AGL in JSBSIM for Unreal goes to 0 when height over 11000 ft

[nmfarras]

Hi I try to implement some feature that need AGL value as the reference. I notice that when the value goes above around 11000 ft, the AGL automatically become 0. I turn the debugging feature but the trace line seems touching the ground. Any idea what's wrong with it?

Above 11000 ft

Below 11000 ft

I try with the default model on UEReferenceApp too and the result more or less similar

Above:

Below 11000 ft:

any insight? I may need the AGL can still be read around 25000 ft if possible

[gallonmate]

Yes there is bug with unit conversion. The code uses meters, instead of Unreal's centimeters.
The original code here on line137 says FEET_TO_METER

jsbsim/UnrealEngine/Plugins/JSBSimFlightDynamicsModel/Source/JSBSimFlightDynamicsModel/Private/JSBSimMovementComponent.cpp

Line 137 in 2a5985c

FVector LineCheckEnd = StartEngineLocation - (AircraftState.AltitudeASLFt * FEET_TO_METER + 0.05 * GeoReferencingSystem->GetGeographicEllipsoidMaxRadius()) * Up;

Open your JSBSimMovementComponent.cpp file and change that to FEET_TO_CENTIMETER, then compile. AGL will now work correctly at any altitude.

[nmfarras]

I never expect that was the case. Thank you for the quick response! Now it work without problem.

[seanmcleod]

@gallonmate will you submit a pull request with this change?

[seanmcleod]

@gallonmate would you prefer me to submit a pull request with your fix?

[gallonmate]

you can if you like, since I'm running behind on things. There's another tiny bug fix I was waiting to submit that's unrelated, but I was waiting for a chance to really sit down, build and test the latest UE5/JSBSim versions, and also re-visit some build issues there were noted by others. And I just haven't had the time. Feel free to submit. It could be a week or another month before I get around to it.

[seanmcleod]

Okay, fixed in commit - 754a4ac

[gallonmate]

@seanmcleod thanks!