I’m a complete noob in log analysis and I’m requesting scrutiny of the log and recommendations for improvement. Comments and recommendations are highly appreciated.
All motors were calibrated individually directly from the Rx. All motors seemed to respond equally against throttle settings of the Tx. Then the calibration procedure in QGC was done.
The LiPo pack used for this hover test is not in the best of shape which is a factor in a fairly quick voltage drop. I do intend to use a newer and better pack for FW transition test.
CG is balanced for FW flight.
FC is mounted at just about at CoT (center or thrust) of MC motors.
Observations:
Upon arming throttle at full idle, #1 and #3 seem to spin faster than #2 and #4 didn’t start spinning until throttle was increase slightly. Most obvious in 2:22 of video
PIDs seem to be sufficient to maintain stable hover for now but recommendations are certainly welcome.
Yaw seemed to be saturating, especially as battery voltage drops below 15v.
Issues:
#1 Motor is very hot, almost burning to the touch.
#2, #3 and #4 are very warm but can be held for an extended period of time.
All ESCs were cool to the touch.
Suspicions:
#1 motor is below par in condition vs. the others and may need to be replaced.
All motors may need to be tilted inward to improve yaw authority?
Yeah motor 1 and 3 are certainly spinning faster than 2 and 4, 1 is saturated during almost all the flight. As 1 and 3 are the front motors, it very much looks like the CG is quite some distance in front of CoT. For really good hover performance you should think about changing that (e.g. move the front motors further forward).
To improve yaw authority, you should think about tilting the motors outwards (not inward), assuming you are using the quad-x configuration (e.g. front right spinning CCW).
I would start with doing a hover flight with the CG moved a bit further back, and also enable MC airmode (set MC_AIRMODE to 1). This should give you more control authority around pitch and roll. And if it’s easy to do, then certainly tilt the motors to also have better yaw.
Thank you very much @sfuhrer and @JulianOes for the quick response. Your analysis is pretty spot on and in line with my suspicions. CG is in fact about 90mm ahead of CoT. Unfortunately, I don’t have any room to move the front motors and could only get away with maybe moving the rear about 25mm forward, which will only move the CoT about 5mm closer to CG.
It seems that my only option is to install more powerful/ higher kV motors on the front to compensate for the saturation. I have SunnySky X2216 - 1250kV that could give about a 40% boost on front motors. What’s your opinion to that solution?
I don’t think installing differently sized motors is a good option, better replace all 4.
But yeah, more powerful motors plus airmode enabled could be sufficient to get a reasonable hovering performance. Fixing the problem in hardware would of course be even better;)
