Back where we left off before last post, it now was the third stage that was in line for assembly.
First made were the tank dome and the engine section. The first and second stage have gimballed engines, they can swivel and by doing so steer the rocket in its trip up to space. The third stage does that by using a vernier engine. A small amount of the fuel is used for an engine with four small nozzles located around the central engine. You can see the base parts f those engines on the photo below. The seams of the tank dome were covered with bare metal foil.
I did some embossing on the lines at the engine section to make it stand out a bit more.
More after the jump.
Now I already asked myself what use the blast holes had since the main engine bell was located under those openings. But after I made those vernier engines, they perfectly fit inside those "slides" I made in the blast openings. So that was what they're for! And I made this with a perfect fit, without even knowing the measurements. That's nice.
Anyway, the rest was pretty straightforward. I used another print on white paper for the Briz-M logo on the stage, this was the easiest way to do so.
Now then, Briz-M itself.
Briz is a classic upper stage. It can serve on different rockets and is comparable to the U.S. Centaur upper stage. It gives the payload that little last kick and is able to restart a couple of times. Big difference is the fuels. Centaur uses cryogenic fuels (liquid oxygen / liquid hydrogen) and Briz uses chemical fuels. dinitrogen tetroxide with asymmetrical dimethyl hydrazine, which the Russians call "the devil's poison". Briz has a special structure; a jettisonable outer part with toroidal fuel tanks, inside of which the central part sits with the payload. Now toroidal shapes are amongst the most difficult parts to design and make in paper modeling and I think Leo Cherkashyn did a very nice job in this one without getting too elaborate. I cut the parts out of chrome coated paper and I used some ball-headed tools to round the assembled shape a bit more and the result is quite nice and shiny. Using this chrome paper also helps showing off the rounding in the torus' shape. Inside this ring-shaped tank the central part will be. The picture below shows the lower part of the torus.
The rest will follow.