9 fighter aircraft avionics-part ii

Fighter Aircraft AvionicsPart II

SOLO HERMELIN

Updated: 04.04.13

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Table of Content

SOLO Fighter Aircraft Avionics

2

Introduction

First generation (1945-1955)Second Generation (1950-1965)

Jet Fighter Generations

Third Generation (1965-1975)Fourth Generation (1970-2010)

4.5 Generation

Fifth Generation (1995 - 2025) Aircraft Avionics

Cockpit Displays

Communication (internal and external)Data Entry and ControlFlight ControlThird Generation Avionics

Fourth Generation Avionics

4.5 Generation AvionicsFifth Generation Avionics

Fighter Aircraft Avionics I

https://skydrive.live.com/redir?resid=58AC07F77D1B50D2!4256

Table of Content (continue – 1)


Earth Atmosphere

Flight Instruments

Flight Management SystemAircraft AerodynamicsAircraft Flight Control

Aircraft Flight Control Surfaces

Aircraft Flight Control Examples

Aircraft Propulsion SystemJet Engine

Vertical/Short Take-Off and Landing (VSTOL)

Engine Control System

Fuel System

Power Generation SystemEnvironmental Control SystemOil System

Table of Content (continue – 2)

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Fighter Aircraft Avionics

Equations of Motion of an Air Vehicle in Ellipsoidal Earth Atmosphere

Fighter Aircraft Weapon System

Safety Procedures

Tracking Systems

Aircraft Sensors

Airborne Radars

Infrared/Optical Systems

Electronic Warfare

Air-to-Ground Missions

BombsAir-to-Surface Missiles (ASM) or Air-to-Ground Missiles (AGM)

Fighter Aircraft Weapon Examples

Air-to-Air Missiles (AAM)

Fighter Gun

Aircraft Flight Performance

Navigation

Part II

References

Avionics

IV

Avionics III





Continue fromFighter Aircraft Avionics

Part I

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6

Earth Atmosphere

7

Earth Atmosphere

8

Earth Atmosphere

The basic variables representing the thermodynamics state of the gas are the Density, ρ, Temperature, T and Pressure, p.

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Air Data System

• The Density, ρ, is defined as the mass, m, per unit volume, v, and has units of kg/m3.

v

mv ∆

∆=→∆ 0limρ

• The Temperature, T, with units in degrees Kelvin ( ͦ K). Is a measure of the average kinetic energy of gas particles.

• The Pressure, p, exerted by a gas on a solid surface is defined as the rate of change of normal momentum of the gas particles striking per unit area.

It has units of N/m2. Other pressure units are millibar (mbar), Pascal (Pa), millimeter of mercury height (mHg)

S

fp n

S ∆∆=

→∆ 0lim

kPamNbar 100/101 25 ==

( ) mmHginHgkPamkNmbar 00.7609213.29/325.10125.1013 2 ===

The Atmospheric Pressure at Sea Level is:

Earth Atmosphere

Speed of Sound (a)This is the speed of sound waves propagation in ambientair. The speed of sound is given by

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Sa TRa ⋅⋅= γγ air = 1.4, Ra =287.0 J/kg--ͦK TS – Static Air Temperature

True Airspeed (TAS)The True Airspeed is the speed of the aircraft’s center of mass with respect to the ambient air through which is passing.

Indicated Airspeed (IAS)The Indicated Airspeed is the speed indicated by a differential-pressure airspeed indicator.

Air Data System

Earth Atmosphere

Mach Number (M)Is the ratio of the TAS to the speed of sound at the flight condition.

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aTASM /=

Dynamic Pressure (q)The force per unit area required to bring an ideal(incompressible) fluid to rest: q=1/2∙ρ∙VT

2 (where VT is True Air Speed-TAS, and ρ is the density of the fluid).

Impact Pressure (QC) The force per unit area required to bring moving air to rest. It is the pressure exerted at the stagnation point on the surface of a body in motion relative to the air.

PT – Total Pressure, PS – Static Pressure

22/1 TSTC VPPQ ⋅⋅=−= ρ

Air Data SystemEarth Atmosphere

12

Earth Atmosphere

Atmospheric Constants

Definition Symbol Value Units

Sea-level pressure P0 1.013250 x 105 N/m2

Sea-level temperature T0 288.15 ͦ K

Sea-level density ρ0 1.225 kg/m3

Avogadro’s Number Na 6.0220978 x 1023 /kg-mole

Universal Gas Constant R* 8.31432 x 103 J/kg-mole -ͦ K

Gas constant (air) Ra=R*/M0 287.0 J/kg--ͦK

Adiabatic polytropic constant γ 1.405

Sea-level molecular weight M0 28.96643

Sea-level gravity acceleration g0 9.80665 m/s2

Radius of Earth (Equator) Re 6.3781 x 106 m

Thermal Constant β 1.458 x 10-6 Kg/(m-s-ͦ K1/2)

