The Boeing X-20 Dyna-Soar ("Dynamic Soarer") was a United States Air Force (USAF) program to develop a spaceplane that could be used for a variety of military missions, including aerial reconnaissance, bombing, space rescue, satellite maintenance, and as a space interceptor to sabotage enemy satellites. The program ran from October 24, 1957 to December 10, 1963, cost US$660 million ($5.16 billion today), and was cancelled just after spacecraft construction had begun.
Other spacecraft under development at the time, such as Mercury or Vostok, were based on space capsules that returned on ballistic re-entry profiles. Dyna-Soar was more like the much later Space Shuttle. It could not only travel to distant targets at the speed of an intercontinental ballistic missile, it was designed to glide to earth like an aircraft under control of a pilot. It could land at an airfield, rather than simply falling to earth and landing with a parachute. Dyna-Soar could also reach earth orbit, like Mercury or Gemini.
These characteristics made Dyna-Soar a far more advanced concept than other human spaceflight missions of the period. Research into a spaceplane was realized much later, in other reusable spacecraft such as the Space Shuttle, which had its first orbital flight in 1981, and, more recently, the Boeing X-40 and X-37B spacecraft.
Problems
Besides the funding issues that often accompany research efforts, the Dyna-Soar program suffered from two major problems: uncertainty over the booster to be used to send the craft into orbit, and a lack of a clear goal for the project.
Many different boosters were proposed to launch Dyna-Soar into orbit. The original USAF proposal suggested LOX/JP-4, fluorine-ammonia, fluorine-hydrazine, or RMI (X-15) engines. Boeing, the principal contractor, favored an Atlas-Centaur combination. Eventually (Nov 1959) the Air Force stipulated a Titan, as suggested by failed competitor Martin, but the Titan I was not powerful enough to launch the five-ton X-20 into orbit.
The Titan II and Titan III boosters could launch Dyna-Soar into Earth orbit, as could the Saturn C-1 (later renamed the Saturn I), and all were proposed with various upper-stage and booster combinations. While the new Titan IIIC was eventually chosen (Dec 1961) to send Dyna-Soar into space, the vacillations over the launch system delayed the project as it complicated planning.
The original intention for Dyna-Soar, outlined in the Weapons System 464L proposal, called for a project combining aeronautical research with weapons system development. Many questioned whether the USAF should have a manned space program, when that was the primary domain of NASA. It was frequently emphasized by the U.S. Air Force that, unlike the NASA programs, Dyna-Soar allowed for controlled re-entry, and this was where the main effort in the X-20 program was placed. On January 19, 1963, the Secretary of Defense, Robert McNamara, directed the U.S. Air Force to undertake a study to determine whether Gemini or Dyna-Soar was the more feasible approach to a space-based weapon system. In the middle of March 1963, after receiving the study, Secretary McNamara "stated that the Air Force had been placing too much emphasis on controlled re-entry when it did not have any real objectives for orbital flight". This was seen as a reversal of the Secretary's earlier position on the Dyna-Soar program. Dyna-Soar was also an expensive program that would not launch a manned mission until the mid-1960s at the earliest. This high cost and questionable utility made it difficult for the U.S. Air Force to justify the program. Eventually, the X-20 Dyna-Soar program was canceled on December 10, 1963.
On the day that X-20 was canceled, the U.S. Air Force announced another program, the Manned Orbiting Laboratory, a spin-off of Gemini. This program was also eventually canceled. Another black program, ISINGLASS, which was to be air-launched from a B-52 bomber, was evaluated and some engine work done, but it too was eventually cancelled.
Legacy
Despite
cancellation of the X-20, the affiliated research on spaceplanes influenced the
much larger Space Shuttle. The final design also used delta wings for
controlled landings. The later, and much smaller Soviet BOR-4 was closer in
design philosophy to the Dyna-Soar, while NASA's Martin X-23 PRIME and Martin Marietta
X-24A/HL-10 research aircraft also explored aspects of sub-orbital and space
flight. The ESA proposed Hermes manned space craft took the design and expanded
its scale.
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