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RV6 rolling left - not flying straight

sebc150

sebc150

I'm New Here
I’m looking at purchasing my first Vans, a -6.
Everything looks straight however hands-off the airplane rolls to the left with about a 5deg/sec rate.

The ball is in the middle and with the stick in the middle and the ailerons neutral it flies straight.
However upon releasing the stick, the stick moves to the left and the airplane banks.

I’m just wondering if this is something that we’ll be able to fix.
 
Do a search of the forum and you'll find a lot of information on this subject. There are a number of things you can do to rectify the roll but first you need to understand the subject... and the info you find on here will really help you with this. There is also some info on the Vans website that will help.
 
sebc150 said:
I’m looking at purchasing my first Vans, a -6.
Everything looks straight however hands-off the airplane rolls to the left with about a 5deg/sec rate.

The ball is in the middle and with the stick in the middle and the ailerons neutral it flies straight.
However upon releasing the stick, the stick moves to the left and the airplane banks.

I’m just wondering if this is something that we’ll be able to fix.
Click to expand...
Is there perhaps an aileron trim that is fitted? It will be a small lever between the seats near the front and is not very obvious because it is hidden under the flap lever (if the standard manual flaps are installed).
 
My 6a does the same. If full left tank and less than full tank right mines rolls left. Make sure you, plus fuel is evenly distribute. These planes fly much differently than pipers and Cessna. If no aileron trim today ,its a fairly simple task to add If you like/require
 
sebc150 said:
The ball is in the middle and with the stick in the middle and the ailerons neutral it flies straight.
However upon releasing the stick, the stick moves to the left and the airplane banks.

I’m just wondering if this is something that we’ll be able to fix.
Click to expand...
If the 6 is designed similar to the 12 then this could help:

Tips for heavy right wing

Looking for some tips in correcting a heavy right wing. The ball is centered, but still a heavy right wing. I remember a tip from other RV models of crimping the trailing edge of the heavy wing aileron. Does this work on the RV12? Thanks
vansairforce.net vansairforce.net
 
What was the loading situation? Single pilot? Two similar weight pilots? Fuel L vs R? Single pilot and/or fuel imbalance and they will roll. As another mentioned, see if it has aileron trim installed.
 
Recommend you get an experienced RV guy to do a pre-buy on the bird. Typically this "heavy wing" can be cured but on an RV6 it might indicate other build issues.
 
Fill the tanks, place someone or weight relatively close to your own in the passenger seat and go fly.
If it still rolls you will have a base line to shoot for.
A well rigged 6 solo and equal fuel left and right will roll as you describe and as noted by others.
It’s a side by side and inherently unbalanced solo. Even a tandem will roll to the direction of the fullest tank.
 
Check the wing angles. The construction manual tells how this is done, when drilling the aft spar bolt hole. If this is not within specs I'd walk away. If it is within specs then you can follow the advice article Van's posted on vansaircraft.com to find & fix.
 
sebc150 said:
I’m looking at purchasing my first Vans, a -6.
Everything looks straight however hands-off the airplane rolls to the left with about a 5deg/sec rate.

The ball is in the middle and with the stick in the middle and the ailerons neutral it flies straight.
However upon releasing the stick, the stick moves to the left and the airplane banks.

I’m just wondering if this is something that we’ll be able to fix.
Click to expand...
This sounds like a narrow problem, fixed by either adjusting the height of the aileron(s) vs the wing or by changing the trailing edge radius on the aileron(s).

Why do I say this? Because the pirep indicates the airplane is properly rigged with the ailerons centered, but the ailerons naturally revert to an off-center condition in flight. That’s indicative of an aileron only problem and can be corrected relatively easily.
 
