SM-65 Atlas - History

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 time, 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 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 lb.

The first Atlas to be 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. Atlas D weighed 255,950 pounds (without payload) and had an empty weight of only 11,894 pounds. The other 95.35% was propellant. Dropping the 6720 lb booster engine and fairing reduced the dry weight to 5174 lb, 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 9000 miles or orbit payloads without an upper stage. The final variants of the Atlas ICBM were the E and F, introduced in 1960–1961. 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).

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 1,500 to 5,000 mi. (2,400 to 8,000 km) 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-resistant coating for the outer skin of the Atlas missile.