Launch ArduPilot + JSBSim + FlightGear, heartbeat waiting

I’m trying to launch the ArduPilot SITL with the JSBSim and FlightGear.

  1. I am running the FlightGear with the following args
nice fgfs \
    --native-fdm=socket,in,10,,5503,udp \
    --fdm=jsb \
    --aircraft=Rascal110-JSBSim \
    --fg-aircraft="$AUTOTESTDIR/aircraft" \
    --airport=BIKF \
    --geometry=1280x768 \
    --bpp=32 \
    --disable-hud-3d \
    --disable-horizon-effect \
    --timeofday=noon \

It’s running fine, except a few warnings like nasal setWeight() - not supported for jsb.

  1. I am running the ArduPilot as
~/ardupilot$ ./Tools/autotest/ -v ArduPlane --console --map -L BIKF -f jsbsim:Rascal

it successfully loads the aircraft model with no errors, but the process stops at

Waiting for heartbeat from tcp:

and the console window is empty

I use the ArduPilot of the latest stable version Plane-4.3.0. The FlightGear version is 2020.3.13. The OS is Linux 20.04. It seems that I forgot to run something.