Wed Sep 10 2008

Right conical bend

This evening I worked on the right conical bend. Clamping the skin to the bench was a bit of a challenge because my vise is bolted to this end of the bench and I didn't want to bother removing it. I rigged up a bar clamp scheme using a piece of oak.

I almost forgot to enlarge the bend relief. Fortunately I remembered before starting the bend.

This bend actually came out better than the other side. And it took me roughly half the time. I had the same problem with the forward holes being offset slightly from their counterparts in the F-776 skin and the F-623R rib. I decided to drill extra holes halfway between the existing ones. The spacing is fine and it'll resolve any strength issues from having oblong holes.

In my opinion, Van's should just omit the prepunched holes along the edge of this side skin where it underlaps the F-776 bottom skin. I'm pretty sure the reason why these holes are offset is because I used a bend radius at the forward edge of the conical bend rather than trying to make it sharp. I'm glad I did, though since the skin will be far less likely to crack there.

The F-623R rib was positioned about 1/64 inch too far outboard, so I've got a 1/64 inch gap between the side and bottom skins. I may use the seaming tool to close this slightly. Overall, I'm quite pleased with the way these bends turned out. Nice and smooth and no cracks!