My Wooden Airplane
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7/18/2010 - 7/19/2010

Bending Wing Skins

This actually turned out to be kind of a pain in the butt. I bought a small, inflatable "kiddie" swimming pool, about 5 feet in diameter, and used it to soak the 1.5 mm plywood skins. They came out nice and pliable, but getting them to conform to the airfoil shape was surprisingly difficult. The top came out okay, but the bottom just didn't want to conform. It was almost as if there was a concave section in the airfoil (which there wasn't - I'm not building the "droop-nose" airfoil). I tried clamping the wet skins in a WorkMate, both right-side up and upside-down, with and without a PVC pipe as a form, but still no luck. I ended up forming them around the wing itself, holding them in place with ratcheting tie-down straps around the entire rib. This still didn't get them to fit perfectly, but it got them close enough that I could hold them down with staples when it came time to glue them. The only downside of doing it this way was that there were still "valleys" between the ribs that gave it a "scalloped" look. Not really sure what to do about that. This is definitely not as easy as other websites make it look!

Update: The designer recommended "heat forming" the skins, rather than soaking them in water. Logistically, however, I'm not sure how this would work. He said I needed a metal pipe about the diameter of the leading edge of the wing, and a way to constantly circulate hot (boiling) water through it while draping the plywood over it, weighting down the edges while
it was slowly bent into shape. I never did get a chance to try this method, but if it works,
I bet it would alleviate the scalloping between the ribs.

Total Time: 3.0 hrs.