Hi Dick,
The flap skins were one of the more difficult pieces to form for me. I wasted a lot of material. There is a lot of info in the old newsletters and some good ideas about how to do it. There was also discussion about using .020" instead of .025" material, as this would be easier to form. I don't know if John Thorp ever confirmed that this would be OK or not, at least in writing. I know that there was discussion about how he supposedly chose .025" in order to utilize existing material & not have to purchase .020" just for this one assembly, & that .020" would be fine. I can't confirm that. Anyway, to your question... this is what I ended up doing. Like Bob said, extra material which is then trimmed away is very helpful. The pictures are of my test strip which I used to develop a sequence which produced an acceptable shape for me. The thing is old & beat-up now, but I hope you can read the markings on it. I made a hole transfer strip to lay out the series of identical holes to hold the skin in "folded" position with clecos. I started with the more gradual upper portion of the curve first (#1 set of holes) & pushed the skin down with a large board (just like we do to form the wing skins), but used a 3" thick "spacer" (2 - 2x4s) in between to automatically limit the amount of bending. I then proceeded to using the other lines of holes in sequence, but this time decreasing my "spacer" thickness in steps down to 3/4" for all the rest. It came out as you see in the last picture. I hope this is halfway clear to you. I'm not saying this is the best or easiest way to do it, but it's what I did.
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