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RV 8 wings don?t fit- what to do?

Douglas

I'm New Here
Attempted to stab the wings on my RV-8 with help of 4 highly experienced builders today. We could not get a fit and using electric calipers we discovered the wing is .08 of a inch wider than the slot it should go into. Other than calling Van?s on Monday has anyone else had this problem or know the fix?
 
Clarification.

Just want to clarify, the wing spars wont fit in the wing spar box?

What did you use for the spacer when you riveted that section together?

Quickbuild or slow build?

I would think that if you are out that much, you need to disassemble the spar box, space it properly and re-rivet. I used a CNC machined spacer I had fabricated and my spars went in with no difficulties.

I know others have used washers. I would think anything compressible like wood may cause your current issue.

Good luck. Call Van?s for their opinion. I would think that any adjustment to the spars would be a no no.

Cheers,



Don
 
A friend had this happen on his RV-9A. The plans are not very clear about using a spacer (I think they say wood) while riveting the bottom front skin to the skin aft of the spar. In his case, he de-riveted this joint, spread the front and rear fuselage spar halves apart and re-riveted. Seemed to work OK and even used the same dimpled rivet holes.

In my case I made hard plastic delrin spacers just wider than the measured wing spar prior to riveting, although I have not yet tried to fit the wings.
 
I used a spreader. A bolt with a nut and washers on both sides. Lots of ways to do it, just make sure you can get it out, and it won't leave a scratch. I put the bolt through the main spar holes, one upper and one lower. It did not take much to move it a few thousands. I did a dry run on each side. Have a magnet on a stick handy.

Easier if there is a block and the bolt can be turned and just hold the nut. I may have a picture.

He's .080" short, that's more than a 1/16 of an inch. Somethings going to give trying to spread it that much and it won't be pretty.
 
Vans

Slow build wings and quick build fuselage.

Worth a call to Vans so they know there's a QB problem. Most likely they will tell you as others said to drill the rivets on the center section, bolt in spacers and rivet back together.
I used Buller spacers but mine was a SB. Spacers were .005" thicker than the wing soars. Wings go in with a little coaxing.
 
What's the dimension ?

Just curious if anyone has the exact width dimension on the upper and lower wing spars where the bolts go through?

Doug's issue is a puzzle? The fuse is a quick build so the spar box should have been assembled at Vans with the correct spacers .... shouldn't it?

Every spar I have stabbed so far (4) has pretty much slid right in once you were holding your mouth right :eek:

Bill
 
Measurement

Just curious if anyone has the exact width dimension on the upper and lower wing spars where the bolts go through?

Doug's issue is a puzzle? The fuse is a quick build so the spar box should have been assembled at Vans with the correct spacers .... shouldn't it?

Every spar I have stabbed so far (4) has pretty much slid right in once you were holding your mouth right :eek:

Bill

Yes. That's why I suggested a call. Clearly they missed because spars are supposed to be so precise they are no longer a matched set with the center section. I have even seen fuses built without spacers and the wings fit.
He did say they were experienced builder helpers so one would assume they know how to get the wing spar to slide in.
My soars were 1.439". My spacers were 1.444". It's a 7.
 
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I used wood spacers from another builder, and my slots came out 10-15 mils narrower than the spars (slow build -7). However, there is enough flex in the structure that by slightly chamfering the ends of spars and greasing the spars and the slots per instructions, the wings went in with surprisingly little effort. I I ever do it again I?ll have some steel or aluminum spacers fabricated.

I would guess that 80 mils would be a different story; that?s about 85% of the diameter of a #3 rivet.:eek: I would be a bit torqued if I?d paid extra for a QB fuselage and got something like that. Drilling out that center section wouldn?t exactly be a trivial task...
 
I will be interested in how this turns out. 80 mils is no small amount and if you disassembled the center section, How are you going to rivet it back with the holes so far off? If the QB is actually off that much, I would want Van to replace it ASAP.
 