Sutherland’s Constant S 110.4 ͦ K

Collision diameter σ 3.65 x 10-10 m

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Flight Instruments

Air Data Calculation (Collison)

Geopotential Pressure Altitude

• Low Altitude (Troposphere) : H< 11000 m (36.089 ft ),

( ) kPaHPS255879.551025577.21325.101 ⋅⋅−⋅= −

• Medium Altitude: 11000 m ≤ H ≤ 20000m (36.089 ft - 65.617 ft )

( ) kPaeP HS

000,1110576885.1 4

6325.22 −⋅⋅− −

⋅=

Air Density Ratio ρ/ρ0

S

S

T

P

⋅=

35164.00ρρ

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Flight InstrumentsAir Data Calculation (Collison)

Mach Number

• Subsonic Speeds (M ≤ 1),

( ) 2/722.01 MP

P

S

T ⋅+=

• Supersonic Speeds (M ≥ 1),

Static Air Temperature TS ͦ K

102.01 2

<<⋅⋅+

= rMr

TT m

S

( ) 2/52

7

17

9.166

−⋅⋅=

M

M

P

P

S

T

True Airspeed (TAS) VT m/s

smTMV ST /0468.20 ⋅⋅=


15

Flight Instruments

Air Data Calculation (Collison)

Speed of Sound a m/s

• Subsonic Speeds (VC ≤ a),

• Supersonic Speeds (VC ≥ a),

Sa TRa ⋅⋅= γ γ air = 1.4, Ra =287.0 J/kg--ͦK

Calibrated Airspeed (CAS) VC m/s

kPaV

Q CC

−

⋅+⋅= 1

294.3402.01325.101

2/72

kPaV

V

Q

C

C

C

−

−

⋅

⋅

⋅= 1

1294.340

7

294.34092.166

325.101

2/7

2/52

2


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Air Data Computer

Air Data Computer uses Total and Static Pressure and Static Temperature of the external Air Flow, to compute Flight Parameters.

17

Central Air Data Computer

Aircraft AvionicsFlight Instruments

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Flow of Air Data to Key Avionics Sub-systems


19Central Air Data Computer


Flight Instruments


20

The t Flight Instruments assist the Pilot to safely fly the Aircraft.

The Flight Instrument provide information about: * Height * Airspeed * Mach Number * Vertical Speed * Artificial Horizon * Velocity Vector * Pitch, Bank, Heading Angles

Thy include:- Pitot – Static Flight Instruments- Gyroscopic Instruments- Magnetic Compass

Flight Instruments


21The Flight Panel - Understand Your Aircraft, Youtube

http://www.youtube.com/watch?v=B23aLyAqqRM

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Flight InstrumentsSOLO Aircraft Avionics

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zdgpd ⋅⋅−= ρ

TRp ⋅⋅= ρ KsmR 22 /287=

zdaTd ⋅−=

aR

g

T

za

p

p ⋅

⋅−=00

1

Altimeter

Flight InstrumentsSOLO Aircraft Avionics

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Altimeter

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Altimeters

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Aircraft AvionicsFlight InstrumentsAltimeters


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Flight InstrumentsAirspeed Indicators

2

2

1vpp StatTotal ⋅+= ρ

The airspeed directly given by the differential pressure is called Indicated Airspeed (IAS). This indication is subject to positioning errors of the pitot and static probes, airplane altitude and instrument systematic defects. The airspeed corrected for those errors is called Callibrated Airspeed (CAS).Depending on altitude, the critic airspeeds for maneuvre, flap operation etc change because the aerodynamic forces are function of air density. An equivalent airspeed VE (EAS) is defined as follows:

0ρρ

VVE =V – True Airspeedρ – Air Densityρ0 – Air Density at Sea Level

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Aircraft AvionicsFlight InstrumentsAirspeed Indicator (ASI)

White Arc – Flaps Operation Range VSO – Stalling Speed Flaps Down VSI - Stalling Speed Flaps Up VFE – Maximum Speed Flaps Down (Extendeed)

Green Arc – Normal Operation Range VNO – Maximum Speed Normal Operation

Yellow Arc - Caution Range VNE – Not to Exceed Speed

Private Pilot Airplane – Flight Instruments ASA, Movie

http://www.youtube.com/watch?v=vICokuUAVAM

http://www.youtube.com/watch?v=vICokuUAVAM


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30


2

2

1VPQPP StatCStatTotal ⋅+=+= ρ

V – True Airspeedρ – Air Densityρ0 – Air Density at Sea Level

Air Density changes with altitude. Assuming an Adiabatic Flow, the relation between Pressure and Density is given by

constCP ==γρ

γ = Cp/CV= 1.4 for air

Momentum differential equation for the Air Flow is

VdVC

PPdVdVPd

C

Pγρ

γ

ρ/1

/1

0

+=+=

=

Subsonic Speeds

SoundofSpeedP

a S

ργ ⋅=


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In the free stream P = PS and V = VT,At the Probe face P = PT and V=0

