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: ''Main article: Atlas (rocket family)'' }} The SM-65 Atlas was the first intercontinental ballistic missile (ICBM) developed and deployed by the United States. It was built for the U.S. Air Force by Convair Division of General Dynamics at the Kearny Mesa assembly plant north of San Diego, California. Atlas became operational as an ICBM in October 1959 and was used as a first stage for satellite launch vehicles for half a century. The Atlas missile's warhead was over 100 times more powerful than the bomb dropped over Nagasaki in 1945. An initial development contract was given to Consolidated Vultee Aircraft (Convair) on 16 January 1951 for what was then called MX-1593, but at a relatively low priority. The 1953 testing of the first dry fuel H-bomb in the Soviet Union led to the project being dramatically accelerated. The initial design completed by Convair in 1953 was larger than the missile that eventually entered service. Estimated warhead weight was lowered from to based on highly favorable U.S. nuclear warhead tests in early 1954, and on 14 May 1954 the Atlas program was formally given the highest national priority. A major development and test contract was awarded to Convair on 14 January 1955 for a diameter missile to weigh about .〔Dennis R. Jenkins, "Stage-and-a-Half, The Atlas Launch Vehicle", ''To Reach the High Frontier'' (University Press of Kentucky, 2002) pp. 74-85〕 Atlas development was tightly controlled by the Air Force's Western Development Division, WDD, later part of the Air Force Ballistic Missile Division. Contracts for warhead, guidance and propulsion were handled separately by WDD. The first successful flight of a highly instrumented Atlas missile to full range occurred 28 November 1958. Atlas ICBMs were deployed operationally from 31 October 1959 to 12 April 1965.〔Mike Gruntman, ''Blazing the Trail'', pp. 221-245, AIAA, Reston Virginia, 2004〕 On 18 December 1958, the launch of Atlas 10B sent the missile into orbit around the Earth (without use of an upper stage) carrying the "SCORE" (Signal Communications by Orbiting Relay Equipment) communications payload. Atlas 10B/SCORE, at was the heaviest man-made object then in orbit, the first voice relay satellite, and the first man-made object in space easily visible to the naked eye due to the large, mirror-polished stainless steel tank. This was the first flight in what would be a long career for the Atlas as a satellite launcher. Many retired Atlas ICBMs would be used as launch vehicles, most with an added spin-stabilized solid rocket motor upper stage for polar orbit military payloads. Even before its military use ended in 1965, Atlas had placed four Project Mercury astronauts in orbit and was becoming the foundation for a family of successful space launch vehicles, most notably Atlas Agena and Atlas Centaur. Mergers led to the acquisition of the Atlas Centaur line by Lockheed Martin, which later became part of United Launch Alliance. Today Lockheed Martin and ULA support a new Atlas rocket family based on the larger "Atlas V" which still uses the unique and highly efficient Centaur upper stage. Atlas V stage one is powered by a Russian RD-180 oxygen/kerosene engine and uses conventional aluminum isogrid tanks, rather than the thin-wall, pressure-stabilized stainless steel tanks of the original Convair Atlas. Payload weights have increased along with launch vehicle weights over the years, so the current Atlas V family serves many of the same types of commercial, DoD, and planetary missions as earlier Atlas Centaurs. ==History== Shortly before his death, John von Neumann headed the top secret von Neumann ICBM committee. Its purpose was to decide on the feasibility of building an ICBM large enough to carry a thermonuclear weapon. Von Neumann had long argued that while the technical obstacles were indeed formidable, they could be overcome in time. Events were proving him right. The weapons had become smaller, and diode-transistor logic enabled the construction of compact guidance computers. (Atlas A, B, C, and D had no onboard computers, but Atlas E (1960) and F (1961) did.) The committee approved a "radical reorganization" and speeding up of the Atlas program. Atlas was informally classified as a "stage-and-a-half" rocket; both engines were started at launch, and there was only a single set of propellant tanks. One engine was jettisoned about 135 seconds into the flight. (A "stage" of a liquid propellant rocket is normally thought of as tanks ''and'' engine(s) together. The jettisoned engine, therefore, constitutes a "half stage".) The booster engine consisted of two large thrust chambers fed by a single common set of turbopumps. The sustainer engine consisted of a single large thrust chamber and two small verniers, once again