I neglected to get a picture of it in place while I was fitting it, but I started out today with a nice, easy task - riveting together the elevator bellcrank. It's a pretty straight forward part, with a bearing, long bolt, and a couple of aluminum spacers I made to keep it centered and in the right place. I pulled it back out for now. It'll go back in down the road when I start rigging controls.
Previously I had gone through the effort to square up all of the flanges on the tailcone bulkheads, because that's what you do. Past me didn't think about the fact that the whole tailcone gets smaller towards the rear, so of course the flanges shouldn't actually be at 90 degrees to the rest of the bulkhead. Duh. I laid a level across the bulkheads to get an idea of what the angle should be, and then bent the flanges upwards to hit an angle that would put them close to that of the skin. If you don't do that, when you rivet them together, the space will close up just fine, but you will get a divot in the skin as the area around the rivet sucks down towards the underlying flange that isn't laying up against the skin.
Just like for the side skins, the top skins also get two J channels as stiffeners. I had made these back when I made the ones for the side skins. I just taped the fore and aft ends to the bulkheads to keep them in place until the skins went on.
I put the rear top skin on first and final size reamed all of the holes (except drilling all of the holes through the J channel - I did that after the other top skin was on as well).
The bulkheads are shockingly floppy until they are locked in place by the skins. The middle and front bulkhead need a gusset that ties them to the longeron as well. The problem is, because the bulkheads can wiggle around so much, you can't put the gusset in place and drill it until you first have the skins on to ensure the bulkhead is sitting in the right position. It was a lot of awkward contorting and reaching to cleco the gussets to the bulkheads, then push them into place so they were parallel to the longeron and clamp them for later. The picture below is of the front gusset after I took the skin off just so you can see what they are.
With the rear skin on, I put the gussets in place on each side, rotated them into position over the longeron (because the bulkhead web flexes and doesn't naturally sit at the right angle), and clamped them.
The front top skin overlaps the rear one, and extends up the sides of the baggage area.
I had drawn a line down the center of the J channels so I could reference it and make sure not to make things too wonky when match drilling holes through the skin (the skin has pre-punched holes, but the channels don't). At the front half of the tailcone there is also a stiffener web that goes from the front bulkhead to the second bulkhead and connects with a small angle bracket I made. I final size drilled it to the top skin as well.
The very rear of the plane by the aft deck (where the horizontal stabilizer gets mounted) gets another bulkhead that closes out the back. I had to go a little overboard with the rivet holes here. When I had put the aft deck on, nothing in the instructions said to make sure that it was perfectly centered on the longerons from side to side. It's pretty close, but not perfect. That would have been fine, except the lower row of rivets in the rear bulkhead that attach it to the vertical flange on the bulkhead came pre-punched, meaning they only match up if the aft deck is exactly centered. I'm off center by about 1/16", which doesn't seem like much, but that's half of a hole. I asked Van's, who said just to put the bulkhead in place and drill new holes in between the pre-punched ones. I'll only have to put rivets in the new holes for it to be structurally sound, but I think I'll probably fill all of the holes just so there's no question down the road about why I have what looks like missing rivets.
After all of the skins were drilled, I pulled them back off. I'll leave them off for a while, since it'll be a whole lot easier to work in the rear without them in place. I drilled and riveted the rear two bulkhead gussets.
I started to rivet the front two gussets to the 706 bulkhead (this is the bulkhead that is at the rear of the baggage area), but realized I need to figure out how to dimple them first. They just get universal head rivets to attach them to the longerons, but the rivets that attach them to the bulkhead are flat head rivets since the rear baggage panel mates up flat against the front side of the bulkhead. Normally dimpling is no big deal, but none of my dies for these 4- rivets will fit in the space. I'll either have to see if someone makes a small diameter 4- die (like they do for 3- rivets) or just come up with a homemade die and use the hammer approach.
