I’ve been analyzing the log from the crash but can’t figure out much from it except for a gps time jump on line 13578 of the log file and a weird alt spike in ctun.
I can’t tell much of what has happened since I was operating a camera and my friend was flying a quad.
On the descend from about 50m, quad started to shake violently and then flipped on it’s back and crashed from about 10m high.
I would kindly like to ask someone to take a look at the log file and see if anything sticks out.
Copter will always wobble when descending quickly (due to descending into it’s own propwash).
How much wobble is going to happen depends on few factors, but the most important one in your case is the PID settings which caused the oscillation.
I would start by running autotune and then working from there.
In the future, way to recover from wobble like this one is to catch it as early as possible and throttle up and the descent slower.
For me, you have a mechanical failure, check your motors, props, esc, (one time the little bolt for motor shaft was loosen in my cuad, one prop lost velocity and crashed).
Thank you for taking the time to look into this log.
Autotune has already been done and the quad is dialed in perfectly. Frame is asymmetrical so it behaved kind of laggy on default settings but now it is really locked in.
I know how to recover from/avoid a wobbly descent but it’s not my quad and I was not flying it.
We will check for mechanical issues after we receive replacement motor adapters. They were bent in the crash and are unusable for now.
My friend said that he switched the quad into stabilize mode to bring it down and it wouldn’t come down so he pulled the throttle back more (maybe too much, I really don’t know.). Maybe it’s just a pilot error.
He also said that the motors were not spinning after the crash. I don’t remember that, I only saw the gimbal motors twitching…
Nevertheless I’m really worried about that GPS time jump. There is a topic on this forum somewhere describing almost the same symptoms as this one that also had a time jump in the log but noone replied anything. Quad flipped and crashed just like here.
Can a time jump cause crash?
Does anyone else have any ideas on this?