Upper stage options for reusable launch vehicle {open_quotes}pop-up{close_quotes} missions

Suborbital separation of an expendable upper stage from a small, single-stage Reusable Launch Vehicle (RLV) to transfer spacecraft into Geosynchronous Equatorial Orbit (GEO) was investigated and found to significantly increase spacecraft mass into GEO (over 400{percent}) although operational issues exist. An assessment of propulsion system options for this {open_quotes}Pop-Up{close_quotes} Mission was performed to determine the propellant combinations, stage configurations, and propulsion technologies that maximize spacecraft mass and minimize size. Propellants included earth and space storable combinations, cryogenic LH{sub 2}/LO{sub 2}, and Class 1.3 solids. Stage configurations employing cylindrical metal and overwrapped tanks, isogrid tanks, and toroidal tanks were considered. Non-toxic earth storable propellants provided comparable performance (5{endash}10{percent}) to existing storables while the use of pressure-fed engines gave about 15{percent} lower performance than pump-fed. Solid stage performance was within 5{percent} of existing storable propellants. Stages employing toroidal tanks packaged more efficiently in length constrained RLV payload bays than 4-cylindrical tank configurations, giving up to 30{percent} greater mass into GEO. The use of Extendable Exit Cones (EEC) for length constrained cases resulted in about 5{endash}10{percent} higher stage performance. {copyright} {ital 1997 American Institute of Physics.}