Aileron heaviness and wedges...?

[MedFlightDoc]

Hello to all,

I've got a question that is perplexing me.
I bought a flying RV-3A, have put about 16 hours in it, (and really enjoy it!) and as I've left the pattern and ventured out on some cross-countries, it has become apparent there is quite a bit of a right wing heaviness (right wing down), causing a slow roll to the right at high cruise speeds.

I noticed that the left aileron has a small wooden wedge underneath, at the trailing edge. It's about 6 inches long and an inch wide. Centered on the bottom trailing edge. Thinking this was causing the problem, I took it off. But the problem is worse. Which in all honesty doesn't make sense in my mind, as I would think that wedge would make that aileron "heavy", causing it to go down...causing the left wing to go up...

Not so.

Looking more closely at the wings, I do notice that the right aileron (the heavy side) has a bit of twist in it. Meaning that when the inboard edge is lined up perfectly with the flap, the outboard edge is bent slightly up (when compared to the tip).

The "light" left sided aileron appears to be perfect.

Sooo, what to do?

I've read a lot of these forums, and this whole idea of "squeezing" the trailing edge of the "light" aileron, but I'm having a hard time visualizing what that means, and what to look for in a picture of how an aileron that would benefit from this squeeze would look.

On the other hand, would putting a bigger wedge back on the left aileron (the light one) help offset the twist on the right (heavy) side?

Is there a way to "untwist" the upward curve in the heavy right aileron? (without damaging the aileron itself?).

If I put the wedge back on, what would one fasten it with? Epoxy?

Thanks, I appreciate any help or suggestions out there.

Ryan Wubben
Madison, WI
N154AB RV-3A

[WingsOnWheels]

The wedge was acting as a trim tab for the aileron. The wedge forced the left aileron up, deflecting the right aileron down counteracting the heavy wing.

I would first make sure the issue is with the aileron and not the wingtip. It is possible that the aileron is fine and the tip is mis-aligned. If there is a twist to the aileron, it might be worth making a new one, they aren't all that hard to do. If it is the tip, then some fiberglass work may be in order.

[sprucemoose]

Ryan,

Wedges, trims tabs and the like are all bandaids that are simply covering up a symptom. You need to diagnose the problem and treat it rather than just apply more bandaids. (How's that for an analogy?)

Here's a good starting point, from Van's. Read through it. You'll find that squeezing an aileron or adding a trim tab is the last step in the process, not the first.

http://www.vansaircraft.com/pdf/Wing_Heavy.pdf

You may have some rigging issues, or you may have a twisted aileron. The former are easy to fix, although there is some trial and error involved. The latter cannot be fixed, there is no way to straighten a twisted aileron, and building a new one may be the solution.

[Ironflight]

Definitely read the link that Jeff posted above - it gives a good, systematic process to go through the airplane and fix the problems. The only thing I will add is that the more you squeeze the aileron, the "heavier" the feel can become. If the surfaces of the ailerons are convex at all, the aileron feel of the aircraft will be extremely light. he more convex, the heavier. So squeezing is an effective way to balance the plane, but oversqueezing has a detrimental effect as well - hence, trim tabs and wedges.

Paul

[L.Adamson]

On the first cross country flight in my 6A, it was apparent that I had a "heavy" right wing. I didn't notice this on the first few laps around the pattern because the control force to counteract it was really light. Yet I have a servo controlled trim tab on the aileron that wouldn't fully correct the situation at full opposite trim.

Since my 6A has a vertical stab that's installed straight, instead of offset as some newer models do, rudder trim tabs or wedges are common. I had taped a temporary wedge on the rudder before a permanent tab and it worked great.

I then figured I'd tape a temporary wedge on the outboard bottom of the left aileron, and possibly make it a permanent, or rivet on a tab. While doing this, I noticed that the trailing edge of the left aileron had a thicker radius than the right aileron. At that point, I did use the "squeeze" method for about 18" starting at the outboard end of the left aileron.

