Aiplane Aerodynamics

8/10/2019 Aiplane Aerodynamics

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DANGER

JET

INTAKE

Centerof Gravity

AerodynamicCenter

LIFT

WEIGHT

DRAGTHRUST

High Ratio

Low Ratio

High

Low

L

AOA

C

THICKNESS-TO-CHORD RATIO

AOA

CL


27/95

PRESSURETEMPERATURE

DENSITY

ALTITUDE

36,000 FT

LC max

LC

StallRegion

AOA


28/95

Cdi=

(CL)2

AR

DRAG

Fixed Wing

VELOCITY (KIAS)Low

AOA

High

Total

Drag

L/DMax

Parasite Drag

Induced Drag

LowHigh


29/95

Roll

LATERALAXIS

VERTICALAXIS

LONGITUDINALAXIS

Pitch

Yaw

CENTER OF GRAVITY


30/95

TIMETIMEDISPLACEMENT

DISPLACEMENT

NON-OSCILLATORY OSCILLATORY

POSITIVE STATIC STABILITY

Equilibrium

Tendency to Return to Equilibrium

POSITIVE DYNAMIC STABILITY:

DISPLACEMENT

Initial Displacement

(Positive Static)(Positive Dynamic)

(Positive Static)(Positive Dynamic)D

ISPLACEMENT

TIMETIMEDISPLACEMEN

T

DISPLACEMEN

T


NEGATIVE STATIC STABILITY

Equilibrium

Tendency to Continuein Displacement Direction

NEGATIVE DYNAMIC STABILITY:

TIMETIMEDISPLACEME

NT

DISPLACEME

NT


NEUTRAL DYNAMIC STABILITY:

(Neutral Static)(Neutral Dynamic)

(Positive Static)(Neutral Dynamic)

NEUTRAL STATIC STABILITY

Equilibrium Encounteredat Any Point of Displacement

the amplitude of motion of a disturbed objectdecreases with time.

the amplitude of motion of a disturbedobject remains constant with time.

the amplitude of motion of a disturbedobject increases with time.

(Positive Static)(Negative Dynamic)

(Negative Static)(Negative Dynamic)


31/95

STABLE

Center ofGravity

AerodynamicCenter

Pitching Moment

NEUTRAL

Center ofGravity

AerodynamicCenter

Pitching Moment

UNSTABLE

Center ofGravity

Pitching Moment

AerodynamicCenter


32/95


33/95

WITH DIHEDRAL

Less Lift

More Lift

More Stable

WITHOUT DIHEDRAL

Destabilizing

Neutral

Stabilizing

Center ofGravity

Centerof Lift

Center

of Lift

Center ofGravity

Centerof Lift

Center ofGravity


34/95

AerodynamicLimitNegative

+AerodynamicLimitPositive

LOADFACTORG FORCE

0

VELOCITY INCREASE

0

Stall

Stall

DAMAGE

DAMAGE

ULTIMATE STRUCTURAL LIMIT, POSITIVE

ULTIMATE STRUCTURAL LIMIT, NEGATIVE

STRUCTURAL LIMIT, POSITIVE

FAILURE

FAILURE

_

STRUCTURAL LIMIT, NEGATIVE

AeroelasticLimit

CorneringSpeed


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DIRECTION OF MOTIONAll waves generated at equal time intervals

Point Source for Pressure Waves

NO MOTION SUBSONIC SONIC (MACH 1.0)a. b. c.


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Bow Wave

SubsonicFlow

ObliqueShock

Waves

Turbulent Air(Subsonic)

Turbulent BoundaryLayer (Subsonic)

SupersonicFlow

ExpansionWave Fan

M = 1.05

Expansion Wave Fan

60

10

20

30

40

50

40200-20-40-60-80

Temperature (C)

Speed of Sound (Knots)

Temperature

Speed of SoundPressureAltitude

(1,000 Ft.)

