dynamics linear aerodynamics and linear control systems analyses
6
CONCLUSIONS
A LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
IG710043-40
7
STOL DESIGN CONCEPTS
High cruise speeds have been a goal of most commercial STOL studies This requirement with a desire for high cruise efficiencies and passenger ride comfort has resulted in airplanes designed with high-wing-loadings To achieve STOL capability these configurations rely on complicated auidlishyary propulsive systems or augmented lift systems which must be carried throughout the mission for use on takeoff and landing only These designs are sensitive to propulsion system failures which affect safety of flight in most cases
The low-wing-loading concept relies on the flight control system to provide satisfactory ride and accepts some reduction in efficiency during high speed cruise This STOL capability is provided with simple flight proven aerodynamic concepts
8
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PROGRAM OBJECTIVE
This document presents results of an analytical study conducted by the Wichita Division of The Boeing Company for the Langley Research Center National Aeronautics and Space Administration under Contract NASI-104100 The primary objective of the study was to determine the feasibility of providing satisfactory ride qualities using modern controls technology on a high performance low-wing-loading STOL aircraft The aircraft configuration was designed to be competitive with present high speed jet aircraft economics and block times and to meet proposed noise requirements
Gust alleviation is not a new concept as indicated by the references shown in the bibliography During the late 1930s and 1940s NACA personnel conducted analyses wind tunnel tests and flight tests of gust alleviation systems and flight demonstrated acceleration reductions of up to 60 percent1
Advances in electronic and hydraulic actuation hardware indicate that mechanization of a satisfactory ride smoothing system is now a realizable goal with current technology This study was conducted to synthesize such a system for a high performance low-wing-loading STOL aircraft
1 Hunter Paul A Kraft Christopher C Jr and Alford William L AFlight Investigation of an Automatic Gust - Alleviation System in a Transport Airplane NACA TN D-532 dated 1961
2
PROGRAM OBJECTIVE
DETERMINE FEASIBILITY OF PROVIDING SATIS-
FACTORY RIDE QUALITIES USING MODERN CONTROLS
TECHNOLOGY ON A HIGH PERFORMANCE LOW-WING-
LOADING STOL AIRCRAFT
IG710043-21
3
PROGRAM SCHEDULE
A configuration was developed to provide a vehicle for the ride smoothing system synthesis Perforshymance analyses were conducted to assess significant airplane capabilities In addition operating costs noise application of advanced composite structure and Prop-Fan propulsion were assessed
4
PROGRAM SCHEDULE
1970 11971 OCT NOV DEC JAN
OCT 12 NOV 24 CONTRACT INITIATED INTERIM PRESENTATION
V V CONFIGURATION DEVELOPMENT
AIRPLANE PERFORMANCE
RIDE SMOOTHING AND HANDLING QUALITY SAS
OPERATING COST -
NOISE EVALUATION
ADVANCED TECHNOLOGY
JAN 18 FINAL PRESENTATION v
JAN 25 FINAL REPORT y
G710043-32
5
CONCLUSIONS
Within the limitations outlined in this document conclusions of this study are shown on this chart Principal limitations were rigid body dynamics linear aerodynamics and linear control systems analyses
6
CONCLUSIONS
A LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
IG710043-40
7
STOL DESIGN CONCEPTS
High cruise speeds have been a goal of most commercial STOL studies This requirement with a desire for high cruise efficiencies and passenger ride comfort has resulted in airplanes designed with high-wing-loadings To achieve STOL capability these configurations rely on complicated auidlishyary propulsive systems or augmented lift systems which must be carried throughout the mission for use on takeoff and landing only These designs are sensitive to propulsion system failures which affect safety of flight in most cases
The low-wing-loading concept relies on the flight control system to provide satisfactory ride and accepts some reduction in efficiency during high speed cruise This STOL capability is provided with simple flight proven aerodynamic concepts
8
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PROGRAM OBJECTIVE
DETERMINE FEASIBILITY OF PROVIDING SATIS-
FACTORY RIDE QUALITIES USING MODERN CONTROLS
TECHNOLOGY ON A HIGH PERFORMANCE LOW-WING-
LOADING STOL AIRCRAFT
IG710043-21
3
PROGRAM SCHEDULE
A configuration was developed to provide a vehicle for the ride smoothing system synthesis Perforshymance analyses were conducted to assess significant airplane capabilities In addition operating costs noise application of advanced composite structure and Prop-Fan propulsion were assessed
4
PROGRAM SCHEDULE
1970 11971 OCT NOV DEC JAN
OCT 12 NOV 24 CONTRACT INITIATED INTERIM PRESENTATION
V V CONFIGURATION DEVELOPMENT
AIRPLANE PERFORMANCE
RIDE SMOOTHING AND HANDLING QUALITY SAS
OPERATING COST -
NOISE EVALUATION
ADVANCED TECHNOLOGY
JAN 18 FINAL PRESENTATION v
JAN 25 FINAL REPORT y
G710043-32
5
CONCLUSIONS
Within the limitations outlined in this document conclusions of this study are shown on this chart Principal limitations were rigid body dynamics linear aerodynamics and linear control systems analyses
6
CONCLUSIONS
A LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
IG710043-40
7
STOL DESIGN CONCEPTS
High cruise speeds have been a goal of most commercial STOL studies This requirement with a desire for high cruise efficiencies and passenger ride comfort has resulted in airplanes designed with high-wing-loadings To achieve STOL capability these configurations rely on complicated auidlishyary propulsive systems or augmented lift systems which must be carried throughout the mission for use on takeoff and landing only These designs are sensitive to propulsion system failures which affect safety of flight in most cases
The low-wing-loading concept relies on the flight control system to provide satisfactory ride and accepts some reduction in efficiency during high speed cruise This STOL capability is provided with simple flight proven aerodynamic concepts
8
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PROGRAM SCHEDULE
A configuration was developed to provide a vehicle for the ride smoothing system synthesis Perforshymance analyses were conducted to assess significant airplane capabilities In addition operating costs noise application of advanced composite structure and Prop-Fan propulsion were assessed
