Trying to tune 250 quad with Pixracer board

During the tune the copter suddenly turned 180 degrees and faced me. The logs show that EKF turned the copter but don’t know why. This happened twice and I have provided a log.

Log: 188.bin


Hi, what do you mean by “the EKF turned the copter”?

To me, it looks like the frame is twisted badly. And it actually appears to happen during the flight. Motors 1 and 2 are near min throttle, and 3 and 4 approach full throttle. Motor 4 actually hits full throttle a couple times just during gentle flight. I think it spun because it had to give up yaw control to prevent it flipping over.

Ok, I think I found it. One of the motors was coming loose and only had one screw left in it. This may account for the yaw condition. I did see in the log though where at the point it yawed that AHR2 yaw value tracked exactly with the yaw movement leading me to believe it wanted to turn the copter.
When I tried to turn it back it started to fall and was unable to gain control as it hit the ground.
I do see in the logs looking at the motors that it started out looking good but later on motor 4 and 3 started to run higher than the rest leading me to believe it started to fight a yaw.

Still trying to tune the Pixracer with a 250 frame.

I did notice that if I set MOT_THST_EXPO = 0 that the motors in Stabilize power up more evenly and respond evenly on take offs.