This thing is cute. Before SpaceX announced Starship, I always expected the first fully-reusable orbital launcher to be very small, because it's so much easier and less expensive to make prototypes, and to come from a small, focused company.
It has some interesting features. Peroxide/alcohol is a well-recognized option for room-temperature propellants, but I hadn't heard before about dissolving propane in the alcohol to make it self-pressurizing. x.com/vbklgd/status/…
@vbklgd Be careful with that bipropellant combination. Peroxide/alcohol is not well-liked because they mix so easily into an explosive, though one could say this is also a problem with methane/oxygen. Non-water-soluble hydrocarbons have some big handling advantages.
@vbklgd If I remember correctly, @ID_AA_Carmack in his Armadillo days turned away from peroxide/alcohol propellants in part because of the hazard they'd pose if they leaked and mixed together.
@SpaceDevClub @vbklgd No, it was more the easy availability of lox. We found that most of the scary stories about rocket propellants were overblown, at least for peroxide and lox. We never worked with hydrazine and nitrogen tetroxide, but I did wonder if they were also not as bad as many claimed.
@ID_AA_Carmack @vbklgd I remembered that high-% peroxide availability was the main factor for switching to lox, but I thought you talked about being worried about explosive puddles with water-soluble fuel and peroxide. I've probably misattributed some 3rd party commentary. Thanks for clarifying.
@SpaceDevClub @vbklgd If we had gone with peroxide biprop we probably would have used kerosene instead of alcohol -- better performance and no miscibility issues, at the cost of needing to clean plumbing more carefully. The Black Arrow rocket was great, getting to orbit with just 5klbf chambers!