4
PROGRAM SCHEDULE
1970 11971 OCT NOV DEC JAN
OCT 12 NOV 24 CONTRACT INITIATED INTERIM PRESENTATION
V V CONFIGURATION DEVELOPMENT
AIRPLANE PERFORMANCE
RIDE SMOOTHING AND HANDLING QUALITY SAS
OPERATING COST -
NOISE EVALUATION
ADVANCED TECHNOLOGY
JAN 18 FINAL PRESENTATION v
JAN 25 FINAL REPORT y
G710043-32
5
CONCLUSIONS
Within the limitations outlined in this document conclusions of this study are shown on this chart Principal limitations were rigid body dynamics linear aerodynamics and linear control systems analyses
6
CONCLUSIONS
A LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
IG710043-40
7
STOL DESIGN CONCEPTS
High cruise speeds have been a goal of most commercial STOL studies This requirement with a desire for high cruise efficiencies and passenger ride comfort has resulted in airplanes designed with high-wing-loadings To achieve STOL capability these configurations rely on complicated auidlishyary propulsive systems or augmented lift systems which must be carried throughout the mission for use on takeoff and landing only These designs are sensitive to propulsion system failures which affect safety of flight in most cases
The low-wing-loading concept relies on the flight control system to provide satisfactory ride and accepts some reduction in efficiency during high speed cruise This STOL capability is provided with simple flight proven aerodynamic concepts
8
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PROGRAM SCHEDULE
1970 11971 OCT NOV DEC JAN
OCT 12 NOV 24 CONTRACT INITIATED INTERIM PRESENTATION
V V CONFIGURATION DEVELOPMENT
AIRPLANE PERFORMANCE
RIDE SMOOTHING AND HANDLING QUALITY SAS
OPERATING COST -
NOISE EVALUATION
ADVANCED TECHNOLOGY
JAN 18 FINAL PRESENTATION v
JAN 25 FINAL REPORT y
G710043-32
5
CONCLUSIONS
Within the limitations outlined in this document conclusions of this study are shown on this chart Principal limitations were rigid body dynamics linear aerodynamics and linear control systems analyses
6
CONCLUSIONS
A LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
IG710043-40
7
STOL DESIGN CONCEPTS
High cruise speeds have been a goal of most commercial STOL studies This requirement with a desire for high cruise efficiencies and passenger ride comfort has resulted in airplanes designed with high-wing-loadings To achieve STOL capability these configurations rely on complicated auidlishyary propulsive systems or augmented lift systems which must be carried throughout the mission for use on takeoff and landing only These designs are sensitive to propulsion system failures which affect safety of flight in most cases
The low-wing-loading concept relies on the flight control system to provide satisfactory ride and accepts some reduction in efficiency during high speed cruise This STOL capability is provided with simple flight proven aerodynamic concepts
8
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
CONCLUSIONS
Within the limitations outlined in this document conclusions of this study are shown on this chart Principal limitations were rigid body dynamics linear aerodynamics and linear control systems analyses
6
CONCLUSIONS
A LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
IG710043-40
7
STOL DESIGN CONCEPTS
High cruise speeds have been a goal of most commercial STOL studies This requirement with a desire for high cruise efficiencies and passenger ride comfort has resulted in airplanes designed with high-wing-loadings To achieve STOL capability these configurations rely on complicated auidlishyary propulsive systems or augmented lift systems which must be carried throughout the mission for use on takeoff and landing only These designs are sensitive to propulsion system failures which affect safety of flight in most cases
The low-wing-loading concept relies on the flight control system to provide satisfactory ride and accepts some reduction in efficiency during high speed cruise This STOL capability is provided with simple flight proven aerodynamic concepts
8
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
CONCLUSIONS
A LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
IG710043-40
7
STOL DESIGN CONCEPTS
High cruise speeds have been a goal of most commercial STOL studies This requirement with a desire for high cruise efficiencies and passenger ride comfort has resulted in airplanes designed with high-wing-loadings To achieve STOL capability these configurations rely on complicated auidlishyary propulsive systems or augmented lift systems which must be carried throughout the mission for use on takeoff and landing only These designs are sensitive to propulsion system failures which affect safety of flight in most cases
The low-wing-loading concept relies on the flight control system to provide satisfactory ride and accepts some reduction in efficiency during high speed cruise This STOL capability is provided with simple flight proven aerodynamic concepts
8
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
STOL DESIGN CONCEPTS
High cruise speeds have been a goal of most commercial STOL studies This requirement with a desire for high cruise efficiencies and passenger ride comfort has resulted in airplanes designed with high-wing-loadings To achieve STOL capability these configurations rely on complicated auidlishyary propulsive systems or augmented lift systems which must be carried throughout the mission for use on takeoff and landing only These designs are sensitive to propulsion system failures which affect safety of flight in most cases
The low-wing-loading concept relies on the flight control system to provide satisfactory ride and accepts some reduction in efficiency during high speed cruise This STOL capability is provided with simple flight proven aerodynamic concepts
8
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
___ __ __
MECHANICAL FLAP
EXTERNALLYBLOWN FLAP
INTERNALLY BLOWN FLAP
JET FLAP
DIRECT LIFT JET
DIRECT LIFT FANG
STOL DESIGN CONCEPTS
-- EXTERNALLY BLOWN FLAP
-- INTERNALLY BLOWN FLAP MECHANICAL FLAP
120- DIRECT LIFT amp JET FLAP
ZLE 1IGLOADING
ws 80- 11
A 60cZI0060shy
n 401
F AR LANDING DESIGN FIELD LENGTH
IG710043S33
9
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
LOW-WING-LOADING STOL CONCEPT
The engine thrust required for takeoff is less for lower wing loadings Since none of the lift is proshyvided by the propulsion system a propulsion system failure will not cause a sudden loss of lift The low thrust requirement also reduces the takeoff and sideline noise and since less fuel is required for takeoff airport pollution is reduced