01 0

/1/1 =+ ∫∫

T

T

S V

P

PVdV

CPdP γ

γ

Subsonic Speeds (continue)

2

1

1

2

/1

11T

ST

V

CPP γ

γγ

γγ

γγ =

−

−

−−γγ

ρ/1/1

1

SPC=

12

12

2

11

2

11

2

−

=

−

⋅−+=

⋅⋅−+= γ

γργ

γγ γ

γργ

a

VV

PP

P T

Pa

TSS

T

S

−

⋅−+=

−=−= − 1

2

111 1

2γγγ

a

VP

P

PPPPQ T

SS

TSSTC


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In the free stream P = PS and V = VT,At the Probe face P = PT and V=0

Supersonic Speeds

1

12

12

11

12

21

−

−

+−−

⋅

+

⋅+

=γ

γγ

γγ

γγ

γ

aV

aV

P

P

T

T

S

T

−

+−−

⋅

+

⋅+

=

−=−=

−

−

1

11

12

21

11

12

12

γ

γγ

γγ

γγ

γ

aV

aV

PP

PPPPQ

T

T

SS

TSSTC

Assume Supersonic Adiabatic Air Flow we obtain


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Mach Number

1

1

2

12

1

1

1

2

2

1

−

−

+−−⋅

+

⋅+

=γ

γγ

γγ

γγ

γ

M

M

P

P

S

T

Subsonic Speeds (M ≤ 1)

γγ

γ

1

1

21

−

⋅

−−==

S

TT

P

P

a

VM

12

2

11

2

−

=

⋅−+= γ

γργ

γM

P

PSPa

S

T

From

Supersonic Speeds (M ≥ 1)


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Flight InstrumentsAirspeed Indicators (Calibrated Airspeed)

Calibrated Airspeed is obtained by substituting the Sea Level conditions, that is PS = PS0 , VT = VC , a0 = 340.294 m/s.

Subsonic Speeds (VC < a0=340.294 m/s)

−

⋅−+= − 1

2

11 1

2

00

γγγ

a

VPQ CSC

20

00

2

0

2

0 2

1

/21

21 C

S

CS

CS

aV

C VP

VP

a

VPQ

C

⋅⋅=⋅

⋅⋅=

−

⋅+≈

<<

ρργ

γγ

Supersonic Speeds (VC > a0=340.294 m/s)

−

+−−

⋅

+

⋅+

=−

−

1

11

12

21

1

12

0

12

0

0

γ

γγ

γγ

γγ

γ

aV

aV

PQ

C

C

SC

( ) mmHginHgkPamkNmbarPS 00.7609213.29/325.10125.1013 20 ====

γ air = 1.4


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By measuring (TT) the Temperature of Free Airstream TS, we can compute the local Speed of Sound

Sa TRa ⋅⋅= γ

True Airspeed (TAS)

By using the Mach Number computation we can calculate the True Airspeed (TAS)

MM

TRMTRMaV T

aSaT ⋅⋅−+

⋅⋅=⋅⋅⋅=⋅=2

21

1γγγ

Vertical Speed Indicator

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Gyroscopic Flight Instruments

Turn Indicator

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Attitude Indicator

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Attitude Indicator

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Turn Coordinator

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Turn-and Slip Indicator

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Heading IndicatorThe Magnetic Compass is sensitive to Inertia Forces. It is a reliable Heading Instrument in the long yerm, but during maneuvers it may swing and be hardly reliable. To provide a more precise Heading Instrument a Directional Gyro is used.

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Aircraft Avionics

Flight InstrumentsThe Earth is a huge Magnet, spinning in space, surrounded by a Magnetic Field made up of invisible lines of flux. These lines leave the surface of the Magnetic North Pole and reenter at the magnetic South Pole. The Magnetic Poles are not coincident with the Geographic Poles (located on the Axis of Rotation of the Earth.

Lines of Magnetic Flux have two important characteristics:1Any Magnet that is free to rotate will align with them.2An Electrical Current is induced into any conductor that moves and cuts across them. Most direction indicators installed in aircraft make use of one of these two characteristics.

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Magnetic Compass

Flight Instruments

Aircraft Avionics

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Aircraft AvionicsFlight InstrumentsFlux Gate Compass System

The Gate Compass System is connected to Radio Magnetic Indicator (RMI) and to Heading Situation Indicator (HSI).

