In real flight, the pusher motor control airspeed and maintain it constantly at trim airspeed with some low oscillations and ground speed changes more because of wind speed. also, the throttle oscillates around the cruise throttle.
but in the gazebo SITL test with the standard plane, thrust increases to 100 % but can not increase airspeed to trim airspeed in the front wind. thrust decrease to 0% but can not decrease airspeed to trim airspeed in a tailwind.
I think may drag calculated by ground speed, not airspeed.
Could you check if this fix https://github.com/PX4/PX4-SITL_gazebo/pull/674 is included in the version you are testing?
yes , it solved this issue a bit.
There is also an issue. throttle is not same for same airspeed. In front wind and back wind airspeed is constant(trim airspeed) and same but throttle differs for back wind and front wind.
@mohammad Do you have a log that shows the problem?
In this log, airspeed trimmed constantly at about 15m/s. Throttle in front wind is 22 % and in the back wind is 47%.
@mohammad Are you sure the log is using the PX4 version with the fix included? The airspeed is changing with the groundspeed in the log you have shared, therefore the throttle varies when you are in headwind/tailwind.
This is precisely the problem we had before the fix
yes , i changed PX4 version but sitl gazebo module did not updated, i changed the gazebo motor model, problem solved.