Technology challenges in the development of cryogenic propulsion systems for the future re-usable space launch vehicle

Technology challenges specific to cryogenic propulsion systems are discussed; these include the development of combined-cycle engines to achieve specific impulse values in excess of 4000 seconds, realization of software packages for high speed computation, simulation using CFD techniques, and design optimization of air-intakes to enhance pressure recovery at high Mach numbers. Data obtained confirmed the feasibility of developing a fully reusable, 'flyback-type' SSTO and two-stage-to-orbit vehicle. Airbreathing propulsion technology and advanced construction materials for these hypersonic vehicles are considered to be the most important areas for concentrated development. A low cost space launch vehicle with an advanced cryogenic propulsion system involving mass augmentation and mass addition during the flight is the most promising vehicle for future missions.