Heading Situation Indicator (HSI).Radio Magnetic Indicator (RMI)

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Aircraft Avionics

Flight Instruments

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Aircraft Avionics

Flight DisplaysIn Modern Aircraft the Flight Instruments are provided on Panel Displays.

Flight Instruments

New Integrated Flight Control System

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Aircraft Avionics

Flight Displays

Chelton’s Flight Logic Reconfigurable Panel Display

Flight Instruments

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Aircraft Avionics

Flight Displays

Avidyne’s Entegra Reconfigurable Panel Display

Flight Instruments

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Aircraft Avionics

Flight CockpitFlight Instruments

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Aircraft Avionics

Flight DisplaysFlight Instruments

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Aircraft Avionics

Flight InstrumentsAutomatic Dependent Surveillance (ADS)

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Aircraft Avionics

Flight Instruments

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Aircraft AvionicsFlight InstrumentsAlert Systems

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Alert Systems

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Aircraft AvionicsFlight InstrumentsAlert Systems

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Aircraft AvionicsFlight InstrumentsHelmet-up-Display

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Aircraft Avionics

Cockpit

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Aircraft Avionics

Instrument Flight

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Navigation

Flight Management System

Top Level Flight Management System FunctionsReturn to TOC

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Aircraft Aerodynamics

Me 109

EllipticalWing

(ModerateAspect Ratio)

1940M=0.55

PureSubsonic

SpitfireTrapezoidal

Wing(High

Aspect Ratio)

Me 262Sweptback

Wing(High

Aspect Ratio)

M=0.8High

Subsonic

1945

MIG 15F86 SabreSweptback

Wing(Moderate

Aspect Ratio)

1950

M=0.9-0.98High

Subsonic(Transonic)

http://en.wikipedia.org/wiki/File:Spitfire_mark19_ps853_planform_arp.jpg

smb://upload.wikimedia.org/wikipedia/commons/a/a0/Messerschmitt_Me_262_Schwalbe_3d_drawing.svg

smb://upload.wikimedia.org/wikipedia/commons/d/d1/Mig-15_schema.svg

http://en.wikipedia.org/wiki/File:North_American_F-86A.svg

64


MIG 25

MIG 21

Delta Wing(Low

Aspect Ratio)

1960M=2.2-2.4Supersonic

F4 PhantomDelta-LikeTrapezoidal

Wing(Low

Aspect Ratio)

F-111

LargeSweptback

(LowAspect Ratio)

M=2.2-3.0Supersonic/

HighSupersonic

1970 TrapezoidalWing

F16StrakeWing

(HybridWing)

1980

M=2.0Maneuvrability(High Angle

of Attack)

F18

smb://upload.wikimedia.org/wikipedia/commons/2/21/F-111_3-view.svg

smb://upload.wikimedia.org/wikipedia/commons/0/05/MiG-25.svg

smb://upload.wikimedia.org/wikipedia/commons/9/91/GENERAL_DYNAMICS_F-16_FIGHTING_FALCON.svg

smb://upload.wikimedia.org/wikipedia/commons/8/88/McDONNELL_DOUGLAS_F-A-18_HORNET.png

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Wing Parameters

1. Wing Area, S, is the plan surface of the wing.

2. Wing Span, b, is measured tip to tip.

3. Wing average chord, c, is the geometric average. The product of the span andthe average chord is the wing area (b x c = S).

4. Aspect Ratio, AR, is defined as:

( )∫−

=2/

2/

b

b

dyycS

( )b

Sdyyc

bc

b

b

== ∫−

2/

2/

1

S

bAR

2

=


66

Wing Parameters (Continue)

5. The root chord, , is the chord at the wing centerline, and the tip chord, is the chord at the tip.

6. Taper ratio,

7. Sweep Angle, is the angle between the line of 25 percent chord and the perpendicularto root chord.

8. Mean aerodynamic chord,

rc

Λ

r

t

c

c=λ

tc

λ

( )[ ]∫−

=2/

2/

21~b

b

dyycS

c

c~


67

STREAMLINESSTREAKLINES

∞V

PRESURE FIELD

VELOCITY FIELD

WING AERODYNAMICS

68

The Effect of Leading Edge Slat, Flap, and Trailing Edge FlapUpon Angle of Attack of Basic Wing

Darrol Stinton “ The Design of the Aircraft”


69

Movement of Shocks with Increasing Mach NumberAircraft Aerodynamics

70

Movement of Shocks with Increasing Mach Number

71High Angles of Attack Flows(Development of a High Resolution CFD)

72High Angles of Attack Flows(Development of a High Resolution CFD)

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Aerodynamics of Flight

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Flow of Air Data to Key Avionics Sub-systems

Aircraft AvionicsAircraft Flight Control

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centre stick ailerons

elevators

rudder

Generally, the primary cockpit flight controls are arranged as follows:a control yoke (also known as a control column), centre stick or side-stick (the latter two also colloquially known as a control or B joystick), governs the aircraft's roll and pitch by moving the A ailerons (or activating wing warping on some very early aircraft designs) when turned or deflected left and right, and moves the C elevators when moved backwards or forwardsrudder pedals, or the earlier, pre-1919 "rudder bar", to control yaw, which move the D rudder; left foot forward will move the rudder left for instance.throttle controls to control engine speed or thrust for powered aircraft.