Kyle Boatright said:
This sounds like a narrow problem, fixed by either adjusting the height of the aileron(s) vs the wing or by changing the trailing edge radius on the aileron(s).
Why do I say this? Because the pirep indicates the airplane is properly rigged with the ailerons centered, but the ailerons naturally revert to an off-center condition in flight. That’s indicative of an aileron only problem and can be corrected relatively easily.
Click to expand...
Agreed. When a newly-built airplane first takes to the air, one of the most common complaints is a "heavy wing" which is usually taken care of by changing the radius of the trailing edge of one or both of the ailerons. My first hour 'tick list' shows a slightly 'heavy left wing'. Easily taken care of by aileron radius change. Has been perfect since.
 
sebc150 said:
I’m looking at purchasing my first Vans, a -6.
Everything looks straight however hands-off the airplane rolls to the left with about a 5deg/sec rate.

The ball is in the middle and with the stick in the middle and the ailerons neutral it flies straight.
However upon releasing the stick, the stick moves to the left and the airplane banks.

I’m just wondering if this is something that we’ll be able to fix.
Click to expand...
Van's published this info on fixing a heavy wing. Well worth following!

www.vansaircraft.com

How to Diagnose and Fix a Heavy Wing - Van's Aircraft Total Performance RV Kit Planes

If there is one question that requires a lot of time answering at Van’s it is the ” I just did my first flight and a wing is heavy, what do I do?” question. It usually is followed by the corollary “which aileron am I supposed to squash?” There turns out to be a bit […] Read More
www.vansaircraft.com www.vansaircraft.com

Also, see Section 5-7 "Folded Trailing Edges" (pages 5-9 and 5-10) of Section 5 which explains how to check the aileron skins and trailing edges for proper shape:


An earlier post mentioned the RV-12. The RV-12 has flaperons and the RV-6 does not. Fixing a heavy wing is different between the two designs.
 
Last edited:
sebc150 said:
I’m looking at purchasing my first Vans, a -6.
Everything looks straight however hands-off the airplane rolls to the left with about a 5deg/sec rate.

The ball is in the middle and with the stick in the middle and the ailerons neutral it flies straight.
However upon releasing the stick, the stick moves to the left and the airplane banks.

I’m just wondering if this is something that we’ll be able to
Click to expand...
Sounds normal to me. I fly an RV-6A IO-360 cs prop and with full tanks and only my 205 lb. body in the left seat it flies to the left till I burn off about 7-8 gallons from the left tank. Now take a bunch of lead and add it to the right seat to equal my weight and it flies quite straight.
Don't go bending/ squeezing anything till you fined out what the situation. You can't un squeeze an alerion or flap.
My luck varies FIXIT
 
Kyle Boatright said:
This sounds like a narrow problem, fixed by either adjusting the height of the aileron(s) vs the wing or by changing the trailing edge radius on the aileron(s).

Why do I say this? Because the pirep indicates the airplane is properly rigged with the ailerons centered, but the ailerons naturally revert to an off-center condition in flight. That’s indicative of an aileron only problem and can be corrected relatively easily.
Click to expand...
Or by centering the trim... we have not heard if this plane has it or not.
 
Oroyo said:
My plane came with flaps adjusted so one was slightly deployed on one side only.
Click to expand...
Remember the pirep. With the ailerons held neutral, the airplane flies straight. Release the stick and it wants to roll. This problem is almost certainly aileron related. Trim -as Alex mentioned, or aileron shape/vertical position.

Any of those three issues is easy to solve.
 
I'm not sure how you perform "ailerons are held neutral" in flight. Hold in alignment with the wingtips? Ah, I've seen plenty of wingtip warpage/alignment problems which makes that unreliable. In alignment with the flaps? Who says the flaps are rigged correctly? With the stick vertical? Who says the aileron pushrods are rigged correctly?

