jay2000dakota

Looking for opinions on a problem guys, My ultimate uses a fair bit of down elevator to stay level when inverted, so that normal. I was thinking its too nose heavy but the stock CG says it tail heavy. Anyone offer some advise?

vertical grimmace

My Feedback: (1)

Have you checked the incidence and engine thrust? Do you carry any up elevator trim to maintain upright flight? This airplane should be "zero" everywhere really. Maybe a little right thrust and that is it.

jay2000dakota

I have a far bit of up trim in it for level flight, I got to thinking I might put some up thrust in it

jay2000dakota

how much you thrust is suppose to have?

alfredbmor

I still remember that the plans show one degree incidence for the horizontal stabilizer, but that one degree is accomplished by building by the plans, when I built mine I received the wrong advice that I should shim the horizontal stabilizer to get the desired incidence, I was in doubt so I measured the plans and got the fact that it was already build that way (with out shimming).
I also have to say that there is no more advice than shimming with two washers the engines mount to acquire a good right thrust, if you already checked the incidence and are still in doubt I second the Vertical Grimmace opinion about the engine thrust. (Up or down)

vertical grimmace

My Feedback: (1)

Without putting a meter on it and checking all of the incidence angles, It is tough to tell you exactly what to do. It could be as easy as adding downthrust to the engine but I bet it is rigged improperly somewhere. You can shim the top wing if needed, but changing the angle of the stabalizer might be tough at this point. Do you have an incidence meter? If not maybe you could borrow one from a flying buddy.

jay2000dakota

I dont think its tail related,the guy who built it is one of the best i've seen. The plane was stored for years. last year I wanted to give'er a go so I put a 125 saito on it. I didn't put any washers behind the engine mounts (I don't have any plans or books for it). does it need to be shimed?

vertical grimmace

My Feedback: (1)

Maybe just start with some downthrust. Add a couple of washers behind the top screws of the engine mount and fly it. The other thing might be to shim the back struts of the top wing. This will lower the incidence here. Only do this slightly. Maybe 1\16" at first.

jetmech05

Bare with me as I am not there to see your airplane...I have an Ultimate bipe...did you trim your airplane at or just under 1/2 throttle?.....Is the elevator faired with the horiztontal stab with the stick at nuetral?..I have the ARF I think I am a tad up at nuetral.....Now rolling over inverted..I want a bit of down elevator to remind me I'm inverted...how much is up to you...if the airplane climbs while inverted you're tail heavy.....if you don't like how much you have to push to maintain level then remove some weight from the nose...
Good flyin