I recently picked up a BT60-sized ramjet type nose cone from Semroc and had to decide what to do with it.  I already built an upscale Teros, and I didn't really feel like doing a Strike Fighter at this time.  So, I decided to upscale the Battle Star Galactica Laser Torpedo.  I'm not actually a BSG fan (have yet to see an episode), but the rocket is a neat design - sort of a variant of the original Photon Disruptor. 

So, that's what I did.  The original model was essentially minimum diameter in its lower section containing the motor mount.  When upscaling the upper section from BT50 to BT60, the lower tube roughly scales from BT20 to 1.25" in diameter.  I could make it BT55, but the proportion would be off.  And I wanted to retain the original layout of min. diameter, with exposed retainer hook and sleeve.  So, I made the lower tube 29mm, which has an OD that is slightly smaller than true scale.  ASP sells retainer hooks long enough for the Estes 29mm BP motors, so that's what I designed it use. 

The only 29mm to BT60 centering rings I could find are fiber, so I used two on each end of the tube joint, basically doubling them up.  The main fins are basswood, whereas the strake fins are hard balsa.  And the engine hook sleeve came from Estes - its the spacer ring that comes with PSII kits, used for placing the centering rings correctly on the motor mount. 

With 29mm power, this will likely be very quick off the pad.  The BP motors will yield impressive performance themselves, but with a composite motor I expect that it'll near teleport.  I may have to invest in a tracker for this one.  According to the sim, anything in the "G" impulse range is enough to break mach - which it isn't built to handle - so I'll have to cap it with a moderate "F"...