Tank Stiffners   October 26th, 2007

The bottom of the fuel tank has two rows of stiffeners to keep the skin from sagging. These come in long rows which have to be cut, trimmed, etc.

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Fabricating Tank Attach Bracket   October 22nd, 2007

The leading edge of the tank attaches to the fuselage with a 90 degree bracket. This part has to be made from a piece of aluminum angle. The plans have a 1/2-scale drawing and some rough dimensions, but the general idea is that the bracket matches the contour of the front of the rib.

First, I sketched out the outline in the angle. I used a hacksaw to cut it slightly to shape, and then used a belt sander for the final shape.

For the other side of the angle, which is supposed to match the contour of the rib, I used the backing plate (which goes on the other side of the rib, opposite from the bracket) to draw the shape to cut. The bottom of the backing plate overhangs the angle by a little bit.

Again, I used a good old hacksaw to cut the shape slightly larger than final size, and then a belt sander to get it to the final shape.

Finally, here is the bracket fitting nicely on the tip of the tank rib.

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Drilling the Tank Skin..   October 15th, 2007

Nothing too exciting here… I took the tank off the wing and match drilled all the holes…

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Fitting the Tank Skin   October 9th, 2007

I first tried to assemble the ribs and fuel tank skin in a cradle, as called out in the manual. Pretty quickly I figured out it wasn’t gonna happen. The skin goes on so tight, I don’t know how you can make things match up in a cradle.

So, I decided to use the same method I used to fit the leading edge skin. I assembled the baffle on top of the spar, and clecoed the ribs to it. I also clecoed one side of the skin to the rivet holes. To keep the ribs from moving out of place when the skin is ratcheted down, I placed wood dowels between each rib. I made each little dowel to fit each individual rib, and yes, it was a pain in the neck, but in the end it was worth it.

Note that I tried ratcheting down the skin as shown in the two pictures above. I couldn’t quite make the holes match. I then switched sides — clecoed the top side and let the bottom side free — and tried ratcheting down the skin again. This time things matched up pretty well.

Here is the end result…

Finally, I went back to check the leading edge to tank fit, and it couldn’t be any better…

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