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  #1  
Old 03-03-2018, 07:59 AM
Belmont Belmont is offline
 
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Default Heavy aileron input

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.
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  #2  
Old 03-03-2018, 08:49 AM
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JonJay JonJay is offline
 
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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.
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Last edited by JonJay : 03-03-2018 at 08:51 AM.
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  #3  
Old 03-03-2018, 10:48 AM
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snopercod snopercod is offline
 
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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.
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  #4  
Old 03-03-2018, 12:00 PM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by JonJay View Post
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 isnít built quite right.
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  #5  
Old 03-03-2018, 12:24 PM
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az_gila az_gila is offline
 
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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.
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  #6  
Old 03-03-2018, 05:26 PM
Rv3Dave Rv3Dave is offline
 
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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 3Bís handling. I am working on changing the stick ratio but have not yet flown the new stick configuration
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  #7  
Old 03-03-2018, 05:56 PM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by Rv3Dave View Post
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 3Bís 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.
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  #8  
Old 03-04-2018, 06:07 AM
Rv3Dave Rv3Dave is offline
 
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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.
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  #9  
Old 03-04-2018, 08:42 AM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by Rv3Dave View Post
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 Vanís. I flew three RV-8ís 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 RVís - 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 thatís 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
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RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
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Dayton Valley Airpark (A34)
http://Ironflight.com
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  #10  
Old 03-04-2018, 09:32 AM
Rv3Dave Rv3Dave is offline
 
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My 3 was built with straight ailerons, and rigged exactly according to the plans and Iím 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.
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