Hi PX4 community,
I’m trying to run PX4 SITL with JSBSim using the hexarotor_x model on Ubuntu 22.04.4 LTS, but I’m facing startup, arming, and movement issues.
My setup:
OS: Ubuntu 22.04.4 LTS jammy
PX4-Autopilot: local source tree
JSBSim version: 1.3.1
JSBSim Version: 1.3.1
GitHub build 1837 / commit 3b25f25e49b42d0489c04ac805674fc1450ca579
May 17 2026
Installed JSBSim packages:
jsbsim 1.3.1 amd64
jsbsim-devel 1.3.1 amd64
FlightGear: installed locally
QGroundControl: normal installed QGC app from the official download page
Launch command I used
cd ~/PX4-Autopilot
export PX4_HOME_LAT=47.451351
export PX4_HOME_LON=8.561944
export PX4_HOME_ALT=400
make px4_sitl jsbsim_hexarotor_x
What happens
PX4 and JSBSim start successfully, and I can see messages such as:
home set
Ready for takeoff!
JSBSim also logs the aircraft model information, and FlightGear opens.
However, I have the following problems:
The drone sometimes appears at the wrong place or altitude in FlightGear.
QGroundControl may show the vehicle on a runway, while FlightGear shows it above the ocean or at a different position.
When I run the following command in the PX4 shell:
commander arm
PX4 says:
Armed by internal command
Then shortly after that, it automatically disarms with:
Disarmed by auto preflight disarming
I am unable to take off.
I am also unable to move the drone using either QGroundControl controls or PX4 terminal commands.
Sometimes FlightGear seems to keep loading for a long time, or QGroundControl controls do nothing.
What I already tried
I cleaned old processes using:
pkill -f px4
pkill -f JSBSim
pkill -f fgfs
I also tried setting the home position manually:
export PX4_HOME_LAT=47.451351
export PX4_HOME_LON=8.561944
export PX4_HOME_ALT=400
Other things I checked:
Ran the simulation from the local PX4-Autopilot tree
Verified the JSBSim version
Confirmed that PX4 terminal shows home set
Confirmed that PX4 reaches Ready for takeoff!
Questions
Is this issue caused by one of the following?
A PX4 / JSBSim / FlightGear compatibility issue
A home position / origin mismatch
A FlightGear startup, scenery, or graphics issue
A PX4 preflight / arming configuration problem
Something specific to the jsbsim_hexarotor_x model
Also, is there a better way to make the home position auto-set for jsbsim_hexarotor_x instead of exporting the coordinates every time?
If needed, I can share the exact PX4, JSBSim, and FlightGear console logs.
Thanks.