Leading Edge Skin Installation - Some tips
After all your hard work to get to this stage of the Wing build, the installation of the leading edge skins is when your wing really starts looking like a wing! It's a lot of fun and can be really rewarding.
I do not consider myself an expert of any stage of my CCEX build but I have learned some things that made the job go well and the final product turn out pretty nice. So I thought I would share some of the things I learned.
Again, I don't claim to have the market cornered on the best procedure but hope these few things help you get your leading edge skins on successfully.
1) Before you proceed with the skins, drill the second hole in the nose ribs. It sure makes that hole a lot easier to find. Mark them with a string-line right across all the nose ribs and then drill the holes. All you have to do is match drill from the underside and thats a lot easier than marking and drilling the nose rib from the bottom. The string line gives you a very nice straight row of rivets down the length of the wing.
2) Secondly, BEFORE hanging the first skin, if you want to make your life easier finding hole number one at the top of the skin down into the nose ribs, be sure to mark AND MEASURE the location of the non-main nose ribs. If you’re not right on with your hole placement, the rib will tip or slide away from your drill. Measuring from the nearest main rib to the center of the non-main rib makes it easy to hit those ribs right where you want to.
3) Use your spring clamps to hang the skin off the spar and then ease your first wood clamp on as close to the middle of the skin but staying clear of your hole location. Put the clamp bolts in place but DO NOT tighten the first one until all other clamps are installed. I used four clamps on every skin. Got a little crowded in a few bays but makes a real nice job when you get all 4 clamps on.
4) Once all the clamps are on, start back at the center and start tightening the top AND bottom wing nuts gradually. The skin will snug right up to the ribs as you get close to full tight and moving back and forth between all 4 clamps and tightening gradually will make this job easy and very rewarding.
5) Take a look at the gap between the wood cutout and the skin. You’ll see a very slight gap at the very bottom of the leading edge….an area about 2” back from the bottom edge. Don’t worry about this if you can’t get it out, just so long as you are consistent right across the whole wing, both wings.
6) Finger tight is not the most accurate measure of “torque” but that’s where to stop. Don’t use any kind of tool on your wing nuts…just finger tight is perfect. (and I did get the bottom to snug to within 1/32nd of the bottom of the nose rib).
7) Leave all the clamps on until all the rivets are installed (except for the inboard edge rivets which you’ll put in once the next skin is overlapped and in place).
8) After you’ve finished the first skin, move to the next skin but leave the one inboard clamp in place until you’ve installed a clamp right next to the joint of the skins which will then hold the overlapped skin in place.
9) One other thing to be aware of is if your clamp is right in the middle of a space between ribs you risk over stressing the skin over the adjacent ribs. Having a slight “transfer” of the line of the ribs show up on the skin is normal but the closer you can place the skin to the ribs the better off and happier you’ll be.
10) Be sure the clamp blocks are seated right up against the inboard side of the spar.
11) Be sure the down turn of the skin is perfectly vertical and tight to the inside surface of the spar when clamped. This puts the bottom edge of this flange dead on the line of the bottom of the spar edge and makes it easier to hit the spar in the correct center location away from the bulb and the radius.
12) Be extremely careful when installing the final rivets in through the skin and into the inboard side of the spar. I kept close track of my time through this process and when tallying up the time to clamp, measure, mark, double check, drill, debur and rivet, it worked out to about 3 minutes a hole. Trust me, this 3 minutes and any time you spend being careful around the spar will be the most important time you spend on your wings.
I hope this helps and look forward to seeing things added to this list that can make this process increasingly easy for the next builders.
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Originally Posted by GreggG
