November 10, 2005

Since I’m waiting for some coax from SteinAir, I figured I should press ahead with the cowling today. You’ll have to forgive me because I forgot my camera. I’ll have to take all the pictures for today’s update tomorrow. I’ll write what I can and fix it all tomorrow with pics.

I started by emptying out all the Skybolts on the work top and reading the destructions. I also read the Van’s cowling instructions. Then I set to it. I measured the thickness around the cowl flanges as about 0.060", and the thickness of the cumulative sheet metal around the flanges of the firewall was about 0.050"-0.060". Everything varied everywhere, so it was hard to pick a good number. I decided to not bother with shims. I’ll find out whether or not this was a mistake eventually I guess!

With that settled, I went ahead and made the flange lips for the skybolts to attach too. These need to protrude forward of the firewall flange by 1 1/8". I made them out of 0.063" and curved them to suit the firewall flanges. I haven’t notched them out yet, because I want to figure out where exacty the Skybolts will be in the cowling before I go cutting these things up. They turned out pretty good so far. In order to finish the top strips, I had to put that blasted top fuselage skin on. This is a tight fitting skin!

I measured the cowling a bit to see if it was at least round at the spinner. It was pretty close, but it didn’t really fit together too well. I also drew the 2" margin line around the fuselage against the firewall edge. When I was doing this, I noticed that the firewall flange wasn’t too clever. Ours is a quickbuild, so we got what we got there. The stainless flange protruded a tiny bit in some places around the firewall. I took this opportunity to dress it back with a sanding disc in a die grinder, and finished it up with the scotchbrite pad.

I plopped the cowling on the plane to see what it was gonna look like, and propped it up at the front with some little blocks of wood. Looks nice! Now then, the question is, how much to allow for engine sag? I think I’m gonna do about a 1/4". Everyone who I’ve spoken too so far has allowed about that, and it seems to have worked out.

I marked the rear edge then took it outside to trim it with the cut off wheel. Then I put it back on. Right now, I’ve not got any allowance for sag. For some reason, I refused to believe that it would happen, so now I have to go back and start wittling away the rear edges until the cowl has dropped enough to get me the 1/4". It sounds like a lot! That’s tomorrows task.