The smaller HLLV was analyzed to compare the non-recurring cost benefits of a less challenging development with the recurring cost increases expected due to losses in efficiency associated with smaller vehicle size. The vehicle payload bay size was selected to be adequate to accommodate the SPS transmitter subarrays fully assembled. This required a square cross-section of 11 meters; the length was set at 14 meters. Paramentric investigations led to a gross lift capability requirement of 120 metric tonnes. The resulting vehicle design is compared with the Shuttle, the Saturn V, and the reference SPS HLLV in Figure 7. Mass estimating revised the parametrically-estimated lift capability to 125 tonnes. Costs were derived by the Boeing Parametric Cost Model (PCM), and cost per flight was estimated by procedures consistent with those used for the reference system. Operational effects of the smaller payload bay were analyzed to develop a total delta cost understanding. Delta environmental effects were also estimated. The end result was that a nonrecurring savings of at least five billion dollars was obtained with a recurring cost penalty of 3% per SPS. Further, the environmental benefits of the small vehicle: reduced sonic overpressure, noise, potential blast effect in the event of an accident, and less modification of the Cape Canaveral area to accommodate launch pads, were deemed more important than the slight increase in upper atmosphere propellant deposition. As a result of these considerations, it is recommended that the small HLLV be adopted as the SPS reference launch system. Important areas remaining to be investigated include: (1) Comparison and selection between series and parallel burn; (2) Configuration development to a sufficient level of detail to permit specific facilities and operations systems definition; and (3) Development of an evolutionary strategy for evolving from the present Shuttle system, through Shuttle improvements or Shuttle-based interim HLLV capability, to the SPS operational configuration. Considerations include engine and subsystem commonality and evolution as well as launch capability to support SPS development requirements as well as other space applications needs. BALLISTIC SSTO ORIGINAL "big onion“ (BOEING IRAQ) Circa 1974 SOOL PAYLOAD < BALLISTIC 2-STAGE HLLV STUDY Circa 1975 STAGING SHOWN ECONOMIC i NOTE LARGE ‘ , SHROUD y > 500K PAYLOADL BALLISTIC 2-STAGE SPS STUDY 1977 RESIZED BOOSTER SMALLER SHROUD/ ► 700K PAYLOAD C Figure 1- SPS LAUNCH VEHICLE CONCEPT EVOLUTION WINGED 2-STAGE SPS HLLV 1980 9W pavi n*n
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