Wing Sheeting Advice

[DesertBearhawk]

Guys, Im About to start on my wing sheeting. Those of you that have completed this process, can you offer any words of advice, do's & don'ts, or gotchas?


Thanks!

[BTAZ]

I just finished my LSA wings and went about it a bit differently then what I've seen.

If your rib positions are matched between the wings and the rib spacing is consistent and the fluting is consistent, you can "match cut" and "match drill" the skins for the two wings at once.

For drilling, I made a template that started at the bottom rear of the front spar and wrapped around the leading edge to the rear of the top of the rear spar. I marked the rivet locations to meet the nominal spacing and clear the fluting. I then drilled the locations on the template exactly 1/2 the rib flange over and made a second set of holes over from that for the seams. Measure thrice to make certain your rivet line will be appropriately centered on the rib and drill the rib locations on both sheets while they are flat on your table. Note I did not drill the skin to spar locations, only the rib holes.

Draw center lines on the ribs and, once the skin is tied in place with ratchet straps, move them as required to line up with your pre drilled holes. I was blessed with having a second set of hands available in my son. Since he had the better eyes, I manipulated the ribs and he drilled the holes.

Check plumb and square continuously as you go.

Rather then forming the leading edge with a vacuum, I used the same size PVC pipe as recommended and with it blocked in at the edge of my table used "abdominal persuasion" (my beer gut) to fold the aluminum over it. The LSA uses .020 top skins so I don't know if this will work for the heavier skins of the others but if it does, it was a lot less fussing then to tape/untape etc. to seal up for the vacuum. As far as where to fold it, treat it just like a break. Measure a test piece to find the sight line, test fit it, and adjust the sight line as necassary. Once you have found the correct measurement, use care to repeat it when you bend the other sheets. The only trimming then required is to the trailing edge of the top skin as the other edges will all line up.

To trim the skins to size, I used an abrasive blade in a Skil saw along with a 8' fence. Leaves a burr but it cleans up easily enough. Loud though so wear hearing protection. Also, since you cut the sheets for both wings at the same time, the plastic melts a bit on the edges which keeps the sheets aligned until you get a few clecos in while match drilling,

If you want to do both wings at the same time and have a cleco in about every third hole, you will need about 1500 of them(for the LSA).

Once all the skins are in place(and you are sure your spars are dead straight and the wing is plumb) you can pull a string line on top of the skin down the center of the spar flange to locate the skin to spar holes

If you are not confident the rib locations etc. are within .050" or so between the two wings, then you are probably better off with the more traditional "Fit each skin oversize, mark the nose rib locations, back drill rib to skin where you can" approach. But if they do match, producing two skins at once(I think you can do even more if you look carefully where they would match) was pretty efficient and I didn't scrap any because of fitment or mis-drilling(I did scrap a couple because of dents as shipped from Aircraft Spruce)

But if you do screw up while drilling, you've made a much costlier mistake....

You can see some of this in my build log linked in the LSA forum.

If you wish to discuss, PM me a phone #

[mswain]

Dave,

I am just about to finish skinning my left wing. I used the vacuum method, and it worked well. I pretty much did it similar to how it's described in Eric's manual. I ended up overlapping my skins opposite of the plans, I didn't want to look out from the cockpit and see the edges. I used a small piece of tank strap as a hole locater, to drill the new skin at the overlap. thats about the only trick I can offer. I show it here: http://mswain.com/bearhawk/?p=111 I had to beg and borrow for clecos....and I am only doing 1 wing at a time. Doing 2 requires a lot of clecos. I went ahead and riveted my top skins before laying out the bottom skin, I think that might be a bit different than the manual.

Mike