0

570 600 630 660


39/95

MAXIMUM LOCAL VELOCITY IS LESS THAN SONIC

MCRIT = .80 Mach for T-45

Flow Accelerates to above Flight Mach

Sonic Flow (m = 1)

FLIGHT MACH IS LESS THAN ONE

SupersonicFlow

Normal Shock Wave

Subsonic Possible Separation

Force Divergent Mach Number = 0.85 for T-45


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Normal Shock Wave

SupersonicFlow

Normal Shock Wave

Separation

Supersonic Flow

Separation

Supersonic Flow

ObliqueShock Wave

ObliqueShock Wave

Force Divergent Mach Number

VELOCITY

0.8 0.85 1.0 1.2

DRAGCOEFFICIENT

MCRIT

CD

CD

Total Drag


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Force Divergent Mach Number

VELOCITY

0.8 0.85 1.0 1.2

DRAGCOEFFICIENT

MCRIT

CD

CD

Total Drag

Supersonic Flow

Supersonic Flow

Oblique

Shock Wave

Oblique

Shock Wave

Lower

SupersonicFlow

Separation

Subsonic

Bow Wave

Supersonic Flow

Supersonic Flow

Separation

Oblique

Shock

Wave

ObliqueShock

Wave


42/95

Compression Wave

Vortex

LiftCoefficient

Span LocationRoot Tip

TransonicLiftDistribution

SmoothLiftDistribution


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HIGH THICKNESS - TO - CHORD RATIO

LOW THICKNESS - TO - CHORD RATIO

Wing Horizontal Tail

IncreasedDownwash

WingHorizontal Tail

Vortex

ResultantFlow

TypicalFlow

T/C RATIO

1:2

T/C RATIO

1:1

5 5

510


44/95

0 1.0 2.0 3.0

0

30

45

60

MACH NUMBER, M

DRAGCOEFFICIENT

CD

SWEEP ANGLE,

C

SWEPT WING

STRAIGHT WING SWEPT WING

Flow OverWing

Spanwise Flow

Flow Producing Lift

DP

V

STRAIGHT WING


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Separation

Ineffective

Effective

Effective

Ineffective

Separation

Separation

IneffectiveEffective

Effective Ineffective

Separation

No direct feedback between the stick andcontrol surface. Stick input ports hydraulic fluidto the actuator effecting control surface

Control stick "feel" is artificial.

IRREVERSIBLE(NO FEEDBACK FROM CONTROL SURFACES)


47/95

Direct mechanical connection between

rudder pedals and control surface.

NO HYDRAULIC ASSIST TO CONTROL INPUTS.

FEEDBACK PROVIDED BY DIRECT LINKAGE.

SupersonicAirflow

NormalShock

Wave

ObliqueShock

Wave

SlowerSupersonic Subsonic Engine

ENGINE INLET


48/95

30

VORTEX GENERATOR

SIDE VIEW

NOTE: All Dimensions in mm51.

17.

CL

12 3 4 5 6 7 8 9

10

11

12

13

14

15

16

17

18

19

PLANFORM VIEWNot To Scale

BL 2120.

BL 2408.

BL 4052.

BL 4589.5

144.

137.

107.5

10

25%CHORD

BL 4698.

20


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With Stabilization Strips

Added to Tail and Rudder

Bow Wave

StabilizedShock Wave

Stabilized

Shock Wave

Rudder

Without Stabilization Strips

Bow Wave

MovingShock Wave

Rudder

MovingShock Wave

0.20"

0.70"

Cross Section ofRudder Shock

Stabilization Strip

VERTICAL FIN

PLANFORM VIEW

50% Chord

Rudder Shock

Stabilization Strips

2.0"

AS SHOCK WAVE APPEARS,AERODYNAMIC CENTER MOVES AFT

Shock Wave

Center ofGravity

Aerodynamic Center


50/95

SmoothLiftDistribution

LiftCoefficient

Root Span Location Tip

TransonicLiftDistribution


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52/95

+

+Stall Point

Stall Develops

Stall Begins Deep Stall

Straight Wing

Swept Wing

AOA0

LIFT


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Unstable

Region of Stall

Center of Pressure

Center of Gravity

Aerodynamic Center

Slat Leading Edge

Stall Strip

WUSS Stall Strip

AIRFLOW

Stall Strip

Leading Edge

of Main Wing

Slat Leading Edge

Stall Strip

Slat Leading Edge

WUS

S

Slat

WING

WUSS Stall Strip

Wing Leading Edge


55/95

3 1/2

CL

ConstantIncidence

Wing

AOA in Degrees

ROOT

TIP

CL

Tip WithoutGeometric Twist

Root WithoutStall Strips

AOA

CL

AOA

Root WithStall Strips

Tip WithGeometric Twist

Adding Stall Strips tothe Root Causes theRoot to Stall Earlier (Ata Lower AOA)

