Atlas (SM-65)

First deployed in September 1959, the Atlas (SM-65), was the nation’s first operational intercontinental ballistic missile (ICBM). The missiles, however, saw only brief service and the last squadron was taken off operational alert in 1965. Despite its relatively short life span, Atlas served as the proving ground for many new missile technologies. Perhaps more importantly, its development spawned the organization, policies, and procedures that paved the way for all of the later ICBM programs.

 

Technical Specifications  

Length: 82.5 feet
Diameter: 10 feet
Weight: 267,136 pounds (fueled) 18,104 pounds (empty)
Fuel: Rocket grade RP-1 (Kerosene)
Oxidizer: Liquid oxygen
Range: Between 6,400 and 9,000 miles
Propulsion: The Atlas propulsion system included three types of engines: two large booster engines, a sustainer engine, and two small vernier engines.
Primary booster: Atlas A, B, and C: two MA-i engines generating a combined 357,400 pounds of thrust.
Atlas D, two MA-2 engines generating 368,000 pounds of thrust. Atlas E and F, two MA-3 engines generating 389,000 pounds of thrust.
Sustainer: A single engine generating 57,000 pounds of thrust
Vernier: Two engines each generating 2,000 pounds of thrust
Guidance: Atlas A, B, C, and D models: Radio-inertial Atlas E and F models: All-inertial

Contractors  

Airframe: Convair (later a division of General Dynamics Corp.), San Diego, California
Propulsion: Rocketdyne Division, North American Aviation, Canoga Park, California
Guidance: Radio-inertial (Atlas A, B, C, and D models): The radar was built by General Electric in Syracuse, New York, and the computer by Burroughs in Paoli, Pennsylvania
All-inertial (Atlas E and F models): American Bosch Arma, Garden City, New York
Reentry Vehicles: Mark 2 and 3: General Electric Corporation, Philadelphia, Pennsylvania Mark 4: AVCO, Wilmington, Massachusetts

Technical Notes

The Air Force built six variations of the Atlas missile. The Atlas A, B, and C models were used exclusively for flight testing. The later Atlas D (PGM-16D/CGM-16D), the Atlas E (CGM-16E), and Atlas F (HGM-16F) models all saw service in the field.

The Atlas incorporated two novel features. The first was its “stage-and-a-half’ propulsion system consisting of two large booster engines flanking a smaller sustainer engine. Unlike the later ICBMs in which the first, second, and third stages fired in sequence, all of the Atlas engines were ignited at liftoff.

Another interesting feature was the pressurized integral fuel tanks. The Convair designers adopted this technique to save weight. The huge tanks, which constituted 80 percent of the missile’s mass, were built from thin sheets of stainless steel, ranging between 0.1 and 0.4 inches thick. When empty, the tanks were filled with nitrogen gas at 5 psi to maintain a positive internal pressure.

System Operation

During the launch sequence, the two boosters and the sustainer engine were ignited on the ground and the two small vernier engines mounted above the sustainer came to life 2.5 seconds after lift-off. After leaving the launch pad, the missile accelerated rapidly, gradually nosing over in a gentle arc toward the target. Once in flight, the booster engines burned for 140 seconds. After receiving a staging signal from the ground station, the booster engines and turbo-pumps were jettisoned into space. The sustainer engine continued to burn for another 130 seconds, and then it too fell silent. Final course and velocity corrections were made by the vernier engines. At the apogee of its elliptical flight path the missile reached an altitude of 763 miles and a speed of approximately 16,000 miles per hour. Elapsed time for a flight of 6,788 miles: 43 minutes.

During powered flight, the Atlas A, B, C, and D models were guided by a General Electric/Burroughs radio-inertial guidance system that received course corrections from

ground-based computers. The Atlas E and F models used the American Bosch Arma all-inertial guidance system. The all-inertial system was capable of detecting deviations from the preprogrammed flight path and formulating midcourse corrections independently.

