Lockheed Star Clipper

Lockheed's Star Clipper was a proposed Earth-to-orbit shuttle based around a large lifting body spacecraft and a wrap-around drop tank. Originally proposed during a USAF program in 1966, the basic Star Clipper concept lived on during the early years of the NASA Space Shuttle program, and as that project evolved, in a variety of new versions like the LS-200.

Although the Star Clipper design did not progress far in the STS program, it had an enormous effect on the emerging Space Shuttle design. The detailed study of the cost advantages of the drop tank design demonstrated a dramatic reduction in development risk, and as a result, development costs. When funding for STS development was cut, the drop tank was taken up as a way to meet the developmental budgets, leading to the semi-reusable Space Shuttle design.

Maxwell Hunter was working at Douglas Aircraft where he formalized the calculation of aircraft operation economics. His methodologies were first published in 1940, and were later applied to the Douglas DC-6 and DC-7. The methodologies were later adopted as a standard by the Air Transport Association.

He later joined the Thor missile project as the chief design engineer, and this introduced him to the world of space launchers. With new upper stages, Thor became the Delta, one of the most-used launchers of the 1960s. In spite of Thor's success, Hunter was dissatisfied with the state of the launcher market and later wrote that "by the end of 1963 the state of recoverable rockets was terrible." He was convinced that as long as launchers were thrown away that access to space would never be affordable.

Several companies had already completed early paper studies of fully reusable designs, like the Martin Marietta Astrorocket and Douglas Astro. The designs used two flyback stages, one of which flew back to the launch point, while the other flew into orbit and landed after its mission. Hunter felt that any such design was tantamount to making two aircraft to do the job of one, and it was only the upper stage that was of any real use. By March 1964 he had developed a new solution to the problem, the stage-and-a-half configuration.

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