Platform: quad, about 2m in diameter, 40" props, and just under 25kg without payload.
Hardware: Cube Orange, 2*Here3 GPSs (blending), Mauch voltage and current sensors.
Running ArduCopter V4.0.5 (3f6b43e3)
Basically, I am experiencing toilet bowling in Loiter, that I think does not come from the compasses, in the first minute of flight, after which I change modes, fly a bit in AltHold and then trying again Loiter, at which time the toilet bowling disappears. In the first minute, I tried twice to counteract the toilet bowl effect with stick input but I also left it some seconds on its own. We have 3 completely identical drones and we have flown them a bit (about 100 flights) without any issues. Here is the log.
What I have done, checked or what you should consider:
- Prior to the flight, compass calibration was done (using only the 2 external ones, which are about 40cm in front and 30 above the AP) along with radio calibration and horizon calibration. All other settings were done in/before prior flights.
- Motors are aligned up to 0.2deg. Structure is fine
- Motors do start at the same PWM
- On the day of the flight there was wind (3~6 m/s)
- Drone was on at least 3 min prior to take-off if I recall correctly
- I found interesting things, though inconclusive from : NKF3 IVN & IVE, NKF4 SV & SP, PSC TPX & PX / TPY & PY
- The drone was not flown since but flew prior without issues, though not too much
- KP index was low. The flight was done quite north. The day was not overcast
Any help would be good. I am out of ideas. Maybe it comes from the GPSs, or Velocity XY PIDs but I was not able to draw a conclusion.