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Beginner: Crash during Auto-Takeoff (Wing/Pusher)

Hello

I am pretty new to Arduplane - I used Arducopter already but regarding flight dynamics a plane is a different thing…

I installed Arduplane on a Matek F405-wing and setup everything correctly for the frame type (just AIL).
The parameters are more or less default and no tuning had been done yet.

I know, I should try it in manual first - and I will do that after the glue is dry :wink:

But I am really interested in what someone experienced can see from the logs. It was crashing so badly that I don´t think it has something to do with poor PID tuning.

Small and short flight log

I would be very thankful if someone has an idea whats going on here…

Greetings

Nicolas

I’m still new at reading logs so take this for what it’s worth:

Double check that your centre of gravity is correct.

It also looks to me like you had a pretty aggressive angle when you launched. I’m guessing you hand launched? If so I think you had it too nose high so it had a hard time building up speed before it really got going.

Your assumptions are all correct.

My CG was correct another launch with lower pitch angle ended with almost same result.

I now assume:

  • Control surfaces have a bit too less travel
  • Motor power is a bit too less for the weight of the plane to gain enough speed fast enough
  • The 100% throttle from the beginning applies to much torgue to the plane and thats why the roll cant get compensated. And perhaps that heavy use of Aileron costs me pitch. I want to try now some smoother start with TKOFF_THR_SLEW

But there is still something I don´t understand:
The throttle get´s lowered during takeoff for some short periods - and I have no idea why that happens. How can I find out why/based on what configuration Ardupilot did that?

Hello Nicolas,
did you check in FBWA mode if the flight controller deflects the rudders in correct direction ?
https://ardupilot.org/plane/docs/guide-elevon-plane.html#servo-setup-reversal
Immediately after automatic start, one has the impression that roll is being driven the wrong way round.

Hi Rolf,

thanks for having a look!

But this is correct, the servos are mouted in the wings both pointing to so outside, so one needs to be reversed.

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