Success! I finished one sub-assembly of the plane today! Picking up where I left off yesterday, I finished riveting the front spar to the skin and then moved on to the main ribs. Riveting with the gun and bucking bar isn't all that hard when you have easy access to locations. It's the awkward positions and blind finger holds of the bucking bar that make it difficult. I finally gave in and realized that I have to get comfortable running the gun with my left hand. Easier said than done, but it's getting easier. The big thing is just making sure you control it so it doesn't walk off of the rivet and pound a huge hole in the skin. I'm slowly getting better.
Once the forward spar was done, the rear spar could be placed on top of the main ribs, clecoed to the skin, and riveted in place. All of the inboard main ribs are connected to the rear spar using blind rivets since there is no access to the back side. Almost all of the spar to skin rivets could be squeezed instead of bucked, which makes for quick progress. Rose even tried her hand at a few rivets just to say she built the plane. 😀 The only rivets that had to be bucked were the ones alongside the hinge brackets, since I couldn't get the squeezer yoke in there.
It's really pretty amazing how rigid the whole thing gets with the rear spar attached.
The one thing that I didn't love, but wasn't about to go back and fix, was how the dimples in the skin nested within the countersunk holes in the spar. Dad and I checked and double checked the countersink depth, and I really thought we had it spot on, but apparently not. It's not bad enough to worry about (the photo actually makes it look significantly worse than it is), but just another thing to try differently in the future. I asked on the Vansairforce.com forums, and a few people said you have to make sure you go slightly deeper than "flush" (in terms of the rivet head when checking), and most guys use test dimple pieces as double checks. So did we, but somehow we still undershot the countersink depth. One person mentioned that Van's recommended to him that he go .007" beyond flush. That's easy enough to calculate with the countersink cage, so I'll try that next time. This plane build is going to do wonders for my lifelong struggle with perfectionism.
One thing that I knew was coming once I hit the rear spar was the need to use some "oops" rivets. When we did the initial assembly of the stabilizer, the rear spar was a real bear to get set correctly. Because of the torque we had to put on it when match drilling there were three holes on the end that ended up oblong. To fix that, I drilled those holes one size larger to make them round. When riveting, there is an easy solution to this common issue - the oops rivet. An oops rivet maintains the same size head as the original rivet, but increases the shank size to the next size rivet up. So by using the oops rivet, I can fill the same dimple with the head as everything else, but also fill the increased hole size. You don't want to use these rivets all over the place, because the should to the head is smaller relative to the shank and hole, but for here or there, it's the standard solution to a problematic hole.
The last step of assembly is attaching the inboard hinge brackets and the bearing that gets sandwiched in between the two pieces. The holes were too tight because of the powder coat, so I had to ream them all to size. Because these are steel, I covered all of the fresh steel in the holes with primer before inserting the rivets. It's not as good as having the powder coat, but I don't see any way around that for these parts. I neglected to do this primer step on all of the other hinge brackets when I reamed those holes. We'll see if I regret that in 30 years. I kind of doubt it will ever be a problem though.
With the bolts in place, all that was left was to torque them and mark them with torque seal. It's eye opening when you torque bolts! These things are only torqued to 20-25 inch pounds, which is far less than seems okay.
Rose helped me move the whole stabilizer upstairs since I can't really think of a good way to store it in the garage right now. It's currently barricaded from wrestling dogs by a couple of big Rubbermaid tubs and a few chairs. I'll have to figure out how to gain some space in the garage to store the parts long-term. The wings will sit in a cradle in the garage when they're built, but the empennage has more actual sub-assemblies that don't get put together until the very end of the build.
