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aargh - Quickbuild wing bottom skin fit

E

eatenbyagrue

Active Member
Hi All,

I could use advice regarding the fit on my QB bottom wing skin. Basically, I've got nearly the whole skin riveted on and am finding the row of holes on the forward spar are all about 1/32" off, enough to not quite let a rivet be pushed in.

When I fit the skin, I had a similar issue. I worked around it by changing my cleco pattern, until I could get cleco's into every few holes. Thinking I had it lined up, I then drilled, deburred etc and and started riveting.

Now I've got the skin almost fully riveted, starting from the trailing edge, and things aren't pulling together again like they did clecoing. The weird thing is, the entire rear spar and ALL the rib holes line up just fine, the only misalignment is with the forward spar. I'm thinking that that bases of the wing ribs weren't quite fluted enough during the QB build, increasing the gap between the "foot" of the rib and the spar.

So, the question is, what now? The holes aren't very far off... my inclination is to redrill the holes to #40 (slightly enlarging them,) and then using the next length rivet in the holes to allow them to swell up a bit. I suppose my next thought would be to drill them all out to #30 and use AD4's, but, that seems like overkill. Thoughts from the VAF?

Thanks much,
Josh (very frustrated)
 
Hi Josh.. I had a similar issue on my slow build left wing (still working on the right wing.. hope i'll not have the same issue!)

I was lucky because I noticed the misalignment before start riveting and, contacted Van's, they told me to start riveting from the main spar down to the rear spar. It worked well (while riveting all the holes came to the proper position) except for a few rivets along the rear spar I couldn't reach with the bucking bar and, as per Van's suggestion, I used blind rivets on those holes.

In your case I suggest you to contact Van's and ask for a solution.. elongating the holes on the main spar doesn't looks to be a good solution. You can check for proper bend/flute of the ribs flanges and start clecoing form the middle of the ribs and proceding to the spars (or starting at the main spar and proceding to the rear one)... if you can cleco the skin, while riveting your fit will be better because the rivets will force the dimples in the proper position. But, again, a call to Van's will give you more usefull informations.
 
Thanks

Thanks for the reply. I am hoping to avoid drilling out every rivet in the skin, but I guess I need to suck it up and do it, if that's what needs to be done. I have an email into Van's, we'll see what they say...
 
Drilling out ALL the rivets in the skin will result in a LOT of enlarged holes.... I don't think it's the way to go.

Let me know what Van's says.
 
It's maybe 75% of them... I was hoping everything would pull together, should have stopped riveting sooner I supposed. One step forward and two back.
 
eatenbyagrue said:
It's maybe 75% of them... I was hoping everything would pull together, should have stopped riveting sooner I supposed. One step forward and two back.
Click to expand...

I say go with the drill the mis-aligned holes out and use the next size up on the rivets... if you drill all the others out, you'll probably do more damage than good by the time its all said and done with... thats just too many to drill out... another thing to try, I use a pin punch sometimes to help line up holes... on occasion, i have to push it in pretty hard to get it to line up. I have a feeling it slighly stretches the skin to the hole, but not by enough to obtain any kind of measurement. You could try that, starting at once side and working your way to the other? Here is the punch I use:

66324%20Pin%20Punch.JPG


I just put it in the hole, and push it up to the tapered part, a little push and a twist or two puts the holes into exact alignment... take it out, drop a rivet in, and pull the trigger!

and here is where I got it:

http://store-planetools.com/pinpunch.aspx
 
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You're going to think I'm crazy, but.....

The wing is on straight padded sawhorses perpendicular to the the spar, right? With the lower skin in place, flip it over, bottom side down. Make sure each sawhorse is under a rib. Have a buddy push down on the rear spar while you push down on the leading edge. Now crawl up under the wing and insert the clecos ;)
 
Dan - that's crazy enough that it just might work. The holes are that close.... now to round up a helper for this weekend....
 
The CNC punch at Vans didn't put the holes in the wrong place. Gravity has deformed your wing because, lacking one skin, it is currently an incomplete structure. Sitting on the sawhorse pulls the spar-to-rib flange a bit longer, like so (small arrows):



Flipping the wing puts that flange in compression, and lo, the skin again fits.
 
Assuming that Dan's idea is not going to work, (it sounds good, but you already have most of the skin on, it's not going to flex that much I am afraid.) I think you might be able to use the punch idea to get it to line up. Otherwise you have to make a decision to either oversize the holes to a 1097 -4 rivet or just clean them up with a #40 bit.

As always give Van's a call when you have a stumbling block. I find they are very helpful and give wise guidance.

Do NOT drill out the rivets. That will be a disaster.
 
For what is worth, I have found (after four RV projects) that standing the wing leading edge down in a wing cradle,clecoing on that last large skin for alignment, and then start riviting at the rib outboard of the double row seems easier for me. Have never had alignment problems. Also able to rivit the whole thing solo with no nasty pull rivits. And I have short arms.

