sim_vehicle.py not sending data to FlightGear

[ugol-1]

Bug report

Issue details

Using FlightGear with ArduPilot SITL as described in https://ardupilot.org/dev/docs/setting-up-sitl-on-linux.html#flightgear-3d-view-optional does not work.

Steps to reproduce:

1. Set up ArduPilot build environment as described in https://ardupilot.org/dev/docs/building-setup-linux.html
2. Install FlightGear:

   sudo apt install flightgear

3. Run FlightGear:

   cd ardupilot && Tools/autotest/fg_plane_view.sh

4. In a second console, run ArduPlane SITL:

   sim_vehicle.py -N -v ArduPlane

5. Load mission and take-off:

   wp load Tools/autotest/Generic_Missions/CMAC-circuit.txt
   mode auto
   arm throttle

Expected behavior: the aircraft takes off in FlightGear Actual behavior: the aircraft sits on the ground in FlightGear

Version Ardupilot: https://github.com/ArduPilot/ardupilot/commit/5cd18dbc451e91d65d686cad5d57ebd343171abc FlightGear version: 2020.3.18

Platform [ ] All [ ] AntennaTracker [x] Copter [x] Plane [ ] Rover [ ] Submarine

Airframe type any

Hardware type SITL

Logs MAVProxy console:

wp load Tools/autotest/Generic_Missions/CMAC-circuit.txt
MANUAL> Loaded 8 waypoints from Tools/autotest/Generic_Missions/CMAC-circuit.txt
Loaded 8 waypoints in 0.15s
Sent all 8 waypoints
Got MISSION_ACK: TYPE_MISSION: ACCEPTED
AP: Flight plan received
mode auto
MANUAL> Got COMMAND_ACK: DO_SET_MODE: ACCEPTED
AUTO> Mode AUTO
AP: Mission: 1 Takeoff
200
waypoint 1
arm throttle
AUTO> Got COMMAND_ACK: COMPONENT_ARM_DISARM: ACCEPTED
AP: Throttle armed
AP: Armed AUTO, xaccel = -0.0 m/s/s, waiting 0.2 sec
AP: Triggered AUTO. GPS speed = 0.0
ARMED
AP: Holding course 35279 at 17.7m/s (-0.0)
height 15
height 26
AP: Takeoff level-off starting at 17m
height 37
AP: Takeoff complete at 41.45m
AP: Mission: 2 WP
height 47
400
waypoint 2
200

FlightGear window:

[ugol-1]

Sending data to FlightGear was disabled by default in 747afd7673e18ab2a8b324fe8ec6c3a9722cea4a, this is why it stopped working.