Avionics Overview
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Transcript of Avionics Overview
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