The evening started slowly with me cutting out the seat. I knew the next steps looked imposing, so I had little confidence that I'd make much progress tonight. But I dove in....
The underside of the seat requires a scarf cut along each side, to an angle of 8 degrees. The plans suggest building a scarf jig for the table saw fence, so I spent half an hour doing that, and probably another 15 minutes getting it adjusted properly. I set it up with a piece of scrap plywood to test the cut and it worked! Somewhat. Well, not really. Quite poorly, in fact. The saw really bogged down, and the wood was scorching. I tried cutting a bit further, but accomplished nothing but filling the workshop and most of the basement with smoke, and I had only cut about 3". The cuts I needed to make were close to 18" total, so it was obvious there was no way I was going to get them done without setting off the smoke detectors. Hmmmm....get out the trusty belt sander. That did the trick nicely - maybe not as smooth as a table saw, but I didn't wake up the kids doing it.
I attached the control spacers to the underside of the seat, and taped it into place (yeah, that's right: tape. Screws will be added later). With that done, the right wing was fitted and screwed temporarily into place. Wow, it looks cool. But it's really getting too big for the workbench. I couldn't find the camera, so I won't get any pics up until tomorrow.