Wed Aug 9 2006

Elevator trailing edge bend

Here I'm starting the bend in the trailing edge of the left elevator skin. While at Oshkosh, I looked at a lot of RVs. Invariably they didn't accomplish exactly the right bend. The intention is to have all of the bend right at the trailing edge so the skin is flat all the way back towards the trailing edge with no bulge. All the RVs I looked at had a bulge ranging from 1/32" (really good) to 1/8". So after giving this some thought I decided to modify the design of the bending tool. I made this bending brakeout of a couple pieces of laminated 3/4" birch plywood. For the bending surfaces themselves, I laminated on a thin (1/8" thick) piece of oak. Then I cut a bevel in the edges of the bending brake so all the bending would happen as close to the trailing edge as possible. The idea was to actually overbend the skin a little so that after springback, the bend would be just right. Well, this sort of worked although I ended up putting a crease about 1/2 inch away from the trailing edge. I got most of it out with some wood sticks and a bunch of hand work. The right elevator went way worse. I screwed up the skin badly enough that I ordered a new one. Then I did it again. ARGHHHHH!!! *bangs head on workbench*