Download - Digital Avionics II
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Digital avionics II
Class Presentation CP 2
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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 groundtarget, reconnaissance or
maritime patrol (Military Aircraft)
Why Avionics Systems
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CORE AVIONICS FUNCTIONS
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Aircraft Mission Requirements to Avionics
System Requirements
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Starting point for designing a digital Avionics system is a clear
understanding of the mission requirements and the
requirement levied by the host aircraft
Top-level Requirement for Military
The customer prepares the statement of need and top-level
description of possible missions
Describes the gross characteristic of a hypothetical aircraft that could
fly the mission
Customer may also describe the mission environment and definestrategic and tactical philosophies and principles and rules of
engagement.
Avionics System Design
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Capability
Reliability
Maintainability
Certificability Survivability(military)
Availability
Susceptibility
vulnerability Life cycle cost(military) or cost of ownership(civil)
Weight & power
Major Req of Avionics System
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Capability:
How capable is avionics system?
can they do the job and even more?
Designer to maximize the capability of the systemwithin the constraints that are imposed.
Reliability: Designer strives to make systems as reliable as
possible.
High reliability less maintenance costs.
If less reliable customer will not buy it and interms of civil airlines the certificating agencies willnot certify it.
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Maintainability:
Closely related to reliability
System must need preventive or correctivemaintenance.
System can be maintained through built in testing,automated troubleshooting and easy access to
hardware. Availability:
Combination of reliability and maintainability
Trade of between reliability and maintainability to
optimize availability. Availability translates into sorties for military aircraft
and into revenue flights for civil aircrafts.
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Certificability:
Major area of concern for avionics in civil airlines.
Certification conducted by the regulatory agencies
based on detailed, expert examination of all facets
of aircraft design and operation.
The avionics architecture should be straightforward and easily understandable.
There should be no sneak circuits and no
noobvious modes of operation.
Avionics certification focus on three analyses:
preliminary hazard, fault tree, and FMEA.
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SONAR
RADAR
Military communications Electro optics (FLIR or PIDS)
ECM OR ECCM
ESM Tactical missile guidance
Integrated Avionics weapon systems
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Essential :A function is essential if its loss degrades the flight
control system beyond operational state III.
Flight Phase Essential:Same as essential except it applies only
during specific flight phases.
Non-Critical:Loss of function does not effect flight safety or
reduce control capability beyond that required for operation
state III
Criticality Classification Definitions-9490
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Five operational States for the flight control system:
Operational State I: Normal Operation
Operational State II: Restricted Operation
Operational State I: Minimum safe Operation
Operational State I: Controllable to an immediate
emergency landing
Operational State I: Controllable to an evacuable flightcondition
Requirements of MIL-F-9490
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Probability of failuresFAR 25.1309
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Primary flight information,
Navigation information, Engine data,
Airframe data,
Warning information.
Infrared imaging sensors,
Radar,
Tactical mission data,
Weapon aiming,
Threat warnings.
Military aircrafts
Primary information required
Crucial Information reqd
Heading
Altitude
Airspeed
Rate of turn
Rate of climb (or descent)
Attitude (relative to the horizon )
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Modern Integrated Primary Flight Info Display
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Instrument layout in AIRBUS 320
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Measurement Units : Generally Followed
Pressure : 1 millibar = 100 N/m^2 = 100 Pa
Distance : 1NM = 6076 .1155 ft = 1852 m
Speed : 1 Knots : 0.5144 m/sec ~ 0.5 m/sec
1 m/s = 2 knots
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