Low-wing-loading causes a larger than necessary wing for cruise which reduces cruise efficiency
At comparable speeds low-wing-loading airplane are more gust responsive than high-wing loading airplanes To provide acceptable passenger ride comfort a ride smoothing control system is required A system failure in a turbulent environment would require a slower speed to maintain satisfactory comfort
10
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
LOW-WING-LOADING STOL CONCEPT
ADVANTAGES
- RELIABLE - SIMPLE - STATE-OF-THE-ART ALL MECHANICAL FLAP SYSTEM
- RELATIVELY LOW THRUST TO WEIGHT
- LIFT NOT AFFECTED BY PROPULSION SYSTEM FAILURE
- ECOLOGICAL BENEFITS - NOISE AND POLLUTION
DISADVANTAGES
- REDUCED EFFICIENCY AT HIGH SPEED CRUISE
- POOR PASSENGER COMFORT AT HIGH SPEEDS WITHOUT RIDE SMOOTHING SAS
IG710043-1811
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
DESIGN OBJECTIVES
The design objectives shown opposite were established to provide a framework for sizing the vehicle
12
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
DESIGN OBJECTIVES
bull PAYLOAD 130 PASSENGERS 18 FIRST CLASSAND 112 ECONOMY CLASS
FAR FIELD LENGTH 2000 FEET
CRUISE MACH NUMBER 08 (APPROX)
UNREFUELED RANGE 750 N MI
(3 EQUAL 250 )N MI SEGMENTS
IG710043-17
13
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
ASSUMPTIONS
The fuselage of the Boeing Model 751 was used for these studies This aircraft was the Boeing configshyuration submitted in response to the requirements of Eastern Air Lines 2 The Model 751 was a high wing loading configuration which used four auxiliary lift engines for high acceleration and deceleration to provide it with STOL capability The configuration also used a small amount of leading edge blowshying for flow attachment
The lower than usual aspect ratio of six was selected since a high aspect ratio would result in a large span for the large area and the reduced lift curve slope somewhat improves the ride Also this con shyfiguration cruises at low lift coefficients where drag due to lift is not important to cruise efficiency
By utilizing supercritical wing technology the sweep of the flap hinge line can be zero for maximum flap effectiveness while maintaining high critical Mach numbers for cruise
Estimated engine performance was based on projected 1975 technology which included increased turshybine temperatures (2900R) and compressor pressure ratios of 24
The operating rules for certification type analysis were based on Tentative Airworthiness Standards 3
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft DQT FAA Flight Standards Service Washington DC August 1970
14
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
ASSUMPTIONS
BOEING MODEL 751 FUSELAGE
ASPECT RATIO = 60
TAPER RATIO = 4
SWEEP OF TRAILING EDGE FLAP HINGE LINE = 0 DEGREES
bull DOUBLE SLOTTED FULL SPAN TRAILING EDGE FLAP WITH MATCHED LEADING EDGE FLAP
1975 ENGINE TECHNOLOGY
SUPERCRITICAL WING TECHNOLOGY
OPERATING RULES PER TENTATIVE AIRWORTHINESS STANDARDS PART XX
IG710043-25
15
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
FLAP SYSTEM
The full span trailing edge flap is a dual purpose surface that performs as a conventional double slotted flap for takeoff and landing The deflection for takeoff is 200 and for landing is 300 The aft segment of the double slotted flap is provided with a high bandpass actuator for use by the ride smoothing conshytrol system The estimated maximum authority required of the aft flap segment is plusmn 100 from its nominal position
16
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
FLAP SYSTEM
C = 125
HIGH LIFT
C = 100
RIDE CONTROL
10710043-3117
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
The low speed aerodynamic characteristics were estimated by Boeing methods 4 This method has shown good agreement with flight test results of the Boeing 727 737 and 747
4 Boeing Document D6-26011TN Low Speed Aerodynamic Prediction Method July 14 1970
18
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
ESTIMATED LOW SPEED AERODYNAMIC CHARACTERISTICS
z 1 g STALLS 0 -- FAR STALLS
rREF D6-26011TN LOW SPEED AERODYNAMIC40 (GEAR DOWN)2-
0 (GA OW) o 30 deg (GEAR DOWN) PREDICTION METHOD
10F f100
6 7 180 2
CD DRAG COEFFICIENT 4 4shy
z 3 03shy
0 2 2
I- o4Oi - 010~ 0
A 200 o 00 10
0 4 8 12 16 20 0 - 2 - 4 - 6 - 8 a-ANGLE OF ATTACK - DEG CMg PITCHING MOMENT
COEFFICIENT IG710043-34
19
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
THRUST REQUIREMENT
A simple parametric study was performed to define the configuration which would satisfy the mission requirements and airworthiness standards 3 A composite of these requirements is presented as a function of wing loading and thrust-to-weight ratio The takeoff requirement is for a 2000 ft FAR field length The takeoff climb requirements and the balked landing requirements are established for the most critical engine inoperative3 The landing field length includes 67 percent conservatism The cruise requirement is for a bypass ratio 4 turbofan engine (determined from sizing studies) at a Mach number of 75 at 30000 ft altitude
The configuration selected for the ride quality studies had a (TW)SLS = 35 and a maximum gross weight wing loading of 50 lbft 2 This configuration has a good match between takeoff and cruise thrust requirements which would not be the case for a higher cruise speed
3 Tentative Airworthiness Standards For Powered Lift Transport Category Aircraft D OT FAA Flight Standards Service Washington DC August 1970
20
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
THRUST REQUIREMENT
50- 0 4 ENGINES 0 BYPASS RATIO 4
oSELECTED
r 40- CONFIGURATION -TAKEOFF
CRIS
(M= 75 AT 30 000 FT) 0 0 ENGINE OUT CLIMB (TAKEOFF)H 30shy
- -- ENGINE OUT CLIMB (LANDING)
too
120-
N 10shy
E-1
0 30 40 50 60 70 80 90
ws- WING LOADING- LBFT 2 1G710043-30
21
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
LOW-WING-LOADING STOL
The study airplane configuration is shown opposite The fuselage represents current wide-body philosophy incorporating a twin-aisle which aids rapid loading and unloading The flight controls are conventional aerodynamic surfaces with minimum augmentation The longitudinal controls are a 30c elevator for longitudinal control and a low-rate all movable stabilizer for trim The directional axis is controlled by a large chord rudder on a conventional vertical tail Lateral control is provided by wing mounted spoilers The spoilers will also be used for landing roll airbrakes
