Wings

Today I continued work on the tank. There are lots of things to do.

I drilled the skin to the stiffeners that I installed yesterday. All the drilling on the tank is almost finished.

The drain valve on the bottom of the tank is now fitted in place and drilled to the skin.

Now comes the somewhat tedious task of fitting and drilling the fuel cap flange to the inside of the skin. The hole for the fuel cap is already cut in the skin, as are the pilot holes, but no holes are in the fuel cap flange. The flange is curved to match the curvature of the skin, so you carefully position it in just the right place and orientation, clamp it in place as shown, and then drill it to the skin, clecoing it in place as you go. I took my time here, because this is highly visible and I don't want to mess it up. As I mentioned earlier (August 29, 2007), I splurged for the deluxe locking fuel caps. They're really nice!

Here's the flange, as seen from the inside of the tank, drilled and clecoed in place. You can see the mark I made for proper orientation of the flange.

Here's another inside view, showing the machining of the flange to match the curvature of the skin. Isn't that nice? Perfect fit!

Back to the outside view, here's the cap in place on the tank for the first time. Now I can't wait to get rid of the clecos and see it all riveted in place.

This shows how the cap lifts up, revealing the lock underneath. Rotate 1/8 turn and it lifts right out. Very nice!

Okay, I couldn't help it! I just had to move the clecos to the inside to get a better idea of how nice this will look when it's riveted in place. I love it! It's about as streamlined as you could get. But now for the real work at hand... I need to dismantle it, deburr the holes, dimple the skin, and countersink the flange for the dimples. Then, of course, a thin layer of proseal gunk will be applied before the final riveting in place. But a few minutes of moving clecos was worth it to get a sneak peek preview of the finished look.

Back to work... I got out the soldering iron and removed the vinyl strips over the bottom stiffeners. Then all the holes in the skin, ribs, drain valve, flange, etc., were deburred (no pictures of deburring... boring). Then, it's on to the chore of dimpling everything. I got to dimple some of this skin twice actually, because I forgot to put my special tank dimple dies in the DRDT-2 Dimpling tool. So, once I realized what I was doing, I switched dies and did it all over again. The tank dies are a bit deeper, allowing room in the rivet hole for a layer of proseal.

I love this tool. It's great for most of the holes in the ribs, too, as you can see above. There are only a few near the very end that you can't reach because of interference with the bottom rib flange, but you just put the dimple dies in the pneumatic squeezer and you can do those in just a few minutes.

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