etl_09_1-airfield planning and design

7/25/2019 ETL_09_1-Airfield Planning and Design

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DEPARTMENT OF THE AIR FORCEHEADQUARTERS AIR FORCE CIVIL ENGINEER SUPPORT AGENCY

28 SEP 2009

APPROVED FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED

FROM: AFCESA/CEO139 Barnes Drive, Suite 1

Tyndall AFB, FL 32403-5319

SUBJECT: Engineering Technical Letter (ETL) 09-1: Airfield Planning and DesignCriteria for Unmanned Aircraft Systems (UAS)

1. Purpose. This ETL provides guidance and criteria for planning and designingairfields that support operations of Department of Defense (DOD) UAS presently fieldedor will be fielded by 2012.

2. Application: All DOD organizations responsible for planning and design of airfieldpavements.

2.1. Authority: Air Force policy directive (AFPD) 32-10, Air Force Installations andFacilities.

2.2.Coordination:

Major command (MAJCOM) pavement engineers

HQ Air Force Center for Engineering and the Environment (AFCEE/TD)

HQ Air Force Flight Standards Agency (AFSSA/A3A, AFSSA/A3I)

HQ Air Combat Command (ACC/A3YU, ACC/A8U1)

UAS system program offices (SPO) and program executive offices (PEO)

2.3. Effective Date: Immediately. This ETL will remain in effect until these findingsare incorporated into joint-Service pavement doctrine and similar technical guidance.

2.4. Intended Users:

Air Force Prime BEEF and RED HORSE units.

Army Corps of Engineers.

Navy NAVFAC offices and Seabee units, and Marine Corps combat engineerunits.

Construction contractors building and expanding DOD airfields.

Other organizations responsible for airfield construction.

3.References.

3.1.Air Force:

Technical Manual 1Q-4(R)A-2-DB-1, 22 April 2008, Version 07.12.001,RAC#7, Global Hawk Technical Orders, 303d AESG/LG, WPAFB, OH 45433,DSN 785-3473.


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Flight Manual TO 1Q-1(M)B-1, MQ-1B and RQ-1B Systems, 1 November2003, Change 8, 22 January 2007, Det 3, 658 AESS, 16761 Via Del CampoCourt, San Diego, CA 92127.

Flight Manual TO 1Q-9(M)A-1, USAF Series MQ-9A Aircraft, 20 February2007, Change 1 30 April 2007, Det 3, 658 AESS, 16761 Via Del Campo

Court, San Diego, CA 92127. Engineering Technical Letter (ETL) 08-6, Design of Surface Drainage

Facilities, 5 February 2008, HQ AFCESA, Tyndall AFB, FL 32403,http://www.wbdg.org/ccb/browse_cat.php?o=33&c=125

3.2. Navy:

A1-MQ8BA-NFM-000, NATOPS Flight Manual, Navy Model MQ-8B,Unmanned Aerial Vehicle, Program Executive Office - Unmanned Aviation &Strike Weapons, PEO (U&W) PMA-266, Multi-Mission Tactical Unmanned AirSystems, 22707 Cedar Point Road, Building 3261, Patuxent River, Maryland20670-1547.

3.3.Army:

Engineering and Construction Bulletin (ECB) 2008-15, Design of SurfaceDrainage Facilities, 22 April 2008, Directorate of Civil Works, WashingtonD.C., http://www.wbdg.org/ccb/browse_cat.php?o=31&c=214

Technical Manual (TM) 9-5895-XXX-10, Operators Manual for Shadow 200TUAV System with RQ-7B Air Vehicle, 27 August 2004, US Army Aviationand Missile Command, ATTN: Unmanned Aerial Vehicle System, ATTN:SFAE-AV-UAV, Redstone Arsenal, AL 35898.