Developmental History

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. Convair’s initial ICBM design was based on the proven V-2 airframe, but incorporated three major modifications: pressurized, integral fuel tanks to reduce weight; gimbaled engines to improve directional stability; and a separable warhead to simplify reentry.

In June 1947, further budget reductions led the AAF to cancel the remainder of the MX-774 program. Since Convair’s work was well under way, the Air Force (it became a separate service in September 1947) allowed 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 Convair’s innovations. The results, however, were not enough to dissuade the Air Force from canceling the project, and without a government sponsor, the future of the ICBM appeared dim. At the last moment Convair decided to support the program itself, and over the next 2 years invested $3 million in it.

The Air Force renewed its support for the ICBM program in January 1951, an action prompted by the enthusiastic endorsement of the Rand Corporation and a substantial increase in research and development (R&D) funding brought on by the Korean War. The Air Force designated the new effort the MX-1593 project and directed Convair to evaluate air-breathing and ballistic missiles capable of carrying an 8,000-pound warhead 5,750 miles and striking within a circular error probable (CEP) of 1,500 feet. (A measurement of accuracy, the CEP is the radius of a circle within which half of the ordnance targeted for the center of the circle can be expected to land.)

Convair completed the missile study in July 1951, and once again the airframe manufacturer reaffirmed its support for ICBM. The design it submitted for the ICBM, which it now called Atlas, called for a mammoth weapon 160 feet tall, 12 feet in diameter, and powered by 5 or 7 large engines.

In September 1951 the Air Research and Development Command (ARDC) urged that Headquarters, USAF (often referred to as the Air Staff) immediately begin full-scale development of the ICBM. ARDC estimated that with the “proper application of funds and priorities” Atlas could be operational by 1960. The Air Staff demurred. It did not share ARDC’s enthusiasm; instead it advocated a more cautious approach. It wanted to develop the major subsystems such as the engines, fuselage, guidance system, and reentry vehicle first, and then build the test vehicle.

New technology soon changed the nature of the debate. In 1952 ARDC learned that forthcoming improvements in nuclear weaponry would soon reduce the weight of the missile’s warhead from 7,000 to 3,000 pounds without reducing the yield. At the same time the United States was also making major strides in developing powerful new rocket engines and precision guidance systems.

In the fall of 1952 those new technologies, coupled with the Army and Navy’s attempts to wrest control of the ICBM program away from the Air Force, forced the Air Staff to act. At its request ARDC formulated a list of military characteristics for a “Strategic Ballistic Rocket System” capable of carrying a 3,000-pound atomic warhead 6,325 miles to within 1,500 feet of its target. ARDC estimated that if Atlas was accorded a 1-A development priority it would be operational by 1962.

The Air Staff refused to accord the missile program with the priority ARDC sought, and as a compromise, in February 1953 ARDC proposed a three-tier test plan using test vehicles powered by one, three, and five engines with the last missile serving as an operational prototype. ARDC estimated that the revised R&D program would take approximately 10 years and cost $378 million.

The Air Staff approved the revised plan in October and issued ARDC a development directive to begin work. The directive, however, 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 Staff’s insistence the Atlas program would have continued down its slow and conservative path had it not been for the February 1954 Teapot Committee report. Chaired by the renowned mathematician John von Neumann, the committee recommended a “radical reorganization” of the entire Atlas program. The committee estimated that if the government followed all of its recommendations, Atlas could be operational in 6 to 8 years.

The Air Force accepted the Teapot Committee recommendations, and 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 place 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.

Basing Strategy

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.

Site Configuration

The Air Force deployed Atlas models D, E, and F; each was based in a different launch configuration.

As an emergency measure, in September 1959 the Air Force deployed three Atlas Ds

on open launch pads at Vandenberg AFB. Completely exposed to the elements, the three missiles were serviced by a gantry crane. One missile was on operational alert at all times.

