Tailsitter VTOL problems in FBWA to QLOITER transition

Hello I am experiencing some problems with a VTOL tailsitter, specifically in the transition from FBWA to QLOITER. First, there is a strong throttle increase until it reaches the configured angle (70 degrees); then, when the transition is done a strong pitch oscillation starts, which eventually leads to the loss of vertical position and control. Usually I have been able to save the plane immediately switching to FBWA, but this latest flight something happened and when in FBWA the plane started spinning nose down and eventually met the runway. Any suggestion to make successful transitions to have the plane in perfect loitering (as it is when I initially take off?), also if possible without gaining so much altitude trying to put the plane vertical?

Please find attached flight log (there is also an erroneous switch to QLAND in the first attempt because I could not find the right switch on the radio). Thanks in advance.


first, you must tune QSTABILIZE, then QHOVER, then you can entertain a FW to VTOL transition…lastly QLOITER…oscillations in QLOITER can come from either the loiter tuning or the basic VTOL tuning…show a log with a stably tuned QSTABILIZE , thenQHOVER…showing stable, hard stick moves in pitch. roll, and yaw…then we can try to work on QLOITER

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Thanks for suggestions, I will run the tuning and keep you posted!