Help with log from crash "Drift" mode !

Today i was flying my hexa just fine and after my first succesfull flight with a demostration of an auto mission i thought i give drift mode a try.

So i started a second flight to finish up my batteries.

I admint i loved the way i flied on drift mode but after a minute or so of quite fast flight my hexa decided to lose stabilisation and kiss the earth ....

If anyone more experienced than me please take a look at my log to define the cause of this disaster i would be greatfull.

Thank you guys

p.s. i enclose a pic of my now destroyed hexa :-((3691088157?profile=original

2014-01-04%2016-16.log

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  • Oh man, regardless of the cause, that's one hell of a smash! I think you've spanked more in one crash than I've done all 2013....:-(

    Hope you're back in the air soon; I know those Xoar props and probably half the motors will not be a cheap repair.

    PS - those are not the standard arms for an F550...a factor maybe?

  • Developer

    Sorry about your crash. Drift mode is a superset of stabilize mode. All of the constraints are there to prevent rolls etc. I've been flying it pitched at 45° near full throttle for a few dozen flights trying to break it and haven't yet.

    When I looked at your logs I see great performance, then a wild divergence. It's a telltale sign of a frame, setup problem or electronics issue. A sudden roll can be:

    - loose motor wire

    - mis-calibrated ESCs which cause the motor to stall out when a very low signal is sent to the ESCs.

    - low voltage cutoff on a single ESC

    - a loose motor that suddenly starts vibrating which causes a major current draw shutting down the ESC

    - a loose motor that creates major vibrations which cause the D Term to overshoot

    Your D term was .009. That's pretty high, but OK for a nice frame like yours. However, if a motor lost a screw and started vibrating bad, those vibes can cause a feeling of being out of control. Even, flip the copter if they are high enough. 

    So that's my guess, the screws in one motor got loose.

    Jason

  • I had a quick look.  It's really hard to see what's going on in the logs in drift mode, but it doesn't look very good.  Did you find it wobbly?

    The actual cause of the crash is hard to tell...  It looks like it rolled upside down?  Now, why did that happen?  Electro/mechanical failure?  Hard to say.  In Stabilize mode, the Roll/Roll-in looks very good, so it's tuned well.  But in Drift, the Roll is all over the place.  You were flying at fairly high speeds, up to 19 m/s.

  • Try to post on support forums of ardupilot.com
  • Anyone ???

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