Can someone please explain why my wing turns into a stall with stall prevention enabled?
The ARSPD_FBW_MIN = 11m/s about 40km/h while the actual stall speed of the wing is around 20km/h?
It’s getting into a stall while in FWBA mode with the throttle cut and the pitch max up. I would expect the stall prevention to kick into action at some point, but it doesn’t?
I recommend to read the description of the function in the Wiki: Stall Prevention — Plane documentation
There it is described in which situations and how the stall prevention intervenes. The purpose of stall prevention is certainly not to prevent a maneuver that clearly for everyone will leads to a stall, such as throttle release at maximum pitch up.
According to the wiki you are wrong:
The FBWA mode has an additional special feature to help prevent straight line stalls. It is often difficult for a pilot to judge the airspeed of a plane when it is coming head on, and so many pilots find themselves flying too slow when they are trying to fly gently in FBWA mode. This is especially true if the ArduPilot pitch controller is well tuned and manages to keep the nose up even when flying slowly.
It doesn’t say that it is certainly not to prevent a maneuver that clearly for everyone will leads to a stall.
What it does says is to make a level flight low speed stall less likely some additional down pitch is added in FBWA and AUTOTUNE modes based on the throttle position.
Well that’s exactly what it doesn’t do on my wing, thus a stall occurs. It automatically recovers from the stall when it gains enough airspeed again but thats not actual stall prevention.
Maybe the TRIM_THROTTLE=37 or the STAB_PITCH_DOWN=2 are wrong?
Never mind I found the answer already:
In FBWB and CRUISE modes, without an airspeed sensor, the autopilot will set the target throttle at TRIM_THROTTLE with the throttle at mid-stick, and adjust pitch to hold altitude.
This is only working in FWBA mode with the throttle at mid-stick…
Previously you wrote:
Once you write that the aircraft is stalled in level flight, the other time you write that the aircraft is stalled at maximum climb in FBWA mode. A log file would be helpful.