Quadcopter goes out of control

I have a new quad build as follows:
A TBS Discovery knock off frame, 2212 100KV motors, 30A generic ESC, Pixhawk 2.4.8, Ublox M7 GPS/Compass, Arducopter 3.6.4, Frsky X4R-SB receiver.
The first flight with this setup after approximately 90seconds in the air the copter suddenly started rotating and descending and it appeared that I had no control. Fortunately there was no damage. The best I could tell from logs was that the compasses were not properly calibrated.
I went through all of the setup steps again and, again, to the best of my knowledge, everything was calibrated correctly.
The next attempt also resulted in a crash. This time after about 60 to 90 seconds at about 15 feet AGL it started a fair pitch to the right and descended to the ground. Again no significant damage.
I cannot find the problem. I would appreciate if someone could take a look at the attached the log file.



I don’t see 60 seconds of flight in that log. I see 3 seconds of motors spinning on the ground followed by 4 seconds of erratic flight.

I don’t think 2212 100KV motors are practical for flying drones. Double check the information you gave for your motors. Propeller data is equally important.

Since 2 motors immediately spin up considerably faster than the other 2 the moment you give some throttle before takeoff, try recalibrating accelerometer unless you’re taking off on a slope.

I would also double check motor locations and spin directions. It appears there’s a mismatch between where the computer thinks your motors are and spin directions and where they actually are.

If I were you, I’d flash to 3.6.7 and begin the firmware setup from scratch using the wizard after fixing the above mechanical problem.

Sorry, I uploaded the wrong log file. This is the right one:

The motors are 1000kv.
I will load the updated FW and try again when it stops raining.

Seems a Motor4 inflight failure. Check rcout4, it goes to saturation without any command…

Thanks, that is it. On the bench, running at mid throttle in stabilize mode, after 2 to 3 minutes motor 4 spins down to an “idle” speed and then goes dead. I swapped motors and had the same issue. So I’m guessing it’s a bad ESC.

Again, thanks for the quick response.