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The Lockheed A-12 was a reconnaissance aircraft built for the Central Intelligence Agency (CIA) by Lockheed's Skunk Works, based on the designs of Clarence "Kelly" Johnson. The aircraft was designated A-12, the 12th in a series of internal design efforts with the A referring to "Archangel", the internal code name of the aircraft. It competed in the CIA's ''Oxcart'' program against the Convair Kingfish proposal in 1959, and won for a variety of reasons. The A-12's specifications were slightly better than those of the Kingfish, and its projected cost was significantly less. Convair's design had a smaller radar cross-section, however, and CIA's representatives initially favored it for that reason. The companies' respective track records proved decisive. Convair's work on the B-58 had been plagued with delays and cost overruns, whereas Lockheed had produced the U-2 on time and under budget. In addition, it had experience running a “black” project. The A-12 was produced from 1962 to 1964, and was in operation from 1963 until 1968. It was the precursor to the twin-seat U.S. Air Force YF-12 prototype interceptor, M-21 drone launcher, and the famous SR-71 Blackbird, a slightly longer variation able to carry a heavier fuel and camera load. The A-12's final mission was flown in May 1968, and the program and aircraft retired in June of that year. The program was officially revealed in the mid-1990s.〔Mclninch 1996, title page.〕 Over the life of the ''Oxcart'' project, the participating US government departments and officials associated the project name "Oxcart" specifically with the A-12. An Agency officer later wrote, "OXCART was selected from a random list of codenames to designate this R&D and all later work on the A-12. The aircraft itself came to be called that as well." The crews named the A-12 the ''Cygnus'' which was suggested by the pilot Jack Weeks to follow the Lockheed practice of naming aircraft after celestial bodies.〔Crickmore 2000, p. 16〕 ==Design and development== With the failure of the CIA's Project Rainbow to reduce the radar cross-section (RCS) of the U-2, preliminary work began inside Lockheed in late 1957 to develop a follow-on aircraft to overfly the Soviet Union. Under Project Gusto the designs were nicknamed "Archangel", after the U-2 program, which had been known as "Angel". As the aircraft designs evolved and configuration changes occurred, the internal Lockheed designation changed from Archangel-1 to Archangel-2, and so on. These names for the evolving designs soon simply became known as "A-1", "A-2", etc.〔("The U-2's Intended Successor: Project Oxcart 1956–1968". ) ''Central Intelligence Agency'', approved for release by the CIA in October 1994. Retrieved: 26 January 2007.〕 The CIA program to develop the follow-on aircraft to the U-2 was code-named ''Oxcart''. These designs had reached the A-11 stage when the program was reviewed. The A-11 was competing against a Convair proposal called Kingfish, of roughly similar performance. However, the Kingfish included a number of features that greatly reduced its radar cross-section, which was seen as favorable to the board. Lockheed responded with a simple update of the A-11, adding twin canted fins instead of a single right-angle one, and adding a number of areas of non-metallic materials. This became the A-12 design. On 26 January 1960, the CIA ordered 12 A-12 aircraft.〔Robarge 2008, p. 6.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lockheed A-12」の詳細全文を読む スポンサード リンク
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