Dreaded Vibrations! - Please help, giving up!

So I am using a pixhawk on a quad and it works great if I just let it hover, POS hold is rock solid and so is alt hold. But in AltHold or POS HOLD as soon as I give it some forward momentum and then back or just sharp turns it instantly goes 100% throttle until I switch it to Stab and I have to let it fall for a bit until its back at the level it started at at.

Now I know it's vibrations because I review my logs and the Z, x y,  accel is great until it it puts out more throttle then it goes crazy and thats when alt hold misbehaves. I tried EKF and issue still happens, I tried really thin "airy" foam but compressed with the same foam on top (made a pixhawk sandwhich), my latest was moongel and I did 2 peices at each end and used its standard pre cut size. I was thinking of doing 2 layers next...

So I am trying to find out which motor, prop is the issue but I have gone through a number of props (I just have been flying normally and not using RTL or alt hold (RTL uses ALT hold so if it goes into RTL I lose my quad in the sky forever)

I switched out a motor since it sounded funny on the bench although I felt minimal vibrations when testing with out props. It just has a "hum" vibration, hard to explain. (this is 4 all 4 motors)

I balanced the props and tested them on the quad and they all produced similar vibes and nothing major

I bought new arms in case some were twisted or something and still same issue.

Tightened all screws

I put it in Poshold and just watched the props for a couple minutes in hover and they looked fine

Frame: Aphid x450 (Uses f450 arms)

Sunnysky xx2212 980kv, 3S, 10x4.5sf plastic.

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  • So an update,

    Purchased new sunnysky motors with t prop adapter, new frame, and new carbon props, seems to fly really well now, hammering the sticks trying to cause massive vibrations and its still good. I think it was motors that caused the issue.

    I am having an issue and I beleive it may be becase of of the moongel, I am losing yaw lock, I have not done compassmot yet but thats the plan later today. Just wanted to ask if anyone had similar issues with moongel?

  • hi, as you say the root of it all is vibration in the motors - so careful balancing will help a lot.

    but for the vibration thats left (theres always some), ive found that stiffer foams work much better.  if you can, get your APM on a board with as much weight as possible (ESCs? battery? radio?) and isolate that as a single block.  in any case i have had much success with neoprene - both a sheet i bought in a local rc shop as "radio mounting foam" and a chopped up mouse mat.  recently i am trying 1/4" sorbothane which is also working very very well.

    one more thing .. i have a TBS discovery flying with the same motors and found that there is more z axis vibration in the centre of the plates between the arms.  mounting at the edge of the plates seems better.

    • Thank you,

      I bought 4 new SS x2212, new frame, new carbon props, I was very rough with the first quadcopter so maybe the motors got a little to much abuse.

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