Ed Booth, Trenton, SC (6, 7, 9A, 10)
 
apkp777 said:
Assuming that Dan's idea is not going to work, (it sounds good, but you already have most of the skin on, it's not going to flex that much I am afraid.)
Click to expand...

The problem is a slight deformation of the bend forming the short vertical rib flange. The skin is indeed riveted along the rear spar and up the ribs before you get to this point.

BTW....it's how I did my own QB wings.
 
skin problem

I have the same problem. What I did worked great. Yes, there is some "sag". Yes, it can be removed.

I lifted the skin slightly and put in clecos in every hole. The clecos will go in on an angle and stay that way until released. I then took a length of 2 x 4 and put it up against the clecos. I then pushed gently. I heard all the clecos snap to full expansion and they stayed upright. I took out one cleco at a time and riveted the skin leading edge with no problems and no gap. There is a lot of pull in 40 -50 clecos. About to do it again on my second wing.

Dave Nellis
 
I had trouble with one of my skins but was able to address it before riveting. I aimed a small heater at the offending skin for a few minuets and it fit fine. Maybe you could put it outside in the sun bottom side up for awhile and see if it makes a difference. It is amazing how sheet metal grows in the sun.
Good luck!
 
So close!

Well, after changing the way the wing is supported, letting it rest overnight and and squishing it a little, I've got a row of cleco's in every other hole along the spar! But, it's so very close, in about half the holes, a cleco will fit, but a rivet will not (I checked, rivets are ever so slightly thicker.)

At this point I think I'm good to run a bit through the holes - they are so close that any enlargement will be minor and easily filled by rivet expansion.

I still have a note out to Van's, I'll update them as well and see what they think.
 
Was the bottom skin ever match drilled? On my SB wings, I had to match drill the skin to the wing with a #40 reamer before a rivet would fit through any of the holes. They are stamped undersize from the factory and require enlargement. I've never seen a QB wing, so I have no idea if this is a required step for you guys.
 
Squish it a little harder and check again....they'll go. I'm about 220 and draped myself across the leading edge wrap while a lighter buddy pushed down on the rear spar. Just make sure the sawhorses are aligned under two ribs.
 
Same issue with SB wings...

I am about to rivet the bottom skins of my SB right wing. With the skins clecoed to the ribs and spars, the gap between the LE, FT and skins is about 3/64ths while on the table. In the cradle, the gap closes up to about 1/64th. But, even though the clecoes go into the skin to main spar holes, the rivets don't quite go in. So, I hope that by riveting the skins on will pull the skin tighter than the clecoes. If not, then I will use Dan's suggestion. Gravity seems to be at work here.

Regards,
 
If you use Dan's "contortion" and find you still have a few that don't fit you might consider a few 1097 rivets for the last extremely stubborn ones (as long as dimples aren't misaligned too badly.
 
mototopo said:
Drilling out ALL the rivets in the skin will result in a LOT of enlarged holes.... I don't think it's the way to go.

Let me know what Van's says.
Click to expand...

With a little practice, you can avoid enlarging the holes when you remove a rivet. A relative of mine worked for Lockheed, and he taught me a nice trick. Drill into the rivet head just enough that a little flick or twist of the drill bit will shear the rivet head off. Make sure you've stopped drilling when you do the little flick action. This works for either c/s or universal rivet heat). Once this is done, it's easier to accurately drill the remaining rivet shank out.

Don
 
Rivets off in spanwise direction?

That is the way mine were on one wing. I installed clecos in every hole in main spar and it pulled it around fine. Like Dan said a little twist in the wing is all it takes to throw you off 1/32" at the main spar. Eyeball down the main and rear spars and they are not perfectly straight. The skins are punched for perfectly straight spars. You just have to pull everything to where it is supposed to be.
 
With a little practice, you can avoid enlarging the holes when you remove a rivet. A relative of mine worked for Lockheed, and he taught me a nice trick. Drill into the rivet head just enough that a little flick or twist of the drill bit will shear the rivet head off. Make sure you've stopped drilling when you do the little flick action. This works for either c/s or universal rivet heat). Once this is done, it's easier to accurately drill the remaining rivet shank out.
Click to expand...
That's almost what I was taught in school, except use the butt end of the same size bit and just drill through the head stopping short of the skin. Use the butt of the bit to pry the head & it pops right off, then you can see the shank and really drill the center. The mfg head actually smears sideways a little when bucked making it off-center with the shank. That's why sometimes when you drill one & swear you're centered on the head but it misses the center of the shank. It's more pronounced with universal heads. The dimple helps keep the head aligned with the shank. Also, it helps to grind the butt of the bit flat & square, grabs better so you don't have to drill as deep. You can get away with bigger holes when squeezing, a big hole while bucking almost guarantees a tipped/smeared shop head.
 
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