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Wing Tip Alignment Tolerance Question

Bart

Well Known Member
I've see this question floating around all the forums and have ignored most of the discussions until today. After having re-read many of the "mismatched wing tip" threads I wanted to ask the -14 crowd about tolerances.

Both my tips are 1/4 inch above the aileron and flap reflex position. The rigging on everything has been near perfect until today. In fact it wasn't until the nut plate installation was finished that I noticed both tips were slightly (1/4 inch) above the flap/aileron line.

I'm torn about cutting the TE open and creating the perfect alignment over seeing what the actual flight conditions might show with my 1/4 inch off alignment. Since both are nearly identical my gut is saying leave alone until we see what happens in flight...but I'd like to hear what other folks have experienced.
 
Tip trailing edge high or low seems to have almost no effect. I even taped a great big tab to the trailing edge of a tip once just to see what happened. Zip.
 
Make a little wing (tip) fence to go there so it looks like that's the way it's supposed to be..............

Fence would also stop any weird airflow thru the gap between the aileron and tip.
 
Tips

Adding a tab to a wingtip and deflecting it up (to roll the airplane toward that side) is not nearly as effective as adding one on the other side, deflected down, to raise that wing. Our RV-6 , not built by me, has a bit of wash-in on the right wing. We ran out of right aileron trim at high cruise speed. I added an old/ timey deHavilland tab to the underside of the left wing and got the rigging closer. It’s just a piece of 1/4” round arrow shaft taped under the trailing edge, parallel to the trailing edge. Adding one on top of the right tip did nothing. I finally put a stronger spring in the aileron trim system and now we can just get it to fly straight at higher speeds. Using fuel out if the left tank helps, too.
 
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Bart,

I assume you are not yet flying, so before you start cutting wing tip trailing edges I recommend some careful measurements to make sure your rigging really is correct. This cannot be done until the wings are on the airplane. For example:
- Are the flaps all the way up? For the RV-10 and 14 this is easier than the previous planes, but should not be glossed over. Take a straight edge across the length of the flaps, is each flap the same over the length and are both flaps the same? You are looking for flap twist and that each flap comes up flush with the fuselage.
- With the flaps up and the elevator clamped in the trail position, do the ailerons line up perfectly with the flaps? For the RV-10 and RV-14 you must clamp the elevator in the neutral position first as any deflection will pull on the aileron push tubes.
- If good, then do the same straight edge on the ailerons that you did with the flaps.
- Finally, with the ailerons softly clamped to the flaps, measure the gap between the leading edge of the aileron and the wing skin. Again across the length of the aileron to make sure it is constant, and both ailerons are the same. On many RVs a heavy wing is caused by an aileron hinge point being too high or too low. Easy to fix if it is.

For builders who have not yet fitted the wingtips, recommend deferring this until final assembly, and after the above checks are done. The little aluminum gig that comes with the kit that it tells you to use is ok for getting stuff in the ballpark, but not for perfect before you drill mounting holes in the wingtip.

Carl
 
- Are the flaps all the way up? For the RV-10 and 14 this is easier than the previous planes, but should not be glossed over. Take a straight edge across the length of the flaps, is each flap the same over the length and are both flaps the same? You are looking for flap twist and that each flap comes up flush with the fuselage.
- With the flaps up and the elevator clamped in the trail position, do the ailerons line up perfectly with the flaps? For the RV-10 and RV-14 you must clamp the elevator in the neutral position first as any deflection will pull on the aileron push tubes.

My understanding is that, on the -14 at least, the ailerons are meant to match the flaps at 0 degrees, not when the flaps are fully up (-3 degrees). Do I have that wrong?
 
Carl,

Thanks for the advice. Wings are attached, I should've noted that. I did recheck the flaps, aileron, and overall alignment. They are very satisfactory. They were QB flight controls and Van's did a great job putting those together. The wing tip aileron gap is 3/10th's, they are about 3/100's difference between both ailerons/wingtips with the elevator neutral position and flap reflex /aileron alignment lightly clamped. No visible twist using a straightedge. My question is...do I need to continue troubleshooting or leave it and see what happens in flight?
 
My understanding is that, on the -14 at least, the ailerons are meant to match the flaps at 0 degrees, not when the flaps are fully up (-3 degrees). Do I have that wrong?

Yes, you have it wrong.
The ailerons are technically always at a - 3 degree reflex (when neutral) for cruise flight (where the airplane spends the majority of its flight time).
 
