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RV3B heavy roll forces

JUSTNUZZA

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I have an issue with heavy aileron roll forces in my RV3B has anyone fixed this issue easily before ?
Any simple ideas to make the aileron slightly convex without damaging paint ? Both ailerons are currently perfectly flat top and bottom.
 
Sounds trailing edges related.

Now I can't remember if sharper or rounded edges produce heavier forces.

When you put a ruler (top and bottom) are they really flat out to the trailing edge?

Finn
 
I thought the convex (pillowed) edges produce the lighter forces.. and you lose some control centering.. flat is the way they should be.
 
Wack them

About the only way to lighten up the forces is to increase the trailing edge radius. When someone squeezed the TE to finish up the bend they went a bit too far. Ive taken a wood block and hammer and gently tap the TE to try and undo the sharp edge. Do one bay at a time, exactly the same on both sides or you will induce a roll. It does not take much.
 
What speeds are we talking about. All RV’s tend to get heavy in roll above 160 or so.

It's the same heaviness at 160 down to 100. Have flown an RV4 and RV6 and they were both feather light in roll in comparison to my RV3B.
 
Last edited:
About the only way to lighten up the forces is to increase the trailing edge radius. When someone squeezed the TE to finish up the bend they went a bit too far. Ive taken a wood block and hammer and gently tap the TE to try and undo the sharp edge. Do one bay at a time, exactly the same on both sides or you will induce a roll. It does not take much.

The wings were factory built. Did you hammer yours when they were painted and did it damage the paint ?
 
Not painted

Well it was 35 years ago, but im fairly sure they were not painted. Sorry not much help.
 
To Justinuzza

I sent a PM but maybe you didn’t get it.
Thin trailing edges, even if straight cause more stick force.
You will get lots of advice to Bump the trailing edge to increase radius. This will logically also pillow the skin to some degree.
I had ailerons with trailing edge smashed too thin and response was dissapointing for an RV3.
Built new alerons. The stamped insert that came in the kit resulted in straight skin surface AND a bigger trailing edge radius than plans. The end result was fabulous aileron and roll response with no side effects like snatch etc.
Good luck increasing the radius 😊
 
Trailing Edges

Barmaby Wainfan did a detailed article on trailing edge shape in Kitplanes several years ago. I have experience with convex(curved outward) aileron trailing edges on two different EAB aircraft, not RV's.
Overdone it can reduce or even eliminate centering force.
the trick is to get it just right.
Look at Beech King Air 200 or larger. You will see a mid aileron span "airfoil modifier" that is a convex add on to the trailing edge.
I highly recommend the Wainfan article.
 
Barmaby Wainfan did a detailed article on trailing edge shape in Kitplanes several years ago.
I highly recommend the Wainfan article.

I googled him and found a bunch of info, good call. My own experience was on an RV4 I purchased secondhand. Had very heavy pitch control that was horrible anywhere over 120kts. After checking everything trying to figure out the problem, one day had it side by side with another RV4 and saw the larger radius on his elevator trailing edges. After a little research determined that was the problem. Built new elevators taking care with the trailing edges and it solved the issue.
 
Aileron force

I have no experience with the RV-3 series, but I have owned a RV-6 in the past. The aileron forces were very light at slow speed and got heavier and heavier with speed increase, specially above 140-150 KIAS. In my opinion, that was great!

The trailing edge radius and skin shape has great effect on aileron forces as others have mentioned and may be the cause and solution of your problem.

From flight testing another aircraft, with totally different control system, but very similar aileron shape, I learned that rigging both ailerons with leading edge down (trailing edge up) exposes the aileron “nose” to the airflow and reduces the forces considerably, increasing the aerodynamic balance effect.

Although playing with the rigging may help with your issue, I DO NOT recommend that path. You may get in to trouble if you do it too much and I have seen ailerons going to full deflection by themselves requiring force to bring the stick back to neutral. How much is too much? Only testing and/or aerodynamic simulation will tell you, so be careful!

My recommendation would be to check if your ailerons are properly rigged (trailing edge down will increase forces and up will reduce forces) and if the hinge is at the correct position. Hinge forward of the correct position or ailerons a little bit high will increase forces considerably.

Good luck and when you find the issue, remember to post the findings here.

Fabricio
 
I have no experience with the RV-3 series, but I have owned a RV-6 in the past. The aileron forces were very light at slow speed and got heavier and heavier with speed increase, specially above 140-150 KIAS. In my opinion, that was great!

The trailing edge radius and skin shape has great effect on aileron forces as others have mentioned and may be the cause and solution of your problem.

From flight testing another aircraft, with totally different control system, but very similar aileron shape, I learned that rigging both ailerons with leading edge down (trailing edge up) exposes the aileron “nose” to the airflow and reduces the forces considerably, increasing the aerodynamic balance effect.

Although playing with the rigging may help with your issue, I DO NOT recommend that path. You may get in to trouble if you do it too much and I have seen ailerons going to full deflection by themselves requiring force to bring the stick back to neutral. How much is too much? Only testing and/or aerodynamic simulation will tell you, so be careful!

My recommendation would be to check if your ailerons are properly rigged (trailing edge down will increase forces and up will reduce forces) and if the hinge is at the correct position. Hinge forward of the correct position or ailerons a little bit high will increase forces considerably.

Good luck and when you find the issue, remember to post the findings here.

Fabricio

Thanks,

I will keep doing my research.
 
Barmaby Wainfan did a detailed article on trailing edge shape in Kitplanes several years ago. I have experience with convex(curved outward) aileron trailing edges on two different EAB aircraft, not RV's.
Overdone it can reduce or even eliminate centering force.
the trick is to get it just right.
Look at Beech King Air 200 or larger. You will see a mid aileron span "airfoil modifier" that is a convex add on to the trailing edge.
I highly recommend the Wainfan article.

Thanks, I will have a read
 
I've seen aerobatic aircraft (Extra? Su-29?) that had some sort of T-shaped extrusions riveted to the trailing edges of the control surfaces. (The T canted over 90 degrees). I was told that this was to lighten control forces considerably by blunting the trailing edges. The T's were something like 3/4 inch in size, so quite large.

Might be worth experimenting with, before you set about building new ailerons... Even if you'd only buy 1/2" plastic strips from Home Depot and duct tape / double sided tape them on temporarily to see what it does.

(And stay away from vne to avoid flutter)
 
Gurney Flap

Look up Gurney Flap. Not sure about lighten up control forces, but can be used as a trim tab.
 
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