Okay, so now I have this big, undrilled, fuel tank skin that I have to get ready to match drill to the ribs.
When I put the skin on to get it located, I was not able to get it to sit squarely against the fixed leading edge skin. At the top (at the leading edge curve) the skin would be tight, but near the bottom (by the spar) there was a gap of a few/32 thou. The way I approached this was by taking the amount that the gap at the spar end was, and then marked that amount to the top (at the leading edge).
Then I tapered that line, down to the spar end gradually thinning out the taper until I met the corner edge. This line is going to be the amount that I need to file off, to get the skin to sit flush against the fixed leading edge.
To file the edge, I put the skin in the standard Van’s fuel tank stand. This worked OK, but at some point I’m going to need to extend this fixture to make it longer.
After filing, I put the skin back on the wing. Below is a picture of how the leading edge is fitting.
But now, when I move down to the bottom of the skin, I still have a gap of just less than 3/32 inch.
Again, I marked the leading edge the same, as that’s the high spot, and then tapered the line back down to nothing…and filed it again. It’s tedious work, because as you can see in the picture below, you need to strap the skins down, tap it into place, just to see that you have to take it all apart again to do more filing. All in all, I ended up doing this process 4 or 5 times before I finally got it all to come together.
Finally, the skin would evenly sit against the fixed leading edge skin, all the way along the skin joint. This isn’t hard work, but it certainly is time consuming. But as you can see, the result is worth it.
In the picture below, you can see some of the notes I made for myself. I marked the high spots and used arrows to indicate the area that needed to be filed (higher) or sanded (finishing / light material removal).
On the lower surface, the skin is still slightly overlapping. For now this is good enough, and next time I have the skin off I’ll be able to file down a few inches to taper that overlap away.
That’s all for today folks! Please comment. I love to hear from my readers. Thanks again for coming along for this ride, you make my work worthwhile.