Heli isn't level in the air

So I’ve been doing the APM with quads and planes and helis for a while so I feel pretty stupid asking this, but I cannot get my heli to stay level in the air while in stabilize mode. I have to give constant stick input to keep it from flying away, and no this isn’t a little bit of wind drift.

I’ve gone through the level process in Mission Planner with no luck. Would the auto-trim feature on channel 7 help here? Should I just trim it with my radio trims?

Also is there a way to just set the level like you can in adruplane, or do I have to do the full accel calibration with arducopter?

This is a complicated topic with helis.

First, yes you absolutely have to do the accelerometer calibration, that is needed for navigation.

Second, which way is it drifting? Predominantly to the left? If yes, then the problem is actually because the tail rotor pushes the heli left, and you need a bit of right tilt to compensate that. This is totally normal on helicopters. You can either choose to deal with it when flying in Stabilize. Or you can do an Ch7 Save Trim to make it hold. Either one works and I don’t have a strong opinion one way or the other. If you Trim it to hover tilted slightly right, you will notice than when you have it sitting on level ground, the HUD will show s little left tilt. This is normal.

Thrid, if it’s drifting in random directions, then chances are your Rate Pitch and Roll I-terms, or Imax values are not high enough.

Fourth, if it’s drifting in some constant direction other than left, then the problem is quite possibly because your swashplate isn’t level. This will result in a rate error. Normally I-term would compensate this, but we have to use a “Leaky Iterm” which means that it can’t completely cancel this error. The amount that it will lean to reach equilibrium is dependent on how off-level your swashplate is, and how high your I-terms are.

So… complicated subject.

Whever everything is set up right, they fly perfectly straight and hands-off hover, but it takes a bit more work to get there than a quad does.


Thanks so much for the information. It’s not a random direction it’s always been forward, and I’m having to give a large amount of back cyclic to keep it from running off. I’ve had this same heli flying great with an older APM, but I believe I replaced the servos. I’ll check my swash plate to see how level it is. If I still have trouble I’ll come back with a flight video with a control stick and HUD overlay to better showcase what I’m encountering.

Rob I just wanted to say thanks again. It was the swash not being level; I fixed that and it did the trick. I must have put the servo horns on a little off the last time I took things apart.