VI-B HEAVY LIFT LAUNCH VEHICLE (HLLV) (E. M. Crum, Future. Programs Office and D. Webb, Resources Management Office) B-l SUMMARY The HLLV is responsible for transporting all SPS freight, except crews and high priority cargo, from Earth to LEO. The launch site is assumed to be KSC and payloads are launched into approximately 500x100 km, 28.5° inclination insertion orbits. Payload circularization and rendezvous propulsion is provided by an orbital maneuvering system (OMS) to decrease launch velocity requirements and facilitate recovery. This imposes a weight penalty of approximately 3% on the payload for the OMS, including propellant, and requires a subsequent return to Earth of at least the OMS engines and avionics by Shuttle or the Personnel and Priority Cargo Launch Vehicle (PLV). The cost of OMS recovery has not been investigated further in this study. The ground rules and requirements developed for the HLLV may be found in the previous section. The key figure of merit for the HLLV is the cost per pound of payload to LEO. Minimizing this cost requires attaining as much reusability as possible with as little refurbishment and parts replacement as can be achieved. Reuse goals of 300 and 500 flights were confirmed to be attainable from a structural design (fracture mechanics) standpoint and are suggested as the range for launch vehicle replacement calculations and costing purposes. A 1995 level of technology is assumed, although no particularly large or vital technical advances appear to be mandatory. Hydrocarbon fuel density improvement over hydrogen allows enough decrease in structure with related cost advantages to outweigh the higher specific impulse of hydrogen fueled engines. Engines considered were:
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