Enlighten me on how the OP would hold the ailerons neutral in flight. Definitely would be a useful thing to do.
 
blaplante said:
I'm not sure how you perform "ailerons are held neutral" in flight. Hold in alignment with the wingtips? Ah, I've seen plenty of wingtip warpage/alignment problems which makes that unreliable. In alignment with the flaps? Who says the flaps are rigged correctly? With the stick vertical? Who says the aileron pushrods are rigged correctly?
Enlighten me on how the OP would hold the ailerons neutral in flight. Definitely would be a useful thing to do.
Click to expand...
The plans will call out the angle of the ailerons that is 'neutral'; of course, this must be done in the hangar......unless you have a really talented wing-walker! 🤣 SO: put the ailerons near neutral and measure the angle of both. You will have to clamp them in place or have someone hold them steady. Port to starboard wing needs to be the same. If not, that could be the problem. Once you have found the neutral position, note the position of the aileron on both the wing tips and the flaps. Look at both port and starboard as they will likely be slightly different. Write down where those positions are as you will get in the air and not remember. See what the airplane does flying with the ailerons in that position. Put the stick in the position that recreates the positions you found on the ground and see if the airplane flies straight or starts to drift. And you get to do more flying! Hard to beat that! Some test pilot stuff! "C'mon, Mav! Do some of that pilot :poop:"

Measure the angle of the flaps in full flap-up position. Make sure there is no play and they are truly fully retracted. They should be the same.

Look at the trailing edges of the ailerons. Sometimes you can look and see if the trailing edges have been 'pinched' too much or not enough. Too much: they almost look concave before the trailing edge. Too little: they look slightly 'fat' before the trailing edge.

Looking forward to the debrief.......!:)
 
so... use the mark 1 eyeball to estimate that the left aileron is "about that much" above / below the left and right flap & aileron. Repeat in the air.
Given the sensitive ailerons in my 6, I suspect a 1/8" error in my eyeball estimation of the position will substantially affect whether it rolls left/right or not.

Also, still haven't heard if the OP measured the wing angle. That CAN be off, and still have the plane fly straight, at some speeds, due to other misalignments cancelling the effect. I've seen it. We corrected some obvious aileron hinge alignment issues on that plane... and it flew WORSE.
 
RV6’s were supplied with a full size pattern that was then used to make a “clam shell” wing clamp that held the ailerons in alignment. The clamp was typically made from plywood, usually one of the shipping crates. You could then drill your aileron hinge brackets with confidence. The wing chord and aileron chord were in line.
I believe they went away from these aileron alignment tools when they went to match drilled kits as you no longer had to worry about aileron hinge brackets being drilled too high or low.
How you digest this and apply to a flying 6? Not sure. Find someone who didn’t throw out the clamp? See if Vans has the template or make your own from the plans?
Lastly, can aileron angle be measured as accurately? I doubt it but haven’t tried. Seems a slight partial degree off could make a pretty big difference.
 
JonJay said:
RV6’s were supplied with a full size pattern that was then used to make a “clam shell” wing clamp that held the ailerons in alignment. The clamp was typically made from plywood, usually one of the shipping crates. You could then drill your aileron hinge brackets with confidence. The wing chord and aileron chord were in line.
I believe they went away from these aileron alignment tools when they went to match drilled kits as you no longer had to worry about aileron hinge brackets being drilled too high or low.
How you digest this and apply to a flying 6? Not sure. Find someone who didn’t throw out the clamp? See if Vans has the template or make your own from the plans?
Lastly, can aileron angle be measured as accurately? I doubt it but haven’t tried. Seems a slight partial degree off could make a pretty big difference.
Click to expand...
Ya and I still have the clamp from 1991 RV-6 hanging on my wall..
Probably never use it again but who knows
My luck varies FIXIT
 
sebc150 said:
I’m looking at purchasing my first Vans, a -6.
Everything looks straight however hands-off the airplane rolls to the left with about a 5deg/sec rate.

The ball is in the middle and with the stick in the middle and the ailerons neutral it flies straight.
However upon releasing the stick, the stick moves to the left and the airplane banks.

I’m just wondering if this is something that we’ll be able to fix.
Click to expand...

Hi Seb, welcome to VAF and RVs.

You’ve already had a bunch of people give you a lot more info than you were expecting.

First step of distilling iit is to fly with two equal weight pilots and equally balanced fuel and see if you actually have a problem.

