Avionic Systems

8/4/2019 Avionic Systems

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To meet the mission requirements with the

minimum flight crew (namely the first pilot and the

second pilot)

Economic benefits like

Saving of crew salaries

Expenses and training costs

Reduction in weigh-more passengers or longer

range on less fuel



IN THE MILITARY CASE

A single seat fighter or strike (attack) aircraft

is lighter

Costs less than an equivalent two seat version

Elimination of the second crew member

(navigator/observer/crew member)

Reduction in training costs



OTHER VERY IMPORTANT DRIVERS FOR

AVIONICS SYSTEMS ARE

Increased safety

Air traffic control requirements

All weather operation

Reduction in fuel consumptionImproved aircraft performance and control

and handling and reduction in maintenance costs

* In the military case, the avionics systems are also being

driven by a continuing increase in the threats posed by the

defensive and offensive capabilities of potential aggressors





COCKPIT DISPLAY Provides

Visual presentation of Information & Data

from A/c sensors and systems

PROVIDE THE PILOT WITH

Primary flight information

Navigation information

Engine data

Airframe data

Warning information



MILITARY PILOT ALSO HAS WIDE

ARRAY OF ADDITIONAL INFORMATION

VIEW SUCH AS

• Infra-red imaging sensors

• Radar

• Tactical mission data

• Weapon aiming

• Threat warning







Head Up Display (HUD)

Helmet Mounted Display (HMD)

Forward Looking InfraRed (FLIR) video picture

through HUD Head position sensor

Night Vision Goggles (NVG) - HMD

HMDs & Virtual cockpit

Colored Head Down Display (HDD)

Multi-Function Display (MFD) with Multi -Function

Keys (MFK)





















Contd..

Two way communication between the ground

bases and the aircraft or between aircraft

Communication radio suite on modern aircraft is

a very comprehensive one and covers several

operating frequency bands

Long range - HF radios operating in the band

2-30 Mhz

Near to medium range (civil aircraft) by VHF

radios operating in the band 30-100 Mhz



Contd..

VHF and UHF are line of sight propagation

systems

Equipment is usually at duplex level of

redundancy

VHF radios are generally by triplex level on a

modern airliner

SATCOM systems in many modern aircraftand provide very reliable world wide

communication





Essential for the crew to interact with

the avionics systems

KEY BOARDS

TOUCH PANELS

DIRECT VOICE INPUT (DVI) CONTROL

EXPLOITS

SPEECH RECOGNITION

TECHNOLOGY



TOUCH SCREENS



Vocabulary size - required size is around

200-300 words

Fully Connected Speech

Must Be Able to Operate in the Cockpit

Environment

Speech template duration - Speech Template

Duration is around 5 Seconds

Contd..

Contd



Duration of utterance - no restriction on the

max. duration of an input utterance

Syntax nodes - max. no. of syntax nodesrequired is 300

Vocabulary duration - Maximum duration

of the total vocabulary is around 160 Seconds

Contd..

Recognition response time - this must be in

real time

EYE TRACKERS

Improved target designation accuracy

Data entry in conjunction with a helmet

mounted display





TWO AREAS

Needed for most swept wing jet a/c

Lightly damped short period oscillatory motion

AUTO STABILISATION (or stability augmentation) systems

FBW FLIGHT CONTROL SYSTEMS

Enables a lighter, higher performance aircraft designed

with relaxed stability

Good consistent handling which is sensibly constant

over a wide flight envelope and range of load conditions



Continuous automatic stabilization of the aircraft by

computer control of the control surfaces

Auto pilot integration

Care free maneuvering characteristics

Ability to integrate additional controls automatically

such as

Leading edge slats/flaps and trailing edge

flaps to generate additional lift

Variable wing sweep

Thrust vector control nozzles and engine thrust



Elimination of mechanical controls runs - friction,

backslash

Small control stick

Aerodynamics versus stealth - the concept of reducing

the radar cross section

Very high integrity, a failure survival system

Ability to exploit aerodynamically unstable configuration



















Air Data SystemsAccurate information on the air data quantities

Altitude

Calibrated airspeed

True airspeed

Vertical speed

Air stream incidence angle (angle of attack)

Mach number

Total air temperature





Attitude and heading information are essential

for a/c mission

Autopilot

Navigation system

Weapon aiming

INERTIAL SENSORS

Gyros - mechanical - electromechanical - RLG-FOG

AccelerometerAHRS

Strap Down

Gimbaled systems





ACCURATE NAVIGATION INFORMATION Aircraft's position, ground speed, track angle (direction

of motion of the aircraft relative to true north)

NEED FOR ACCURATE NAVIGATION

Effective operation of any a/c

Automatic because of speed

Density of air traffic on major air routes to fly in a

specified corridor defined by ATC authorities-3D-4D

(time) - high accuracy NAV is essential & forms part of

FMS



For military operation - to enable the a/c to fly low &

take advantage of terrain screening from enemy radar

Use of weapon - released from several Kms away from

target also requires an accurate knowledge of the a/c

position in order to indicate the mid course inertialguidance of the missile.

