basic flying principles & aerodynamics-new

5/20/2015

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Basic Flying Principles &

Aerodynamics

Content

Bernoullis Principle & Basic forces on aircraft

Control of aircraft

Speed measurement

Altitude measurement

Aircraft Instrument

Aircraft Engine

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Bernoullis Principle

Static Pressure + Dynamic Pressure = Constant

Increase in speed of fluid Decrease in static pressure

A

B


Weight gravitational force

Thrust generated by engine

Lift produced by wing

Drag induced drag + parasitic drag

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Weight

Aircraft own weight, fuel, passengers, baggage

Mass constant, but weight varies

Gravitational force + aircraft acceleration

Example roller coaster


Thrust

Driven by propeller

Accelerate a mass of air - slipstream

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Lift

Provided by wing

Wing span

Wing chord

Wing tip

Leading edge

Trailing edge

Efficiency

Wing area/camber


Drag

Parasitic drag (skin friction) ~ V2

Induced drag caused by

production of lift

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Control of Aircraft

Thrust > Drag = accelerate

Thrust < Drag = decelerate

Lift > Weight = climb

Lift < Weight = descend

Control of Aircraft

Angle increases, lift increases

Critical angle, flow separation

Stall

CL angle of attack

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Control of Aircraft

Control of Aircraft

Pitch elevator

Roll aileron

Yaw rudder

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Control of Aircraft

Pitch

Control column down

Elevator down

Pitch down

Control column up

Elevator up

Pitch up

Control of Aircraft

Roll

Differential aileron differential

lift on wings

Left down Right up roll to right

Left up Right down roll to left

Secondary effect adverse yaw

More lift more drag

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Control of Aircraft

Yaw

Rudder right

yaw right

Rudder left

yaw left

Secondary effect

adverse roll

Control of Aircraft

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Control of Aircraft

Flap

Increase camber(trailing edge)

Initial flap increase lift > drag

Final flap increase drag > lift

Slat

Increase camber (leading edge)

Spoiler (speedbrake)

Destroy the flow

Reduce lift and increase drag

Control of Aircraft

Slots:

air accelerate

mixed with boundary layer

Delay flow separation

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Speed measurement

Unit: Knots (nautical mile/hr)

Three main types:

Indicated Air Speed (IAS)

Ground Speed (GS)

True Air Speed (TAS)

Pitot-static system

Pressure measuring equipment

Consists of Pitot tube (dynamic pressure) and static port (static pressure)

Static pressure density of air

Dynamic pressure density of air + velocity of flow

D-S air speed

Speed measurement

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Speed measurement

IAS corrected for instrument error: Calibrated Air Speed

(CAS)

CAS corrected for density error: True Air Speed (TAS)

Density error:

Higher Altitude lower air density lower air pressure

Same IAS

Higher higher TAS

Higher faster

Speed measurement

What if pitot block during climb?

Speed = Dynamic pressure static pressure

= (velocity + static pressure) static pressure

Blockage of pitot tube - Aeroper Flight 603 (2 Oct 1996)

70 people died

Constant due to

blocked

Decrease

when climb

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Speed measurement

Ground Speed reference to ground

Actual distance travelled per hour

Vector sum of TAS + wind speed

Head wind GS = TAS wind speed

Tail wind GS = TAS + wind speed

Different flight duration to/back

Uses

GS: trip calculation

IAS: for flight control (stall/overspeed)


Altimeter

Measure static pressure

Pressure decrease, capsule

expand

Altitude, height and Flight

Level?

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Height reference to specific datum

Altitude- reference to sea level

Sea level: 1000mb

980mb

600ft

600ft 1200ft

Pressure unit: millibars (mb) or hectopascals (hPa)

Pressure decreases when height increases

30ft = 1mb/hPa

QFE: 980mb 600ft QNH: 1000mb 1200ft

Height (reference to ground) = 600ft


Problem

High to Low, watch out below!

Cadet interview question:

What is the reading after typhoon?

1010mb 980mb

Set local QNH

= 1010mb Altimeter shows 1500ft

Altimeter still shows 1500ft

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Change QNH often?

Standard temperature &

pressure setting

at mean sea level (15 lapse rate = -1.98 /1000ft)

1013.25hPa

Flight level

Transition level

QNE = the International Standard Atmosphere (ISA). It is the average mean

sea level pressure around the globe. It is planet earths mean atmospheric pressure at sea level basically


Set 1013.25hPa

Altimeter shows 15,000ft/ FL150

Standard pressure = 1013.25hPa

Local QNH = 1003hPa

FL150

Transition level

Set QNH 1003hPa

Altimeter shows 9,800ft

0 ft

(sea level)

9,800 ft

11,000 ft

FL110

airport

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Aircraft instrument

Airspeed Indicator (ASI)

Attitude Indicator (AI) (Artificial Horizon, AH)

Altimeter

Turn Coordinator

Heading Indicator/

Direction Indicator (DI)

Vertical speed indicator (VSI)

Basic T?

Which is the most important?

Aircraft instrument

Attitude Indicator

Gyroscope rapidly spinning wheels (negligible influence by

external force)

Provide horizontal reference

Measure pitch attitude/banking angle

Turn Coordinator

Gyro system

Sense roll and yaw

Measure rate of turn

Rate 1 turn = 3 degree per second

Balance indicator (skidding/slipping)

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Aircraft instrument

Direction indicator

Gyro system

Align with compass

Vertical speed indicator (VSI)

Rate of change of static pressure

Climb/descend

Pressure difference

Delayed

Aircraft engine

Piston engine

Cylinder, piston, crankshaft

Inside cylinder, fuel air mixture ignite

Expansion/explosion push the piston

down and turn the crankshaft

Propeller links with crankshaft

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Aircraft engine

Four Stroke cycle (Otto cycle)

Aircraft engine

Turbine Engine

Compressor: compress the incoming air to high pressure

Combustion area: burn fuel and produce high pressure high

velocity gas

Turbine: extract the energy from high pressure high velocity

gas

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Aircraft engine

Turbine engine vs Piston engine

High compressibility better performance , esp high altitude

Smaller size with higher power

Use more fuel and more expensive

Turbine engine

Turbo-jet

Turbo-fan

Turbo-prop

Aircraft engine

Turbofan engine

Turboprop engine

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Aircraft Engine

Bypass ratio

High

low noise

save fuel

Engine Major applications

Bypass ratio

Rolls-Royce (turbojet) Concorde 0:1

Pratt & Whitney F100 F-16, F-15 0.36:1

Eurojet EJ200 Typhoon 0.4:1

Klimov RD-33 MiG-29, Il-102 0.49:1

Kuznetsov NK-321 Tu-160 1.4:1

General Electric GEnx 747, 787 8.5:1

Rolls-Royce Trent 900 A380 8.7:1

General Electric GE90 777 9:1

Rolls-Royce Trent 1000 787 10:1

Zero bypass

Low bypass

High bypass

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Bibliography

Aircraft General Knowledge, Flight Performance and

Planning, Jeremy M Pratt, Airplane Flight Equipment

Limited, 2004. - ISBN: 9781874783237

Aircraft General Knowledge, Navigation, Meteorology,

Jeremy M Pratt, Airplane Flight Equipment Limited, 2003. -

ISBN: 9781874783183

Hong Kong Government Flying Service, HKSARG,

http://www.gfs.gov.hk/eng/home.htm

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