Unexplained dive

ArduPlane VTOL Plane
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1

I have been flying my MFE freeman 2100 for a while now and I am having some unintended dive manuevers. It seems to happen after the vehicle completes transition from quadcopter mode to fixed-wing mode. MFE uses 12 m/s as the min transition speed and I am using 14 to be safe. I expect the vehicle will complete transition and then continue on with the planned mission at the correct altitude. However, I notice that the vehicle loses altitude rapidly as it is transitioning. I suspect that the vehicle has stalled and is losing altitude because of that but I’m not certain.

Can anyone help me understand why the vehicle dives during/after transition and how I could remedy the situation? I’ll leave a link to the bin file below. Any help would be greatly appreciated.

2

After the transition is completed, FC attempts to accelerate the aircraft to cruise speed.
When in fixed wing mode, if the aircraft’s speed is less than the target speed, TECS attempts to convert potential energy into kinetic energy by lowering the pitch. That is why the altitude drops after transition.

To avoid this, the following actions could be taken.

  • Make the transition speed closer to the cruising speed.
  • Set the transition altitude higher in anticipation of a drop in altitude after the transition.