Here you can see what I was talking about regarding the stringers pushing the F-706 bulkhead out of line. In this photo I've already trimmed them back some, but the bulkhead still has a wave in it from being pressed from behind.
Once the stringers are trimmed and the aft top skin is clecoed in place, the bulkhead becomes straight again. I subsequently trimmed the tabs on the stringers to be flush with the bulkhead flange.
The aft end of the F-688 gusset gets beveled to make the skin lay down against the underlying structure:
Then I drilled the stringers to the top skin. Unfortunately, I goofed one of them up! Somehow I managed to let one of the stringers slip out of position while drilling, which introduced a slight twist over the forward-most few inches. You can see in the photo below that the last four or five holes in the stringer don't have enough edge distance. Argh!
Here's my fix. I unclecoed the forward part of the problematic stringer, clamped it securely back where it needed to be with no twist, and re-drilled the offending holes. This resulted in some elongated and figure-eight rivet holes, so I put in another bunch of rivets, spaced evenly between the problem ones. The result is a strong and straight stringer that just happens to have some doubled-up rivets in the forward part. And of course, me being me, I had to do the same thing to the stringer on the opposite side just to make things come out symmetrical, even though that stringer didn't have any problems. Now it looks like I planned it to come out that way. Yeah, that's the ticket.
Before calling it quits for the day I managed to get the F-6111 stiffeners drilled to the aft top skin. These took a ton of fitting, twisting, fluting, and flanging, but they turned out a lot better than I figured at first. Aluminum really does not want to conform to a funny curve like that without a fight, but I managed to conquer this task. For what it's worth, this forum thread is a good place to start when installing these guys.
You can't really see it here, but I got the F-6111's to lay down against the longerons really well on their forward end. They don't really lay down very well against the bulkhead at the top end, but they fit the skins well, so I'll call this a victory and move on.
