November 14, 2010

Finished Wing Root Fairing, Flap Pushrod Hole - 5.0 Hrs.

Today I finally got around to finishing the wing root fairing for the left wing. I started by trimming it for the proper gap required, then smoothed and deburred the edge.

I clecoed it in place once more before dimpling, just to check the fit and measure the gap. Looks good! So I scuffed up the bottom side, cleaned and primed it. When it was dry, I dimpled it for the #8 screws and put it aside on the shelf. Other than the exterior paint, it's finished.

Now it's time to move on to the flap pushrod, and enlarge the opening in the fuselage as I did earlier on the other side. Here's a photo showing what you start with. A small pilot hole in the side and bottom of the fuselage.

Above, here's a closeup of the pilot hole, as it comes from Vans. I got the idea of making a template of some kind, using the other side as a model. This should greatly speed up the process of enlarging this hole compared to the first one. Below, here's the finished hole on the right side. You can see the work that needs to be done. It's an odd shaped hole, and I spent a lot of time working slowly a bit at a time to get it right without overdoing it. If there's one thing I can't stand, it's repeating work that I've already done. If there's an easier way to do it the second time around, I'm all for it! By the way, the stuff you see just inside the hole is the soundproofing foam I installed earlier in the build. You can go back in my log to my entry from October 25, 2009 and read all about it if you like.

So here's my idea for the template. I simply taped a piece of paper over the hole, folding it underneath and taping it tightly to the belly of the fuse as well. The trick to getting accurate placement on the other side of the fuselage is to mark a reference point. I decided to use the 6th and 7th rivets, counting aft from the wing rear spar bracket, and marked them on the paper as you can see above. Then I used a very sharp knife point to cut the paper out around each of the 4 rivets seen above. This is very easy to do, and it makes a perfect reference to line it up just right on the other side of the fuselage. Then I just cut the paper out around the hole, and the template was finished!

This shot is overexposed, but you get the idea. This is what it looks like from underneath with the hole cut out of the template.

Next, I took the template off the right side and removed the tape. The paper is then unfolded and folded back the other direction for the left side, since it's a symmetrical mirror image. As you can see above, it's repositioned on this side of the fuse with the #6 and #7 rivets, and the aft two rivets right in position under the holes I cut out. Tape it in place. Then use a sharpie to mark the side and bottom of the fuse where the opening needs to be cut. So simple! This is so much faster and easier than doing all that slow careful iterative work again.

Then remove the template, and here you go. The sharpie marks I made on the side and bottom show me where to cut the opening.

Here's my weapon of choice for cutting the hole. It's my Dremel tool with a sharp cylindrical burr bit. It rips through this aluminum like crazy! Yet, it's easy to precisely control the work.

I used the bit on the left for this job. I've used this tool with these bits a lot throughout the project. I highly recommend getting one of these if you don't have one. Then I carefully filed and deburred and smoothed the hole. Works great!

And here's the finished hole. Perfect! A nice mirror image of the other side. I installed the flap pushrod and hooked it up and tested it. It's nicely done and works perfectly, just like the other side. Yippee! It's great to have these finished.

I also trimmed the inboard end of the flap for clearance, just like I did earlier on the other side.

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