The high lift system is a full-span double-slotted trailing edge flap with a matched leading edge flap The aft segment of the trailing edge flap will be used for the ride smoothing control system
22
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
LOW-WING-LOADING STOL
BAGGAGE CONTAINERPo o--
ECONOMY CLASS58 SEATING ARRANGEMENT264
- i 196
1500
000 1400
WING
S = 2600 FT2
b = 1500 IN MAC = 2649 IN
Ai = 6 Z_-4
25c 971
23
0 0 00000000000
n n+
IG710043 36
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
MISSION RULES
An unrefueled range of 750 n mi composed of three 250 n mi segments was chosei as the primary mission design objective Airplanes sized for the primary mission were recycled to determine their size compatibility with a 1000 n mi alternate mission
The airplanes were sized for the reserve requirements shown as distances A and B on the chart 2 5
Distance A indicates a 12 hour continued cruise and descent to sea level followed by a missed approach Distance B is 100 n mi composed of a climb to 10000 ft cruise and descent to an alternate field
Takeoff and landing allowances were
Taxi out time = 3 min
Takeoff time = 1 min
Landing time = 1 min
Taxi in time = 3 min
2 Operational Requirements and Guidelines for VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
5 Boeing Document D6-24431-2 Boeing Model 751 CSTOL Performance Report November 18 1969
24
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
MISSION RULES
PRIMARY MISSION H oo p4
0 250 RANGE
500 - N MI
750 i
PRIMARY MISSION RESERVES FT 010000
0 250 500A
ALTERNATE
MISSION
E- 0
p
RANGE - N MI 1000
ALTERNATE MISSION RESERVES
~I FI
25i 000F
1000F
0 RANGE -N[
25
k-----B If
z4
IG710043 41
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
SIZING STUDY
As indicated in the chart a cruise altitude of 30000 feet for the selected design configuration results in the lightest airplane that can reach cruise Mach number with a TW less than 35 when referenced to sea level static takeoff rated power
For low bypass ratio engines the engines are sized by the takeoff requirement As bypass ratio is increased the engines become sized by the cruise thrust requirement due to the thrust lapse -rate characteristics of the engine
26
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
SIZING STUDY
200
WS = 50 LBSFT2
o M = 75 X - ENGINES SIZED FOR CRUISE TW 3 5
0E - ENGINES SIZED FOR TAKEOFF TW =35 -- - AIRPLANES MUST DESCEND BEFORE
REACHING CRUISE MACH NO
190
180
170o
amp160shy00
150shy02
o 140 4
DESIGN CONFIGURATION
130 6
1201
20
CRUISE
30
ALTITUDE
27
- 1000 FT
40
IG710043-16
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
Above Mach 6 gross weight is extremely sensitive to cruise Mach number The small block time advantage between Mach 7 and 75 may not be enough to merit the additional weight A block time savings is indicated for cruise Mach numbers higher than 75 This is due to the lower climb times with the higher TW required to fly faster than 75 However it is questionable as to whether the resulting weight penalty would be economical A more extensive configuration development could further refine the selected airplane by optimizing for economy
28
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
CONFIGURATION SENSITIVITY TO CRUISE MACH NUMBER
m
150- 5
CoALTERNATE
o WS = 50 LBSFT2
e CRUISE ALTITUDE = 30000 FT BYPASS RATIO = 4
- PRIMARY MISSION --- MISSION
140- 0 4
H DESIGN CONFIGURATION
130--0
3
120 21
40- -mm
5-shy
0o 30 -
201- I _ I E_
4shy
3 I I It
4 5 6 7 CRUISE MACH NO
8 4
29
5 6 7 8 CRUISE MACH NO
IG710043-15
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
ECONOMIC CHARACTERISTICS
The Direct Operating Cost (DOC) of the STOL airplane is less than that of the 727-200 for trip distances lesslthan 1000 n mi This comparison is shown using ATA rules 6 for the 727-200 and the Eastern Air Lines DOC formula2 for the STOL airplane The costs were inflated to 1975 dollars
The Boeing Model 751 DOCs shown are estimated using the Eastern Air Lines DOC formula However time limitations prevented computing the Model 751 costs to 1975 dollars If this effect were applied the Model 751 costs would be increased
Since the data shown opposite are calculated for different rules the conclusion is that the DOC of the low wing loading STOL airplane is in the ball park with DOCs of the other two vehicles
2 Operational Requirements and Guidelines For VSTOL Systems Eastern Engineering Report No E-482 August 12 1969
6 Boeing Document ATN 70-007 CAPATAR - Commercial Airplane Performance Using Air Transshyport Association Rules December 11 1970
30
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
ECONOMIC CHARACTERISTICS
AIRPLANE PASSENGERS DOLLAR COST RULESBASE
LOW WS STOL 130 1975 EASTERN DOC FORMULA 727-200 134 1975 ATA
751 130 1969 EASTERN DOC FORMULA
301
1000 POUNDS 201----BLOCK FUEL shy
10-
30-UIII BLOCK TIME- HOURS i0j - --- I
10
40
0 -- DIRECT OPERATING COST
-
20shyCENTSSEAT STATUTE MILE
10shy
4 6 CAB RANGE - 100 N MILES
IG710043-37
31
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
NOISE
The trend of todays advancements in engine technology is toward smaller lighter and more efficient propulsion packages Engines used for this study were assumed to be 1975 reflections of this trend which is advantageous from the engine efficiency standpoint but not necessarily compatible with minishymum engine noise
A critical point for STOL noise is the sideline Data for 1000 ft sideline are shown opposite
32
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
NOISE (1000 FT SIDELINE)
130-
120-
a 4 ENGINES TRTENGINE = 11500 LBS o TITMAX = 2900degR
COMPRESSION RATIO = 24 bull 2 SPOOL FRONT FAN TURBOFANS
UNSUPPRESSED IlIIIIIl 1975 SUPPRESSION
02z nr
N 100
2 4 BYPASS RATIO
TURBOFANS
33
PROP-
FAN IG710043 38 RI
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
URBAN POLLUTION
The low-wing-loading STOL configuration with its relatively low thrust-to-weight will produce less pollution due to engine exhaust than other airplanes The thrust-to-weight ratio of this configuration is approximately equal to present day jet transports Because of the lower takeoff speeds the total takeoff fuel is less The takeoff time of the 727-200 is about 30 seconds compared to about 12 seconds for the low wing loading STOL configuration A powered lift STOL configuration such as the Boeing Model 751 with lift engines has a total thrust to weight ratio of about 75 and a takeoff time of about 12 seconds The data shown opposite reflect fuel burned from brakes release to clearing the 35 ft obstacle
