I have been experimenting with QAUTOTUNE on the 4.1 release of ArduPlane which generally leads to poor results.
The aircraft is similar to an X8 Tri-tiltrotor and the test bed in SITL on XPlane 11. After several hours with QAUTOTUNE fails, I decided to trust my own intuition to tweak the PIDs and managed to achieve stable hovers and transitions.
Then I decided to check if QAUTOTUNE could improve things a little more using my healthy starting point. Roll check, Pitch check and Yaw check - Ardupliot confirmed successful completion of the QAUTOTUNE. When I took the controls back on the joystick I realized the aircraft was again in a poor state with a lot of oscillations in pitch, roll and Yaw!
What should I take away from all this? I take that QAUTOTUNE works fine for several people with varying aircraft designs.
Are there any aircraft design conditions that prohibit QAUTOTUNE from doing its job? In retrospect, the new AUTO TUNE for conventional flight works perfectly… I am a little puzzled.