Atlas Missile System Development
The Atlas traces its lineage to 1945 when the Army Air Forces (AAF) first expressed interest in developing a "strategic" missile with a range of 5,750 miles. The Consolidated Vultee Aircraft Corporation, commonly referred to as Convair, submitted a proposal to study the matter and in April 1946 the AAF awarded it the MX-774 project to evaluate long-range air-breathing and ballistic missiles.
Within a year budget cutbacks forced the AAF to cancel the air-breathing portion of the study, freeing Convair to concentrate on the ballistic missile. Convairllowed the company to use its remaining funding to build three small missiles to test the feasibility of the swiveling motors, guidance system, and the separable warhead. The tests, conducted in late 1948 and early 1949 at the White Sands Proving Grounds in New Mexico, were encouraging. The missiles, called the Hiroc (for high altitude rocket) or RTV-A-2s, confirmed the practicality of Convairprovements in nuclear weaponry would soon reduce the weight of the missile, lacked the vigor that ARDC sought. It estimated that the R&D phase would not be completed until sometime after 1964 and also assigned Atlas a 1-B development priority.
ARDC designated the Atlas program Weapon System (WS)-107A. Although scaled down from earlier designs, the missile remained an ambitious undertaking. It was 110 feet high, 12 feet in diameter, and when fully loaded, weighed 440,000 pounds. Propulsion was to come from five engines: four first-stage engines clustered around a single sustainer engine.
At the Air nd on May 14, 1954, it accelerated the Atlas program to the "maximum extent that technology would permit." It accorded Atlas a 1-A top priority status, and of equal importance, directed that it be given priority over all other Air Force programs.
During the spring and fall of 1954 the Air Force and the two most important contractors, Ramo-Wooldridge Corporation (systems engineering and technical direction) and Convair (structures and assembly), worked feverishly to revise the Atlas design based on a 1,500-pound, 1-megaton warhead. The thorough redesign cut the size of the missile almost in half: the weight decreased from 440,000 to 240,000 pounds and the number of engines was reduced from five to three.
Flight testing for the Atlas A began in June 1957. The initial test vehicle, the Atlas A, contained only the two booster engines and a dummy nosecone. Six of eight test flights blew up on the launch pad or were destroyed shortly after takeoff. Two missiles had successful flights of 600 miles.
The Atlas B series was a more sophisticated missile complete with a sustainer engine and separable nosecone. In July 1958 the first one exploded soon after launching, but the following November an Atlas B roared 6,000 miles down range.
The Atlas C was a semi-operational version that contained several advanced features. It was first launched successfully in December 1958.
The Atlas D was equipped with radio-inertial guidance. First tested in April 1959, three Atlas Ds were placed on operational alert at Vandenberg AFB in late 1959.
The Atlas E was the first to use an all-inertial guidance system and the improved MA-3 propulsion system. Its first successful test flight was in February 1961.
The Atlas F had an improved fuel loading system that allowed the missile to be fueled and fired more quickly. It was also designed to be stored vertically in hardened silos. The first successful Atlas F flight was in July 1961.
The hallmark of the Atlas deployment schedule was urgency; escalating tensions with the Soviet Union sent the Air Force scrambling to deploy the missiles as rapidly as possible. Initially the Air Force planned to deploy 4 squadrons of 10 missiles each, but in December 1957 the Department of Defense expanded the missile force to 9 and later 13 squadrons. Originally the location of the launch sites was determined exclusively by the missile's range; they had to be within 5,000 miles of their targets in the Soviet Union. Later, other factors that influenced the placement of the sites was that they be inland, out of range of Soviet submarine-launched intermediate range missiles; close to support facilities; and as a cost cutting measure, be built on government property whenever possible. Read more about the deployment here.