34
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
URBAN POLLUTION
140shy
~
P54
0 r
120shy
100-
L
[A
80shy6shy
60
40shy
0
20-
IIII
II
727-200 LOW WING LOADING STOL
BOEING MODEL 751
35 IG7 1004329f
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
ADVANCED TECHNOLOGY
To investigate the potential performance benefits possible through application of advanced composite structure technology an estimate of the structural weight savings possible was predicted and an air shycraft was sized to do the design mission The primary structural weight of the wing tails and fuse shylage was reduced one-eighth which reduced the gross weight approximately 7 percent
For subsonic speed requirements (M = 07 to 08) the Hamilton Standard Prop -Fan concept offers potential performance improvements and produces less noise than a comparable turbofan installation A Prop -Fan configuration was determined using Hamilton Standard performance data 7 The configurshyation has not been optimized for cruise altitude or Mach number and additional improvement may be possible
A Prop-Fan configuration was also defined using composite structure technology
7 Hamilton Standard Preliminary Prop-Fan Generalized Performance Weight and Noise Data Revision One August 28 1970
36
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
ADVANCED TECHNOLOGY
STRUCTURE WEIGHT
PROPULSION WEIGHT
SYSTEMS FIXED EQUIP AND USEFUL LOAD
OPERATING WEIGHT EMPTY
PAYLOAD
FUEL
MAX GROSS WEIGHT
TURBOFAN
CONVENTIONAL STRUCTURE
44000
9000
25000
78 000
26000
26500
130500
BYPASS 40
ADVANCED COMPOSITES
37500
8500
25000
71000
26000
25000
122000
PROP -
CONVENTIONAL STRUCTURE
43000
11500
25000
79500
26000
22500
128000
FAN
ADVANCED COMPOSITES
37000
11500
25000
72500
26000
21000
119500
tG710043-24
37
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
RIDE SMOOTHING SAS SYNTHESIS
The SAS synthesis consisted of three elements
o Ride quality criteria definition
o Ride smoothing SAS conceptual trades
o Performance benefits of the final configuration at three selected flight conditions
Results of the synthesis are shown on the following pages
38
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
RMOOTHING SAS SYNTHESIS
IG710043 26
39
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
MATHEMATICAL MODELS
Small perturbation linear rigid body equations of motion with six degrees of freedom were used in the airplane mathematical models
Three flight conditions were selected to provide a reasonable variation of conditions within the STOL flight envelope Wing loading was held constant at 46 lbft2 A cruise condition was selected since a significant portion of flight time is spent at this condition The most severe ride occurs at high speed descent where the airplane is sensitive to turbulence During landing approach with corresponding low dynamic pressure large control surface deflections are required to produce aerodynamic forces and moments sufficient for ride smoothing purposes
Random turbulence and discrete 1-cos gusts were used in the analyses to define surface rate and disshyplacement limit effects Random atmospheric turbulence was modeled with a Von Karman power spectral density function
Four aerodynamic control surfaces were considered full span trailing edge flap elevator spoiler and rudder The 30 percent chord elevator and 18 percent chord rear segment of the full span double slotted flap were used in the longitudinal SAS The 40 percent chord rudder was used in the lateral SAS
40
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
MATHEMATICAL MODELS
AIRPLANE EQUATIONS OF MOTION - LINEAR RIGID BODY SMALL PERTURBATION SIX DEGREES OF FREEDOM
WING
MACH NO VELOCITY LOADING FLIGHT CONDITIONS WEIGHT ALTITUDE
CRUISE 120000 LBS 30000 FT 75 283 KCAS 46 LBSFT 2
DESCENT 120000 LBS 15000 FT 75 370 KCAS 46 LBSFT 2
LANDING 120000 LBS 50 FT 12 79 KCAS 46 LBSFT 2
APPROACH
ATMOSPHERIC RANDOM TURBULENCE - VON KARMAN POWER SPECTRAL DENSITY FUNCTION
ATMOSPHERIC DISCRETE TURBULENCE - Vg = 30 (1 - COS wt) Otlt Z9 -w CONTROL SURFACES AVAILABLE - REAR SEGMENT OF FULL SPAN DOUBLE
SLOTTED FLAPS - ELEVATOR
- RUDDER
- SPOILERS
IG710043-22
41
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
TURBULENCE LEVEL CRITERIA
The probability of exceeding a specified RMS Twst velocity varies as a function of altitude as shown by these constant exceedance probability curves 19 An exceedance probability level of 10- 3 was selected for this study Corresponding RMS gust velocities for the selected cruise descent and landing approach conditions are 56 82 and 98 ftsec respectively
8 NACA TN-4332 An Approach to the Problem of Estimating Severe and Repeated Gust Loads for Missile Operations September 1958
9 ASD-TR-61-235 Optimum Fatigue Spectra April 1962
42
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
TURBULENCE LEVEL CRITERIA
P - EXCEEDANCE PROBABILITY REFERENCES - NACA TN 4332
- ASD - TR-61-235
TURBULENCE llSTUDY
LEVEL USED
60- P = 10- 4
C
40
=00 -
p - CRUISE
20 DESCENT
LANDING APPROACH
0 4 8
RMS GUST VELOCITY
43
12
- FTSEC
16
(TRUE)
20
IG710043-27
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
Criteria for determining STOL aircraft ride qualities were based on passenger compartment vertical and lateral linear accelerations Based on results of SST ride quality moving base simulator tests 1 0
11 and a review of Boeing 727 and 720B commercial transport acceleration levels 10 acceptable accelshyeration criteria for a 1o-3 exceedance probability turbulence were set at 011 gs vertically and 0055 gs laterally The lateral acceleration criterion was set at one-half the vertical criterion since the SST tests indicated that at rigid body frequencies humans are approximately twice as sensitive to lateral oscillations as vertical oscillations 10
In general the selected criteria are conservative and are less than acceleration levels of current commercial aircraft at comparable flight conditions and turbulence levels
This chart illustrates the severity of the passenger ride problem at the high-speed descent condition The aft passenger compartment requires vertical and lateral acceleration reductions of 65 and 47 percent respectively to meet the selected criteria
10 Boeing Document D3-7600-7 Supersonic Transport Passenger Ride Quality Criteria Analysis Development and Validation Testing Results February 1969
11 Boeing Document D6-2575 Vol I Development of a Power Spectral Gust Design Procedure for Civil Aircraft - Final Report March 1965