Vans reply

Well, their answer was to drill out the bottom front flange on the spar box, and then bolt the spar in so that it is pulled baaaaack into position. Check the holes and hope they haven't moved much or possibly upsize the holes to a -5 rivet and rivet the front lower flange back in place.

That's an easier fix than removing the whole spar box. It also appears that the left side is tight but doable. If the left will go in, we'll try Vans answer on the right side and see what happens.

It's aluminum so you can fix anything .... :( ... if you have to.

Bill
 
With a tight fit, I found gently spraying each part with Corrosion X helped a lot.

A little lub is better than 2 dry surfaces.
 
Wow

This is a somewhat timely post for me. I will end up with a similar situation - slow build wings and a QB fuselage. I'm now getting ready to order the QB fuse. This post serves to remind me to attach a note to my order to REMIND Vans to use the proper spacers in the spar box....

As stated in an earlier post - I would most definitely be fumed if I found out they did not build this area of the QB fuse properly. I guess I would also like more info from the Vans response - did they state that this was the reason for the mismatch - that they probably did not use the spacers properly as they should have when they constructed the QB fuse?
 
Check it out ....

Now having seen this for the first time, I would suggest that you mike(mic?) your spars and then mike the spar box clearance when you get the fuse. That's the right time to think about what to do if they are off. At that point, you could send it back .... in theory.

If the fix turns out to be this easy, it wouldn't be worth the time to return it. Remember, you are building an experimental airplane and not everything will be perfect. I think Vans does way better than we have a right to expect so I don't think the small fix is a problem....key word is small :)

Just my .02

Bill
 
Update

Just an update .... this is our assessment and not that of an aero'engineerical type .... we dug up a digital micrometer and verified that the spar box was 60 thousandths too small to take the spar. Both spars measured out at 1.450 and the left box at 1.44 and the right box at 1.39, a full 60 thousandths too small. 60 is about the thickness of two thick plastic credit cards.

We tried various spreading techniques and the best we could get was another 10 which wasn't nearly enough. Vans recommended fix was to drill out the right 6-8 rivets on the front flange of the spar box and the lower 5 side rivets and then spread it open.

We started down that path and found that the flange on the right side had zero clearance to the lower longeron. That is probably why we couldn't spread it. The left side had at least 60 thou+ by eyeball. We suspect that this was done in assembly and that is why the box closed up. It took about 20 minutes to drill out the rivets and then we pried up the flange so that it would ride up over the lower longeron. Once that was done, we were able to easily spread the box to 1.470 and it was a done deal. Don't think we will even need to upsize the replacement rivets.

The long and the short and the narrow is that the right side spar box appears to have been assembled incorrectly but the fix was relatively painless.....(that said by the guy who didn't own the airplane :rolleyes:)


Left Spar Box showing 1.45

img_2018_02_11_175439_02-46605887.jpg


Right Spar Box showing 1.39

img_2018_02_11_175441_03-37040627.jpg


This is the outside spar dimension on the standard micrometer with the internal set inside to show the physical difference between 1.45 and 1.39. The picture makes it look bigger than it was but it was easily two heavy credit card thicknesses.

img_2018_02_11_175437_01-52847749.jpg



Now note obvious gap between lower flange and lower longeron on left side.

img_2018_02_11_175446_06-22107698.jpg


Note there is zero clearance between the flange and the lower longeron on the right side. It actually popped as we pried it up before trying to spread the box again.

img_2018_02_11_175448_07-69426749.jpg


This is with the spar installed. Note how far the lower flange is pushed up over the lower longeron....looks like about 60 thousandths ...

img_2018_02_11_175449_08-92173135.jpg


So good call on Vans on the fix, poor quality control on assembly, but a relatively happy outcome. Some would say that's bad QC on Van's part but I am still amazed that the other 99% fits so well.... and it is experimental. ;) It's all good!


Still got the Grin :)
 
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