Clecoed the tail cone and aft bulkheads to the assembly. Sounds simple. It's relatively simple, once you bend the tail cone into submission. It needs to fit the bulkheads with no force being exerted by the clecos. Otherwise it would be nearly impossible to get all the parts together.
So I took all the aft parts back out and started shaping the tailcone. Tried by hand first, but the metal is too thick. So ended up clamping a lengthwise edge into my bending clamp. The goal is to get the longitudinal edges to 90 degrees to the bottom. It took a serious amount of bending. I curled the entire piece over nearly on itself. The other side would be touching the table, with the clamped edge flat to the table. And that still wasn't enough. After about 20 minutes of extreme bending, was able to put the finishing touches on it with the flange bending tool. When done, the tail cone skin practically hugs the three aft longerons, and the straight edges are flat to the tabs where the stringers will fit.
Whew!
Once the tail was all clecoed together, setup two plumb bobs. I hung them from 707 and 709. It' difficult to line the plumb bob up with the tooling holes, but easy to hang them on center. Then you can sight down the axis, line up the two strings by eye, and then notice where that plane falls on the tooling holes. By choosing the correct vantage point and using reflections, you should be able to line up the two strings, the top center rivet of 710, the top tooling hole on 712, and the bottom tooling holes of 708 and 709. It those all line up, then everything is straight. If a line between the tooling holes on 712 also lines up, there's no twist.
This picture is the laser light show I created with a laser level and the plumb bobs. I lined up the laser with the plumb bobs, and it confirmed that everything was lined up correctly. Since I've always been fascinated with pretty lights, I coudn't help but turn off the lights in the garage. Putting the two plumb bobs in motion created a great light show as the laser was blocked by the strings swinging back and forth.
