So, in theory, for this application, energy/mass density is important, so a lox/aluminum powder monoprop mixture has great energy per unit mass (16KJ/g) and could be good (better than LH/LOX at 13KJ/g).optimal energy efficiency of a rocket engine is when the velocity of the exhaust is about the same speed as the vehicle moves at...Correct, but for chemical rockets, in general you care overwhelmingly about *mass* efficiency and not at all about energy efficiency. What matters is the momentum imparted to the vehicle by a given amount of mass from the tanks, and that is maximized by recruiting as much outside air as possible, taking the exhaust velocity as low as possible.
[Well, beryllium + ozone is better- 26KJ/g, but... ;-) Lithium and oxygen manages 20KJ/g, that's not quite so bad ]
I did some BOE that suggested it could be just a few hundred kg of fuel for 7 tonnes to 30km, but the equipment to heat the air and put it through a nozzle is complex and possibly too heavy. (Some kind of jet engine/ramjet could work, but thrust to weight is a reasonably big problem.) Still, jets are limited by temperature, but squirting in extra LOX in the inlet may work according to Mitchell Burnside Clapp.
Henry Spencer [EMAIL PROTECTED]_______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