You probably have aileron trim, but it’s still simple to fix if you don’t (and aileron trim is easy to add).

If you’re new to RVs, it might help to know how finely balanced these aircraft are. In my RV-6, when it’s trimmed in pitch and roll to fly hands off, in still air I can “steer” it by shifting my body weight.

If I lean to the left or right, I get a very gentle roll. If I slacken the shoulder straps and lean forward, the airplane will subtly pitch down and accelerate. I can counter it by leaning back and stretching my neck so my head tilts back over the baggage compartment, which will make the nose slowly pitch up. Absolutely extraordinary the first time you see it, you’ll be giggling all the way to the hangar.

Very small changes in weight distribution are significant for RVs, that’s why they fly so beautifully.

You either have uneven weight distribution which can be trimmed-out, or you have an aileron radius mismatch which can be solved by following the SB everyone’s been pointing you at.

But don’t make any SB changes unti lyou’ve confirmed there’s actually a problem. If you’re flying solo in a side by side RV, there’ll almost always be a left turning tendency because there’s no weight on the passenger seat. That’s why we have aileron trim!

- mark
 
I had exactly this problem on the 6 I bought. I checked everything was straight as it should be and all was well. Finally tried the aileron squeeze and was amazed that the roll disappeared. I have to admit I was not expecting such a significant result with the first attempt.
 
Very common. If the ailerons deflect with your hand off the stick, the aileron hinges are not aligned with the chord line as they should be. Only fix is to drill them off and try a new set - a lot of work if you're not a builder. Note: don't do the "pinch the trailing edge" thing. All that results in is a permanently deformed aileron that doesn't fix the problem. Ask me know I know!
 
71459 said:
Very common. If the ailerons deflect with your hand off the stick, the aileron hinges are not aligned with the chord line as they should be. Only fix is to drill them off and try a new set - a lot of work if you're not a builder. Note: don't do the "pinch the trailing edge" thing. All that results in is a permanently deformed aileron that doesn't fix the problem. Ask me know I know!
Click to expand...

It may not have worked for you, but has worked for hundreds (thousands?) of others, including me. Very easy to do. And to overdo if you're not careful.
 
Kyle Boatright said:
It may not have worked for you, but has worked for hundreds (thousands?) of others, including me. Very easy to do. And to overdo if you're not careful.
Click to expand...
If the airplane wants to roll hands-off the airframe is out of trim and something is aerodynamically wrong. It might be a twist in the wings, empennage misalignment, asymmetrical flaps, wheel pant misalignment, or one or both ailerons are out of alignment with the wing chord line. Squeezing the trailing edge of one but not both ailerons is not fixing the flaw - it's adding in yet another flaw. One does not want the aileron shapes to not match. I'm suggesting finding the real reason and actually fixing it at the cause, not covering it up with a brand-ade.
 
Thanks for the overwhelming response!
Seems like I have a list of things to check, which I will do as soon as I get back to the aircraft.
It could very well be a flap alignment issue or something like that. I'll get back to this thread with more info as soon as I have it.

I suppose there is always the option of a trim tab rather than squeezing the trailing edge?

For those that have done it, what roll rate effect does squeezing an aileron have in terms of degrees/sec?
 
71459 said:
If the airplane wants to roll hands-off the airframe is out of trim and something is aerodynamically wrong. It might be a twist in the wings, empennage misalignment, asymmetrical flaps, wheel pant misalignment, or one or both ailerons are out of alignment with the wing chord line. Squeezing the trailing edge of one but not both ailerons is not fixing the flaw - it's adding in yet another flaw. One does not want the aileron shapes to not match. I'm suggesting finding the real reason and actually fixing it at the cause, not covering it up with a brand-ade.
Click to expand...
Who said the aileron shapes shouldn't match? Even a tiny difference can cause the problem the OP describes. A minute adjustment can fix it...

Remember, the OP's airplane flies in trim if he holds the ailerons in trail. If he releases the stick it rolls. That is exactly the problem the trailing edge (or aileron height) adjustment corrects.
 
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