A Report to the Cabal:
Further refining the mockup of the rocket motor portion of the 3rd stage, I soldered together the foundation plate upon which the rocket motor sat, transmitting its thrust force through a gimbal mount to the rest of the vehicle structure. The initial representation was a simplistic termination of the four support struts at the base of the combustion chamber. However, the proper item is a platform atop the four struts. And that's what I built this evening.
The 'gimbal plate' was soldered from brass tube and brass sheet. Again, using the central 1/16" diameter brass wire as an alignment aid, I first cut four short lengths of brass tube, tack gluing them atop the struts, and then solder them to the gimbal plate. Making things removable permitting me to test fit different subassembly looks and positions, and to test various subassembly fabrication techniques. Case in point: I was so satisfied with the process used to make the gimbal plate, that I've made up my mind to employ an identical fabrication methodology for model parts. That's the virtue of a mockup -- you can play around till you find the 'right' way to do things.
Here's the struts topped with the 'gimbal plate.'
The parts that make up the gimbal plat. To hold the plate in place between the four strut mounted tubes I ran a 1/16" alignment rod up from the hole in the tank-top/firewall. Heat was applied after slathering on some acid type flux and solder flowed in to bond tubes to plate.
The gimbal plate filed, sanded, and buffed down with '0000' steel wool. Note how the vertical alignment rod is used to support the turbo-pump unit and rocket motor.
The gimbal plate atop the struts. Everything here is a friction fit and can be disassembled or assembled in a minute.
The basic subassemblies comprising the 3rd stage rocket motor mockup.
The ability to easily and quickly test-fit sub-assembles lets me play around with slightly different looks and arrangements. All this work will insure that the final masters fit and look like what is seen in the cartoons and the filmed short, Tomorrow the Moon.
A quick attachment to the Cargo Rocket body, to check for form. Looking better all the time!