That's all it took. The plane would now fly perfectly level with my electric activated trim tab in the neutral position. It was surprising how such little effort made such a big difference.

My ailerons, as well as flaps & wing tips do end up in a nice straight line. That does make a difference. I've seen an RV4 as well as a Glastar that have opposite trim tabs on each aileron. I know that the Glastar had a bit of a warp, but I didn't check out the RV4 for possible causes.

L.Adamson ---- RV6A

[Alan Carroll]

Originally Posted by MedFlightDoc

Hello to all,

I've got a question that is perplexing me.
I bought a flying RV-3A, have put about 16 hours in it, (and really enjoy it!) and as I've left the pattern and ventured out on some cross-countries, it has become apparent there is quite a bit of a right wing heaviness (right wing down), causing a slow roll to the right at high cruise speeds.

Ryan - are in town this weekend? If so we could take a look at the ailerons (it would also be a good idea to print out the "heavy wing" instructions from Van's). I just emailed my cell phone number.

[Andy Hill]

Ryan...

No disagreements with the above - just some added info. In test flying some RVs (equivalent of your "Phase 1") I've had "heavy wings" up to almost 15deg/sec (let go of stick, 60deg AoB in less than 5s ), and cured by squeezing to an almost imperceptible amount not even the whole Aileron span.

Best done 1 panel at a time, using Hand Seamers, and use reflections on the top surface to judge when some "squeezing" has been achieved.

I would say you will hopefully do this to a degree that you cannot sense any alteration in aileron "heaviness".

Finally, your "aileron twist" is more likely to be misalignment of the wing tip when it was fitted. If you are not inclined to become an RV builder, the comments here that "building a new aileron is no big deal" you might disagree with A "digital level" would quickly show what, if any, twist is in the aileron.

Judgement call as to whether re-reigging the tips / wings / ailerons worthwhile, or just go for the squeezing technique

Hope that helps...
Andy

[rvbuilder2002]

Originally Posted by Andy Hill

Ryan...

No disagreements with the above - just some added info. In test flying some RVs (equivalent of your "Phase 1") I've had "heavy wings" up to almost 15deg/sec (let go of stick, 60deg AoB in less than 5s ), and cured by squeezing to an almost imperceptible amount not even the whole Aileron span.

Best done 1 panel at a time, using Hand Seamers, and use reflections on the top surface to judge when some "squeezing" has been achieved.

I would say you will hopefully do this to a degree that you cannot sense any alteration in aileron "heaviness".

Finally, your "aileron twist" is more likely to be misalignment of the wing tip when it was fitted. If you are not inclined to become an RV builder, the comments here that "building a new aileron is no big deal" you might disagree with A "digital level" would quickly show what, if any, twist is in the aileron.

Judgement call as to whether re-reigging the tips / wings / ailerons worthwhile, or just go for the squeezing technique

Hope that helps...
Andy

I agree with Andy (and everyone else with the exception that I think you should use a straight edge to monitor the aileron shape while making adjustments. In fact, since you didn't build the airplane, it would be a very good idea to check all of the control surfaces for proper shape as described here. Making adjustments so that it flys in trim may not be all that is needed to make its handling and flying qualities as good as they could be.

http://www.vansairforce.com/communit...ad.php?t=57684

Between the info in the already mentioned document on Van's web site and this thread I linked too, you should be able to start getting a bit of an understanding.

[MedFlightDoc]

Thank you for all the reply's, I'm learing a lot here.

I'm not inclined to build a new aileron (I bought this aircraft flying and am not a builder, but a flyer), so I'm leaning more towards these other options.

I've read the last string of posts on rvbuilder2002's post immediately above, but one thing that is confusing me is to try and visualize this convexity in the aileron's that is described, and how to "squeeze" the aileron. Are there any good photos' showing what this looks like, and what to do about it?

Thanks again!
Ryan

[Ironflight]

Here are a few thoughts and pics on squeezing ailerons:

http://www.vansairforce.com/communit...ad.php?t=55326