The bottom forward longerons are 1 x 1 x 1/8, and the factory shipped two pieces for that. They were labeled F-450 and I didn't think anything about them. I managed to ruin them both, and replaced them from stock. It turns out that unlike the stock angles, the F-450 are special. They've been opened up to fit the bottom skin. On my plane that is only necessary at the aft end, and it should taper to the standard 90 degrees at the forward end. It didn't appear as if the F-450 did taper, it appears, looking at the scrap, as if it had been opened up full length.
I replaced the original ones that were 90 degrees with a pair of new F-450s. They fit just fine. Keep an eye out for them in your kit, if you're building one of these.
In the view of the lower gussets and that lower forward diagonal longeron in the previous posting, you can see that the forward end of that diagonal longeron is outside the firewall fitting. The plans specify that it be inside, but in order to fair to the skin, it either needs to be outside or I'd need a joggle or a shim. Since the lower longeron is the same thickness - and in fact the fitting was positioned for that - outside it is.
The spacing of the flap weldment and its bearing blocks, F-377, is such that the fuselage is about 0.58" wider than needed, so I added a pair of 1/4" plastic spacers:
These have the added benefit of slightly reducing the friction on the weldment, since they reduce the overlap.
With these in place I jiggled the position of the flap weldment assembly to minimize the interference with the longeron (some trimming still required):
Then I drilled the pilot holes for the bearing blocks to the seat rib angle and clecoed them:
Using fairing strips of aluminum, I was able to locate the corner aft bottom pieces of the seat bulkhead. These are sketched in on Drawing 19 and Sketch 43 and have an RV-4 part number, F-407C, which doesn't show up on the RV-3 plans.
Then these got drilled and clecoed, taking care to avoid the rear spar carry-through.
Looking around, it appeared to be time to yank the spar bulkhead out for some of the small work that's been taking my time.
The fuselage sure seems sparse without that, doesn't it?
The photos are also hosted here, here, here, here, here, here, here,
and finally, here.