Adding GeometricTwist Causes the Tip toStall Later (At a HigherAOA)

3 1/2


56/95

CL

WING

WINGWITHFLAP

S

AOA in Degrees


57/95

STABILATORVANE

(CL) max

(CL) max

STRAIGHTWING

SWEPTWING

(CL)

Coefficientof Lift

Angle Of Attack (AOA)

CL

AIRFLOWAOA in Degrees

DOWNWASH


58/95

ARTIFICIAL STALL

WARNINGSTALL BUFFET STALL

NOTE: All Speeds Are KIAS Above Stall Speed

CLEAN

APPROACH

21.5 Units / 10 KIAS 25 Units / 1-2 KIAS 26 Units / 0 KIAS

29-30 Units / 0 KIAS28 Units / 1 KIAS21.5 Units / 10 KIAS


59/95

PHASE COCKPIT INDICATIONS

Normal FlightENTRYINPUT

RECOVER

Y

AOA above stallREDUCE

STICK FORCESTALL

DEPARTUREAircraft no longer responds tocontrol inputs

NEUTRAL

CONTROLS

INDUCED YAW

POST - STALLGYRATIONS

AOA turn needle,and airspeed oscillation

NEUTRAL

CONTROLS

INCIPIENT

SPIN

AOA and turn needle

pegged; airspeed oscillation ANTI - SPIN

CONTROLSAOA and turn needlepegged; airspeed steady oroscillating slightly

STEADY -STATESPIN

SUSTAINED YAW


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RUDDER

AIRFLOW


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45-DEGREE TRUE AOA SPIN INDICATIONS30-DEGREE TRUE AOA SPIN INDICATIONS

28 Units or More AOA

Positive G

Turn Needle in Direction of Spin

180 KIAS

1,200 Feet / Turn

10 Turns / Minute

30 Units AOA

Positive G


100 to 110 KIAS

1,000 Feet / Turn

15 Turns / Minute30

45

45

60


63/95

Altitude Loss Per Turn 1,000 ft

Airspeed 50 to 120 kts

15 - 20 Turns / Minute

-60AOA

-30 Pitch-60AOA Spin

-40AOA Spin-50Pitch

Airspeed 100 - 160 kts

15 - 20 Turns / Minute


-40AOA

-25AOA Spin

-65Pitch

Airspeed 140 - 200 kts

10 Turns / Minute


0 Units AOA

Negative G


Steady State IAS


64/95

PHASE COCKPIT INDICATIONS

Normal FlightENTRYINPUT

R

ECOVERY

AOA above stallREDUCE

STICK FORCESTALL

DEPARTURE Aircraft no longer responds tocontrol inputs

NEUTRAL

CONTROLS

INDUCED YAW

POST - STALLGYRATIONS

AOA turn needle,and airspeed oscillation

NEUTRAL

CONTROLS

INCIPIENTSPIN

AOA and turn needlepegged; airspeed oscillation ANTI - SPIN

CONTROLSAOA and turn needlepegged; airspeed steady oroscillating slightly

STEADY -STATESPIN

SUSTAINED YAW


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66/95

30

1010

20

0ANGL

E

OFATT

ACK

OFF

WHEELS

Transmitter ProbeCarrierApproachLights

AOA Indexer

AOA Indicator

ADIDisplay


67/95

T- 45A T- 45C

Digital AOA

AOA Bracket

Waterline

Digital AOA

AOA Bracket

Velocity Vector


68/95

AN AIRCRAFT MUST POSSESS ADEQUATE

STABILITY TO MAINTAIN A FLIGHT PATH

AND

BE MANEUVERABLE ENOUGH TO

ACCOMPLISH ITS MISSION

CONTROL STABILITY

CONTROLLABILITY AND STABILITY

ARE A TRADEOFF


69/95

13,500

13,000

12,500

12,000

11,500

11,000

10,500

10,000

9 11 13 15 17 19 21 23 25

AftGearUp

AftGearDown

Upper

FuselageFuel

LowerFuselage

Fuel

OuterWing

Fuel

CenterWingFuel

Forward

Limit

2Crew

Mem

bers

GearUp

GearDown

(less

than

0.8

Mac

h)

C. G. - %M.A.C.

AIRCRAFTWEIGHT(LBS.)