Unified Facilities Criteria (UFC) 3-230-06A, Subsurface Drainage, 16 January2004, http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4

3.4. Joint:

Pavement-Transportation Computer Aided Structural Engineering (PCASE)design and evaluation computer program, http://www.pcase.com/

UFC 3-260-01,Airfield and Heliport Planning and Design,http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4

UFC 3-260-02, Pavement Design for Airfields,http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4

4. Acronyms.

ACN Aircraft Classification NumberASC/658 AESG Aeronautical Systems Center, 658 Aeronautical Systems GroupC CelsiusCBR California Bearing RatioDOD Department of DefenseETL Engineering Technical LetterF Fahrenheitft feet


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GCS ground control stationGDT ground data terminalin inchesk modulus of subgrade reactionlbs pounds

NAVFAC Naval Facilities Engineering CommandPCASE Pavement-Transportation Computer Aided Structural Design andEvaluation

pci pound per cubic inchPCN Pavement Classification NumberPGCS portable ground control stationPGDT portable ground data terminalPrime BEEF Priority Improved Management Effort - Base Engineer EmergencyForcepsi pound per square inchpsig pound per square inch gauge

RCR Runway Condition RatingRED HORSE Rapid Engineers Deployable Heavy Operations Repair SquadronEngineers

TALS Tactical Automated Landing SystemTDP touchdown pointUAS unmanned aircraft systemsUPS uninterruptible power supply

5. Defini tions.

5.1. Pass. The movement of an aircraft over a specific spot or location on apavement feature.

5.2.Sun Screen. A cover to protect aircraft from the suns ultraviolet rays.

6. Aircraft Characteristics. Table 1 lists aircraft covered in this ETL. Tables 2 through7 list each aircrafts dimension, weight, and operational characteristics.

Table 1. Aircraft by Service

Service Aircraft

Air Force

RQ-4A/B Global Hawk

MQ-9A ReaperRQ-1B/MQ-1B Predator

ArmyRQ-7B Shadow 200

MQ-1C ERMP Warrior

Navy/Marine CorpsMQ-8B Fire Scout

RQ-4B Global Hawk


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Table 2. RQ-4 Global Hawk(See Figures 1 through 4)

RQ-4A RQ-4B

Wing Span (ft) 116.2 130.9

Length (ft) 44.4 47.6

Height (ft) 15.2 15.4

Vertical Clearance (in) 19.5 20.65

Tread (ft) 10.6 21.1

Wheel Base (ft) 14.8 15.4

Pivot Point (ft) 75 31.24

Aircraft Turning Radius (ft) 67 20.7Controlling Gear Main Main

180 Turn (ft) 133 97

Basic Empty Gross Weight (lbs) 11,900 15,317

Basic Mission Take-Off Weight (lbs) 26,750 32,190

Basic Mission Landing Weight (lbs) 12,900 16,325

Max Landing Gross Weight (lbs) 26,500 32,250

Take-Off Distance, Ground Roll (ft) 3,500 4,800

Take-Off Distance, to 50-ft (ft) 4,300 5,800

Landing Distance, Ground Roll (ft) 8,000 7,800

Landing Distance, from 50-ft (ft) See Note See Note

Assembly Configuration Twin Tricycle Single Tricycle

% of Gross Load on Assembly 88.5% on Main 89.5% on Main

Tire Pressure, Nose Gear (at Max T/O weight) 88-98 psig 109-119 psig

Tire Pressure, Main Gear (at Max T/O weight) 201-206 psig 289-299 psig

Note: Not applicable since block 10 (RQ-4A) typically flares between 45 ft (AboveGround Level [AGL]) to 55 ft (AGL) over the runway. The flare initiation altitude is afunction of sink rate. Mission planners build landing approach for a 4.5 degree glideslope (with engine on) and 5.25 degree (engine out). They survey the area for terrainand obstacle clearance required to safely fly on the glide slope autonomously.


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Table 3. MQ-9A Reaper(See Figure 5)

Wing Span (ft) 66

Length (ft) 36.2

Height (ft) 11.8

Vertical Clearance (in) 20

Tread (ft) 12

Wheel Base (ft) 10.2

Pivot Point (ft) 32 to inside wing tip

Aircraft Turning Radius (ft) 98 to outside wing tip;71 to outside wheel

Controlling Gear Main180 Turn (ft) 196

Basic Empty Gross Weight (lbs) 4,900

Basic Mission Take-Off Weight (lbs) 10,500

Basic Mission Landing Weight (lbs) 8,500

Max Landing Gross Weight (lbs) 10,500

Take-Off Distance, Ground Roll (ft) 3,450

Take-Off Distance, to 50-ft (ft) 3,600

Landing Distance, Ground Roll (ft) 4,375

Landing Distance, from 50-ft (ft) 5,000

Assembly Configuration Single Tricycle

% of Gross Load on Assembly 90% on Main (assumed)

