Common aircraft properties

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WORK IN PROGRESS

TODO: standardise locations most common to existing aircraft to ease transition

With reference from: http://wiki.flightgear.org/Property_Tree/Reference

a suffix of norm means a normalised value for example a float/double of 0 to 1 to indicate full deployment or retraction of gears, as opposed to degrees.

With common aircraft properties found in uncommon locations, assigning buttons in joysticks to certain functions became mostly a hit or miss affair. For example speedbrakes and thrust reversers are found in different location in the property tree, even across official FlightGear planes! Without standard locations, joystick code tends to be aircraft specific.

There was an attempt to unify it all with a nasal script but after consultation and comments with others, this attempt was replaced with the solution to standardise common aircraft properties in standardised locations.

This document will exhaustively list property tree locations where aircraft developers should store their common aircraft properties (if not alias them).

Values in states should be used to set states and to animate cockpit internals like levers. Values in transition properties should be used to animate external objects such as animating a retracting gear.

define /sim/propertystd = 1

Gear

Properties marked with an '✲' are standard across all aircraft and should always be set. For example, an old aircraft without any autobrakes should still define /controls/gear/autobrake although set it to 0

States

/controls/gear is a backward compatible alias for /controls/gears

• In /controls/gears
  • /controls/gears/brake-parking ✲
    0 = Off
    1 = On
  • /controls/gears/brake-left
    a backward compatible alias for /controls/gears/gear[1]/brake (or the property for the left brake)
  • /controls/gears/brake-right
    a backward compatible alias for /controls/gears/gear[2]/brake (or the property for the right brake)

• • /controls/gears/inputs/pilot-pedal-toe-left
    a backward compatible alias for /controls/gears/brake-left
  • /controls/gears/inputs/pilot-pedal-toe-right
    a backward compatible alias for /controls/gears/brake-right
  • /controls/gears/inputs/pilot-pedal-heel-left alias for
  • /controls/gears/inputs/pilot-pedal-heel-right alias for
  • /controls/gears/inputs/copilot-pedal-toe-left
    a backward compatible alias for /controls/gears/brake-left
  • /controls/gears/inputs/copilot-pedal-toe-right
    a backward compatible alias for /controls/gears/brake-right
  • /controls/gears/inputs/copilot-pedal-heel-left alias for
  • /controls/gears/inputs/copilot-pedal-heel-right alias for

• • /controls/gears/outputs/pilot-pedal-toe-left
    a backward compatible alias for /controls/gears/brake-left
  • /controls/gears/outputs/pilot-pedal-toe-right
    a backward compatible alias for /controls/gears/brake-right
  • /controls/gears/outputs/pilot-pedal-heel-left alias for
  • /controls/gears/outputs/pilot-pedal-heel-right alias for
  • /controls/gears/outputs/copilot-pedal-toe-left
    a backward compatible alias for /controls/gears/brake-left
  • /controls/gears/outputs/copilot-pedal-toe-right
    a backward compatible alias for /controls/gears/brake-right
  • /controls/gears/outputs/copilot-pedal-heel-left alias for
  • /controls/gears/outputs/copilot-pedal-heel-right alias for

• • /controls/gears/brake-chokes ✲
    0 = Off
    1 = On
  • /controls/gears/antiskid ✲
    0 = Off
    1 = On
  • /controls/gears/autobrake ✲
    0 = Fully Off
    1 = Fully On
  • /controls/gears/launchbar ✲
  • /controls/gears/servicable ✲
  • /controls/gears/brake-servicable
  • /controls/gears/brake-temperature
  • /controls/gears/brake-hydraulic-pressure
  • /controls/gears/tyre-temperature
  • /controls/gears/tyre-pressure
  • /controls/gears/brake-available ✲
  • /controls/gears/retractable ✲
  • /controls/gears/brake ✲
  • /controls/gears/gear-down
0 = Retracted
    1 = Extended

nosewheel-steering alias for gear[0]

tailwheel-lock alias for

wheel[n]/alternate-extension alias for

• In /controls/gears/gear[n]
  Due to the complex nature of gear configuration, gear numbering is not enforced. However, where possible, 0=nose, 1=left, 2=right, 3=tail. And where there are multiple, independent struts, they should be grouped under the side they appear. For example front strut on the left gear at gear[1]/gear[0]
  • /controls/gears/gear[n]/brakes/temperature
  • /controls/gears/gear[n]/brakes/hydraulic-pressure
  • /controls/gears/gear[n]/brakes/brake-pressure
  • /controls/gears/gear[n]/brakes/available

• • /controls/gears/gear[n]/tyre/temperature
  • /controls/gears/gear[n]/tyre/air-pressure-norm
  • /controls/gears/gear[n]/tyre/air-pressure-real

water-brakes

compression-ft

compression-norm

steering-norm

tailhook

lights

lights-angle

wheel speed

water rudder <-- should this be here?

Transitions

• In /gears/gear[n]
  • /gears/gear[n]/position-norm
0 = Fully Retracted
    0.x = Transitioning
    1 = Fully Extended
• In /controls/gears/gear[n]

brake-pressure 0 0.x 1

friction-ground

friction-ground-real

friction-bearing

friction-bearing-real

friction-side-slip

friction-side-slip-real

Speedbrakes

engine

--thrust reversers

flaps

tailhook

Radios

The following is for virtual devices. Should you use a a different radio, you should use your own structure and update these values.

