First thing on the list to do today was to bite the bullet and rivet the spar to the top skin. I have no idea why, but Van's designed the spar so that the flange opens to the closed, pre-bent portion of the skin. I'm sure there's a reason, but it's awfully inconvenient for riveting. If it faced the other direction, it would be pretty easy to rivet, but as is you can't get a bucking bar anywhere near the rivets without figuring out a way keep the skins open while at the same time allowing the spar to line up for riveting. So without having the free labor of family, I was back to using ropes, clamps, and weights to open the skins up and keep them that way. In the end it worked out pretty well, but boy was it awkward. I'm learning awkward riveting positions are pretty much the norm though, so getting used to it.
All of these rivets had to be bucked blind, but after a while you learn the rhythm and sound of good and problematic rivets. I had to go back and hit a few again after visual inspection, but the vast majority turned out fine the first time around. I'm still anal enough that I check at least my first handful of rivets with a rivet gauge each day, but it's becoming easier and easier to tell by eye how they are. For the blind ones, pushing a finger against the shop head and then looking at the divot in my skin is really the only way to get a quick idea of how things are going. If I repositioned to look at every single rivet, I'd add hours to each riveting session.
After the spar was riveted to the top skin, I repeated the previous method of back riveting the stiffeners to the bottom skin. The weights might be overkill, but they really help to keep the skins flat so I have to use less pressure to ensure that I don't get a rivet bulge in between the parts.
And here's where I stumbled on another task where I questioned why it's not done earlier in the build sequence. The counterbalance ribs and skin are next to be riveted to the spar and skin, but because the skin is already riveted to the spar, access to the rivets holding the ribs to the spar is extremely tight. It sure would have been a lot easier to rivet the counterbalance ribs in place before doing the spar. I still haven't figured out how I'm going to pull this off. You can just barely see two of the 4 problem rivets tucked in behind the curved skin. I tried getting a squeezer in there by opening up the skin, but there is still too much other stuff in the way. I think I'm going to have to figure out a long, thin bucking bar and try to buck these. I hung it up for the night so I could do a little digging and see if anyone has come up with a better way. I'll tackle these tomorrow and then move on to the trailing edge.
