GENERAL DYNAMICS CONCEPT-D [SHUTTLE PHASE-A] [1969]
Notes:
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General Dynamics also received a $0.15-million Phase-A extension from NASA/Marshall to further study its shuttle concepts. The Triamese design was abandoned in September 1969 after more detailed analysis indicated that the development cost showed no considerable advantages vs. traditional two-stage systems. It had proven difficult to to have one aerodynamic shape serve both as booster and orbiter; too many compromises had to be made. The designers then tried to “stretch” the Triamese orbiter but this, in turn, reduced the design commonality and hence cost savings. The company finally settled for a similar two-stage design with V-tails to provide hypersonic roll control and aerodynamic stability. The booster/orbiter staging point was at 56.7km altitude and 193 seconds after launch when the vehicles were flying at 3325 meters/second. The straight-sided bodies were designed to accommodate cylindrical propellant tanks efficiently. Variable geometry switch-blade wings would still be used for subsonic flight and landing. This would have reduced the thermal protection system requirement (GD was the only company that still proposed a “hot structure” metallic TPS at the end of Phase A) . But the General Dynamics concept also had the same problem as MSC's/North American's DC-3 design since it had comparatively poor reentry crossrange capabilities. The payload capability to a 555km space station orbit was 22,680kg.
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“Progress in Technology for Space Shuttles”-- Rainey, AAS 1970/vol.28/p. 3
“Characteristics of the Space Shuttle” -- Jean & Scott, AAS 1970/vol.28/p.141
”Space Shuttle” -- Dennis R. Jenkins, 1981, ISBN: 0963397451