44
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PASSENGER RIDE QUALITY CRITERIA AND PROBLEM
LOW WEIGHT HIGH SPEED DESCENT CONDITION
RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL to U2
1 30 z A2PLA--
a 15shyz
H STOL AIRPLANEWITHOUT SAS
- 0 WITHOT SASSTOL
65 REDUCTION AIRPLANE
4 20 10 WITHOUT SAS 0 O47 REDUCTION
4 CRITERIA
m p CRITERIA
REQUIRED _
0 - ------- 05
0-FWD MID AFT
0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
iG710043-11
45
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
The final longitudinal stability augmentation system (SAS) developed during the synthesis consists of two feedback loops c g vertical acceleration driving the aft segment of the full span trailing edge flap and pitch angular rate driving the elevator The acceleration feedback provides ride smoothing and the pitch rate feedback provides satisfactory handling qualities A high-pass filter in the acceler shyation feedback improves phugoid mode stability and a low -pass filter in the elevator feedback provides proper phasing for handling qualities
Although no attempt was made during this initial study to define gain scheduling requirements it may be necessary to schedule gains as a function of flight condition
46
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
LONGITUDINAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
K 25 50 10 K6 262 435 14
WGUST (FTSEC)
+ 30 (DEGSEC) 5 ELEVATOR ++30 (DEG) -bE
COMMAND ACTUATOR AIRPLANE
3_ZcFTSEC DYNAMICS 2)
[amp ]-30 (DEG) _ __
ACTUATOR
K S
K 2
IG710043-2
47
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
LATERAL STABILITY AUGMENTATION SYSTEM
During cruise and descent the synthesized lateral stability augmentation system uses aft body lateral acceleration and yaw rate feedback signals driving the rudder to provide ride smoothing and satisfactshyory handling qualities At landing approach lateral acceleration feedback produces excessive spiral mode divergence and is therefore not used at this condition A high-pass filter in the acceleration loop minimizes this effect at cruise and descent conditions In the yaw rate loop a high-pass filter washes out steady state signals providing satisfactory coordination during turns
Although gain scheduling will probably be required no attempt was made to establish gain scheduling requirements because of the limited scope of the study
48
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
I
LATERAL STABILITY AUGMENTATION SYSTEM
CRUISE DESCENT APPROACH
Kp 2 2 0 K 435 435 192 VGUST (FTSEC)
(DEGSEC)
6RUDDER + 30 6R AIRPLANE
COMMAND (DEG) DYNACS AFT (FTSEC) ACTUATOR
+~ 25)
IG710043-3
49
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PASSENGER RIDE QUALITY DURING CRUISE
Passenger compartment vertical and lateral accelerations at the three selected flight conditions (cruise descent and landing approach) are illustrated in the following three charts Acceleration levels are for RMS gust velocities corresponding to an exceedance probability of 10- 3
At the cruise conditionairplane without SAS vertical acceleration fails to meet the criteria although the lateral acceleration criteria is met at all passenger compartment locations
With the ride smoothing SAS vertical and lateral acceleration criteria are met RMS vertical accelshyerations are approximately 006 g s and RMS lateral accelerations range from 001 to 003 g s
50
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PASSENGER RIDE QUALITY DURING CRUISE
RMS GUST VELOCITY
VERTICAL
bnD 31
2
2-
BN 1- - -
CRITERIA
01
oS
AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
02
FWD MID AFT r
PASSENGER COMPARTMENT LOCATION
51
= 57 FTSEC
LATERAL
15shy
10shy
CRITERIA 05
AIRPLANE WITHOUTSS AIRPLANE
WITH SAS
FWD MID AFT
PASSENGER COMPARTMENT LOCATION
IG710043-10
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PASSENGER RIDE QUALITY DURING DESCENT
The high speed descent condition (370 KCAS at 15000 feet) was selected for analysis because of the severity of the ride at this condition With a gust velocity of 82 feet per second the airplane withshyout SAS has a cg RMS vertical acceleration of 028 gs and an aft body RMS lateral acceleration of 011 gs
With the ride smoothing SAS vertical and lateral accelerations meet the criteria at all passenger comshypartment locations
52
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PASSENGER RIDE QUALITY DURING DESCENT
9 RMS GUST VELOCITY = 82 FTSEC
VERTICAL LATERAL
r= AIRPLANE WITHOUT SAS D
St 15shyz z
FAIRPLANE WITHOUT SAS
2- 10shyr)
CRITERIA CRITERIA
[ RITERIAWITH SAS i AIRPLANE1 AIRPLANE 005WITH SAS
o-440 -l 0 0 4 FWD MID AFT 0 FWD MID AFT
PASSENGER COMPARTMENT PASSENGER COMPARTMENT LOCATION LOCATION
[G710043-12
53
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PASSENGER RIDE QUALITY DURING LANDING APPROACH
At the landing approach condition the airplane without SAS aft passenger compartment has a RMS vertical acceleration of 022 gs and a RMS lateral acceleration of 0 067 gs With the ride smoothing SAS vertical and lateral accelerations are reduced to levels that meet the criteria
54
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PASSENGER RIDE QUALITY DURING LANDING APPROACH
RMS GUST VELOCITY= 98 FTSEC
VERTICAL LATERAL
ul
I 3- 15 z zo0
AIRPLANE WITHOUT SASS
2- q 10
AIRPLANE
CRITERIA 0 CRITERIA WITHOUT SA
RPLANAIRPLANE z05-WITH SAS WITH SAS
04 N 0- 4 4
FWD MID AFT FWD MID AFT PASSENGER COMPARTMENT PASSENGER COMPARTMENT
LOCATION LOCATION IG7100435
55
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
This chart illustrates vertical and lateral acceleration time histories at the descent -condition with and without the ride smoothing SAS in random vertical and lateral turbulence At the descent condition the SAS reduces RMS vertical acceleration levels 72 percent and RMS lateral acceleration levels 60 percent
56
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
--
AFT PASSENGER ACCELERATION RESPONSE TO RANDOM TURBULENCE DURING DESCENT
o RMS GUST VELOCITY = 82 FTSEC
VERTICAL AIRPLANE WITHOUT SAS
gs 0-- _shy
4 - l ~ - -- - - I 1 1 1i L U C l r shy
- -
AIRPLANE WITH SAS gs 0-
-4 _Ii l I -II l l--- -I L- -Ei FT~--- - =-f- ~ ~ - I -L---l-
LATER4-------- -------------z-------------LATERAL AIRPLANE WITHOUT SAS - t------- --- --- -shy
2-- Sshy- 4----------------------- =shy
2- AIRPLANE WITH SAS
gs 0shy- n I I I1 -- l-l --- - f II KL- -Il- I1 -71- I I
SEC G71004342
57
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
AIRPLANE ANGULAR RATES
