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Atlas A



Atlas A Fact Sheet
Written and Edited by Cliff Lethbridge

Classification: Inter-Continental Ballistic Missile Prototype

Length: 75 feet, 10 inches

Diameter: 10 feet

Range: 600 miles


Originating as the X-11, Atlas A was the name given to the first series of Atlas missiles delivered to Cape Canaveral for flight testing.

Atlas A missiles were designed primarily to test the airframe and propulsion system, which could be accomplished in relatively short-range flights. For this reason, the Atlas A did not employ a sustainer engine.

Thus, it was the only "single stage" version of the Atlas. It was, however, an improved version of the X-11 as conceived. The X-11 was originally designed to fly with just one booster engine.

The Atlas A operated with two North American booster engines, each of which provided a thrust of 120,000 pounds at liftoff. It also employed two vernier engines, located on opposite sides of the missile above the booster engine fairing.

The vernier engines, a trademark of Atlas vehicles, were designed to control the roll of the missile and trim its final flight velocity.

The booster and vernier engines were all fed by liquid oxygen/RP-1 (kerosene) liquid propellant, and all engines were ignited at liftoff.

The missile carried a semi-inertial guidance system which was supported by radio commands from ground stations.

In general terms, the Atlas A made a pre-programmed turn to a ballistic trajectory at an altitude of about 20,000 feet. The two booster engines shut down about two and one-half minutes into the flight.

In a flight profile unique to the Atlas A, the two booster engines did not need to be jettisoned after shutdown, and remained attached to the missile's main body to water impact.

About ten seconds following booster engine shutdown, the two vernier engines shut down, and the nose cone separated. By this time, the nose cone had been guided to its proper flight path, and could reach its target without further guidance.

On June 11, 1957 an Atlas A had the distinction of becoming the first Atlas launched from Cape Canaveral. The missile strayed off course and was destroyed by the Range Safety Officer less than one minute into its flight. However, some test objectives regarding the missile's launch systems and airframe were met.

Although only three of the eight Atlas A missiles launched from Cape Canaveral completed their flights as planned, the "failures" were themselves instrumental in determining that the Atlas airframe was strong enough to survive violent twists, turns and loops in low-altitude "heavy air".

The A Series Tests also determined that the Atlas launch system and gimbaled engine flight control system worked effectively

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