Fearless

Fearless

Well Known Member
Builders and Flyers,

I got about a 1/32 gap between my leading edge and tank skin. The rivet and screw attachment holes in the main spar are lining up for the leading edge and tank where I have clecos in place. Is the gap a problem or will I be okay with it. I'm not sure I can get it closed up any tighter. Is this a case where it is good enough or do I need to be more anal about the fit.

Thanks
 
I'm about at the same spot for my RV-9A wings - there wasn't much laterally between the two skins (tank and leading edge), but there is between the tank and main wing skins. One builder (Smitty, I believe) said that after riveting, it closed up. We'll see... .
 
I'm not entirely sure you want the two much closer. Think of the expansion and contraction and general flexing of a wing. If you have those two pieces touching, for example, and a really expensive coat of paint over it, I can't imagine that would be a good thing long term.
 
What about the nutplates on the attachment strip

Carl,

I don't see how the skin will close up once it is riveted. The holes for the nutplates have been predrilled at this point and I would think the screws would keep them from closing up anymore once they are installed in the nutplates unless when they are dimpled it draws the skin surrounding the dimple tighter which might cause it to tighten up.

I searched for postings earlier and found where one builder had a problem with the skins laying flat once the screws were inserted where his skins didn't lay flat on the attachment strip.

Thanks for the replies so far.
 
I had about that gap on my both wings. I just finished riveting the top skins on the left wing and it is pretty much zero at the leading edge now.

My right tank doesn't sit perfectly flush with the attach strip between the 1st,2nd,3rd screws from the leading edge. My left tank is flush though. I'm wondering if things will change a bit once I get the right skins put on...

I think it's one of those things you don't have too much control over. A few 1/100s of a inch up or down in spar sag or a few 1/100s in twist will show up as changes in tank-leading edge gap. I don't think you can do much to prevents little gaps or a slight twist in the wing. Get it as good as you can and go from there. With luck everything lines up perfect... But we can't all be lucky.
 
Tank to Wing Leading Edge Mismatch, RV-8

Help. I just mounted the left tank and have much worse fit to the W-423 joint plate and leading edge. I did the right wing, tank assembly last weekend and it came out perfect. the only mismatch was in the thickness difference of hte materials. You can see from the first photo that it fits flush if I just barely place the tank on the reinforcing plate and the outer rib is not on the outer z-bracket.
http://img144.imageshack.us/img144/4710/img2757xt2.jpg As I slide the tank out and into position, I have to lift it and the mismatch occurs. The other photo show the resulting gap between the tank skin and the aft-top wing skin.

Since my right wing came out perfect, I'm not wanting to just accept this. Could I fit everything with out the baffle in place to remove it's thickness and hope nut plate will pull it in tight? I'm going to try clecoing the whole thing to the spar and see if I can pull it down.http://img117.imageshack.us/img117/6649/img2759jm8.jpg
http://img117.imageshack.us/img117/7901/img2760op5.jpg
 
Same question and hopefully now with the photos

Help. I just mounted the left tank and have much worse fit to the W-423 joint plate and leading edge. I did the right wing, tank assembly last weekend and it came out perfect. the only mismatch was in the thickness difference of hte materials. You can see from the first photo that it fits flush if I just barely place the tank on the reinforcing plate and the outer rib is not on the outer z-bracket.
img2757xt2.jpg
As I slide the tank out and into position, I have to lift it and the mismatch occurs. The other photo show the resulting gap between the tank skin and the aft-top wing skin.

Since my right wing came out perfect, I'm not wanting to just accept this. Could I fit everything with out the baffle in place to remove it's thickness and hope nut plate will pull it in tight? I'm going to try clecoing the whole thing to the spar and see if I can pull it.
img2759jm8.jpg
img2760op5.jpg
 
dbuds2, I had the exact same fit only the left was PERFECT and the right looks just like your bottom pic. (the one with the thumb). I don't see any way to fix it so I'm just going with it. Your not alone.

The gap will close a little when you put all the #8 screws in but not all the way.
 
Fit is now perfect without baffle

Sorry for the large size photo, first time.
Took out the baffle and the fit is just like the right wing.
img2765dh3.jpg


I doubt the nut plates and final riveted z-bracket/baffle/rib will reduce the stack to fit perfectly when all done. What do you think?
img2766cv6.jpg
 
Same deal on my 9 wings...

My tanks were QB SB wing- but I had to 'massage' the curvature of the leading edge to match the tank (tank already riveted). I could increase the curvature of the tank a little by pinching it together by hand.

I was also able to get a little better fit by inserting the screws along the wing first then work up the leading edge.

Riveting does close up a hair of the gap- the clecos have a little slop in them.

After working and working- A 32nd is pretty good. It looks worse with bare aluminum.

A final note-

the 1/32" gap along the leading edge or 'slight' gaps from the screws is only cosmetic and doesn't affect the flying ability of the plane. Don't let it slow you to a crawl. Having just finished the wings and now starting the Ailerons- we're only about 20% complete- keep banging away.
 
My tanks had to be persuaded into position. I just pushed down on them and installed four of the tank skin to spar screws. This held everthing in place while I drilled the Z brackets and outboard attach holes on the tanks. This actually bends the baffle slightly.

Another method is shown below (from Brad O's site):

060121_001.jpg
 
If it's not fitting, before you manhandle the tank. Check to make sure the jack on the bottom spar (if you're using a jig and , to me, this is a good reason to), hasn't gone soft.

I had the same problem and it turned out the wing was sagging. Two pumps of the bottle jack and it popped right into place. This is most definitely the cause if you have a gap (especially one that changes) from leading edge to main spar).
 
Bob, that was the first thing I looked at too (spar sag). But with BOTH top main skins clecoed in place (every third hole), my spars had NO sag at all. The skins held everything exactly straight. However, I agree it should be checked :D
 
I used Dan Checkoway's method of building my RV-7A tanks and mounting them on the wing. It's perfectly described on his website and I'm very thankfull to him for sharing..

Worked out great and I agree that sag plays an important role. Check wingstand and support jack for an absolute straight set-up. Not almost straight but perfectly straight..

cimg2150nq1.jpg
 
PH-SCP said:
I used Dan Checkoway's method of building my RV-7A tanks and mounting them on the wing. It's perfectly described on his website and I'm very thankfull to him for sharing..
Click to expand...
Wish I could take credit for it but I can't. I stole it from an RV-8 builder! I forget his name, but it was posted in the rv-list archives years ago. Happy to pass it on, though.
 
Still a poor fit

After double checking, the spar is still straight as a string. One thing I did do was to line drill the tank to W-423 doubler with the tank baffle removed. Without the baffle, all fits are line-on-line perfect. I'm hoping the mating dimples at that joint will naturlly pull the tank skin aft. As well as the tank skin to spar attachments. I'm also going to fill a little off of the Z stiffeners.

I'll let you know, as I intend to mount it again before accepting it as it is.
 
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