Although the ride smoothing system was not designed to reduce airplane angular rates it significantly reduces roll pitch and yaw angular rates at the three flight conditions investigated
58
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
--
AIRPLANE ANGULAR RATES
APPROACHU 25- AIRPLANE WITHOUT SAS
20- AIRPLANE WITH SAS
S15shy
z 10shy
5 CRUISE DESCENTF-LM _q [---I I -1
C 25- c 25- APPROACH APPROACH
20- 20shy
1515-
AC4R0 SDESCENT I 10 01 I
h l cP 0 5 CRUISEiH -Hi_0 _ 05 DESCENT
0- 170 l I IG710043-13
59
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
EFFECTS OF FLAP DOWNWASH TIME DELAY
To determine dynamic effects of flap downwash on the horizontal tail a downwash time delay was included in the analysis using a second-order Pads time delay approximation Effects were small at all flight conditions At the descent condition the time delay increases RMS vertical acceleration approximately 05 percent and RMS pitch rate 75 percent The downwash time delay also has a slight destabilizing effect on the short period and phygoid modes
60
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
EFFECTS OF FLAP DOWNWASH TIME DELAY
o DESCENT CONDITION
U09 AIRPLANE WITH SAS 09 -FLAP DOWNWASH TIME
DELAY = 0shy---FLAP DOWNWASH TIME
L 5 DELAY = 042 SEC
08
FWD MID AFT PASSENGER COMPARTMENT 6 SHORT PERIOD
20- 0 4- Ppi
PHUGOID 0 ii i im
I- I - I I
Pi
pI I I I I
61
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
HANDLING QUALITIES
Longitudinal handling qualities were evaluated at the three flight conditions using airplane pitch rate response criteria contained in SST design requirements 12 This chart illustrates typical longitudinal responses at the cruise and descent conditions At all three conditions the airplane without SAS meets the criteria Adding acceleration feedback for ride smoothing degraded airplane response Therefore pitch rate feedback was required for satisfactory longitudinal handling qualities
Lateral handling qualities were evaluated based on rigid body characteristic root requirements conshytained in M[L-F-8785B(ASG) dated 7 August 1969 All lateral criteria are met except for spiral mode time -to-double -amplitude at the landing approach condition The spiral mode time -to -double -amplitude at this condition is 82 seconds compared to a requirement of 20 seconds or greater Future studies should consider the feasibility of using roll feedback to eliminate this handling qualities deficiency
12 Boeing Document D6-6800-5 Stability and Control Flight Control Hydraulic Systems and Related Criteria
62
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
HANDLING QUALITIES
LONGITUDINAL LATERAL
- AIRPLANE WITHOUT SAS
AIRPLANE WITH SAS
CRITERIA (MIL-F-8785B)
30-
-CRUISE-
DESCENT
DUTCH ROLL MODE
FLIGHT CONDITION DAMPING DAMPING
RATIO FACTOR I4 tN
CRUISE 10 gt35
DESCENT gt19 gt35
ROLL MODE
CONSTANT (SEC)
lt14
lt14
SPIRAL MODE TIME TO
OIMEDUBLE AMPL (SEC)
gt20
gt20
- ltDESCENT APPROACH gt08 gt20 lt10 gt20
10-
0
0 1 2 3 4 TIME
5 - SEC
6 7 8 9
63
AIRPLANE WITH SAS SATISFIES LATERAL HANDLING QUALITY CRITERIA EXCEPT DURING APPROACH THE SPIRAL MODE TIME TO DOUBLE = 82 SEC
1G710043-8
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
Three-sigma control surface deflection and rate requirements for a 10- 3 exceedance probability turbulence level were determined for the three conditions The approach condition requires maximum control surface deflection and rates At this condition a flap deflection of plusmn9 degrees a rudder deflectshyion of plusmn8 degrees and a flap rate of 100 degreessecond are required
These requirements are based on an actuator bandpass of 30 radianssecond As shown on the next chart lowering the actuator bandpass reduces the rate requirement Follow-on studies should consider trades of control surface deflection and rate requirements versus actuator bandpass to obtain maximum acceleration reductions with minimum control system complexity
64
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
9
SAS CONTROL SURFACE DEFLECTION AND RATE REQUIREMENTS
SURFACE DEFLECTION SURFACE RATE
8 120
rzl7 -i pq
6 N 90M
OrO
PN r7
3-3 Nu2 F
0 2 N- i4 5 m P4
RUDDER FLAP ELEVATOR RUDDER FLAP ELEVATOR
IG710043-7
65
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
EFFECTS OF FLAP ACTUATION BANDPASS
Effects of flap actuator bandpass on midpassenger vertical acceleration and flap rate requirements were evaluated at the high speed descent condition Based on this rigid body analysis an actuator bandpass of 10 radianssecond and a corresponding maximum flap actuator rate of 45 degreessecond provide satisfactory vertical acceleration reductions
Further studies should consider trades of actuator bandpass and corresponding rates to minimize hydraulic power requirements and control system actuation complexity
66
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
EFFECT OF FLAP ACTUATION BANDPASS
DESCENT CONDITION
RMS GUST VELOCITY = 82 FT SEC
b 15 90shy
i L)
0 1I0 Q 60shy
rA 05- Pq 30
gt 0-0
0 10 20 3b 0 10 20 3b
ACTUATOR BANDPASS - RAD SEC ACTUATOR BANDPASS - RAD SEC IG710043-28
67
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PASSENGER ACCELERATION RESPONSE TO I-COS GUST
Effects of flap displacement and flap rate limits on acceleration reductions were determined at the descent condition for a 1-cos discrete gust with a peak velocity of 60 feetsecond Frequency of the gust was adjusted to provide maximum acceleration (28 gs) without the SAS
With SAS the peak acceleration is reduced to less than one g with flap displacements of plusmn10 degrees and flap rates of plusmn30 degreessecond
68
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
PASSENGER ACCELERATION RESPONSE TO 1-COS GUST
o DESCENT CONDITION 25- AIRPLANE WITHOUT SAS e Wg = 30 (1-COS 7t)
a CG PASSENGER LOCATION
FLAP LIMIT a GUST FREQUENCY SELECTED20- FOR MAXIMUM AIRPLANE4 WITHOUT SAS POSITIVE plusmn-- ACLRTOl H 8 0AIRPLANE WITH SASrn ~~~ ACCELERATION
bD 15-5-AIRPLANE WITHOUT SAS
AIA 3 FLAP RATE 10- LIMITlet 2 plusmn lo 0SEC r - degdego~o AIRPLANE
r 5- [ -~30 degSEC o
2 ---- 30 SECWITH SAS0o 3- o 3T-
C)
-25- v gtshyIG710043-35
69
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
POTENTIAL PROBLEM AREAS
This study shows the feasibility of significantly reducing vertical and lateral accelerations of a low-wingshyloading STOL airplane However the study was based on a linear analysis using a rigid body airplane mathematical model with an ideal single channel flap mechanization Several areas not considered within this limited study could present potential problems