Mean

AerodynamicChord

AERODYNAMIC CENTER

CENTER OF PRESSURE


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STABILATORVANE


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73/95

Yawing Moment AboutDownwind Gear

Less Drag

WIND

More Drag


74/95

ExhaustCombustion

Section

VinorV1

VexhorV2

Compressor

Section

Turbine

N1Compressor

N

Compressor2 NN 2 1

Turbines

Section

Exhaust

Section

AfterburnerCombustion

Section

VariableExhaust


75/95

N1Compressor

N

Compressor2

Fan(Outboard)

Combustion

Section

NN

21

Turbines

Section

Exhaust

AirCombustionand Exhaust

Bypass Duct

Bypass Duct


76/95

20 30 40 50 60 70 80 90 100

20

40

55

75

90

100

% RPM

%T

hrustAvailable

T-45

Theoretical

SEA LEVEL STANDARD DAY

JET ENGINE RPM THRUSTVS.

100

100

99

97

95

84

90

69

80

46

70

29

% of MAXRPM

% of MAXTHRUST


77/95

0 100 200 300 400 500 600 700 800

5,200

5,400

5,600

5,800

6,000

Calibrated Airspeed - Knots

Thrust(lbs.)

5,000

Actual

Theoretical

Ta= Q (V2- V1)

AIRSPEED

THRUST

Ta

V2- V1EFFECT

RAM EFFECT (Q)

ALTI

TUDE

0.4 0.6 0.8 1.0SEALEVEL

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

THRUST

DENSITY

TROPOPAUSE


78/95

THRUST

KTAS

T SEA LEVEL

T FL 350

SEA LEVEL

FL 350

r

r

Vmr

Vmr

30 40 50 60 70 80 90 100 110

1,000

2,000

3,000

4,000

5,000

% RPM

Thrust(lbs.)

- 42F. Day

Standard Day

0

105F. Day

6,000


79/95


80/95

(L/D)MAX

0 100

1,000

2,000

3,000

4,000

5,000

TRUE AIRSPEED - KNOTS

ThrustorDrag(lbs.)

0

6,000

200 300 400 500 600

DT= Tr

SEA LEVEL

STANDARD DAY

(CLEAN)

(L/D)MAX

0 100

1,000

2,000

3,000

4,000

5,000


Thrus

t(lbs.)

0

6,000

200 300 400 500 600

SEA LEVELSTANDARD DAY

(CLEAN)

VMR

Tr


81/95

(L/D)MAX

0 100

1,000

2,000

3,000

4,000

5,000


Thrust(lbs.)

0

6,000

200 300 400 500 600

T

SEA LEVEL

STANDARD DAY(CLEAN)

T at Sea Level

VH

a

r

1,000

2,000

3,000

4,000

5,000


Thrust(lbs.)

0

6,000

Region ofNormal

Command

Total Drag

Region ofReverse

Command Tr

(L/D)MAX


82/95

0 100

1,000

2,000

3,000

4,000

5,000


Thru

st(lbs.)

0

6,000

200 300 400 500 600

at Sea Level

10,000 LBS.

12,000 LBS.

(L/D)MAX

aT

0 100

1,000

2,000

3,000

4,000

5,000


Thrus

t(lbs.)

0

6,000

200 300 400 500 600

-SL

T at Sea Level

VMRFL 350

TrTr

a


83/95

0 100

1,000

2,000

3,000

4,000

5,000


Thrus

t(lbs.)

0

6,000

200 300 400 500 600

at Sea Level

TrHIGHER DRAG

(L/D)MAX

TrLOW DRAG

aT

0 100

1,000

2,000

3,000

4,000

5,000


Thrus

t(lbs.)

0

6,000

200 300 400 500 600

at Sea Level

14 units

23 unitsCLEAN

APPROACHCONFIGURATION

17 units

aT


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Documents

Aiplane Aerodynamics