A Conceptual Design for a SSTO Space Station Service Vehicle
Olds, John R.
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The objective of this research was to design a single-stage-to-orbit aerospace vehicle to service a U.S. space station. Several restrictions were placed on the design, such as minimum landing speed (165 knts.), stability at low and high speeds, and use of LOX/LH2 propellants. The vehicle must be able to carry 20,000 lbs. into orbit and return 40,000 lbs. to earth. Computer programs were required for the analysis. APAS, POST, and AVID were used at NASA-Langley. The preliminary vehicle configuration has a landing speed of 131 knots at 15º angle of attack, gross lift-off weight of 4,680,000 lbs., and length of 252 ft. The payload weight fraction (payload weight/Lift-off weight) is .004274. The LOX/LH2 propellant tanks make up 41% of the internal volume of the fuselage and 87% of the gross lift-off weight. The launch performance of the vehicle allows a minimum ∆V of 29,740 fps and a 7.76 mass ratio on ascent to insertion orbit (50 Nmi. x 100 Nmi.). An additional ∆V of 600 fps is required to obtain the final 250 Nmi. circular orbit of the space station. Improvements in the packing factor would greatly increase the performance of the vehicle. Technology improvements of 10% in structural and subsystem weights were assumed in the design process. Engine improvements are also required. Further investigation is required to evaluate reentry performance, structural integrity, and thermal protection.