The first full Atlas D squadrons became operational in 1960. In these so-called “soft” sites, which could only withstand overpressures of 5 pounds per square inch (psi), the missiles were stored horizontally within a 103- by 133-foot launch and service building built of reinforced concrete. The missile bay had a retractable roof. To launch the missile, the roof was pulled back, the missile raised to the vertical position, fueled, and fired.

An individual Atlas D launch site consisted of a launch and service building, a launch operations building, guidance operations building, generating plant, and communications facilities. The launch operations buildings were two-story structures built of reinforced concrete measuring 73 by 78 feet with earth mounded up to the roof lines. Constructed much like blockhouses at missile test ranges, these buildings housed the launch operations crew and were equipped with entrance tunnels, blastproof doors, and escape tunnels. The guidance operations buildings, which sent course corrections to the missile in flight, were one-story structures, 75 by 212 feet, with a full basement. The basement walls were reinforced concrete and the remaining walls were of concrete block. The power plant was a 63- by 65-foot single-story, concrete block building. It housed three large diesel generators and the pumps for the water system.

At the first Atlas D squadron at F.E. Warren AFB, six launchers were grouped together, controlled by two launch operations buildings, and clustered around a central guidance control facility. This was called the 3 x 2 configuration: two launch complexes of three missiles each constituted a squadron. At the two later Atlas D sites, a second at F.E. Warren AFB, and at Offutt AFB, Nebraska, the missiles were based in a 3 x 3 configuration: three launchers and one combined guidance control/launch facility constituted a launch complex, and three complexes comprised a squadron. At these later sites the combined guidance and control facility measured 107 by 121 feet with a partial basement. To reduce the risk that one powerful nuclear warhead could destroy multiple launch sites, the launch complexes were spread 20 to 30 miles apart.

The major enhancement in the Atlas E was the new all-inertial system that obviated the need for ground control facilities. Since the missiles were no longer tied to a central

guidance control facility, the launchers could be dispersed more widely. Thus, the three Atlas F squadrons located at Fairchild AFB, Washington; Forbes AEB, Kansas; and F.E. Warren AFB, Wyoming; were based in a 1 x 9 configuration: nine independent launch sites comprised a missile squadron.

The Atlas Es were based in “semi-hard” or “coffin” facilities that protected the missile against overpressures up to 25 psi. In this arrangement the missile, its support facilities, and the launch operations building were housed in reinforced concrete structures that were buried underground; only the roofs protruded above ground level. The missile launch and service building was a 105- by 100-foot structure with a central bay in which the missile was stored horizontally. To launch a missile, the heavy roof was retracted, the missile raised to the vertical launch position, fueled, and then fired. The 54- by 90-foot launch operations building was 150 feet from the missile launch facility; the two were connected by an underground passageway. The launch operations building contained the launch control facilities, crew’s living quarters, and power plant. The Atlas E launch sites were spaced approximately 20 miles apart.

The Atlas F, the most advanced of the Atlas series, were designed to be stored vertically in “hard” or “silo” sites. With the exception of a pair of massive 45-ton doors, the silos, 174 feet deep by 52 feet in diameter, were completely underground. The walls of the silo were built of heavily reinforced concrete. Within the silo the missile and its support system were supported by a steel framework called the crib, which hung from the walls of the silo on four sets of huge springs.

Adjacent to the silo, and also buried underground, was the launch control center. Built of heavily reinforced concrete, it was 27 feet high, 40 feet in diameter, and contained the launch control equipment plus living arrangements for the crew. The control center was connected to the silo by a cylindrical tunnel 50 feet long and 8 feet in diameter. The tunnel provided access to the silo and served as a conduit for the launch control cabling.

In the firing sequence the missile was fueled, lifted by an elevator to the mouth of the silo, and then fired. Although the silo sites were by far the most difficult and costly sites to build, they offered protection from overpressures of up to 100 psi.