Carl,

Thanks for the advice. Wings are attached, I should've noted that. I did recheck the flaps, aileron, and overall alignment. They are very satisfactory. They were QB flight controls and Van's did a great job putting those together. The wing tip aileron gap is 3/10th's, they are about 3/100's difference between both ailerons/wingtips with the elevator neutral position and flap reflex /aileron alignment lightly clamped. No visible twist using a straightedge. My question is...do I need to continue troubleshooting or leave it and see what happens in flight?

As Dan already said, the position of the wing tip trailing edge (unless grossly off) has pretty much zero influence on the roll trim.
 
Splitting the trailing ends and adjusting to be more visually appealing is very easy.

Dennis - can you provide pics when you adjusted your TE to match. I think I know how I might do it but why pave new ground if I don?t have to.
 
If you just split the trailing edge of the wingtip and move the area next to the aileron to match the aileron, the outboard portion of the tip trailing edge doesn't move, and that could cause the tip TE to misalign with the aileron TE.
If you want to move the whole tip TE vertically, you have to cut the tip forward from the TE for some distance, which can get messy. Ask me how I know.
 
Carl,

Thanks for the advice. Wings are attached, I should've noted that. I did recheck the flaps, aileron, and overall alignment. They are very satisfactory. They were QB flight controls and Van's did a great job putting those together. The wing tip aileron gap is 3/10th's, they are about 3/100's difference between both ailerons/wingtips with the elevator neutral position and flap reflex /aileron alignment lightly clamped. No visible twist using a straightedge. My question is...do I need to continue troubleshooting or leave it and see what happens in flight?

No - if my plane I would fly what you have. No need to fix problems that do not yet exist.

Carl
 
Well maybe it was an Easter miracle...I completed installing the wing tip rib with the anticipation that I may have to split the TE to resolve what was looking like a fairly large swail under the tip (midway down on the bottom side) and bring the alignment in with the aileron and flap line. When everything was riveted into place the aileron/flap line is now 3/100's below the tip. I'm going to say TLAR (that looks about right) on this little event. Right tip tomorrow....I'll keep my fingers crossed the same result happens.
 
Time for me to check in with similar questions. My wings are in the cradle and I'd like to get as much wing tip finishing done as possible before painting and final assembly. I've already drilled each wingtip for cleco installation. Continued with the left wing; installed the aileron, centered it with the aileron jig and taped the aileron securely in place with 20mil PVC tape before removing the jig (very stable; aileron is locked in position. Trimmed the edge of the left wingtip for aileron clearance (nailed the gap at 1/4") and clecoed the tip on the wing.
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As you can see, the trailing edge of the wingtip hangs below the aileron about 1/4". The relative lineup is pretty straight, but the wing tip trailing edge extends about 1/8" beyond the aileron. My question is this: should this be left as is until the airplane is flying, or at least after final assembly? I know I had the flaps and ailerons lined up nicely after setting the incidence and first rigging. I'm thinking of leaving things as they are until after final assembly... but I'd really like to get that aft rib in place now. If I end up needing to slice and adjust the trailing edge alignment, it should be done before the aft rib is installed. Any input is welcome... I'd especially like to know what Dan Horton and/or Carl Froehlich would do if they were me. ;)
 
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Leave the wing tips as they are until you hang the wings on the plane and get the control surfaces rigged properly.
Then make the tips match the ailerons and flaps.

It may make no difference to flight characteristics but when I see tips not aligned with control surfaces I wonder what other things were "good enough"
 
I had a similar 3/16” mismatch on one wing when the wing was in the stand before final assembly. Once I hung the wings on the fuselage and did the final rigging it pretty much disappeared.
 
RV8 wing tip

A lot of debate around when to fit the wingtips. But why wait until the wings are mounted? As long as the aileron bracket is used to find neutral, why wait until the wings are mounted? The bracket establishes the same neutral position regardless if the wings are installed or not, correct?
 
We’ve hashed this around a lot in the past. I did my tips in the wing stand and they’ve turned out great. When the flaps are in the stops and the ailerons are clamped to match the flap position the tips are easy to set. I liked doing the tip in the stand so as to not have to get under the wing to drill and fit it on the fuselage.
 
I installed my tips with the wings mounted to the airframe and could not get them to match using the supplied aileron jig bolted in place. Finally determine that the jig was out from one wing to the other. Nothing to do with the tips. The hole location was out on one wing versus the other. They are quick build wings. I could not determine that the wings or ailerons were twisted. I finally took the advice found here to align ailerons to flaps fully up to the stops then align wing tips to ailerons.

I would suggest waiting until wings are mounted to airframe.
 
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