Section: Horizontal stabilizerother aircraft sections
The horizontal stabilizer is complete now. The bottom half of the skin has been riveted on. Despite the spars and tip ribs lining up perfectly, the two inner middle ribs were mis-aligned by just a hair too much, and they wouldn’t shift any farther. Rather than create an oblong hole in either the skin or the rib, I opted to drill out to a #20 and use A5 rivets instead of A4.
After getting a torque wrench tonight I bolted the center hinge bracket to the rear spar of the horizontal stabilizer. With that in place, and bottom side of the skin already riveted in place, we spent a fair amount of time getting the top side of the skin lined up and cleco’ed in place. I had to get out the ratchet straps again, but it eventually found its place.
I drilled out the hard-to-reach holes in the gusset and hinge bracket with my new, long bit, then widened them from the other, more accessible side. I finished putting together and riveting the entire skeleton, and had my first mistake that required me to remove some rivets. I forgot to add the doublers before attaching the bracket, so I drilled out and removed the top and bottom rows of rivets, added the brackets, then reassembled everything.
I ordered a long drill bit so that I can attach the center hinge gusset and center hinge bracket with straight, perpendicular holes. In the meantime while waiting for that to arrive, I took everything apart, deburred, and scrubbed the mating surfaces with scotch-brite while watching the Cubs pull off a miracle. When the drill arrives I’ll finish the rear bracket, widen the holes, debur it, then apply Cortec to all the mating surfaces.
I flipped over the horizontal stabilizer and used some ratchet straps to start pulling it tight. I only had 4, and there was a little too much bending around each of them for my comfort, so I pulled them off and put a long 2x4 under it to distribute the pressure. Unfortunately now it was really difficult to apply lateral pressure to pull the skin into place, and it was wanting to press down more than anything.
Tonight I enlarged the holes on the top of the horizontal stabilizer, then flipped it over to attach some ratchet straps to pull it tight. To keep the straps from bending the overhanging skin on the rear spar I’ll need some more precisely sized 2x4s, but it’s a bit too late to be cutting so I’ll get started on that tomorrow.
I start attaching the skin to the top of the horizontal stabilizer, and it just didn’t want to line up. The distance between the front and rear spars was too much to match with the pilot holes on the skin. Noticing some gaps between the ribs and the spars, I took everything apart, cleaned it up, deburred everything, and put it back together. It helped quite a bit, though the skin was still really tight and required a lot of force to get it aligned and clecoed.
The front brackets, which will hold the stabilizer to the fuselage, turned out to be easier than I expected since it came with pre-drilled pilot holes, so measuring and alignment wasn’t an issue. I widened the holes to #20 and set it aside. After a lengthy detour to fix the compressor regulator, I clecoed and drilled the rear and nose ribs. The tip ribs were attached, and I sized, cut, and drilled L-angles to attach to it from the front spar.
Tonight, along the same lines as the rear spar, I drilled and clecoed doublers in the front spar, as well as attached L-brackets to the ends.
Tonight I got started on the horizontal stabilizer. Clamped the doublers to the rear stabilizer, drilled through the doublers with a #40 and secured with clecos, then went back and widened the holes with a #30.