$100/kg of payload to geostationary orbit. In the FRG analysis of the HLLV, a single-stage-to-orbit (SSTO), ballistically-recovered vehicle of very large size was selected. Their indicators were that at least 700 metric tons of payload per flight resulted in minimum cost and that launch from the European Space Agency (ESA) facilities at Kourou, French Guyana, can increase the payload of a specific vehicle by 10% to 20% over that achievable by launch from the United States KSC launch complex. The ballistic single-stage-to-orbit vehicle was found to be feasible in the near term but the winged (SSTO) was not now feasible, particularly at the very large size indicated as most cost-effective. The ESA analysis of the HLLV considered only chemical propulsion for orbit- to-orbit transfer, did not consider a possible difference in the risks of intact recovery of the vertical landing at sea (required of the ballistic entry vehicle) and the runway landing achieved by the “Reference System” winged vehicles. In response to a question, the opinion was expressed that even larger vehicles (more than 700 tons) may be less expensive yet, that size is no technical barrier; and that the propellant and sheet metal tanks were the least expensive element of the system. This comment may not give sufficient weight to the increased development and acquisition costs of rocket engines, control systems, facilities, etc. for the very large vehicles. Boeing rendered the next report for NASA at the transportation session. They described the two-stage VTOHL reference system, a large vehicle of 425 ton payload capability. The controlling factors leading to Boeing making their selection were the “Reference System” satellite characteristics (mass and unit payload size), construction location (low orbit or geostationary orbit), and the SPS placement scenario. They stated that the expected low density of the payloads was a strong determinant in the vehicle configuration. The Boeing studies indicate that SPS payloads to low orbit will be of low density, in the range of 70 to 100 kg/m3 (approximately the same as liquid hydrogen). The winged vehicle selected is more expensive to develop and to purchase than the earlier Boeing ballistic entry concepts, but the trajectory analysis indicated that this vehicle, used in the reference system cost buildup, actually can place into orbit a payload of approximately 900,000 Ib/m (450 tons). This illustrates the inherent sensitivity of launch vehicle performance to detailed definition and points out the need for a larger effort in systems definition in the immediate future. Boeing indicated that parallel burn HLLV configuration with cross-feed, as advocated by Langley Research Center and MSFC/RI, can gain an additional 10% to 20% payload at the risk of introducing some additional operational complexities. Boeing believes that the issue of cross-feed is still open for further analysis. In what 1 believe to be the most significant part of the Boeing briefing, the results of work done by Boeing on the launch vehicle subsequent to selection of the “Reference System” was disclosed. This work was done, in part, to respond to the criticism rendered by congressional staffs and others that NASA was advocating development of a “$30 billion white elephant HLLV” to serve the SPS. Boeing recently analyzed a smaller vehicle of 120 tons payload having a gross lift off weight (GLOW) of 11,000 tons. This vehicle appears to be technically feasible and is potentially very attractive to an operational SPS program. The Boeing cost work on this vehicle is still underway and is scheduled for completion before May 1, 1980. An existing transportation “scenario analysis” computer routine at Boeing will be employed to redefine the program scenario and the costs consequent to downsizing of the launch vehicle. The booster stage of this vehicle is of an appropriate size for the current Space Shuttle orbiter and a reduced volume external tank and may, therefore, be
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