Crash + AUTO mode heading down instead of up

Stabilized mode was working really well, so i decided to switch to auto mode to see what would happen. I gained 100 meters of altitude and once in auto mode, the plane started to lose altitude instead of climbing. I had the next waypoints at a higher altitude than the actual plan altitude.

Nevermind, i switch back to stabilize and i try to recover the plane (third time i try auto that day and i save the plane switching back to stabilize/manual). This time however, stabilize doesn't work (i did not have the cold blood to switch to manual and to try to save it that way). I lost my plane yesterday this way.

1) Stabilized mode should have made the plan go flat, but it made it keep diving. Any guesses on why? I had the elevator completely back (as in, make the plane climb) for the whole fall, but that didn't save the plane from crashing. Why?

2) Why when i switched to auto mode the plane decided that i should have had to go down instead of up? As i said, the stabilized mode was working really great. So i don't really understand it. Also, i triple checked the WP altituded.


Any help is welcome. I have attached every log possible. Thanks.

2013-08-01 16-56 61.log

2013-08-01 16-56 61.kmz

2013-08-01 16-56 61.log.gpx

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  • Moderator

    Sorry for your crash.

    Hard to tell from these logs as not much is recorded, a tlog would be better, but from around point 33000 on the graph the lines go flat indicating nothing being recorded during that period. Speed never recovers but pitch and roll then show what I presume is the crash.

    I'm not an expert but it's possible that a brownout caused this, with the voltage of the APM going too low, maybe caused by something (servo maybe) drawing a lot of current (at speed?) which stops drawing when the crash occurs hence the return of the roll and pitch lines.

    3692790439?profile=original

  • Your log is not complete enough to make a good analysis. You only have attitude mode and GPS logging enabled. You should also enable CTUN and NTUN logging in CLI.
    From the data out your log i'm guessing your pitch PID control loop is badly out of tune. I can see some hefty oscillations on the pitch attitude.

    BUT I'm guessing because the data for a proper analysis is missing.

    Fly once more with CTUN and NTUN enabled, and you should also try FBWA instead of stabilize. This way you can see if the ardupilot is controlling the plane good enough for auto navigation.
    Did you do the preflight checks? all control surfaces moved in the right direction?

    Oh and next time switch to manual!! it will save your plane!

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