Hey guys, I'm having some rather painful migraines which are leaving me doubtful that I'll attend tonight's propulsion meeting. AFAIK Nathan is still going, so tonight would be a good time to actually compare designs in open rocket.
Keep in mind that changing the fin dimensions or adding ballast to the nose cone is fair game if your design isn't stable in flight (recall that stability is a function of the positions of the center of mass and the center of pressure, both of which are changing dynamically with time, velocity, angle of attack, altitude, and also with reynolds number and mach number among other things). It's okay if its not totally stable for the first half second or so right off the launch rail (assuming that it doesn't ruin your simulation). If somebody is able to get a legit design to 100 km, take the burn time and rocket dry mass to get the mass ratio, and plug that back into the rocket equation to compare with our super simple 1.4 km/s dV estimate. My bet is it will be 1.5X-2X as high. I'm guessing the 100 km rocket with steel tanks isn't doable for us in a single stage. But I'm curious if we can pull it off with aluminum. We also assumed a pressure fed rather than pump driven propellant feed system, which is good because if anything this means our current numbers will be pessimistic (because we are using a design calling for heavier, high pressure tanks). I'm hoping this whole exercise will give you an intuitive appreciation for how ridiculously parameter sensitive rocket design is. Ad astra, Erin Schmidt
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