VI-C PERSONNEL AND PRIORITY CARGO LAUNCH VEHICLE (PLV) (C. Mac Jones, Future Programs Office) GENERAL The PLV will be utilized to transport all personnel to low Earth orbit (LEO) and in addition can fulfill high priority delivery functions of a modest scale. The approach taken in this study is to modify the current Space Shuttle vehicle to fulfill these requirements. In-house IR&D studies by the Boeing Aerospace Company and Rockwell International Corporation have indicated that the baseline Shuttle system can be improved in both payload capability and operating cost by replacement of the two solid rocket boosters (SRB) with a new booster utilizing liquid oxygen and hydrocarbon propellants. Such a booster, herein called the "Liquid Replacement Booster" (LRB), could be developed using the F-l engines from the Saturn V first stage. If available for heavy lift vehicle use, a new more efficient oxygen/hydrocarbon engine can be advantageously employed to increase the payload capability of this growth Shuttle or enable a decrease in propellant requirements. Briefly, the LRB is a 10M (33 ft.) diameter stage with integral propellant and mounted beneath the Shuttle external tank (ET). The stage is recoverable downrange following a parachute water landing. The following vehicle sizing results presented are a product of the EDIN Computer Design Center effort on Alternate Shuttle configurations. The EDIN computer graphic depiction of the Shuttle/ET/LRB mission sequence is presented on Figures VI-C-1 (a)-(d). ASSUMPTIONS AND GUIDELINES The design points for the study are under the groundrules for Shuttle Reference Mission 1 (due east launch from the Eastern Test Range to 50x100 NM orbit), modified to achieve a payload of 45 metric tons (100,000 pounds). Resultant payload to the proposed SPS LEO operational altitude of 500 km circular will be approximately 36 metric tons. The launch trajectory is constrained to pass through both the RTLS/AOA and MECO Doints of the Shuttle Reference Mission 1. The initial tilt rate and exo-atmospheric pitch profile are optimized to obtain the trajectory for maximum payload or minimum gross lift-off weight (GLOW) in each study case. The trajectories employ a gravity turn from end of tilt to booster engine cut-off (BECO) and are constrained to prohibit dynamic pressure in excess of 650 psf and longitudinal acceleration in excess of 3.0g by engine throttling and/or shutdown. The LRB and ET are sized to satisfy performance requirements with minimum GLOW. The LRB is sized according to weight estimating relationships based on Saturn technology. ET sizing is accomplished by employing a fixed mass fraction to distribute ET component weights in accordance with the Shuttle ET weight statement. The Orbiter is modified to include
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