John Kahrs

Tail section, Part II
Last night I bedded down some channel nuts into the tail spar.

Tonight I put the counterbalance off to the side. I pretty much wrecked it with impatient, novice machining, and I can't give it another try until some virgin parts arrive from Sequoia. I can put that thing together sometime next week. I want it to be right, and totally secure. This is not something that you want rattling off and clunking around in the tail years from now. I'm trying to maintain momentum, and a big part of that is getting myself to press on with something else instead of sitting around waiting. This is easy to do because already the project has fragmented into a half dozen subprojects. Without that push to keep going, I might spend the evening pouting and looking at the parts wondering if they might just be okay. But that wouldn't end up being a very productive evening.

So I busted out the water level and cut some leveling blocks to rest the tail spars on. I spot epoxied them to the workbench and made sure the span was as flat and straight as I could get it. By midnight I was laying out the leading edge ribs for the elevator, and now they're all glued and clamped. Already I can tell that I have about one fifth as many clamps as I'll need. There are a lot of newfangled looking plastic clamps out there that I've been snobbish about when I see them on the store shelves: they don't twist when you tighten them, and don't look like they exert as much pressure as the old school besseys. But now I realize that's exactly what I need: moderate pressure and no twisting.

I've mixed up a half dozen mini batches of Aerolite now and I have complete trust in it. When I first got the sequoia parts, the gluelines looked so brittle and strange to me, all cracked and milky. And the application was weird- gloppy glue on one surface, watery acid hardener on the other? Bizarre! Then I glued up some test blocks. The blocks are simple- just three squares of wood with the middle one shifted higher. When it cures, you smash it with a hammer and if the shear load tears apart more wood than glue, you're honky dory.

Well, trust me, it works. The maple is strong, but that Aerolite is stronger. I built one out of spruce just for kicks and waited only 6 hours before I smacked it. The thing split right down the middle, the gluelines ignored me. I whacked one of the maple ones after two weeks of curing and it was pretty much the same story. Actually, I have trouble getting them to split at all with a 5 lb hammer. I'll have to get the real sledge out at some point, but if that's the case, then I'm satisfied that the stuff works.



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