N212DM - Ben's RV-12is Build

Vertical stabilizer complete

Extra long session today because I really wanted to complete Section 6 (Vertical Stabilizer) this weekend. This consisted of attaching the main and forward skins of the stabilizer to the skeleton, which was a challenging task. The idea is that you attach the skin (which is one piece) on one side of the skeleton, then check the hole alignment on the opposite side. If the holes aren't aligned (spoiler alert: they won't be), then you detach the skin and re-shape the ribs ever so slightly, then try again. This is a very tedious process and I'm not a fan. Still, I got it to a place I was satisfied with.

Next Van's wants you to remove one cleco at a time, replacing each with a rivet. I understand that it is necessary to minimize the internal stresses between the parts, and it ensures the best possible alignment, but it about quadruples the time required. It's very slow when you have to change tools between every operation. Nevertheless, I gritted my teeth and did it Van's way, at least for all of the rivets to the front spar and the ribs. (You start riveting with the leading edge and move aft along the stabilizer.) When I got to the last holes, along the rear spar flanges, I stopped setting them one at a time. By that point the whole of the skin, nearly, was riveted solidly on both sides, and so I felt comfortable removing every other cleco along the spar flange and setting all of those rivets at once. Then I removed the remaining clecos and set the remainder, then repeated the process on the opposite side.

Next I tackled attaching the hinge hardware I created back on day 1, along with the front skin. These tasks require the use of different hardware—bolts, washers, and screws—than the main skin, which is riveted. In order to be sure I was using the correct hardware, I found that I needed to sort many of the parts that come in mixed zip-top bags into individual containers. This took an hour or so but will save me dozens of hours and lots of heartache later, so it felt worthwhile.

Speaking of bolts, I continue to feel uncomfortable attaching them to the nut plates that Van's provides. So much force is required to screw in a bolt or screw into a "virgin" nut plate that it really feels like you're tapping it. A modest use of lubricant like Boelube helps to reduce the force required, but then I worry that the lubricant will affect the staying power of the bolt or screw. Folks have debated this ad infinitum in places like the Van's Air Force forums, so I know I'm not alone. In this particular case, I had trouble with the lower starboard AN3-5 bolt that attaches the upper hinge to the rear spar. Unlike its peers, this one felt a bit like it had stripped its nut plate when I was trying to install it with a ratcheting socket wrench. I was horrified at the idea that I might need to replace it, considering the amount of work that might involve, so I gave it another try with a simple solid wrench, and happily I found that it just needed a little nudge to re-engage the threads and I was able to secure it. At least, that's what it felt and looked like; when I torque it to its final value I will test it again.

Still speaking of bolts, the AN3-5 bolts that secure the upper and lower hinges to the rear spar are screwed into nut plates and per Section 5, should be torqued to between 20 and 25 inch-pounds. I had previously purchased an electronic torque wrench (this one) for this purpose, but when testing it out beforehand (thankfully, not on the real part) I wasn't ever able to get it to "break" at the indicated torque. It seemed happy to apply all of the torque I could pull on it no matter what its setting was, and since it's about 16" long, this is a lot. I was very uncomfortable with it and decided I would not torque the bolts to their final values yet, for fear that I'd overdo it. I sent an email to the company for support, and though I haven't heard back yet I also just purchased an analog, horizontal dial torque wrench calibrated in inch-pounds from my favorite online store ever.

I should say something here about my endurance, I think. Although I'm improving, I am still finding that spending more than a couple of hours on my feet working on the project is giving me pretty severe back, neck, and foot pain. I'm managing it by taking frequent short breaks, stretching, and a judicious use of ibuprofen, but it's still very distracting. The pain was worst today at about the 4 hour mark. That's when I got a sort of "second wind" and the last couple of hours were not so bad. By the end of the day I was finding it difficult to walk, so I tried soaking my feet in an ice bath for half an hour or so, and that really helped a lot.

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