U Can Do pitch coupling with rudder input
 

I've got a couple of flights on my U Can Do, and so far I'm pretty happy with it. The only issue at the moment is a pretty strong pitch coupling, it pitches rather strongly toward the belly with rudder input in either direction.

Any suggestions? I'm inclined to just mix it away, but if there's a reasonably easy way to fix it without a mix I'd go that route first.

Thanks in advance,

David

CG and Mix
 

Hroachen, we're all finding the same thing that you did. I started with my UCD at 5"CG, and set up the mix so that it would knife edge straight, problem solved for the most part. I then moved my CG back to 6", and I had to substantially reduce the pitch mix. On right rudder input, it went from 14% to 8% from what I remember. So if you experiment to find a CG you're comfortable with, the mix may change a little.

U Can Do pitch coupling with rudder input
 

Thanks,

My CG is pretty well forward at the moment, I guess I'll first get it back to where I want it, then just mix out whatever pitch coupling remains.

David

U Can Do pitch coupling with rudder input
 

Why mix it out? I just use elevator and a little aileron while in knife edge to keep it flying nice and straight...

another thread
 

there is another whole thread on the why tos, and why nots of rudder mixing. If you look here in 3D, you'll find it.