FGproperties/velocities/u v wbody-fps
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description
those are the plane velocity in ECEF (relative to the earth) expressed in the plane body axis:
- /velocities/uBody-fps: velocity projeted along the longitudinal plane axis, positif forward
- /velocities/vBody-fps: along the lateral axis, positif on the right
- /velocities/wBody-fps: along the normal axis, positif is down
unit: foot per second
main use
- sometimes used in wheels animation, they are transmitted to mp plane without the need of xml configuration (FG 3.0 +).
- before FG 3.0, ubody-fps was used in true air speed indicator for yasim plane, this has to be replaced with:
/instrumentation/airspeed-indicator/true-speed-kt
don't forget the unit change!!
- the main reason for the bug fixe is that those propreties are used in the motionInfo packet, and they should not be relative to the wind, but describe the plane velocity in ECEF. It make it possible to predict the plane position to compensate for the lag.
conflict-solution
Yasim was providing the speed relative to the air mass, giving spinning wheels with stopped plane, but acurate tas.
JSBSim was ok, giving a false tas if used.
see bug report #202 for the fix