Van's RV-9A in Aurora

The Big Picture

The Big Picture
Flying! 8/28/2011

Wednesday, August 19, 2009

2.0 hrs
Removed and deburred 920 armrests.

Spent a few minutes checking the straightness of the longerons. These need to be level as a reference for building, and I was beginning to wonder how straight they were when the assembly was placed on sawhorse upside down. So used a laser plane and lined it up with the holes at the top edges of the skins. Sure enough, it was off just a bit, and required the front support point to be lifted almost half an inch. This might have taken about half an hour. Afterwords, the laser line slices through all the holes from the tail up to the downward bend in the 970. This work paid off, since it was much easier to reinstall the 970 after the next step, and the skin lays nice and flat against the longerons without any clamps.

So on the next step. Removed the right 970 skin and prepared to make the lower aft conical bend. The wing kit includes two long 3/4 .125 angles. The remaining longerons will consume 1 and a half of these. After laying out what's needed for the longerons, found that I could safely cut about 15 inches off of one. Drilled this to the lower aft corner of the 970.

Used another piece of angle to clamp the skin to the table, then used a crescent wrench to start making the bend. It took a while, slowly adding a set the skin, comparing against what I thought the bend should look like. After I thought the aft curve looked about right, I used a clamp to tighten the forward end down tight, thus setting the forward end with it's tight, nearly 90 degree bend.

[Edit] Using this setup I tore the other side. On this side, I think I got lucky. But for the other side, I realized I should have cut the vertical corner off of the left end (in this picture). Lo and behold, I looked at the pictures in the narrative, and Van's had done exactly that.

It worked perfectly. Clecoed the skin back on, and it lined up very nicely.

After getting that all clecoed in place, I realized that something needed work at the aft end of the bend where it joins to the aft fuselage. It meets the fuselage at an angle, but the fuselage is straight. Ahh, so that's why there are fingers. Obviously, I need to bend the fingers on the aft fuselage out to match the angle of the 970 skin. With one done, and the other not done, it should be easy to use a woodworking reference angle to get all of the fingers bent just right.