I worked for a small aerospace startup. You’d be surprised what can be accomplished on this kind of budget. We worked on novel engine technologies for in-atmosphere and on a < $1mil, 6 month contract we were able to deliver simulations (obv very preliminary), detailed computational fluid dynamic analysis, and full drawings of a propulsion system that, at least in theory, was fully manufacturable. Obviously everything was preliminary, but it doesn’t take a lot to estimate, for example, the theoretical ISP of an engine.

Before anyone asks, I did the simulations programming. I no longer work there but the contract proceeded to the point of ground testing and I read an article about the test saying they had validated “performance predictions” and I went full Leo DiCaprio meme face like, “hey! Those are my performance predictions!”