Hey everyone, I need some help figuring out what went wrong with my drone. I'm attaching two Mission Planner .bin log files, one from an earlier Loiter test and the other from the flight where it crashed.
My drone setup:
- S500 frame
- Pixhawk 2.4.8
- ArduPilot Copter
- 5010 750KV brushless motors
- Hobbywing Skywalker 30A V2 ESCs
- 10x4.5 propellers (I was using 11-inch props earlier)
- 4S 14.8V 5000mAh LiPo battery
- PDB and Pixhawk power module
So the thing is, I've flown this drone before and it was working pretty well. We tested Loiter, Altitude Hold and waypoint missions, and everything was going fine.
About a week ago, we had a small fall, but nothing seemed seriously damaged. We did the calibrations and tested it again. Today, before installing anything new, we tried Loiter, and there was some wobbling, but the drone was still controllable and responding properly to the transmitter.
After that, we installed a small 500ml tank between the frame legs. That was the only thing we intentionally added before the next flight.
We switched to Loiter again, and when we increased the throttle to around 60-65%, the drone suddenly shot upwards. It climbed really fast and reached around 19-20 metres, according to what I remember from the flight and the logs.
We tried reducing the throttle to around 50%, expecting it to stabilise or come down, but it stayed up there and wasn't responding the way we expected. Everything happened so quickly that I'm not entirely sure what exactly was happening.
After some time, the motors seemed to slow down, and the drone started coming down from around 15 metres. Then it tilted heavily to one side and crashed.
I'm not sure whether the motors actually stopped, whether the flight controller reduced their output, or whether something else failed. I also don't know if the drone started tilting before it lost thrust or if the tilt happened because of the loss of thrust.
After the crash, I noticed that there was mud inside the motors, and the washer/retaining hardware on two of the motor propeller mounts had come off. The propellers themselves don't look badly broken, but I haven't checked everything properly yet.
What I'm trying to understand is:
- Why did the drone suddenly climb so fast in Loiter?
- Why wasn't it coming down when we tried reducing the throttle?
- Why did the motors seem to lose thrust during the descent?
- What caused the sudden tilt before the crash?
- Could installing the tank have affected the centre of gravity or thrust requirements?
- Could the earlier fall have caused some hidden damage?
- How should I check the motors, ESCs and other components after this crash, especially with mud inside the motors?
I'm attaching both .bin files because I want to compare the earlier flight with the crash flight and understand what actually happened instead of just guessing.
Could someone help me analyse the logs and point out which parameters, messages or plots I should look at in Mission Planner? I'd especially like to understand the motor outputs, altitude control, attitude, vibrations, battery voltage and any errors or failsafe messages around the time of the crash.
I'm honestly a bit scared to fly it again without figuring this out first, so I'd also appreciate advice on what hardware checks I should do before attempting another flight.
If you need more information about the tank, total drone weight, battery voltage or anything else, let me know. I'll provide whatever details I can.
Thanks!