Tire Pressure, Nose Gear (at Max T/O weight) 80 psig

Tire Pressure, Main Gear (at Max T/O weight) 170 psig


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Table 4. RQ-1B/MQ-1B Predator(See Figures 6 and 7)

Wing Span (ft) 48.7(MQ-1B Block 10 &15 is 55.25)

Length (ft) 27.0

Height (ft) 6.9

Vertical Clearance (in) 5.3

Tread (ft) 9.1

Wheel Base (ft) 10.2

Pivot Point (ft) TBD

Aircraft Turning Radius (ft) TBD

Controlling Gear Main180 Turn (ft) 196

Basic Empty Gross Weight (lbs) 1,680(1,760 with Ice Protect System)


Basic Mission Landing Weight (lbs) TBD

Max Landing Gross Weight (lbs) TBD

Take-Off Distance, Ground Roll (ft) 1,800

Take-Off Distance, to 50-ft (ft) 2,500Landing Distance, Ground Roll (ft) 1,150







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Table 5. MQ-1C ERMP Warrior

Wing Span (ft) 56.3

Length (ft) 27.5(29 with Alpha Probe attached)

Height (ft) 9.9 - Level(10.32 - for uneven surfaces,allow for an additional 5 inches)

Vertical Clearance (in) TBD

Tread (in) TBD

Wheel Base (in) TBD


Aircraft Turning Radius (ft) 97.5

Controlling Gear Main

180 Turn (ft) TBD

Basic Empty Gross Weight (lbs) TBD



Max Landing Gross Weight (lbs) 3,200

Take-Off Distance, Ground Roll (ft) TBD

Take-Off Distance, to 50-ft (ft) TBDLanding Distance, Ground Roll (ft) TBD







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Table 6. RQ-7B Shadow 200

Wing Span (ft) 14

Length (ft) 11.33

Height (ft) 3.2Vertical Clearance (in) TBD

Tread (in) TBD

Wheel Base (in) TBD


Aircraft Turning Radius (ft) TBD

Controlling Gear Main

180 Turn (ft) TBD

Basic Empty Gross Weight (lbs) 252 to 257

Basic Mission Take-Off Weight (lbs) 370 to 375


Max Landing Gross Weight (lbs) TBD

Take-Off Distance, Ground Roll (ft) TBD

Take-Off Distance, to 50-ft (ft) TBD

Landing Distance, Ground Roll (ft) TBD

Landing Distance, from 50-ft (ft) TBDAssembly Configuration Single Tricycle


Tire Pressure, Nose Gear (at Max T/O weight) TBD

Tire Pressure, Main Gear (at Max T/O weight) 35+1 psig


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Table 7. MQ-8B Fire Scout(See Figure 8)

Max Length (Main rotor Spread, tail rotor vertical) (ft) 31.67

Length (nose to tail, main rotor folded over tail, tail rotorvertical) (ft)

23.25

Length (nose to tail rotor horizontal)(ft) 24.73

Width (outer diameter of skid tubes) (ft) 6.2

Height of main rotor blades (ground to flat rotor disc) (ft) 8.92

Height of vertical stabilizer antenna (ft) 9.75

Main rotor diameter (ft) 27.71

Tail rotor diameter (ft) 4.25

Ground clearance (fuselage, Water Line to ground) (in) 21Ground clearance (tail skid) (ft) 3.25

Turning Radius in tow (ft) 20

Maximum gross take-off weight (lbs) 3,150

Maximum towing weight (lbs) 3,150

Basic Empty Gross Weight (lbs) 2,029

Assembly Configuration Skid tubes

5.2. Aircraft Classification Numbers. The International Civil Aviation Organization(ICAO) has developed and adopted a standardized method of reporting pavementstrength for conventional rigid and flexible pavements. The procedure is known asthe Aircraft Classification Number/Pavement Classification Number (ACN/PCN). The

ACN is a number that expresses the effect an aircraft will have on a pavement. ThePCN is a number that expresses the capability of a pavement to support aircraftoperations. The ICAO manual specifies that the bearing strength of a pavementintended for aircraft of mass greater than 5,700 kg (12,500 lbs) shall be madeavailable using the ACN/PCN method. Therefore, the Global Hawk is the only UASaircraft that will be included. Figures 9 and 10 are ACN relationships for the GlobalHawk on flexible and rigid pavements respectively.


