What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Heavy aileron input

Belmont

I'm New Here
A friend and I have recently finished an RV 3b and today completed the 40 hours of Proving Flight. My friend has built and flown an RV6 and RV9. I have been involved in building and flying an RV6, two RV7's and an RV8. All the flying reports we have read comment on how light the controls of an RV 3 are. We have trimmed our aircraft to fly straight and level but experience heavy aileron input, when compared with the other RV's we have flown, as the speed increases. Have any other RV builders had a similar experience and if so how have you solved the problem ? Our aircraft has a Lycoming IO 320 and MT two bladed prop.
 
Check your aileron trailing edge radius. Also, lay a straight edge edgewise fore to aft and make sure there isn't a bulbous transition near the trailing edge.
Over squeezed or under formed trailing edges can cause what you are experiencing.

RV3 stick pressures are about the same as the 6, the airplane is just a little more responsive and a little better balanced.
 
Last edited:
I don't know anything about RV-3s, but the original Lancairs had a heavy aileron response. That was "fixed" by making the trailing edge of the aileron 1/4" thick.
 
Check your aileron trailing edge radius. Also, lay a straight edge edgewise fore to aft and make sure there isn't a bulbous transition near the trailing edge.
Over squeezed or under formed trailing edges can cause what you are experiencing.

RV3 stick pressures are about the same as the 6, the airplane is just a little more responsive and a little better balanced.

JonJay has it right - you can make any RV with folded trailing edges lighter or heavier (by huge amounts!) by checking the concaivty or convexity of the upper and owner surfaces as they die into the trailing edge radius.

Check that before anything else. The design is fine - you just have something that isn?t built quite right.
 
Following on Paul's comment -

Don't know about the -3s, but the other early RVs have non-symmetrical aileron bellcranks.

A check against the drawings to ensure the aileron bellcranks in the wings are in the correct orientation might be a good idea.
 
I have exactly the same issue with my new 3B. I have built a 6a and a 8, both had significantly lighter stick forces. A search of the archives I found several posts on this problem. I seems the new wing design has changed the bell crank. Several builders have modified the bell crank back to the original design.
I am quite disappointed in the 3B?s handling. I am working on changing the stick ratio but have not yet flown the new stick configuration
 
I have exactly the same issue with my new 3B. I have built a 6a and a 8, both had significantly lighter stick forces. A search of the archives I found several posts on this problem. I seems the new wing design has changed the bell crank. Several builders have modified the bell crank back to the original design.
I am quite disappointed in the 3B?s handling. I am working on changing the stick ratio but have not yet flown the new stick configuration

We used the stock aileron bellcranks supplied in the 3B kit, and our stick forces are feather light. Lots have guys have messed with the bellcrank geometry over the years, but I personally think the problem is with the shape of the aileron, and have observed and felt the change in handling with various aileron shapes.
 
What I would appreciate is information from builders who actually had this problem and how they solved it. Opinions from people who have other models or did not have the problem are just that, opinions.
 
What I would appreciate is information from builders who actually had this problem and how they solved it. Opinions from people who have other models or did not have the problem are just that, opinions.

Opinion? Sure - based on flight test experince and many discussions with the engineering and design staff at Van?s. I flew three RV-8?s on the same day one time, one with concave ailerons, one with convex, and one straight. The straight ailerons provided a good, baseline roll control that was what I would call normal for RV?s - and I have flown every model of RV designed by Van, except the RV-5. The concave ailerons provided a very heavy feel. The convex were so light as to be close to unstable.

These results have held as I have flown examples of numerous RV-4, -6, -7, and -8 (all with the same aileron designs as the -3).

But that?s just my opinion of course.

My hypothesis BTW, is that folks who have corrected a heavy wing by squeezing an aileron have tended toward concave, (heavier ailerons), so as they balanced the airplane, the feel gets heavier.

Paul
 
My 3 was built with straight ailerons, and rigged exactly according to the plans and I?m simply saying it does have heavy ailerons. BTW I have built several award winning RVs.

Many parts in the 3 kit have been changed to later model parts. Especially in the control system. My hypothesis is that these changes are behind the change in control force required.

You are fortunate that your 3 has light controls, I wish mine did as well.
 
While I do not have as much different RV time as Paul, I have flown more than a few and agree to look at the aileron shape. My 8 has firm aileron stick forces with flat control surfaces. Several others I have flown had overly light stick forces with under bent, convex, control surfaces.

The thin control surfaces on the 3 can be easily overbent convex or bent with a smaller than ideal trailing edge radius. Would be worth a close look. In my opinion.

George Meketa
 
My RV3B also has heavier ailerons then some other RVs I have flown. RV3 RV4 RV6 RV7 RV8 RV9 and RV10. My ailerons are built to plan and are neither convex nor concave and fair evenly onto the bottom and top wing skins. I have compared the early RV3 aileron bell crank to the RV3B bell crank and they have the same ratio. I agree that the trailing edge shape can be used to trim wing heaviness in either direction. To lighten the stick forces some what I have welded in a bushing just bellow the original which has reduced the pivot to aileron push rod distance from 3 1/2 to about 3 1/8 inches. One possible explanation I might try to quantify is the speed of my airplane. It has a 160 HP 0-320 and wide open at sea level it will do 222 mph. I normally cruise at at 2550 RPM resulting in 190 mph average ground speeds. I tend to do aeros at cruise speeds and obviously speed has an effect on control forces.
 
Heinz

I need to know the prop you are using and the empty weight of your plane. My 3 needs to go as fast as yours!
 
I need to know the prop you are using and the empty weight of your plane. My 3 needs to go as fast as yours!

I don?t know, and can?t speak for, Heinz, but in Phase 1 testing we also got 193 knots (which is 222 mph) in level flight, at zero MSL, wide open and best power. Prop is a Whirlwind 151 three-blade constant speed. IO-320 by Mattituck.

Of course, that is 8 knots over airframe redline, so we haven?t repeated that run!
 
Forces

Barnaby Wainfan wrote an excellent article on this and much more in Kitplanes. This was some time ago and I don't have the exact date,
On some non RV airplanes if you bulge the trailing edge out too much is will completely take away the centering force.
 
Back
Top