My quadplane keeps losing altitude during its transition to forward flight. It dips about 10 - 15 metres every time it transitions, and I can’t seem to figure out why.
The quadplane frame is physically able to maintain altitude during a QHOVER --> FBWA transition if I hold some up elevator and keep the throttle at 100%. However, the aircraft gets a commanded -5 degrees of pitch and also reduces forward throttle during the transition which causes the aircraft to dive towards the ground before being able to pull up.
Things I’ve tried
- TECS_SPDWGT from 1 to 0.7 to 0.5 (favour altitude control with pitch)
- ARSPD_FBW_MAX from 23 -> 30 to make sure throttle doesn’t cut off before reaching max airspeed
- TRIM_THROTTLE from 17 -> 20 to hold a higher airspeed during transition - worse altitude drop.
- Increase Q_TRANSITION_MS from 5000 ms to 15000 ms, and from 15000 ms to 2000 ms. Both almost resulted in a crash as the aircraft dived harder.
I’ve attached a log with two flights demonstrating the issue: https://drive.google.com/open?id=1_AfBhg7mkQOlIf3N8l1t0K1C66eEG63L
Any idea what causes this?