Thursday, June 19, 2008

Upper Longerons

I started working Ch.5 around the beginning of June. Ch.5 is where you build the left and right sides of the fuselage. I finished up the upper longerons last week. Overall, they went pretty well. The only issue I had was with the jigs "FJA." The jigs are there to provide proper curvature for the upper longerons and then the fuselage sides.

Most are simple cuts (i.e. 42" long with one side 6" high going to 1.5 " high - a nice simple strait line) but FJA has a bit more curvature to it. The first time I made the 4 FJA jigs, I did them each seperately and ended up with something I was not happy with. The second time around a cut one FJA jig exactly how I wanted it, but about 1/20th of an inch to high. I then traced my "master jig" for the cutting of the other jigs, clamped them all together and sanded with a 1/4 sheet finishing sander until all of the FJA jigs were identical and at the proper hieghts. Also, the plans call for 2 1"x 1"x 8' pine boards. I needed 4. Even if I hadn't destroyed a set of FJA jigs I would have needed 3.

Here are the jigs laid out and ready for the longerons. I screwed the jigs into my tabletop:

The longerons are made of 3 thin strips of spruce held together with epoxy between each strip. I went ahead with the plans method and used nails to hold them in place while curing. Looking on other people's sites, I saw that many of them had 30 or so of those nice $20 clamps that they were able to use to hold them in place. If I had 30 of those nice big clamps, I would have gone with that method. The nails seemed to work pretty well though.

Both sides:
Here's a closeup of the nailed sections:
Doubler's and stiffner's with saw cuts for bends:
All weighted down:
And complete. Not sure why a bunch of stuff up there got underlined. Couldn't make it go away, oh well.

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