DR systems

Position fixing systems

Contd..





Self contained and independent of external systems DR navigation systems used in aircraft are

Air data/heading reference system - lower accuracy

Doppler/heading reference systems - widely used

in helicopters

Inertial Navigation systems - most accurate and

widely used systems

Doppler/Inertial navigation system - combination



POSITION FIXING SYSTEMS

Range and bearing (R/ ) radio navigation aids

VOR/DME

TACAN- Accuracy of 1-2 miles

HYPERBOLIC RADIO NAVIGATION SYSTEMS

LORAN C - positional accuracy of around 150 m

8 LORAN C chains comprising 34 ground station

transmitters

OMEGA - accuracy around 2 NM -VLF at 10 khz

using 8 ground stations



GPS - most important & accurate position fixingnavigation System

Used by a/c, ships & land vehicles

Eqpt is passive & requires only a receiver

Accuracy

C/A code - 100 m

P- code 16m - position, 0.1 m/s - velocity



APPROACH GUIDANCE TO THE

AIRFIELD/AIRPORT ILS, MLS

A full navigation suite on an aircraft include

INS, GPS, VOR/DME, ILS, MLS

Many of these systems are at duplex level andsome may be at triplex level









Weather radar

Installed in all civil airliners & in many generalaviation aircraft

To detect water droplets and provide warning of

storms, cloud turbulence and severe precipitation-

aircraft can alter course and avoid such turbulentconditions

It should be noted that in severe turbulence,

the violence of the vertical gusts can subject the

aircraft structure to very high loads and stresses

These radars can also generally operate in

ground mapping and terrain avoidance modes.

Modern fighter aircraft generally



Modern fighter aircraft generally

Have a ground attack role as well as the prime

interception role and carry very sophisticated multi-

mode radars

In the airborne interception mode, the radar, must

be able to detect aircraft upto 100 miles away and

track while scanning and keeping tabs on several

aircraft simultaneously (typically at least 12 aircraft)

The radar must also have a 'look down' capability

and be able to track low flying aircraft below it.

In the ground attack or mapping mode, the radar

system is able to generate a map type display from the

radar returns from the ground, enabling specific

terrain features to be identified for position fixing and

target acquisition.





The term 'house keeping' management has been usedto cover the automation of the background tasks which

are essential for the aircraft's safe and efficient operation

Such tasks include

Fuel management. The embraces fuel flow and fuel

quantity measurement and control of fuel transfer

from the appropriate fuel tanks to minimize changes

in the aircraft trim

Electrical power supply system management



Cabin/cockpit pressurization systems

Environmental control system

Warning systems

Maintenance and monitoring systems. Thesecomprise monitoring and recording systems which are

integrated into an on-board maintenance computer

system. This provides the information to enable speedy

diagnosis and rectification of equipment and system

failures by pin-pointing faulty units and providing all the

information, such as part numbers etc., for replacement

units down to module level in some cases





Control and the efficient management and monitoring

of the engines

Electronic equipment involved in a modern jet

engine is very considerable

It forms an integral part of the engine and is

essential for its operation

Contd..

E i t l l t i i h i ll t d



Engine control electronics is physically mounted

on the engine FADEC

Automatically controls the flow of fuel and respondto throttle command

Control system ensures the engine limits in terms of

temperatures, engine speeds and accelerations are not

exceed and the engine respond in an optimum manner

to the throttle command

Full authority in terms of the control it can

exercise on the engine and a high integrity failuresurvival control system is essential

A FADEC engine control system is thus similar in

many ways to a FBW flight control system

Other very important engine avionic systems



Other very important engine avionic systems

include

Engine health monitoring systems which measure,

process and record a very wide range of parameters

associated with the performance and health of the

engines

Give early warning of engine performance deterioration,

excessive wear, fatigue damage, high vibration levels,

excessive temperature levels etc



Avionic Systems

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