Thu Apr 22 2010

(re)drilling horizontal stabilizer to fuselage

Well the time has come to have another go at drilling the horizontal stabilizer to the fuselage. With the HS clamped in place, I checked the level.

WTF?!?! I dunno where this is coming from, but the HS still seems to be low on the left side. For whatever reason, it still needs about a 0.016 thick shim on this side. Whatever. I'm just gonna move on.

You may recall that previously I wasn't able to find a long #12 bit for my angle drill, so I used a #11. Well this time around I decided that I really did want to use a #12, but since I didn't have one I called a bunch of friends, then a bunch of local suppliers to see if anyone had one. No one did. :-(

Well after doing some more searching, I found a short #12 bit and realized that I must have a long one somewhere since I had bought them in sets. Sure enough after some more searching, I found my long #12 angle drill bit buried under some other tools. WooHoo!

In order to do a good job of drilling up through the longerons into the front spar of the HS, I wanted to use some guide bushings. A quick trip to the local hobby store and about $4 later, I had these three brass tubes. They are nicely sized so they will slide into each other.

After some cutting, filing, and reaming, I had these three short bushings. I got this idea from my brother, Chris, who is building an RV-6A.

Here they are all nested together.

Well after a bunch of drilling, here's the horizontal stabilizer. Note there's a 0.016 inch thick shim under the left side (right side in this picture). The only thing I'm not totally happy with is that the although vertical bars that attach the HS to the fuselage are well centered at the back of the HS, the HS appears shifted to the right about 3/32 inch where the front spar is. I'm not sure how it ended up that way, but the result is that the edge distance for the far left hole on the front spar is not so good. It's about 1D. The right side has about 2D edge distance. Perhaps I'll call Van's in the morning.