Flight Controls, Movie

http://www.youtube.com/watch?v=A2BcAMl04AI

smb://upload.wikimedia.org/wikipedia/commons/b/b8/ControlSurfaces.gif

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Differential ailerons

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The effect of left rudder pressureFour common types of flaps

Leading edge high lift devices

The stabilator is a one-piece horizontal tail surface that pivots up and down about a central hinge point.

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Flight Control


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Control Surfaces

Aircraft Flight Control SurfacesReturn to Table of Content

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To be replacedAerodynamics of Flight

Return to TOC

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Aircraft Flight Control

Traditional Pitch Autopilot and Autothtrottle

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Traditional Roll Autopilot and Yaw Damper

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Un-Powered Flight Controls

Simple Hydro-Mechanical Servo-Actuator

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Hawk-200 Push-Pull Control Rod System (BAE Systems)

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Mechanical, Power-Boosted System

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Flight Controls - Hydraulic Booster, Movie

http://www.youtube.com/watch?v=90OeBXyylds

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Falcon 7X Digital Flight Control System, Movie

http://www.youtube.com/watch?v=A0o27bPsmuc

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F-16 Flight Control System

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F-16 Flight Control System Functional Schematics

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F-16 Flight Control System Redundancy Concept

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F-16 Pitch Functional Schematic Diagram

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F-16 Roll Functional Schematic Diagram

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F-16 Yaw Functional Schematic Diagram

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Integrated Servo-Actuator Schematic Diagram

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F-16 Flight Control System Electrical Power Schematic Diagram

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F-16 Hydraulic Power Schematic Diagram

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F-16 Electronic Signal Selection and Failure Monitoring

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RSS – Relaxed Static Stability

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F-16 Performance Benefits Derived from Relaxed Static Stability

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Russia - SU-37 Aircraft

• Canards and thrust vectoring (TV loop not shown.).• Longitudinal controller synthesized with classical control methods.

SU-37 Terminator

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F/A-18 Control System Components

smb://upload.wikimedia.org/wikipedia/commons/8/8d/FA-18-NAVY-Blue-Diamond.jpg

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F/A-18 Flight control System Functional Diagram

smb://upload.wikimedia.org/wikipedia/commons/8/8d/FA-18-NAVY-Blue-Diamond.jpg

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Jaguar Fly-by-Wire Architecture

smb://upload.wikimedia.org/wikipedia/commons/b/bd/JaguarGR1_41Sqn_Gulf1991.jpeg

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•Controller structure decouples flying qualities from a/c dynamics.•Regulator/Commands implement desired.•Effector blender optimally allocates desired acceleration commands.•On-board model.

•Control effectiveness matrix.•Estimated acceleration for dynamic inversion.

JSF Flight Control Laws

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Aircraft Propulsion SystemSOLO

The Fighter Aircraft Propulsion Systems Consists of: - One or Two Jet Engines - The Fuel Tanks (Internal and External) and Pipes. - Engines Control Systems * Throttles * Engine Control Displays

Engine Control Systems – Basic Inputs and Outputs

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http://www.ausairpower.net/APA-Raptor.html 122

Aircraft Propulsion System


123


Diagram of a typical gas turbine jet engine

Turbojets consist of an - Air Inlet- Air Compressor- Combustion Chamber- Gas Turbine (that drives the air compressor) - Nozzle.

The air is compressed into the chamber, heated and expanded by the fuel combustion and then allowed to expand out through the turbine into the nozzle where it is accelerated to high speed to provide propulsion

Turbojet animationPropulsion Force

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Jet Engine

smb://upload.wikimedia.org/wikipedia/commons/4/4c/Jet_engine.svg

smb://upload.wikimedia.org/wikipedia/commons/9/9e/Turboreacteur_anime.gif

124

Propulsion Force = Thrust

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The net Thrust (FN) of a Turbojet is given by

where: ṁ air = the mass rate of air flow through the engine

ṁ fuel = the mass rate of fuel flow entering the engine

ve= the velocity of the jet (the exhaust plume) and is assumed to be less than sonic velocity

v = the velocity of the air intake = the true airspeed of the aircraft(ṁ air + ṁ fuel )ve = the nozzle gross thrust (FG)

