I got a few things done today, but had to give up when I couldn't feel my fingers anymore. The infrared heater works great, but only if you're in the shadow of where it radiates. Step outside of that range and the 15 degree metal is a tad chilly to handle after a while.
First up, the elevator control horns need to be lined up and drilled for the pushrod bolt. I clamped the elevator counterbalance arms even with the horizontal stab again (neutral position). The first pushrod bolt hole in one control horn is drilled based on measurements, but the hole in the other control horn has to be drilled by aligning the two together. If the holes aren't perfectly aligned, the right and left elevators won't set the same (one high, one low). In order to get as close as possible, I stacked up some aluminum the same thickness as the space between the two control horns. Then I drilled a hole through the material using the drill press, hopefully getting a perfectly perpendicular guide hole. I slid the stacked aluminum between the control horns, lining the hole up with the one already in the right control horn, clamped it all in place, and drilled the matching hole in the left side. Then I took it all apart and drilled the final size 3/16" hole in each side for the bolt.
Now that the elevators are set up, I took them off and put the horizontal stab back on the fuselage.
The next part took forever, and all I have to show for it is a single hole (although the most important single hole I've drilled in a long time!). The stab gets bolted to the aft deck in a number of places, but these aren't pre-drilled holes, or even measurements called out in the plans. There are two pieces of angle on the front horizontal stab spar that set on the deck and each get two bolts that attach to the aft deck and underlying structures. The outside bolt goes through the longeron and a piece of angle that sets below it. The inside bolt goes through the deck and a number of spacers/angle. All of these pieces are completely hidden, and the edge tolerances are very tight when you're talking 3/16" holes, so getting the center right is very important. It's a spot where a lot of builders mess up and have to fabricate doublers or rip things apart and make new parts to try again. I knew this was a trouble spot, so when I built the underlying angle pieces that nest under the longeron, I made them longer than the plans call out so they'd set as far into the longeron corner as possible. That gives a little more wiggle room for edge distance than the measurement in the plans give.
Before any drilling happens the horizontal stab has to be set as close to perpendicular to the longitudinal center of the fuselage as possible. You don't want it canted either direction. I clamped the stab in place, then measured from the outside edge to the front corner of the firewall. Since there is nothing to keep the stab centered on the aft deck (it just sets on top), this wasn't as simple as just pivoting one outside corner of the stab to get even measurements. Every time I'd move a corner, the whole stab would also slide on the aft deck. After 500 trips back and forth, I finally got it within about 1/32" from side to side.
After the stab was aligned properly, it was time for the dreaded first hole to be drilled through the attach angle on the front spar. It sounds easy, until you realize that nothing is designed to have edges line up with anything else, there are no right angles to measure off of, and you can't see anything you're drilling through except the first layer. In the end, the outside hole has to be centered on the hidden 5/8" horizontal leg of the longeron (the vertical leg is an additional 1/8") as well as centered on a second piece of angle that is under the deck and nests under the longeron. Needless to say, it sounds fairly straight forward, but not all that easy in reality. I measured 20 times and finally got up the courage to drill a pilot hole. I figured if I drilled a small hole and it was too far off, at least I had a chance of correcting it for the larger hole.
I stuck my camera under the deck to see how I did. Thankfully, that pilot hole ended up exiting exactly where I wanted it to! What a relief! Here's hoping the right side goes just as well. That's for another day after I thaw out though.
