Atlas (missile)

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Atlas was a missile built by the Convair Division of General Dynamics. Originally designed as an ICBM in the late 1950s, Atlas was the foundation for a family of successful space launch vehicles now built by Lockheed Martin. The Atlas rocket family is today used as a launch platform for commercial and military satellites, and other space vehicles.

Contents 1 History 2 Design 3 Current Atlas Family 4 Service history 5 Specifications (Atlas ICBM) 6 References 7 External links 8 Related content

[edit] History

The Atlas, first tested in 1959, was the United States' first successful ICBM (Intercontinental Ballistic Missile). It was a "1.5 stage", liquid-fueled (LOX and RP-1) rocket, with three engines producing 1,590 kN of thrust.

Atlas, named for the Atlas of Greek mythology, got its start in 1946 with the award of an Army Air Forces research contract to Convair for the study of a 1,500 to 5,000 mi. (2,400 to 8,000 km) range nuclear armed missile. The Convair team was led by Karel Bossart. This was the MX-774 or Hiroc project. 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 1955, the CIA learned that the Soviet ICBM program was making progress so 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" 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 Atlas-F was known to be deployed in a 175 foot deep underground missile silo that were "hardened" against all but a direct nuclear hit. These silos were usually located together in groups of 12–15 silos throughout the midwest. The 551st Strategic Missile Squadron (551st SMS) located in Southeastern Nebraska is an example of this. From the mid-1960s, the Atlas (and its 'bigger brother', the Titan) were phased out in favor of the LGM-30 Minuteman, a solid-fuelled rocket which could be stored for long periods and launched, without fueling, at the turn of a key.

Though never used in combat, the Atlas was used as the expendable launch system with both the Agena and Centaur upper stages for the Mariner space probes used to study Mercury, Venus, and Mars (1962–1973); and to launch ten of the Mercury program missions (1962–1963). Atlas was suggested for use by the United States Air Force in what became known as Project Vanguard. This suggestion was ultimately turned down, however, as Atlas would not be operational in time and was seen by many as being too heavily connected to the military for use in the U.S.' IGY satellite attempt.

However, the Atlas saw the beginnings of its "workhorse" status during the Mercury-Atlas missions, which resulted in Lt. Col. John H. Glenn Jr. becoming the first American to orbit the earth on February 20, 1962 (Major Yuri A. Gagarin, a Soviet cosmonaut, was the first human in orbit on April 12, 1961.) Atlas was also used throughout the mid-1960s to launch the Agena Target Vehicles used during the Gemini program. Direct Atlas descendants have continued to be used as satellite launch vehicles into the 21st century. An Atlas rocket is shown exploding, in the 1983 documentary film Koyaanisqatsi, directed by Godfrey Reggio, in the penultimate shot.

[edit] Design

Atlas was unusual in its use of balloon tanks for fuel, made of very thin stainless steel with minimal or no rigid support structures. Pressure in the tanks provides the structural rigidity required for flight. An Atlas rocket will collapse under its own weight if not kept pressurized. The only other known use of balloon tanks at the time of writing is the Centaur high-energy upper stage, although some rockets (such as the Falcon series) use partially pressure-supported tanks. The rocket tank had two small side rockets called Vernier Rockets that helped to steer its trajectory.

Atlas also had a unique and somewhat odd staging system. Most rockets stage by dropping both engines and fuel tanks. However, when the Atlas missile was being developed, there were considerable doubts as to whether or not a rocket motor could be ignited in space. Therefore, the decision was made to ignite all three of the Atlas' engines at launch—later, two of the engines would be discarded, while the third continued to burn. Rockets using this technique are sometimes called stage-and-a-half boosters. This technique is made possible by the extremely light weight of the balloon tanks. The tanks make up such a small percentage of the total booster weight that the weight penalty of lifting them to orbit is less than the technical and weight penalty required to throw half of them away mid-flight. Depending on how you look at it, this makes Atlas a single-stage-to-orbit booster (though most call it a 1.5 stage to orbit).