ṁ air v = the ram drag of the intake air


Jet Engine

125

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• Cold Section: • Air Intake (Inlet) — The standard reference frame for a jet engine is the aircraft itself. For subsonic aircraft, the air intake to a jet engine presents no special difficulties, and consists essentially of an opening which is designed to minimise drag, as with any other aircraft component. However, the air reaching the compressor of a normal jet engine must be travelling below the speed of sound, even for supersonic aircraft, to sustain the flow mechanics of the compressor and turbine blades. At supersonic flight speeds, shockwaves form in the intake system and reduce the recovered pressure at inlet to the compressor. So some supersonic intakes use devices, such as a cone or ramp, to increase pressure recovery, by making more efficient use of the shock wave system.• Compressor or Fan — The compressor is made up of stages. Each stage consists of vanes which rotate, and stators which remain stationary. As air is drawn deeper through the compressor, its heat and pressure increases. Energy is derived from the turbine (see below), passed along the shaft.• Bypass Ducts much of the thrust of essentially all modern jet engines comes from air from the front compressor that bypasses the combustion chamber and gas turbine section that leads directly to the nozzle or afterburner (where fitted).


Jet Engine

smb://upload.wikimedia.org/wikipedia/commons/c/c0/Turbofan_operation.png

126

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• Common: • Shaft — The shaft connects the turbine to the compressor, and runs most of the length of the engine. There may be as many as three concentric shafts, rotating at independent speeds, with as many sets of turbines and compressors. Other services, like a bleed of cool air, may also run down the shaft.

• Diffuser Section: - This section is a divergent duct that utilizes Bernoulli's principle to decrease the velocity of the compressed air to allow for easier ignition. And, at the same time, continuing to increase the air pressure before it enters the combustion chamber.


Jet Engine

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• Hot section: • Combustor or Can or Flameholders or Combustion Chamber — This is a chamber where fuel is continuously burned in the compressed air.• Turbine — The turbine is a series of bladed discs that act like a windmill, gaining energy from the hot gases leaving the combustor. Some of this energy is used to drive the compressor, and in some turbine engines (i.e. turboprop, turboshaft or turbofan engines), energy is extracted by additional turbine discs and used to drive devices such as propellers, bypass fans or helicopter rotors. One type, a free turbine, is configured such that the turbine disc driving the compressor rotates independently of the discs that power the external components. Relatively cool air, bled from the compressor, may be used to cool the turbine blades and vanes, to prevent them from melting.• Afterburner or Reheat (chiefly UK) — (mainly military) Produces extra thrust by burning extra fuel, usually inefficiently, to significantly raise Nozzle Entry Temperature at the exhaust. Owing to a larger volume flow (i.e. lower density) at exit from the afterburner, an increased nozzle flow area is required, to maintain satisfactory engine matching, when the afterburner is alight.• Exhaust or Nozzle — Hot gases leaving the engine exhaust to atmospheric pressure via a nozzle, the objective being to produce a high velocity jet. In most cases, the nozzle is convergent and of fixed flow area.• Supersonic nozzle — If the Nozzle Pressure Ratio (Nozzle Entry Pressure/Ambient Pressure) is very high, to maximize thrust it may be worthwhile, despite the additional weight, to fit a convergent-divergent (de Laval) nozzle. As the name suggests, initially this type of nozzle is convergent, but beyond the throat (smallest flow area), the flow area starts to increase to form the divergent portion. The expansion to atmospheric pressure and supersonic gas velocity continues downstream of the throat, whereas in a convergent nozzle the expansion beyond sonic velocity occurs externally, in the exhaust plume. The former process is more efficient than the latter.


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Air Intake Preceding the compressor is the air intake (or inlet). It is designed to be as efficient as possible at recovering the ram pressure of the air stream tube approaching the intake. The air leaving the intake then enters the compressor. The stators (stationary blades) guide the airflow of the compressed gases.

Klaus Hünecke, “Jet Engines – Fundamentals of Theory, Design and Operation”, 1997

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Air IntakeKlaus Hünecke, “Jet Engines – Fundamentals of Theory, Design and Operation”, 1997


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Air IntakeAERO 315USAF ACADEMYDEPARTMENT OFAERONAUTICS


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An animation of an axial compressor. The stationary blades are the stators

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CompressorThe compressor is driven by the turbine. The compressor rotates at a very high speed, adding energy to the airflow and at the same time squeezing (compressing) it into a smaller space. Compressing the air increases its pressure and temperature.In most turbojet-powered aircraft, bleed air is extracted from the compressor section at various stages to perform a variety of jobs including air conditioning/pressurization, engine inlet anti-icing and turbine cooling. Bleeding air off decreases the overall efficiency of the engine, but the usefulness of the compressed air outweighs the loss in efficiency.Several types of compressor are used in turbojets and gas turbines in general: axial, centrifugal, axial-centrifugal, double-centrifugal, etc.Early turbojet compressors had overall pressure ratios as low as 5:1 (as do a lot of simple auxiliary power units and small propulsion turbojets today). Aerodynamic improvements, plus splitting the compression system into two separate units and/or incorporating variable compressor geometry, enabled later turbojets to have overall pressure ratios of 15:1 or more. For comparison, modern civil turbofan engines have overall pressure ratios of 44:1 or more.After leaving the compressor section, the compressed air enters the combustion chamber.

