Large Quadcopter initial flight Crash

I was wondering if you guys could help me diagnose the cause of this crash. I looked at the logs and don't see anything obvious other than the final crash's requested pitch and roll and actual pitch an roll.

The vibrations looks within limitations which was my first suspicion, my other theory is just the PIDs are way off for such a large frame.

The Quad is a Foxtech Devourer 130 with 28" foxtech props. Power is more than ample as hover is right around 40% and the first flight was fine. You could tell it was under tuned as it was sluggish, but was flying. On the second flight I gave it a bit more roll input to see how it would react and it over shot then went vertical and flew to the ground.

We had compass error issues, but, were only flying in stabilize mode for testing at the field so that should not have had any effect on the crash.

 Could you please review the logs and let me know if you see anything else wrong before I try again?

Should I try more vibration dampening (I am currently using the supplied foam pads)

Does it just need tuning?

Here's the logs: ... MU2ba?dl=0

Thank you

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  • After building a big quadcopter with U8 and 28" props, what I can tell you is that at those low revolutions, more dampening was making things worse. I started with the Pixhawk mounted on those rubber dampeners but it was barely flyable. Now it sits only on adhesive foam tape and flies very good. 

    If you suspect vibrations, try to solve the cause first.

    Oh and I have the Rate P's at 0.2500

    • Thank you for the response! I was suspicious of the large dampeners as well. On a heli those dampeners are almost certain failure in terms of vibrations and I guess a quad with large props would be similar. I will switch it out with some double sided tape and try again. Thank you!
      • Sure thing, hope you sort it out so you can enjoy it, it is quite a view!

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