Dr. J. Shanmugam

Prof of Avionics

M. I. T., Anna University

Chennai

    Combination of aviation and electronics

    Avionics system or Avionics sub-system dependent on

electronics

    Avionics industry- a major multi-billion dollar industry world

wide

    Avionics equipment on a modern military or civil aircraft\

account for around

      30% of the total cost of the aircraft

40% in the case of a maritime patrol/anti-submarine aircraft (or helicopter)

Over 75% of the total cost in the case of an airborne early warning aircraft

such as an AWACS

To enable the flight crew to carry out the aircraft

mission safely and efficiently

Mission is carrying passengers to their destination

(Civil Airliner)

Intercepting a hostile aircraft, attacking a ground

target, reconnaissance or maritime patrol (Military Aircraft)

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 consumption Improved 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

AIRPLANE PARTS

Aircraft MotionPitching

Elevator

Aircraft MotionRolling

Aileron

Aircraft MotionYawing

Rudder

COCKPIT DISPLAY Provides

Visual presentation of Information & Datafrom 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 aircraft

and 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

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 Systems

  Accurate 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

Accelerometer

AHRS 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 inertial guidance 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 fixing navigation 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 and some may be at triplex level

Radar systems

Infrared sensor systems

All weather, night time operation

Transform the operational capability of the aircraft

Weather radar

Installed in all civil airliners & in many general aviation aircraft

To detect water droplets and provide warning of storms, cloud turbulence and severe precipitation-aircraft can alter course and avoid such turbulent conditions

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

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 radarsystem 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 used to 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 fuelquantity 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. These comprise 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..

Engine control electronics is physically mounted on the engine FADEC

Automatically controls the flow of fuel and respond to throttle command

Control system ensures the engine limits in terms of temperatures, engine speeds and accelerations are notexceed and the engine respond in an optimum mannerto the throttle command

Full authority in terms of the control it can exercise on the engine and a high integrity failure survival 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 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

NAVIGATION MANAGEMENT SYSTEM

• Comprises the operation of all radio navigation aid systems and combination of the data from all the navigation sources, such as GPS and INS systems to provide the best possible estimate of the aircraft position, ground speed and track.

• system then derives the steering commands for the auto pilot so that the aircraft automatically follows the planned navigation route, including any changes in heading as particular waypoints are reached along the route to the destination.

AUTO PILOT AND FMS

• Very close degree of interaction between these systems on modern civil aircraft.

• Apart from basic modes like Altitude holds, Mach hold, Heading hold, it also provide applications as automatic landings in poor or even zero visibility conditions.

• In military applications, the autopilot system in conjunction with a suitable guidance system can provide automatic terrain following, or terrain avoidance. This enables the aircraft to fly automatically at high speed at very low altitudes( 100 to 200 ft) so that the aircraft can take advantage of terrain screening and stay below the radar horizon of enemy radars.

Sophisticated FMS have come into wide scale use on civil aircraft since the early 1980s and have enabled two crew operations of the largest, long range civil jet airlines. The tasks carried out by the FMS include:-• Flight planning • Navigation management• Engine control to maintain the planned speed or Mach

number.• Control of the aircraft flight path to follow the optimized

planned route.• Control of the vertical flight profile.• Ensuring the aircraft is at the planned 3D position at the

planned time slot; often referred to as 4D navigation. This is very important for air traffic control.

• Flight envelope monitoring.• Minimizing fuel composition.

LCA

SUKOI