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Figure 1. RQ-4A Global Hawk Dimensions


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Figure 2. RQ-4A Clearances and Turning Radii*(Diameter)


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Figure 3. RQ-4B Dimensions


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Figure 4. RQ-4B Clearances and Turning Radii

*RADII

FEETMINIMUMTURNING WIDTH


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Figure 5. Dimensions of MQ-9A Reaper


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Figure 6. Dimensions of RQ-1 B Predator


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Figure 7. Dimensions of the MQ-1B Predator


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Figure 8. Dimensions of the MQ-8B Fire Scout


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Load (kips) A (> 13) B (>=8 - =4 -


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Load (kips) A (> 400) B (>=200 - =100 -


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6. Dimensional Criteria. This section presents design considerations for UAS airfields.These criteria are provided as a supplement to the criteria given in UFC 3-260-01,

Airfield and Heliport Planning and Design.

6.1. Runway and Overrun Descriptions.Criteria presented in UFC 3-260-01 will be

used. Only exceptions for UAS will be identified herein. The Global Hawk requires aClass B airfield as defined in UFC 3-260-01. The Reaper, Predator, and ERMPrequire a Class A airfield, with some noted exceptions due to support equipment thatmust be in close proximity to the airfield. Criteria for the Shadow 200 and the FireScout are included in this ETL.

6.1.1. Global Hawk. Takeoff distances are a function of the engine thrust, runwayslope, runway condition rating, takeoff gross weight, temperature and pressurealtitude and wind. Landing distances depend on brake rate, gross weight,temperature and pressure altitude, runway condition rating, runway slope,spoilers, and wind. Runway length requirements for the RQ-4A Global Hawk can

be calculated from the following figures. Figure 11 gives the density ratio as afunction of the temperature and pressure altitude at the runway site. Figures 12to 15 give the landing distance as a function of density ratio, wind, and runwayslope. Takeoff distances are shown in Figure 16 as a function of density ratio,wind, and runway slope. Performance data for the RQ-4B is being developed andnot available.

Example of calculation of runway length requirements for RQ-4A Global Hawk:

Given:

Pressure Altitude = 4,000 ft.Average high temperature for warmest month = 89 FGross Weight of Aircraft = 26,500 lbsWind= 0 knotsRunway Slope= 1% uphillBrake Rate= 8 ft/secRunway Condition Rating = 15 (wet)

From:

Figure 11 Density Ratio = 0.81Figure 13 Corrected landing distance - touchdown waypoint to stop =

9,400 ft.Figure 16 Corrected takeoff ground run = 5,000 ft.

Runway length requirement would be 10,000 ft. This could be shortened sincethe aircraft will not likely land at maximum weight.


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Runway width requirements are related to navigation quality, which is a rating ofsignal strength as determined by system site selection and communicationspersonnel. The theoretical runway width requirements for operations at variousnavigational quality values are shown in Table 8. For operations from a typical150-foot-wide runway, the minimum required navigation quality is 17. (Note: A

navigational quality of 17 is always considered the minimum for takeoffs,regardless of the actual runway width.) As the widest runway likely to beencountered is 300 feet, a minimum navigational quality of 15 would be requiredfor landings. When navigation quality values are degraded to less than requiredfor the available runway width, an alternate landing site, such as a dry lakebed orunoccupied auxiliary airfield, should be identified as a safe alternative.

Table 8. Theoretical Runway Width Requirements

Navigation QualityTheoretical Runway Width (ft)

Requirements

18 148

17 148

16 208

15 268

14 328

13 388

12 448

Another exception to the Class B runway requirements is the longitudinal slope.Runway slope limits apply to constant slope runways. The slope on downhillrunways could match or exceed the flare sink rate, causing excessive flaredistance and possible runway departure. The slope on uphill runways could limitflare distance, causing a hard landing. For takeoffs and landings, the maximumuphill slope is 1.0%. For landings, the maximum downhill slope limits vary withgross weight, ranging from 0.25% to 0.5% with decreasing gross weight, asindicated in Figures 12 thru 14.


