Thursday March 13, 2008
Fuel Tank Stuff (Fuel Tanks)
4.2 Hours

This is the baffle and end ribs of the fuel tank that I drilled through to the Z-brackets the other night.

Here is one of the stiffeners I fabricated last night.

First thing tonight, I put the fuel tank and leading edge back together on the spar. I also added 1/8" clecos in the fuel tank to spar screw holes (the row of orange looking clecos at the bottom of the tank). This seems to have solved a big portion of the "gap" problem between the leading edge and fuel tank skins.

The gap is much, much smaller now. I think once everything tightens up with riveting, it will snug up. If not, I can always shim the nose of the leading edge out a little bit to match the fuel tank. I'm glad not to worry about this any more.

Next, I did a whole bunch of uninteresting match drilling between the fuel tank skin, ribs, and baffle.

Here, I'm countersinking the fuel tank skin where it gets riveted to the baffle, since we don't dimple the baffle. Countersinking is pretty easy, but tedious.

What makes it so easy is this countersink cage that stops the bit at exactly the right depth. Once you get the depth set you can go pretty fast.

This little leading edge jig makes it easy to work on the fuel tank.

Here I've drilled all of the fuel tank stiffeners to the fuel tank skin.

The inboard-most Z-bracket under the fuel tank has the nut plates installed on the spar rather than the Z-bracket. Here's the spot where you have to do the riveting. I countersunk the holes where the rivets will go for the nutplates. They have to be flush because the Z-bracket will sit right on this spot.

The riveting here looks a bit tricky, but bottom of the spar here is mostly obstructed by ribs and I haven't done any shooting or bucking in nearly a year, so I want a little practice before I go shooting rivets on my wing spar. Furthermore, I need to buy some new air hoses that aren't contaminated with oil from the air compressor.

Soo, I moved on to this bracket that connects the forward inboard section of the fuel tank to the fuselage. It's a special little curvy angle piece that you get to fabricate from angle stock. You can see the piece I started with and the drawing of the finished piece below it.

Here it is after some rough cuts by hand. This is one of those times where it would be nice to have a band saw. Tomorrow, I'll go to work on it with my cutoff tool for the die grinder and then finish up with the bench grinder. Should be a piece of cake.

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