This is my first biplane so I'm not sure if this is a normal flight characteristic but I'm guessing it's not.
When I do a tight loop my plane is wanting to roll out at the top. If I do a large loop it doesn't do it. The thing is that I'm doing this in low rates so my loops aren't even that "tight". Maybe I need to see if my elevator halves are off a little or something. Or maybe a radio mix is necessary to fly straight tight loops. Any advise would be appreciated.

Are you using two servos or 1 servo with a split pushrod? If you are using 1 servo the split pushrod can flex off to one side and case this.

David

That is normal behavior for most of the smaller Ultimates...

Due to the torque of the motor, and the angle of the wings and elevators, one side is stalling faster than the other.

You can INCREASE the throws at high rates, to cause the wings to stall faster and more evenly during high rate pulls, and reduce the throws at low rates a bit at a time, until you find the point that the loops stay round with the stick fully back.

I've owned a slew of Ultimates and biplanes and most show this characterstic with certain throw positions.

Opjose,
Thanks for your input on the flight characteristics. I did however find that my elevator halves were a few millimeters off at full throw (on high rates) not sure how much of that was the cause of my problem, or if it had anything to do with the rolling out at all. I'm confused about how my wings would have stalled out at the top of the loop even though I still had plenty of power and forward motion. (not doubting you, just trying to figure this out). You also mentioned engine torque, and that leaves me wondering if I should cut way back on the throttle at the top of the loop ( which I should probaby do anyway so I don't end up with an ultimate monoplane). Now that I have fixed my elevator halves, I will give it a test flight tomorrow and see if I still get the roll out. I'm also curious to see if the roll is the same way each time.
Thanks for the help, and If anyone else has anymore advise I would really appreciate it.

Too much elevator?

I wouldn't think it would be too much considering that it is on low rates. And I have it set up the way the manual suggests

A slight mismatch will certainly produce the results you see.

-

With most Ultimates the relatively short length of the wings permits the engine to introduce a fair bit of unhindered torque to the airframe...

If you level out all of your control surfaces, you'll find that your Ultimate will want to roll left as it leaves the ground.

So you compensate with a bit or right aileron trim for level flight.

As the plane gets slower, this is one of several things that comes back to haunt you in loops. You'll find that it will always go out of round in one direction because of those four trimmed control surfaces.

I find that there are sort of sweet spots for the elevator to cure the uneven loop problem on smaller planes.

The larger Ultimates seem to have a lesser tendancy to do this, but they still will if pushed.

Anyway, I usually adjust my low rates to the point where the out of round looping begins from full throttle level flight once full up elevators are applied, then I back off a bit to stop the out of round loop.

For high rates I adjust the rates so that the plane practically stalls without looping then back off until I get the tightest loop possible.

Somewhere in between is the area where the planes tend to loop out of round.