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Figure 11. Density Ratio from Temperature and Pressure Altitude


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Figure 12. RQ-4 Landing Distance for 4 Ft/Sec Brake Rate


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Figure 15. RQ-4 Landing Distance for 12 Ft/Sec Brake Rate wi th Override Selected


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Figure 16. RQ-4 Takeoff Ground Run


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6.1.2. Reaper, Predator and ERMP. Runway and overrun requirements for theReaper and Predator will conform to those of an Air Force Class A runway andthe ERMP to those of an Army Class A runway as described in UFC 3-260-01.

6.1.2.1. Reaper. Takeoff and landing figures for the MQ-9A Reaper are

referenced to a Standard Day. A Standard Day is at a temperature of 59 F(15 C). Figures 17 and 18 give the takeoff ground roll and correction forrunway slope for a Standard Day. Figures 19 and 20 are for a takeoff groundroll for a Standard Day plus 30 F. Figures 21 and 22 give landing distancesand correction for runway slope for the MQ-9A.

Example of Runway Length calculation for MQ-9A Reaper:

Given:

Pressure Altitude = 4,000 ft.

Average high temperature for warmest month = 89 FGross Weight of Aircraft = 10,500 lbsWind= 0 knotsRunway Slope= 1% uphillRunway Condition Rating = 15 (wet)

From:

Figure 19 STD+30F (59F+30F=89F) Takeoff Ground Run= 5,600 ft.Figure 20 Ground Roll with slope= 6,250 ft.Figure 21 Landing Ground Roll = 4,950 ft.Figure 22 Corrected Landing Ground Roll for Slope = 4,000 ft.

Runway length requirement would be 6,500 ft.

6.1.2.2. Predator. Takeoff and Landing figures for the RQ-1B/MQ-1B Predatorare shown in Figures 23 to 26 with corrections for runway slope and RunwayCondition Rating (RCR).

Example of runway length requirement for MQ-1B Predator:

Given:

Pressure Altitude = 4,000 ft.Average high temperature for warmest month = 89 FGross Weight of Aircraft = 2,250 lbsWind= 0 knotsRunway Slope= 1% uphillRunway Condition Rating = 15 (wet)


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From:

Figure 11- Density Ratio = 0.81Figure 23 Takeoff Ground Run = 3,600 ft.Figure 24 Takeoff Ground Run with slope correction= 4,200 ft.

Figure 25 Landing Ground Roll = 1,360 ft.Figure 26 Landing Ground Roll with corrections for Slope and RCR= 1,600ft.

Runway Length requirement = 4,500 ft.

Note:For assistance with conditions other than those covered in Tables 17through 27, contact:

ASC/658 AESGArea B, Bldg 11

WPAFB, OH 45433(937) [email protected]

6.1.2.3. ERMP. Performance data for the ERMP has not been developed.Runway length and width requirements are 4,500 feet by 100 feet and shouldfollow the criteria for a Class A Army airfield.

6.1.3.Shadow 200. The launch and recovery site requires a clear, flat area, largeenough for the required landing touchdown dispersion and runway length andwidth. The overall site consists of a rectangular area at least 450 feet long and164 feet wide. In addition to the main rectangular area, an additional area oneither side of the operating strip called the net run-out area is required. Each netrun-out area is 100 feet long and 50 feet wide. This makes the operating surfacewith net run-out areas at least 650 feet long and 50 feet wide. The maximumlength of the rectangular area is 1080 feet and the maximum length of theoperating surface is 1280 feet (see Figures 27 and 28). The site should bealigned with the prevailing wind direction. Maximum permitted tail wind duringlanding is 5 knots. The overall site length includes at least 100 feet of rolloutspace beyond the barrier net. The rollout space shall be provided to permit airvehicle net arrestment without any obstacles or ruts larger than 2 inches in size.The minimum overall site length may be reduced to 650 feet if the grade (slope)along the runway centerline is near zero. The runway direction slope may notexceed 1.7% grade within the entire runway and rollout space. The slopeperpendicular to runway direction must also fall within the 1.7% grade. Typicallayouts for the long field and short field are shown in Figures 27 and 28. Inaddition to runway dimension and grade restrictions, obstacle /terrain clearancesmust also be observed. Figures 29 and 30 describe the required clearances. Allobstacle and terrain height restrictions are measured relative to the touchdownpoint (TDP) elevation.