Structural flexibility may make it difficult to reduce the accelerations to the extent indicated with a rigid body model Adequate structural mode stability may limit system ride smoothing performance
Control system nonlinearities during severe turbulence can cause excessive structural loading and reduced stability Based on nonlinear analyses design criteria must be defined to prevent this possibility
This study assumed that the flap rear segment can be driven in retracted and extended positions Potential problems associated with mechanizing a high response aft segment full -span double -slotted flap should be considered Related areas for study include redundancy hydraulic power and flap segment requirements
Although the primary objective of the SAS is to provide ride smoothing handling qualities and manshyeuvering requirements must be satisfied within the airplane operational flight envelope Compatibility of these two functions must be thoroughly analyzed
70
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
POTENTIAL PROBLEM AREAS
STRUCTURAL FLEXIBILITY EFFECTS
CONTROL SYSTEM NONLINEAR CHARACTERISTICS IN
SEVERE TURBULENCE
FLAP ACTUATION SYSTEM MECHANICAL DESIGN
RIDE SMOOTHINGHANDLING QUALITIES COMPATIBILITY
IG710043-19
71
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
SUMMARY
Conclusions of this limited study indicate that a low-wing-loading STOL aircraft with ride smoothing stability augmentation provides satisfactory ride qualities and competitive high speed performance
Further studies should be conducted to analyze potential problem areas in depth and to obtain additional confidence in the concept
72
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
SUMMARY
RESULTS OF THIS LIMITED STUDY INDICATE THAT A
LOW-WING-LOADING STOL AIRCRAFT WITH RIDE
SMOOTHING SAS PROVIDES
- SATISFACTORY RIDE QUALITIES
- COMPETITIVE HIGH SPEED PERFORMANCE
FURTHER STUDIES SHOULD BE CONDUCTED
POTENTIAL PROBLEM AREAS IN DEPTH
TO ANALYZE
IG710043-20
73
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
BIBLIOGRAPHY
Donely Philip and Shufflebarger CC Tests of a Gust-Alleviating Flap in the Gust Tunnel NACA TN 745 dated 1940
Shufflebarger CC Tests of a Gust-Alleviating Wing in the Gust Tunnel NACA TN802 dated 1941
The Effects of Variation of Time Intervals Between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 49-62
A Second Approach to the Problem of the Effects of Variation of Time Intervals between Accelerations Upon Sickness Rates Jour Psychology Vol 19 dated January 1945 pp 63-68
The Effects of Various Accelerations Upon Sickness Rates Jour Psychology Vol 20 dated July 1945 pp 3-8
The Effects of Waves Containing Two Acceleration Levels Upon Sickness Jour Psychology Vol 20 dated 1945 pp 9-18
McFarland Ross A Human Factors in Air Transport Design McGraw-Hill Book Co Inc dated 1946 pp 367-377
Russell AE Some Engineering Problems of Large Aircraft Jour RAS Vol 51 No 434 dated February 1947 pp 145-170o
Mickleboro Harry C Evaluation of a Fixed Spoiler as a Gust Alleviator NACA TN 1753 dated 1948
Dynamic Analysis of a Gust Load Alleviation System for the C-47 Airplane Rep No SM-13699 Douglas Aircraft Co Inc dated 18 January 1950
Phillips William H and Kraft Christopher C Jr Theoretical Study of Some Methods for Increasshy
ing the Smoothness of Flight Through Rough Air NACA TN 2416 dated 1951
74
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
Boeing Document D6-24431-9 Boeing Model 751 CSTOL Passenger Compartment Baggage and Freight dated 6 October 1969
Boeing Document D3 -7853 Simulated Gas Turbine Engine Performance Modular Computer Program
(SEP) dated 16 April 1970
Boeing Document D6-23827 Aircraft Noise Time History Prediction Program dated 4 March 1969
Federal Aviation Regulations Volume III Part 36 Noise Standards Aircraft Type Certification dated December 1969
AFFDL-TR-158 Aircraft Load Alleviation and Mode Stabilization (LAMS)
AFFDL-TR-161 Aircraft Load Alleviation and Mode Stabilization (LAMS) B-52 System Analysis Synthesis and Design
AFFDL-TR-162 Aircraft Load Alleviation and Mode Stabilization (LAMS) C-5A System Analysis and Synthesis
AFFDL-TR-163 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Activities
AFFDL-TR-164 Aircraft Load Alleviation and Mode Stabilization (LAMS) Flight Demonstration Test Analysis
Boeing Document D3 -6434-4 Critical Analysis of B-52 Stability Augmentation and Flight Control Systems and Improved Structural Life Part I (Analysis and Synthesis of Advanced Stability Augmenshytation Systems)
Boeing Document D3 -6950 Stability Augmentation System Analysis ECP 1195 Prototype
Boeing Document D3 -7600-5 SST Longitudinal SAS Conceptual Study Results
75
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
Kraft Christopher C Jr and Assadourian Arthur Experimental Study of an Angle -of -Attack Vane Mounted Ahead of the Nose of an Airplane for Use as a Sensing Device for an Acceleration Alleviator NACA TN 2415 dated 1951
Chalk Charles Flight Test of an Autopilot Installation as a Lateral Gust Alleviator in a PT-26 Airplane WADC Tech Rep 55-269 US Air Force dated March 1956
Boucher Robert W and Kraft Christopher C Jr Analysis of a Vane-Controlled Gust-Alleviation System NACA TN 3597 dated 1956
Kraft Christopher C Jr Initial Results of a Flight Investigation of a Gust-Alleviation System NACA TN 3612 dated 1956
Cooney RV and Schott Russell L Initial Results of a Flight Investigation of the Wing and Tail Loads of an Airplane Equipped with a Vane -Controlled Gust-Alleviation System NACA TN 3746 dated 1956
Zbrozek J0 Smith KW and White D Preliminary Report on a Gust Alleviator Investigation of a Lancaster Aircraft R amp M No 2972 British ARC dated 1957
Technical Report 550-003-03H Report No FAA-NO-69-1 Conference on STOL Transport Aircraft Noise Certification DOT FAA Office of Noise Abatement Washington DC dated 30 January 1969
Boeing Document D3 -7949 Users Manual for ASAMP Aircraft Sizing and Mission Performance
Program
USAF Stability and Control Handbook (DATCOM) Douglas Aircraft Company dated 1969
ATN 70-001 Direct Operating Cost WATFOR Program dated 26 February 1970
Boeing Document D6 -3727-363 Boeing 727 Model 727-251 Northwest Airlines Operations Manual
76
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77
Boeing Document D3-7600-6 SST Lateral SAS Conceptual Study Results
Boeing Document D3-7600-10 ISST Longitudinal LAMS SAS Conceptual Study Results
Boeing Document D3-7600-11 SST Lateral SAS Conceptual Study Results
77