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Combustion ChamberThe burning process in the combustor is significantly different from that in a piston engine. In a piston engine the burning gases are confined to a small volume and, as the fuel burns, the pressure increases dramatically. In a turbojet the air and fuel mixture passes unconfined through the combustion chamber. As the mixture burns its temperature increases dramatically, but the pressure actually decreases a few percent.The fuel-air mixture must be brought almost to a stop so that a stable flame can be maintained. This occurs just after the start of the combustion chamber. The aft part of this flame front is allowed to progress rearward. This ensures that all of the fuel is burned, as the flame becomes hotter when it leans out, and because of the shape of the combustion chamber the flow is accelerated rearwards. Some pressure drop is required, as it is the reason why the expanding gases travel out the rear of the engine rather than out the front. Less than 25% of the air is involved in combustion, in some engines as little as 12%, the rest acting as a reservoir to absorb the heating effects of the burning fuel.Another difference between piston engines and jet engines is that the peak flame temperature in a piston engine is experienced only momentarily in a small portion of the full cycle. The combustor in a jet engine is exposed to the peak flame temperature continuously and operates at a pressure high enough that a stoichiometric fuel-air ratio would melt the can and everything downstream. Instead, jet engines run a very lean mixture, so lean that it would not normally support combustion. A central core of the flow (primary airflow) is mixed with enough fuel to burn readily. The cans are carefully shaped to maintain a layer of fresh unburned air between the metal surfaces and the central core. This unburned air (secondary airflow) mixes into the burned gases to bring the temperature down to something a turbine can tolerate.

Turbojet animation

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Combustion Chambers

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A Multiple Combustion Chamber

Flame Stabilizing andGeneral Flow Pattern

Tubo-Annular Combustion Chamber

Annular Combustion Chamber


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Combustion Chambers

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The combustion efficiency of most aircraft gas turbine engines at sea-level takeoff conditions is almost 100%. It decreases nonlinear to 98% at altitude cruise conditions. Air-fuel ratio ranges from 50:1 to 130:1. For any type of combustion chamber there is a rich and weak limit to the air-fuel ratio, beyond which the flame is extinguished. The range of air-fuel ratio between the rich and weak limits is reduced with an increase of air velocity. If the increasing air mass flow reduces the fuel ratio below certain value, flame extinction occurs

Typical combustion stability limits of an aircraft gas turbine

Typical combustion efficiency of an aircraft gas turbine over the operational range


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Gas Turbine

A twin turbine and shaft arrangement. A triple turbine and shaft arrangement.

The Gas Turbine energy is used to drive the Compressor, and in some turbine engines (i.e. Turboprop, Turboshaft or Turbofan Engines), energy is extracted by additional turbine discs and used to drive devices such as propellers, bypass fans

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Nozzle

The primary objective of a nozzle is to use the heat and pressure of the exhaust gas to accelerate the jet to high speed so as to efficiently propel the vehicle. For air-breathing engines, if the fully expanded jet has a higher speed than the aircraft's airspeed, then there is a net rearward momentum gain to the air and there will be a forward thrust on the airframe.

Many military combat engines incorporate an afterburner (or reheat) in the engine exhaust system. When the system is lit, the nozzle throat area must be increased, to accommodate the extra exhaust volume flow, so that the turbo machinery is unaware that the afterburner is lit. A variable throat area is achieved by moving a series of overlapping petals, which approximate the circular nozzle cross-section.

Variable Exhaust Nozzle, on the GE F404-400 low-bypass turbofan installed on a Boeing F/A-18 Hornet

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Gas-Turbine Working Cycle in Pressure-Volume and Enthalpy-Entropy Diagram



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“The Jet Engine” Rolls-RoyceVertical/Short Take-Off and Landing (VSTOL)

Reaction control system.


