After the previous work on the midbulkhead, I was told that the specifications I’d been working from had changed. So I dumped all that and designed a boilerplate version instead.
PDF of print. And yes, it now has four holes, but I haven’t renamed it. It’s made out of a 0.75″ plate of plain carbon steel, and weighs 5.11 lb, compared to 1.31 lb for the 7075/PMMA laminate proposed in the last post.
Rick Maschek asks, You say “I remain not a fan of this overall approach.” Reasons and or suggestions for something different?
There’s a saying that “An engineer is someone who can do for a dollar what any fool could do for two.” At this point we’ve definitely spent a metaphorical three dollars in time and effort on the midbulkhead concept. The best approach to it, since its function is just a check valve, would be to make a check valve. It’d be a bit more complex, but would be easily reusable and easy to test.
More generally, a two burn sugar motor is never going to go to space, the stated goal of the project. A two stage rocket is the way to go and is superior in almost every way. It would require relatively little R&D compared to the four dollars that’s been spent on the two burn concept so far.
If it turns out that it isn’t possible to build a sugar motor large enough to be a first stage for a two stage rocket due to the propellant’s physical characteristics, then it similarly wouldn’t have been possible to do a two burn rocket of the same size. Time spent trying to figure out the two burn architecture is time wasted until it’s been demonstrated that it’s possible to even get one burn of sufficient impulse.