The Air Force deployed six squadrons of Atlas Fs, one each at Schilling AFB, Kansas; Lincoln AFB, Nebraska; Altus AFB, Oklahoma; Dyess AFB, Texas; Walker AFB, New Mexico; and Plattsburg AFB, New York (the only ICBMs ever based east of the Mississippi). Each squadron included 12 launch sites. Distances between the sites ranged from 20 to 30 miles.

References

Information for the Atlas technical specifications came from two reports by the Convair Division of General Dynamics: “Atlas Intercontinental Ballistic Missile,” 1960, file K208-20A, Air Force Historical Research Agency, Maxwell AFB, Montgomery, AL (hereafter AFHRA) and “Standard Missile Characteristics, HGM-16F,” March 1964, file OA-40105501, folder F ICBM, National Air and Space Museum Archives, Washington, DC, (hereafter NASM). Another very valuable source is the comprehensive “SM-65E Missile Weapon System General Manual,” T.O. 21-SM65E-lY, dated September 1960, in folder Ci/Atlas/ops at the Research Center, USAF Museum, Wright-Patterson AFB, Dayton, OH (hereafter the Research Center). Other helpful material came from: The Chronology of the Ballistic Missile Organization:

1945—1990 (Norton, CA: Ballistic Missile Organization History Office, 1993); lain Pike, “Atlas: Pioneer ICBM and Space-Age Workhorse,” Flight International 81 (January 1962), pp. 89—96; and Jane’s All the World’s Aircraft 1962 —1963 (London, Jane’s Publishing, 1963).

Information for the development history came from several sources. A useful summary is Jacob Neufeld, The Development of Ballistic Missiles in the United States Air Force 1945—1960 (Washington, DC: Bolling AFB, 1989). For a detailed look at the bureaucratic and technological factors that shaped the debate over Atlas, see Edmund Beard, Developing the ICBM: A Study in Bureaucratic Politics, Institute of War and Peace Study Series (New York: Columbia University Press, 1976).

A very useful summary of Atlas deployment is Henry Narducci, From Snark to Peaceheeper: A Pictorial History of Strategic Air Command Missiles (Offutt, AFB, NE:

Office of the Historian, HQ, Strategic Air Command, 1990). The size of the Atlas force, and the basing strategy that guided the placement of the launch sites are discussed in the correspondence of Brig. Gen. Charles M. McCorkle, the Assistant Chief of Staff for Guided Missiles, in the records of the Air Force Chief of Staff for Guided Missiles (hereafter AFCGM records) Federal Records Center, Suitland, MD (hereafter FRC Suitland) RG 341, box 2, folder “AFCGM Correspondence—1957” and box 3, “AFCGM Correspondence—1958.” For an excellent summary of ICBM basing strategy see the memo from General Curtis LeMay, Vice Chief of Staff, to Secretary of the Air Force, subj: ICBM Siting, 6 June 1958, AFCGM records, FRC Suitland, RG 341, box 3, folder “AFCGM Correspondence—1958.”

For a comparison of the different launch site configurations, see Convair’s “Base Activation,” n.d., in folder C1-0 at the Research Center. An exhaustively well documented survey of the Atlas F silos is General Dynamics Astronautics, “Integrating Contractor’s Base Activation Project Manual, Series F Silo Bases,” Report No. 600-200, n.d., in folder C1-0 at the Research Center.

For a summary of ICBM site construction, see T.J. Hayes, “ICBM Site Construction,” The Military Engineer (November—December 1966): pp. 399—403. For detailed information on the construction and location of the Atlas launch sites, see the Corps of Engineers Ballistic Missile Construction Office (CEBMCO) site construction histories in the Research Collection, Office of History, Headquarters, U.S. Army Corps of Engineers, Alexandria, VA. Another valuable source is the pending “Historic American Engineering Record of the Atlas F Missile Site S-8,” prepared by the Tn-Services Cultural Resources Research Center of the U.S. Army Construction Engineering Research Laboratories, Champaign, IL, for the Fort Worth District, Corps of Engineers.

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