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6.1.4. Fire Scout. The Fire Scout is designed to be launched from a ship or fromland. The Fire Scout can utilize any cleared area to launch and recover. Thelimited-use helipad (50 ft by 50 ft) described in UFC 3-260-01 is acceptable forthis aircraft. Line of site in any launch and recovery area to the UHF/VHF

antennas connected to the ground control station is mandatory. Performance andclearance requirements are being developed.

6.2.Clear Zones, Accident Potential Zones, and Imaginary Surfaces.The clearanceand grade requirements for runways that support the UAS outlined in this ETL shallfollow the requirements in UFC 3-260-01. For the Reaper and Predator, supportinfrastructure includes ground control stations (GCS), satellite communication links,ground data terminals (GDT), and associated equipment such as HVAC systemsand generators. The GDT provides a line-of-sight communication link from the GCSto the aircraft and may create sighting issues requiring the need to apply for apermissible deviation per Attachment 14 of UFC 3-260-01.


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Figure 17. MQ-9 Predator Takeoff Ground Roll for STD Day


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Figure 18. Corrections for Runway Slope for MQ-9 on STD


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Figure 19. Takeoff Ground Roll for MQ-9 on STD +30 F


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Figure 20. Runway Slope Corrections for MQ-9 on STD + 30F


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Figure 21. Landing Ground Roll for MQ-9.


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Figure 22. Runway Slope Corrections for MQ-9 Landing Ground Roll


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Figure 23. RQ-1B/MQ-1B Predator Takeoff Ground Run


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Figure 24. RQ-1B/MQ-1B Runway Slope Correction on Takeoff Ground Roll


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Figure 25. RQ-1B/MQ-1B Landing Ground Roll


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Figure 26. RQ-1B/MQ-1B Landing Ground Roll Corrections for Slope and RCR


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Figure 27. Shadow 200 Launch and Recovery Site (Long Field)

* The approach-direction distance from runway edge to TDP may be reduced from 160 ft to100 ft if the approach terrain is of an appropriate grade. This will reduce the overall length from710 ft to 650 ft and the runway length from 510 ft to 450 ft. See paragraph 6.1.3 for specificrequirements. There is no limitation on the maximum approach-direction distance from runwayedge to TDP.

Figure 28. Shadow 200 Launch and Recovery Site (Short Field)


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Figure 29. Shadow Lateral Obstacle Clearances

From Figure 30 in this Region


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Figure 30. Shadow Approach Obstacle Clearances

6.3. Taxiways and Aprons. The widths and turning radius of taxiways shouldconform to the Class B requirements for the Global Hawk and the Class Arequirements for the Reaper, Predator, and ERMP.

6.3.1. Global Hawk. Parking areas for the RQ-4A Global Hawk should bedesigned with dimensions shown in Figure 31. Layouts for the tie-downs for the

RQ-4A are shown in Figure 32. Parking areas for the RQ-4B Global Hawk shouldconform to dimensions shown in Figure 33. Locations for tie-downs on theRQ-4B are shown in Figure 34 but specific dimensions for the tie-down pointhave not been provided. Tie-downs should be designed to resist an uplift forceequal to the rated capacity of the tie down chain (i.e., typically 10,000 pounds).Special apron areas for hot refueling or arming/disarming are not required for theGlobal Hawk.

6.3.2.Reaper and Predator. These UAS are typically parked under sun screensduring daytime and in hangars at night and during severe weather, negating theneed for tie-downs. As discussed in paragraph 6.2, support infrastructure for

these systems must be sited in accordance with UFC 3-260-01.


