Thanks for that comment.
Mostly I?ve been working on the flanges of the bulkheads for the top tailcone skin. The skin is F-323, for reference, and it?s .025 thick.
As Paul Dye noted during the construction of their RV-3B, the top sections of the tailcone flanges don?t really fit. At the longerons, they?re too narrow, all of them, and elsewhere they?re either too high or too low or poorly curved. First, I tried to correct the F-305 seat bulkhead and then the F-309 bulkhead, the aft most one that this skin attaches to.
Here?s the before and after photo of the seat bulkhead flanges at the longeron. The rest of that bulkhead isn?t too bad, and will be accepted as is.
The aft canopy latch goes through this one. It goes right through that gap between flange segments.
Then I did the F-309 bulkhead flanges. These needed thickening, not much, and rounding. I started with the areas adjacent to the longerons and filled the small gap with a thickened G-flex epoxy. It?s the same epoxy I?m using elsewhere with some flox and aluminum powder added for hardness. All it is, is a bit of a shim.
That worked out so well that I did the same thing to add some roundness to the too-straight flange segments. You can see that the topmost flange is essentially flat. I arranged the aluminum form so that it faired to the fuselage shape and at the top, faired to the seat bulkhead forward.
The blue vinyl is a decent release surface all by itself. To make certain, though, I put a couple coats of paste car wax on it. It came off with no problems.
The next bulkhead forward is the F-308 bulkhead. For this, I removed the flanges on that bulkhead. I?ll make totally new ones. The material thickness is .032 on this bulkhead, in case you?re ever in the same spot. The process I?m following is outlined this thread by Paul Dye and Louise Hose:
http://www.vansairforce.com/community/showthread.php?t=61927
And I bought more magnets on order to hold the new flanges in place. I use p/n ZD84PC-PNK magnets from K&J Magnetics. They grip well, are easy to find when they jump away from sight, and seem to be very robust compared to the all-metal kinds. Recommended.
The plywood work platforms that I?ll need to squirm into the tailcone are all cut out now. I realized that although the flap weldment is not yet installed, the work platform needed to clear it when it was installed, too I had to trim it. Having flat seat ribs makes supporting the platform a lot easier in that area. Remember, on this airplane the seat pan is removable, so the platform could be handy one day.
The tennis ball protects the area around the control stick when the stick moves around. This sometimes happens when I roll the fuselage around. With a 1? hole the tennis ball goes right on.
So far I?ve only got part of one of the new flange strips cut out.
I strapped the tailcone top skin in place and was mildly surprised that it?s big enough. And even better, with some straps and cheap angles, it fits without needing rebending - the first curved fuselage skin to do so.
Here?s what the cave looks like. You can easily see where the new flanges will go and why they are needed.
Unfortunately the work platforms aren?t completely finished yet. It?s unfortunate, because I believe that the top skin is currently where I?d like it and I?d like to back drill some holes, and it takes climbing in the cave to do that.
You know, I?ve been thinking that I missed an opportunity to make the platforms fit the sides. If the fuselage was rolled on its side, there would be more width but less height and it might be easier to back drill the rivet holes. On the other hand, they'd be useless once I got the wings on, wouldn't they?
The work platforms got a final coat of finish after I took the photo, but it?ll be a day before they are dry enough to work on. I?m using Minwax?s polyurethane varnish. I?ve got plenty of experience with the product, with several of Minwax?s line, actually, and am happy with it. Their products go on well, cure quickly and are durable. And the best part is that I had a can on hand from a different project.
The alternate hosting links are -
First one,
Second one,
Third,
Fourth,
Fifth,
Sixth,
Seventh,
and the eighth and final one.
Dave