For example a user will set comm[0] frequency at /instrumentation/comm[n]/frequencies/selected-int. Your device should monitor this value and on change, assume an input. You then do your tests and own logic and set the /instrumentation/comm[n]/output/selected-int. The purpose of this dual step process is to account for faulty instruments. The frequency that FlightGear will then use for audio will be the output/selected-int

To ignore failures, it is ok to alias output to input. Always set values on input though and FlightGear will read from output. Only the FlightGear F12 menu may read from input.

You should therefore your own input with the default input, and likewise with the outputs

Common across all radios in /instrumentation/*/
For example /instrumentation/comm[1]/power/voltage-min

• • power/voltage-min
  • power/voltage-typical
  • power/voltage-max
  • power/current-typical
  • power/current-quiesecent
  • power/current-xmit
  • power/current-min
  • power/current-max
  • power/real-voltage (current voltage it is getting)
  • power/real-current (current current it is getting)
  • power/fused
  • power/short-after-fuse
  • power/short-before-fuse
  • operable
  • serviceable (bool)

Common across all radios in /instrumentation/*/ except Transponder

• • audio/squelch-xmit
  • audio/squelch-recv
  • audio/volume-xmit
  • audio/volume-recv

Comms

• In /instrumentation/comm[n]/
  • /instrumentation/comm[n]/frequencies/selected-int
  • /instrumentation/comm[n]/frequencies/standby-int
  • /instrumentation/comm[n]/input/swap-btn
  • /instrumentation/comm[n]/input/test-btn
  • /instrumentation/comm[n]/input/ptt-btn
  • /instrumentation/comm[n]/output/selected-int
  • /instrumentation/comm[n]/output/standby-int
  • /instrumentation/comm[n]/illumination
  • /instrumentation/comm[n]/ptt

Deprecated

• • frequencies/selected-mhz
  • frequencies/standby-mhz
  • volume
    deprecated alias for /instrumentation/comm[n]/audio/volume-recv

Transponder

• In /instrumentation/transponder/
  • altitude-valid
  • inputs/digit[n] LSB First
  • inputs/ident-btn
  • inputs/mode
  • inputs/altitude
  • outputs/mode
  • outputs/altitude
  • outputs/id-code
  • outputs/ident

Deprecated

• id-code
• ident
• transmitted-id
• /instrumentation/transponder/altitude deprecated alias for /instrumentation/transponder/inputs/altitude
• /instrumentation/transponder/inputs/knob-mode deprecated alias for ** /instrumentation/transponder/inputs/mode

- /instrumentation/adf

adf-btn

bfo-btn

display-mode

error-deg

enroute-timer/running, start-time, time

flight-timer

frequencies/selected-khz, standby-khz

ident = BED

ident-audible

in-range

indicated-bearing-deg

mode

operable

power-btn

fight-display

rotation-deg

serviceable

set-btn

volume-norm

- /instrumentation/nav

dme

fuel indicator

failures

Fuel

• In /controls/fuel/
  • dump-valve
  • dump-valve-norm (dimensionless dump value normalised to 1 where 1 equals the fuel-flow-litres-max)
  • fuel-flow-pressure-norm (dimensionless pressure value) default 1 (negative numbers and numbers beyond 1 allowed)
  • fuel-flow-resistance-norm (dimensionless "reverse" pressure value) default 0 (negative numbers and numbers beyond 1 allowed)
  • fuel-flow-norm (dimensionless fuel flow value based on pressure minus resistance) default inherited/calculated = 1
  • fuel-flow-litres
  • fuel-flow-litres-typical //define default max burnrate at max throttle and nose diving
  • fuel-density-kgpm3 (average)
  • fuel-density-ppg (average)
  • total-fuel-norm

• In /controls/fuel/tank[n]/boost-pump[n]/
  • fuel-flow-pressure-norm (dimensionless pressure value) default 1 (negative numbers and numbers beyond 1 allowed)
  • fuel-flow-resistance-norm (dimensionless "reverse" pressure value) default 0 (negative numbers and numbers beyond 1 allowed)
  • fuel-flow-norm (dimensionless fuel flow value based on pressure minus resistance) default inherited/calculated = 1
  • fuel-flow-litres
  • fuel-flow-litres-typical //define default max burnrate at max throttle and nose diving
  • fuel-density-kgpm3 (average)
  • fuel-density-ppg (average)

• In /consumables/fuel/weight/
  • total-capacity-lbs
  • total-capacity-kg
  • total-lbs
  • total-kg

• In /consumables/fuel/volume/
  • total-capacity-litres
  • total-capacity-gals_imp
  • total-capacity-gals_us
  • total-litres
  • total-gals_imp
  • total-gals_us

• In /consumables/fuel/tank[n]
  • level-fuel-norm

• In /consumables/fuel/tank[n]/weight/
  • level-capacity-lbs
  • level-capacity-kg
  • level-lbs
  • level-kg

• In /consumables/fuel/tank[n]/volume/
  • level-capacity-gals_imp
  • level-capacity-gals_us
  • level-capacity-litres
  • level-gals_imp
  • level-gals_us
  • level-litres

• Deprecated values
  • /consumables/fuel/total-gal_imp deprecated alias for /consumables/fuel/total-gals_imp
  • /consumables/fuel/total-gal_us deprecated alias for /consumables/fuel/total-gals_imp
  • fuel-selector
  • to_engine
  • to_tank

Implementation with custom locations: If you require your values be stored in a custom location, be sure to alias them in the standard location: <property alias="../../params/n1"/>

Related content

• Aircraft-set.xml
• Property tree