Copter Yaws CCW during takeoff

After arming copter, it spins CCW during takeoff.

Datalog: 11 12-31-1969 4-00-01 PM.bin (528.4 KB)

Things I checked

  • Verified correct motor direction and order
  • Recalibrated my RC 3 times and verified that other stick inputs do not affect yaw
  • No mechanical tilt of motors apparent

Data shows that yaw rc input appears to be at max pwm even though I’m not physcially pushing on yaw stick, so confused on what’s actually causing that.

I’m using a new tx16s transmitter, so maybe it could be a trim issue. I believe I have disabled the trim buttons though.

Sometimes this can happen by holding the yaw stick a fraction too long - I used to get that too but changed to an Arm/Disarm switch combination.
In your case it is largely due to the compass being affected by the sudden battery current increase. In fact the whole time the compass is affected by battery/motor current (throttle).
Can you move the compass further away from battery and wiring?
Also do a flight with lots of yaw and circles and we can run that log through MagFit to improve the compass calibration. It would help if you had voltage and current monitoring.

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I thought that the compass is not used when flying in stabilize mode - is that not true?

Unfortunately, I’m pretty limited on space, so may not be able to move gps any further away.


Not true and in any case you need to address this. Run Magfit as Shawn suggests. It’s the right way to calibrate and compensate the compass.

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Thanks for the recommendation. For the magfit flight, would a simple hover with a few full 360deg yaw rotations suffice?

A couple figure 8’s and some varying throttle if you want data for mag cal and motor comp. Magfit does both. There is a cool Lua script available that will automate it.

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Thank you @dkemxr and @xfacta. Doing the magfit cal ended up resolving my yaw issues!