M

McGraff

I'm New Here
To rv-4 builders please,
I am fitting the fuel tanks on my rv-4 wings. As I can see the plans call for #8 screws until about 12 inches from inboard behind the spar. Farther than this, the thickness of spar caps prevents putting nutplates. What will be holding the skin in this area? It is a kit I bought last year ... and the skin isn't fitting very well under. There is a rather large, constant gap there between wing and fuel tank skin (around 3/32)... not sure what to do with it by now... any suggestions?
Thanks in advance,
McGraff
 
Is this a problem on both sides? On the left side there's the "wing walk doubler" I just nudged it forward so it just barly goes over the tank in that area and holds it down where there are no screws. On the right side I used a hand seamer and ever so lightly bent down the tank skin. After the tank was completly screwed on, I just tapped out any uneveness with a rubber mallet. mui bien. I can get pictures if you like.
 
OK so if I understand well, the wing walk overlaps a bit the fuel tank skin on the upper left side, and elsewhere, I should bend fuel tank skin a bit so that it sits down on the spar once screwed. I would appreciate a photo if you already had one.
As for the rather large gap, it is under the wing on the left side. Tank skin was already trimmed too much by previous builder...if anyone had an idea how to fix it other than building a new tank, it is welcome!
Thanks a lot for answering.
 
I think I miss-understood. I thought you meant the tank skins wern't touching the spars where there are no screws. If you have a problem with the tank skin not touching the wing skin and everything is already riveted in place, I don't think there's much you can do. Anyone else?
 
Mc Graff, I really want to help because the guys on this site are almost building my -4 for me and I owe others. The problem I have is understanding your problem. I could send a picture (have to take it first) but it would show exactly the same as Dwg. 17a.

Can you perhaps send a picture of the problem?

Are we talking upper or lower surface? I presume upper.

Is it the row of screws along the rear flange of the tank at the top which screw into the FRONT of the spar? The plans show 14 and indicate 2 1/4 spacing at the inner end and 3.5 at the outer. I guess I am puzzled 'cos these dont give up at the 12" point.

The bottom right picture on my blog might just help you if you double click it. It will become larger. The other potentially useful picture does not respond to double click for a reason I do not understand.

Let us know if there is anything more I can do.

Cheers!
 
fuel tank skin

Hello Steve,
As for how the tank skin is held, I'm ok now. Second part of my post was related to this ugly thing: a large gap between fuel tank skin and wing tank under the wing.
http://img230.imageshack.us/my.php?image=fueltankskinzn1.jpg[/url]
Hope image is ok...
 
The picture helps. This is a tough one because the leading edge of the tank matches the leading edge skin next to it right? So you can't build a new tank to match the bottom skin behind it because it then wouldn't match the leading edge skin. Come to think of it (I'm retarded) I'm having the opposite problem you are. On my right side tank, the skins touched with no gap... but the leading edge didn't match...to get the leading edge to match, I had a huge gap and the nutplates didn't match my holes. (I discovered this months ago and left it for later due to anger issues at the thought of building another tank) I wonder if Vans made a few tank skins too small. I do have another tank skin in the shop, I'll have to check and see if it fits better. If not, I guess something went wrong somewhere, and I'll have to fill it with fiberglass filler or ???
 
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You're right. Leading edges match quite nicely. I suspect now that since I had to trim on up side, the tank skin was not properly centered on the ribs, hence the missing material bottom side. Now nutplates fall too near from spar caps inside. It is simply impractical to put #8 screw past the 4-5 first starting from outboard. Think it would be ok with smaller #6 but then I have to put more screws to get same strength...
and then fill the skin gap under the wing...oh boy...I will try to get an advice from Van's and I'll tell you the result.
Thanks a lot for posting.
This image should be clearer.
http://img220.imageshack.us/my.php?image=fueltankskinks0.jpg
 
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