Crash multiple times

ArduCopter Copter 3.4
1

I am having few navio2 based DIY drones with APM:Copter V3.4.6 (5221448a). The real problem I am facing is, after it did 1-2 successful takeoff and land, in the next attempt, it gets crashed after few rotation in the air immediately after take off. I am not able to find what reason it getting crashed. After initial 3-4 crash, I was thinking that it is the calibration issue and did calibration (accel and compass) of drone every time, before going to takeoff. That also didn’t help. Today I had one more crash.

Earlier I was calibrating drone with radio receiver and after successful takeoff/land, I removed the received and tried to takeoff with mission planner software. Just immediately after takeoff, it started rotating in the air and got crashed. So today after I removed the radio receiver, I did only onboard compass calibration but that also didn’t help.

The navio2 device has 2 compass, I enabled both assuming that it will add more accuracy and tried. But Didn’t help.

I am attaching the log here. I always see “Large change in mag_field” message in the log, I am not sure what reason it is showing.

Successfull takeoff and Land
https://drive.google.com/open?id=11tqraZOCMClCmuMXFivqTPkTu_1gSqgN

Crash
https://drive.google.com/open?id=1_f9FSkp3b0rvYQNZv4IN-AxbzX5stUOs

Anybody can help me in finding the reason for the crash, that will be really helpful.

2

The crashless flight had decent, not good vibrations, also a bit on the high side for such a simple flight.

During the crash flight, you had very high vibrations, thus all the EKF warnings you got…
Too high vibrations, and sensor clipping.
Balance your propellers, dampen your flight controller, make sure nothing is loose.

3

Thank you very much for the reply. During the crash flight, the drone was kept on rotating. I was thinking the vibration is because of this continuous rotation.

Since the drone took off and landed safely 2-3 times, I was under assumption it is safe to take off once again. But that one crashed.

4

If you removed the receiver and didn’t override the yaw RC with MP then the yaw value will be zero and will command a max yaw condition unfortunately. See the discussion here for more details:
https://discuss.ardupilot.org/t/copter-crash-in-rtl-mode/26036/7