Any ideas on how to make the BB II's wasp waist?

I've got this idea to upscale the Estes Black Brant II to a BT-60 (either 29mm,or 24mm powered). I've got ideas on how to do the tail cone, however the wasp waist (aka coupler) has me stymied.

Any ideas out there?

Thanks!
Jim

I made mine from a series of card stock centering rings. Since I also built mine with an 18mm motor mount, I could make the connector part of the motor mount assembly. Printed on 110# card, it took quite a few rings. Sadly, I cannot find the file that had those rings in it. If I do, I'll see about posting it.

Thanks Greg!

I had thought about rings, but at 110# card, that'd take a hella lot of 'em. I guess I could always us OR to create a template for them.

Not as bad as you'd think - it takes a total of 37 centering rings (including two rings that center the assembly in the BT-55 tubes). I could not find the file, so I recreated it this evening. I have attached it as a pdf file. Again, I made mine for BT-20 motor mount and 18mm motors, so that is what this is set up for. The smaller rings get a little flimsy if you put a 24mm motor mount in this bird, and it flies great on B6 and C6 motors. Arrow straight flights.

I am attaching two files. The first is the set of centering rings. Each ring is numbered 1 through 37, and you just stack them up on a BT-20 and glue them together. Once the glue is dry, you can coat with CA to give it a rock hard finish, but the white glue should make them tough enough and will take the paint fine. Again, you'll have to make a couple of adjustments to the Estes design to make this tail assembly work, but it shouldn't be too tough. The other file is the fin template, tail cone and rear centering ring (fits just inside the back of the back of the tail cone. Between this ring and the rings of the tail cone coupler, this should be enough to mount the motor tube. I included two tail cones and rear CRs in case you mess up one (plenty of space on the page, so why not). Remember to print these on 110# card, or the length and shape won't be right (I designed it with an average .007" thickness per ring). There is a half inch margin around both pages, so any printer that can handle card stock should print these just fine - just be sure to turn Print Scaling OFF.

View attachment BB coupler rings.pdf

View attachment BBII tail cone fin.pdf