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Has anybody tried squeezing the trailing edge of the aileron on the light wing to correct for a heavy wing as they do on Vans Aircraft. I did this on my RV4 and it worked a treat, it does not take much to correct quite a high roll rate. I have a Sonex tail kit which I hope to start soon, so if anybody has done the aileron squeezing technique also known as the Kutta condition how successful was it as I do not like the idea of flying with one flap low?

When I acquired my plane from the builder and after I started to get her down I determined she was left wing heavy and constantly rolling slightly left. Didn't do it on the test flight with him. I measured the heck out of everything to make sure she was put together OK. And everything checked out. Double checked the right flap and it was good.

Took someone flying and.... she didn't roll left. Was that really it? She was rolling into me sitting left side? REALLY?

I put a small and very thin bit of bungee into the system next to the stick to trim her when I was flying solo to eliminate the roll. Next time I took a passenger - she rolled right into my bungee trim.

So - I've now arranged that the bungee can be easily hooked/unhooked depending on passenger.

Looking out on the wing to see how much "break" this has caused in the trailing edge. It's imperceptible.

But the ball is now easier to keep centered.

Might want to try applying some lateral trim before squeezing an aileron?

YMMV

Paul Johnson wrote:Has anybody tried squeezing the trailing edge of the aileron on the light wing to correct for a heavy wing as they do on Vans Aircraft.

Paul,

There have been several Sonex builders to squeeze trailing edges to correct wing heaviness. The technique is pretty much the same as Vans uses (reduce the trailing edge radius of the light wing), but the only challenge is controlling the amount of squeeze-down to apply. The Sonex rounded edges on the control surfaces are pretty tough to compress, and it can be a bit tricky to press them down uniformly. Having said all that, with a little care it works just fine.

As Graeme noted, the Sonex often shows a little wing-heavy tendency when adding or removing a passenger. If you trim it for one condition, it might not be trimmed for the other (e.g. it's OK solo, but wing-heavy with a passenger). Some builders have made a removable "wedge" stlyle aileron trim tab that attaches to the bottom of one aileron with industrial velcro, and that reportedly works well. I think for the rest of us, the light stick forces allow you to keep it level with very little effort so we don't pursue it any further.

If you really want to get creative, ask John Gillis about his electric aileron trim wired to his hat switch. Super simple, and pretty nifty.

Jeff

I have completed three RV's an 8.9 and a 4, both the 8 and the 4 had a roll to the left, the roll on the 8 could be controlled with aileron trim, with good fuel management (wing tanks) the aileron trim was not needed. The roll on the 4 could not be controlled with aileron trim but the stick force required to keep the wings level with neutral aileron trim was very light and aileron deflection hardly noticeable but stick free would command a rapid roll rate, squeezing the aileron of the light wing cured the heavy wing.

My Sonex flies hands off solo, but the left flap is set about 3/8" lower than the aileron in cruise, the builder must have done this to correct a heavy wing, I think this looks awful.

Graeme and Jeff thank's for your comments, I agree with you both a simple spring or bungee trim system would be the way to go especially as the amount of aileron deflection is very small, but if that was not adequate I would rather squeeze an aileron as I know how easy and effective this can be. The squeezing is quite easy and controllable with g clamps.

Paul Dye posted this.

http://www.vansairforce.com/community/s ... hp?t=55326

GraemeSmith wrote:When I acquired my plane from the builder and after I started to get her down I determined she was left wing heavy and constantly rolling slightly left. Didn't do it on the test flight with him. I measured the heck out of everything to make sure she was put together OK. And everything checked out. Double checked the right flap and it was good.

Took someone flying and.... she didn't roll left. Was that really it? She was rolling into me sitting left side? REALLY?

I put a small and very thin bit of bungee into the system next to the stick to trim her when I was flying solo to eliminate the roll. Next time I took a passenger - she rolled right into my bungee trim.

So - I've now arranged that the bungee can be easily hooked/unhooked depending on passenger.

Looking out on the wing to see how much "break" this has caused in the trailing edge. It's imperceptible.

But the ball is now easier to keep centered.

Might want to try applying some lateral trim before squeezing an aileron?

YMMV

G'Day Graeme,

I would like to see photo's/sketch of your nice simple lateral trim system