fed by a single common set of turbopumps. The verniers provided roll control and final velocity trim. The total sea level thrust of all five thrust chambers was 360,000 lb''f'' (1,600 kN) for Atlas D. Later model Atlas E and F variants were built with two separate booster engines, each with a single large thrust chamber and its own independent set of turbopumps. Total sea level thrust for these three-engine Atlas Es and Fs was 389,000 lbf (1,730 kN). The first Atlas flown was the Atlas A in 1957–1958. It was a test model designed to verify the structure and propulsion system, and had no sustainer engine or separable stages. This was followed by the Atlas B and C in 1958–1959. The B had full engines and booster engine staging capability. An Atlas B was used to orbit the SCORE satellite in December 1958, which was the Atlas' first space launch. The C was a slightly more developed model using even thinner skin in the propellant tanks. Finally, the Atlas D, the first operational model and the basis for all Atlas space launchers, debuted in 1959.〔Andreas Parsch, "Atlas D, Historical Essay", Encyclopedia Astronautica, 2003〕 Atlas D weighed (without payload) and had an empty weight of only , the other 95.35% was propellant. Dropping the booster engine and fairing reduced the dry weight to , a mere 2.02% of the initial gross weight of the vehicle (still excluding payload). This very low dry weight allowed Atlas D to send its thermonuclear warhead to ranges as great as or orbit payloads without an upper stage.〔M. D. Black, ''The Evolution of ROCKET TECHNOLOGY'', p. 54, Native Planter, SLC, 2012, payloadz.com under ''ebook/History''〕 The final variants of the Atlas ICBM were the E and F, introduced in 1960–61. E and F had fully self-contained inertial navigation systems (INS) and were identical to each other except for interfaces associated with their different basing modes (underground silo for F). The Atlas's complicated, unconventional design proved difficult to debug compared with rocket families such as Thor and Titan which used conventional aircraft-style structures and two stage setups and there were dozens of failed launches during the early years. After watching an Atlas ICBM explode shortly after launch, Mercury astronaut Gus Grissom remarked "Are we really going to get on top of one of those things?" The numerous failures led to Atlas being dubbed an "Inter County Ballistic Missile" by missile technicians, but by 1965 most of the problems had been worked out and it was a reliable launch vehicle. By 1965, with the second-generation Titan II having reached operational status, the Atlas was obsolete as a missile system, and was gradually phased out in the mid-1960s. Many of the retired Atlas D, E and F missiles were used for space launches into the 1990s. Atlas, named for the Atlas of Greek mythology and the contractor's parent Atlas Corporation, got its start in 1946 with the award of an Army Air Forces research contract to Consolidated Vultee Aircraft (later Convair) for the study of a range missile that might, at some future date carry a nuclear armed warhead. At the time (the late 1940s), no missile conceived could carry even the smallest nuclear warheads then thought possible. The smallest atomic warheads were all larger than the maximum theoretical payloads of the planned long range missiles. The Convair team was led by Karel Bossart. This was the MX-774 or Hiroc project. It was for this reason that the contract was canceled in 1947 but the Army Air Forces allowed Convair to launch the three almost-completed research vehicles using the remaining contract funds. The three flights were only partially successful. However they did show that balloon tanks, and gimbaled rocket engines were valid concepts. In the mid-1950s after practical thermonuclear weapons had been demonstrated and an independent design breakthrough drastically reduced the weight of such weapons, along with the CIA learning that the Soviet ICBM program was making progress, Atlas became a crash program of the highest national importance. The missile was originally given the military designation XB-65, thus making it a bomber; from 1955 it was redesignated SM-65 ("Strategic Missile 65") and, from 1962, it became CGM-16. This letter "C" stood for "coffin" or "Container", the rocket being stored in a semi-hardened container; it was prepared for launch by being raised and fueled in the open. The Atlas-F (HGM-16) was stored vertically underground, but launched after being lifted to the surface. The penetrating lubricant WD-40 found its first use as a corrosion-inhibiting coating for the outer skin of the Atlas missile.〔(【引用サイトリンク】 publisher = WD-40 )〕 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「SM-65 Atlas」の詳細全文を読む スポンサード リンク
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