I got a set of fins from Semroc a while back for a Moonraker, and they've been in my parts box ever since. Last night, I pulled together the parts to build it, and then had a better idea.
Here's the parts layout:
Moonraker Variation Parts Layout
If you're familiar with the Moonraker, you'll realize they weren't normally fitted with 13mm engine mounts. One of the complaints I always had with my original (now lost) Moonraker is that you had to display it with an engine casing inside to hold it together. This one is built like the Cyclone, with a coupler on top of the lower section.
I couldn't find the length of the upper tube, but the Centuri instructions listed the lower tube as 1 1/8" long. Knowing that the classic kit's nose cone had a 1/2" shoulder, I added in the 2 3/4" length of a standard 18mm engine, and then deducted a quarter inch for overhang. The overall tube length should thus be 3". So I took a 3" ST-7 tube and cut it at 1 1/8".
The engine mount is a section of BT-5 cut to 1 3/4" long; the nose cone is actually a BT-20 cone from Semroc I've had for years and never used. It's a bit small, but I'll sand the edge of the tube down to make it come out even.
I glued the upper ring to the coupler, then tried to glue it into the lower tube. I've had trouble with Semroc ST-7 couplers being too tight before, and this was never more a problem than with this rocket... the glue swelled the tube and made insertion impossible. I quickly pulled a BT-20 coupler out of my parts box and glued it in place, then went looking for another centering ring.
Oops. No more of that size. I did find a BT-20 thrust ring that was close, but I'll have to go back and fill in a slight gap between it and the engine tube. Probably mix up some epoxy, rather than try to siip something in there. So I glued that ring into place, then installed the engine mount (assembled in the usual way, with a belt made of glued copy paper wrapped twice around it to retain the hook).
I notched the upper tube opposite the fin line with a hole punch, then glued the half-circle to the correct (marked) spot on the coupler. I've used this kind of key arrangement on several rockets, to keep things lined up; heck, I even used it on the nose cone of my Big Daddy to keep the stripes in line. I glued the launch lug on the same line (after gluing on the fins).
This morning everything was dry, so I put it together and shot this picture:
Moonraker Variation Assembled
and this one of the two parts separated:
Moonraker Variation Separated
Once I'm done with gluing the upper ring, I'll be ready to paint it. I'm torn between a red upper and white lower paint job, and one that is yellow on top and black on the bottom. Not going with blue and white like the catalog; my old Moonraker was done in those colors.
... Hmm. I have some pearlescent (sp?) purple paint left from one of the projects my 4-H kids did a few years ago. I might go with that on top and white on the bottom.
Will have to think about it.