Heli spins in alt hold!

hey everyone,

I really need to get my helicopter done by the end of the week for my project.
It needs to be functioning smoothly in loiter and I am one step away and its driving me insane.

Today when testing in alt hold I was able to get a repeatable failure. The helicopter spins on its own, for no reason. I see in the logs a negligible or small ch4 in, but when the ch4 in stops, then the heli continues to want to yaw, ch4 out doesn’t go back to zero. The mag and the gyro all read this happening and do nothing.

Why does this happen, and why only in altitude hold?
Could this be a collective precomp issue?

This is just in a stable hover or slow forward flight.

Logs here
drive.google.com/file/d/0B30gog … sp=sharing

Please help me figure this out,


Hi Seb,

I had a look at the log, and I actually can’t really even see the undesired spinning. Can you point it out exactly?

I had a look at the parameters, they seem to be reasonably set. Vibes seem good. Control looks not bad in yaw, though roll/pitch could use some work still, actually Roll mostly. I think your swashplate is not levelled properly.

I’m not really seeing a spinning problem.

Please look at the last time I switch from Alt Hold->Acro, at the end of the flight
You will see that I ask for a little bit of yaw input, and then ch4 out keeps going, despite me pulling it back.

What is the difference in yaw control between stabilize and alt hold? Does alt hold make use of the compass while Stablize does not?