It worked perfectly at first, but I did a vertical speed test and it wasn’t moving as quickly nor drawing as much current as it should. Instead of drawing about 90 amps at full throttle, it was drawing 20 amps.
So I thought it might be due to the ESC’s being miscalibrated. Once I did an all-in-one ESC calibration, I began noticing the yaw rotation.
And here’s where it gets interesting. After the calibration, it then draws 50 amps at full throttle. That’s a drastic improvement, but it’s still not the 90 amps I’d expect. But also remember that only every other motor gets warm – the CCW ones.
It’s almost like one or two motors still aren’t calibrated, which is introducing rotation into the copter’s thrust. Then the motors that would need to counter that thrust all work extra hard to stop the rotation. I could see the mixer slowing-down half the motors to stop the yaw, which would explain why I only see about a 50% current draw at full throttle.
The other theory you’ve touched on. Maybe the compass went bad. I may just try another compass with it and see if that helps. I wish someone would look at my logs and see if the compass looks unusually noisy or otherwise “off”.
Also, I know there is a motor test in CLI mode. But is there a test where I could run-up each motor individually and look at the current output? What would be great is to fixture the copter, then run each motor separately at 0, 25%, 50% and 100% throttle, just to see how much current it’s using. That would answer the ESC calibration question but would also answer a number of questions about wiring, motor status, solder joints, etc. etc.