Toilet Bowling - Only Starts Halfway Through Auto Mission


I am doing tech support for a university group. Although I recently repaired their copters and ran successful test flights, the university group is running into toilet bowling when they try to fly.

I have attached log files. In both cases the copter seems to fly perfectly straight for the first few tracks of the mission, and then starts toilet bowling violently enough (pitch/roll past 45 degrees) that they put it in loiter (still toilet bowling) and cut the mission short.

I have not run into this before- usually if the compass settings are bad I can tell right off the bat, but this problem doesn’t seem to start until well into the duration of the flight. Any assistance would be greatly appreciated.

I should add that they are using 3DR X8s, with the GPS/Mag mast and everything.

Wild guess: any sticky tape or welcro getting loose over time due to short term vibration, and heals by itself when vibration stops?

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  • COMPASS_OFS_Y and COMPASS_OFS_Z are 0 - redo compass calibration.
  • The Z accelerometer is significantly offset - maybe redo the accelerometer calibration.
  • Maybe do COMPASSMOT as well, just to be safe. Do it with props on and don’t throttle up far enough that the copter moves.