When flying a Quadplane (Pixhawk, ArduPlane V3.8.0beta5) mission in AUTO mode, transition from VTOL to FW resulted in very high pitch and roll angles (with wind about 4 m/s) at about 50m of altitude. Aircraft is saved by changing mode to “QHOVER” and landed safely.
I dont have DataFlash logs due to “No IO Thread Heartbeat” error, but .tlog and videos (from ground and from onboard camera) are provided below.
I see that before transition started, the aircraft was hovering fine in the wind with attitude oscillations (Pitch: -12deg, Roll:13deg). When FW THR (% 100) is applied, attitude changes very fast (Pitch: 23deg, Roll:-25) and reaches up to very high values (Pitch: 61deg, Roll: -121deg) with the help of the wind.
So, my suggestions are;
- Angle and angular rate limits may be defined before switching to FW, in order to ensure that the aircraft is not moving prior to applying full FW throttle.
- Instead of applying full FW throttle instantly, a time interval may be defined so that throttle rises gradually, as in shutting VTOL motors with Q_TRANSITION_MS. This would also decrease power demand at the beginning of the transitions and improve altitude loss due to instant voltage drop.
Any other opinion?