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Difference between revisions of "Head-up display"

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(first stage of a complete revision)
(added autopilot features and more screenshots)
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[[File:HUD_default_overview.png|thumb|520px|Huds/default.xml]]
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[[File:HUD_default_overview.png|thumb|420px|Huds/default.xml]]
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[[File:HUD_minimal_overview.png|thumb|420px|Huds/minimal.xml]]
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[[File:HUD_NTPS_overview.png|thumb|420px|Huds/NPTS.xml]]
 
== Features ==
 
== Features ==
 
=== Control inputs ===
 
=== Control inputs ===
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: [[Avionics and Instruments#Turn Coordinator|Turn Coordinator]]
 
: [[Avionics and Instruments#Turn Coordinator|Turn Coordinator]]
 
: Properties: <code>/orientation/roll-deg</code> and <code>/orientation/side-slip-deg</code>
 
: Properties: <code>/orientation/roll-deg</code> and <code>/orientation/side-slip-deg</code>
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 +
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[[File:HUD_default_autopilot.jpg|thumb|420px|HUD autopilot]]
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=== Autopilot ===
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If the autopilot is active the HUD displays its settings. For each active function (heading, altitude and speed) a box will appear below the gyrocompass containing information on its mode and, if existent, the associated value.
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; Heading control
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: Whether it is active or not and on which mode it operates is determined by the content of the  <code>/autopilot/locks/heading</code> property.
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: The values are taken from <code>/autopilot/settings/heading-bug-deg</code> and <code>/autopilot/settings/true-heading-deg</code>.
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 +
; Altitude control
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: Active mode: <code>/autopilot/locks/altitude</code>
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: Their values: <code>/autopilot/settings/target-altitude-ft</code>, <code>/autopilot/settings/vertical-speed-fpm</code> and <code>/autopilot/settings/target-agl-ft</code>.
 +
 +
; Speed control
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: Active mode: <code>/autopilot/locks/speed</code>
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: Their values: <code>/autopilot/settings/target-speed-kt</code> and <code>/autopilot/settings/target-speed-mach</code>
  
  

Revision as of 20:40, 27 January 2013

WIP.png Work in progress
This article or section will be worked on in the upcoming hours or days.
Note: Article is going to be completely reworked.
See history for the latest developments.

The Head-up display (HUD) is an important instrument in modern, mostly military, cockpits. FlightGear provides a XML-based system to relatively easily create HUDs for aircrafts such as the F-14 and F-16.

However, this article's focus is on FlightGear's default head-up displays. Those are available for any craft which does not include its own set. Have a look at #Further Information if you're planning to create a HUD.

Activate the HUD with the [h]-key. Pressing it repeatedly moves through the configured colours and turns it off again. To change the brightness, press [shift]+[h]. Press [shift]+[i] to go through the available HUD's. Press [i] to switch back to the first one at any time. Have in mind that some aircraft do assign one or more of those keys differently and therefore one or more function/s is/are missing on them.

Some of the head-up display's options can be altered in the menu: View --> Adjust HUD Properties


Huds/default.xml
Huds/minimal.xml
Huds/NPTS.xml

Features

Control inputs

Aileron
Monitors the bearing of the control input on the aileron's axis. Attached along the upper side is the indicator for the trim input on that axis.
Properties: /controls/flight/aileron and /controls/flight/aileron-trim
Elevator
Monitors the bearing of the control input on the elevator's axis. Attached to the left the trim on this axis.
Properties: /controls/flight/elevator and /controls/flight/elevator-trim
Rudder
Monitors the bearing of the control input on the rudder's axis. Attached to the bottom the trim input.
Properties: /controls/flight/rudder and /controls/flight/rudder-trim
Throttle
Monitors the throttle input axis.
Property: /controls/engines/engine/throttle


Instruments

AMSL (Height above mean sea level)
Current altitude relative to sea level in feet (ft) (1 ft = 30.48 cm).
Property: /position/altitude-ft
g-load
The g-force appealing to the pilot - to avoid black-/redout.
Property: /accelerations/pilot/z-accel-fps_sec with factor -0.03108095
Gyrocompass
This is an ideal version of a gyrocompass without the drawbacks of a real one. It shows heading of the aircraft relative to the geographical North Pole (true north) in degree (360 degree scale).
Property: /orientation/heading-deg
KIAS (Knots Indicated Airspeed)
Current speed relating to the ambient air in knot/knots (kt/kts) (1 kt = 1.151 mph = 1.852 km/h).
Property: /velocities/airspeed-kt
Latitude / Longitude
Current location according to the geographic coordinate system.
To change the format of the displayed coordinates, go to Autopilot --> Set Lat/Lon-format.
Properties: /position/latitude-string and /position/longitude-string
Pitch ladder
Displays the aircraft's pitch and roll relative to the ground's level/horizontal in degree. It's used as an artificial horizon (Attitude indicator).
Properties: /orientation/roll-deg and /orientation/pitch-deg
Radio altimeter
Shows current altitude above ground level (AGL) in feet. Relating to the location of the aircraft's radio altimeter, it's not zero if the aircraft is on the ground.
Property: /position/altitude-agl-ft
Turn-bank-indicator
Turn Coordinator
Properties: /orientation/roll-deg and /orientation/side-slip-deg


HUD autopilot

Autopilot

If the autopilot is active the HUD displays its settings. For each active function (heading, altitude and speed) a box will appear below the gyrocompass containing information on its mode and, if existent, the associated value.

Heading control
Whether it is active or not and on which mode it operates is determined by the content of the /autopilot/locks/heading property.
The values are taken from /autopilot/settings/heading-bug-deg and /autopilot/settings/true-heading-deg.
Altitude control
Active mode: /autopilot/locks/altitude
Their values: /autopilot/settings/target-altitude-ft, /autopilot/settings/vertical-speed-fpm and /autopilot/settings/target-agl-ft.
Speed control
Active mode: /autopilot/locks/speed
Their values: /autopilot/settings/target-speed-kt and /autopilot/settings/target-speed-mach


Further Information

The setup of the default HUD is defined at $FG_ROOT/Huds/default.xml.

Documentation can be found at $FG_ROOT/Docs/README.hud.

HUD's may be replaced or added by changing or adding their path(s) to preferences.xml (<hud> tag) or by setting the paths as command line options. To change the order of the existing ones the options would be: --prop:/sim/hud/path[1]=Huds/minimal.xml --prop:/sim/hud/path[2]=Huds/default.xml --prop:/sim/hud/path[3]=Huds/NTPS.xml


Additional HUDs

HeliHUD
Designed to fly helicopters in Helicopter View it is also handy for any craft with a not yet finished cockpit. It also contains a minimalistic HUD only showing some navigation informations such as compass and GPS. The download contains instructions and specs.