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“The Jet Engine” Rolls-RoyceVertical/Short Take-Off and Landing (VSTOL)

Deflector Nozzle

Side mounted swivelling nozzle

Thrust deflector systems


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Lockheed_Martin_F-35_Lightning_II STOVL

The Unique F-35 Fighter Plane, Movie

USP 3” part F35Joint Strike Fighter ENG,

Movie

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Vertical/Short Take-Off and Landing (VSTOL)

Cutaway Yakovlev Yak-38 Folger



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Military Turbofan Engines


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Engine Control System Basic Inputs and Outputs

Engine Control System Input Signals:• Throttle Position (Pilot Control)• Air Data (from Air Data Computer) Airspeed and Altitude• Total Temperature (at the Engine Face)• Engine Rotation Speed• Engine Temperature• Nozzle Position• Fuel Flow• Internal Pressure Ratio at different Stages of the Engine

Output Signals• Fuel Flow Control• Air Flow Control

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A Simple Engine Control Systems : Pilot in the Loop

A Simple Limited Authority Engine Control Systems

TGT – Turbine Gas TemperatureNH – Speed of Rotation of Engine ShaftTt - Total TemperatureFCU – Fuel Control Unit


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A Simple Engine Control Systems : Pilot in the Loop

A Simple Limited Authority Engine Control Systems

Engine Control Systems : with NH and TGT exceedence warning

Full Authority Engine Control SystemsWith Electrical Throttle Signaling :


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A Modern Simplified Engine Control System

VSV – Variable Stator Vane

EGT– Exhaust Gas Temperature

PMA - Permanent Magnet Alternator

FMU – Flow Management Unit

AVM – Aircraft Vibration Monitoring


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Turbojet Engine (EJ200 in Eurofighter Typhoon)



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Fuel System

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Fuel System

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Fuselage and Engine Fuel System

Siphoning theFuel from the Drop TankTo Main Tank

Pump Transfer Distributed (Left)And Centralized (Right)

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Fuel Control System

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Location of fuel tanks in JAS 39 Gripen

“On Aircraft Fuel Systems Conceptual Design and Modeling”Hampus Gavel

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Probe and drouge Air-to-Air Refueling of JAS 39 Gripen

“On Aircraft Fuel Systems Conceptual Design and Modeling”Hampus Gavel

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F15 C/D Fuel System

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Fuel System

F-35 JSF Return to Table of Content

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Power Generation System

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F-18E/F Variable-Speed Constant-Frequency (VSCF) Cycloconverter

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F-22 Power Generation and Distribution System


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Environmental Control System

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Aircraft Oxigen SystemSOLO

On Board Oxygen Generation System (Honeywell Aerospace Yeovil)

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Aircraft Oxigen SystemSOLO

Oil System

Engine Oil systemReturn to Table of Content

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Go to Fighter Aircraft Avionics

Part III


References

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PHAK Chapter 1 - 17http://www.gov/library/manuals/aviation/pilot_handbook/media/

George M. Siouris, “Aerospace Avionics Systems, A Modern Synthesis”, Academic Press, Inc., 1993

R.P.G. Collinson, “Introduction to Avionics”, Chapman & Hall, Inc., 1996, 1997, 1998

Ian Moir, Allan Seabridge, “Aircraft Systems, Mechanical, Electrical and AvionicsSubsystem Integration”, John Wiley & Sons, Ltd., 3th Ed., 2008


Ian Moir, Allan Seabridge, “Military Avionics Systems”, John Wiley & Sons, LTD., 2006

References (continue – 1)

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S. Hermelin, “Air Vehicle in Spherical Earth Atmosphere”

S. Hermelin, “Airborne Radar”, Part1, Part2, Example1, Example2

S. Hermelin, “Tracking Systems”

S. Hermelin, “Navigation Systems”

S. Hermelin, “Earth Atmosphere”

S. Hermelin, “Earth Gravitation”

S. Hermelin, “Aircraft Flight Instruments”

S. Hermelin, “Computing Gunsight, HUD and HMS”

S. Hermelin, “Aircraft Flight Performance”

S. Hermelin, “Sensors Systems: Surveillance, Ground Mapping, Target Tracking”

S. Hermelin, “Air-to-Air Combat”

References (continue – 2)

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S. Hermelin, “Spherical Trigonometry”

S. Hermelin, “Modern Aircraft Cutaway”

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TechnionIsraeli Institute of Technology

1964 – 1968 BSc EE1968 – 1971 MSc EE

Israeli Air Force1970 – 1974

RAFAELIsraeli Armament Development Authority

1974 – 2013

Stanford University1983 – 1986 PhD AA

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Civilian Aircraft AvionicsFlight Cockpit

CIRRUS PERSPECTIVE

Cirrus Perspective Avionics Demo, Youtube Cirrus SR22 Tampa Landing in Heavy Rain

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Flight Displays

CIRRUS PERSPECTIVE

Civilian Aircraft Avionics

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Flight Displays

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Flight Displays

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Flight Displays

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Flight Displays

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Flight Displays

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Flight Displays

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Flight Displays

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Science

9 fighter aircraft avionics-part ii