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Figure 31. Parking Area Dimensions for RQ-4A Global Hawk


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Figure 32. Tie-Down Layout fo r the RQ-4A Global Hawk


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Figure 33. Parking Area Dimensions for RQ-4B Global Hawk


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Figure 34. Locations for Tie-Downs for RQ-4B Global Hawk


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7. Structural Design Criteria.

7.1. Procedures for the structural design of airfields to support the UAS arepresented in this section. These criteria are submitted as a supplement to that givenin UFC 3-260-02, Pavement Design for Airfields. The proliferation of UAS throughout

the DOD resulted in requiring the criteria to be updated to include these aircraft.

7.2. Procedures and requirements for site investigation; base, subbase, andsubgrade; frost design; and stabilization should follow those outlined in UFC 3-260-02. It is expected that the Global Hawk, Reaper, Predator, and ERMP will onlyoperate on surfaced pavements. Design curves for both flexible and rigid pavementsfor the Global Hawk are shown in Figures 35 and 36. Designs for all other aircraftshould follow the minimum thickness requirements for both rigid and flexiblepavements as outlined in UFC 3-260-02. The PCASE program is recommended fordetail design, but manual designs are as follows:

7.2.1. Flexible Pavement Example for Global Hawk:

Given:

Design Subgrade CBR 6 percentAircraft Load 32,250 poundsAircraft Pass Level 10,000 passes

Enter Figure 35 at 6 CBR. Go vertically to the aircraft load of 32,250 pounds.Go horizontally to 10,000 passes, then go vertically to read a 10.5-inch designthickness requirement.

From Table 8-5 of UFC 3-260-02, the minimum surface thickness is 4 inchesover a 100 CBR base course and 5 inches over an 80 CBR base course.

Design with a 100 CBR base course would be:

4 inches of asphalt surface course6.5 inches of 100 CBR base courseCompacted subgrade

Design with an 80 CBR base course would be:

5 inches of asphalt surface course6.0 inches of 80 CBR base course (Minimum base thickness controls.)Compacted subgrade


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Figure 35. Flexible Pavement Design Curve for the RQ4-B Global Hawk

7.2.2. Rigid Pavement Design Example.

Given:

Design Flexural Strength of PCC 640 psiDesign Modulus of Subgrade Reaction, k 25 pciDesign Aircraft Load 32,250 poundsDesign Pass Level 10,000 passesTraffic Area A

Enter Figure 36 at a flexural strength of 640 psi. Move horizontally to k valueof 25 pci. Move vertically to the aircraft load of 32,250 pounds. Movehorizontally to the pass level of 10,000. Move vertically to Traffic Area A, thenmove horizontally to read a required design thickness of 8.5 inches.

The design would be 8.5 inches of PCC over a minimum of 4 inches ofaggregate base course or that to meet minimum thickness for drainage layersas shown in UFC 3-230-06A, Subsurface Drainage.

RQ4-B GLOBAL HAWK (Traff ic Area A)

10000

Passe

s100

0Pass

es10

0Pass

es

32250lbs

25000lbs16000lbs

1

10

100

1 10 100

Thickness, in

1 10 100

CBR


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RQ4-B GLOBAL HAWK (Traffi c Area A)

10000 Passes

1000 Passes

100 Passes

322

50

lbs

2500

0lb

s

1600

0lb

s

500K

250K

100K

25K

Traffic Area A

400

500

600

700

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1200

1300

1400

0 5 10 15 20 25 30 35 40

FlexuralStrength,psi

0

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18

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Thickness,

In.

Figure 36. Rigid Pavement Design Curve for the RQ4-B Global Hawk

8. Point of Contact. Recommendations for improvements to this ETL are encouragedand should be furnished to the Pavements Engineer, HQ AFCESA/CEOA, 139 BarnesDrive, Suite 1, Tyndall AFB, FL 32408-5319, DSN 523-6439, Commercial (850) 283-

6439, [email protected].

LESLIE C. MARTIN, Colonel, USAF 1 AtchChief, Operations and Programs Support Division 1. Distribution List


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SPECIAL INTEREST ORGANIZATIONS

Information Handling Services (1) Construction Criteria Base (1)

15 Inverness Way East National Institute of Bldg SciencesEnglewood, CO 80150 Washington, DC 20005

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