This section was pretty massive, and admittedly took me probably a few months of casual weekends to complete. In fact, it's still not complete, as the vents on the very last step I'd like to color match with the exterior paint, and will probably not attach them until the very end of the build. First up is bolting up a section of 2x4 to one spar to stand the whole assembly on its side to work on the bottom skins. I used a rattle-can self-etching chromate primer on overlapping regions of skin because I didn't want to break out the spray gun and mix paint for this one-off operation.
Getting the center side plate, upper drag fitting, and side skin riveted together was a tad more challenging than expected. Back riveting seemed the obvious choice of method here, however, driving AD4 rivets through a large and heavy piece made it very difficult to keep the assembly flush and tight against the back rivet plate. What ended up happening if I laid everything flat on a table is that the manufactured heads would protrude from the skin just enough to be unacceptable, and I had to drill them out. My solution was to purchase a long reach c-clamp from harbor freight to reach all the way to the drag fitting and clamp the assembly tight against the underside of the table supporting the back rivet plate. This worked great, and the rivets were now perfectly flush.
Installing the bearings on the control column. Had to trim the powder coat a bit to get the bearings to fit, but otherwise everything lined up here perfectly.
Cutting notches in the longerons and various other parts were done with a basic cut-off wheel from a high-speed rotary tool. Just go really slow so as to not have the tool jump. Bending the longeron took some significant twisting. I think I had to bend the assembly almost 360 degrees to achieve the 10 degree permanent twist. This took me some time to work up to as I was afraid of folding the aluminum channel, but it's surprisingly robust.
Cutting the roll bar angles was done with a band saw then primed.
Assembly is pretty straightforward and access is pretty good. I was able to drive almost all of the rivets solo, except for the lower corners of the fuselage. Some of the rivets, especially around the intercostals were tricky to get t, and I found that I was having to be quite creative with my collection of bucking bars to get into tight spaces.
I elected to install a custom canopy latch from JD Air and it seemed appropriate to do this now while everything is accessible, but in really it probably doesn't matter since the fuselage side is always going to be accessible. The install involves printing a template and cutting out additional material beyond the pre-cut slot from the factory handle. I used a rotary cut-off wheel for most of this, then used a hand file to get it to final size. I went super slow here, since I was aiming for as tight a tolerance as possible given that any gaps are going to be exposed to the elements right next to you in the cockpit. The only thing I didn't like about the install is the single rivet hole between the two sections of the handle. The instructions say to dimple and put a dummy rivet in, but then you have to drill out material from the handle to accept the protruding rivet. Instead, I decided to just fill the hole with an epoxy filler and keep it flush. I suppose the worst thing that could happen is that it breaks out eventually.
I did decide to drill a hole into the bracket that will insert into a slot on the underside of the handle, presumable to accept a locking bolt. I'm not sure if I plan to actually install a canopy handle lock, but if I can find a design I like it would go below the handle and raise a bolt through the underside of the assembly.
Lastly was sealing up all the seams and holes around the firewall and mating surfaces with proseal.