[edit] Current Atlas Family

Main article: Atlas (rocket family)

• Atlas II
• Atlas III
• Atlas V
• GX

The Atlas II series had 63 successful flights with the last launched August 31, 2004, it is considered one of the most reliable launchers in the world.

The newest version of Atlas, the Atlas V, is an Atlas in name alone as it contains little Atlas technology. It no longer uses balloon tanks nor 1.5 staging, but incorporates a rigid framework for its first stage booster much like the Titan family of vehicles. The rigid fuselage is heavier, but easier to handle and transport, eliminating the need for constant internal pressure.

Ironically, given Atlas's origin as a military ICBM weapon against the Soviet Union/Russia, the Atlas III and Atlas V use Russian-designed/built Energomash RD-180 engines. These engines are now prepared for license production by Pratt and Whitney company in the US.

[edit] Service history

The Atlas missiles were assigned to the following Strategic Air Command units:

• 389th Strategic Missile Wing/706th Strategic Missile Wing/4320th Strategic Missile Wing - Francis E. Warren AFB, Wyoming
  • 549th Strategic Missile Squadron
  • 564th Strategic Missile Squadron
  • 565th Strategic Missile Squadron
  • 566th Strategic Missile Squadron

• 392d Strategic Missile Wing/704th Strategic Missile Wing - Vandenberg AFB, California
  • 576th Strategic Missile Squadron

• 92d Strategic Aerospace Wing - Fairchild AFB, Washington
  • 567th Strategic Missile Squadron

• 40th Strategic Aerospace Wing - Forbes AFB, Nebraska
  • 548th Strategic Missile Squadron

• 11th Strategic Aerospace Wing - Altus AFB, Oklahoma
  • 577th Strategic Missile Squadron

• 96th Strategic Aerospace Wing - Dyess AFB, Texas
  • 578th Strategic Missile Squadron

• 98th Strategic Aerospace Wing - Lincoln AFB, Nebraska
  • 515th Strategic Missile Squadron

• 380th Strategic Aerospace Wing - Plattsburgh AFB, New York
  • 556th Strategic Missile Squadron

• 310th Strategic Aerospace Wing - Schilling AFB, Kansas
  • 550th Strategic Missile Squadron

• 6th Strategic Aerospace Wing - Walker AFB, New Mexico

Fairchild AFB, Vandenberg AFB, , Walker AFB, Dyess AFB, Altus AFB, Forbes AFB, Schilling Air Force Base, Lincoln AFB, Offutt AFB and Plattsburgh AFB.

The number of Atlas intercontinental ballistic missiles in service, by year:

CGM-16D Atlas Intercontinental Ballistic Missiles assigned:

• 1959 - 6
• 1960 - 12
• 1961 - 32
• 1962 - 32
• 1963 - 28
• 1964 - 13

CGM-16E Atlas Intercontinental Ballistic Missiles assigned:

• 1961 - 32
• 1962 - 32
• 1963 - 33
• 1964 - 30

HGM-16F Atlas Intercontinental Ballistic Missiles assigned:

• 1961 - 1
• 1962 - 80
• 1963 - 79
• 1964 - 75

[edit] Specifications (Atlas ICBM)

• Length: 75 ft. 1 in. (22.9 m) with Mk 2 re-entry vehicle, 82 ft. 6 in. (25.2 m) with Mk 3
• Diameter: 10 ft. 0 in. (3.05 m)
• Launch weight: 255,000 lb. (116,000 kg) for Atlas D, 260,000 lb. (118,000 kg) for Atlas E and F
• Range: 10,360 miles (16,670 km) for Atlas D, 11,500 miles (18,500 km) for Atlas E and F
• Powerplant: 1 × Rocketdyne LR105 rocket engine with 57,000 lbf (254 kN) thrust, 2 × Rocketdyne LR89 rocket engines with 150,000 lbf (670 kN) thrust, 2 × Rocketdyne LR101 vernier rocket engines with 1,000 lbf (4.4 kN) of thrust
• Warhead: Mk 4 re-entry vehicle with W-38 warhead (4 MT yield) (Atlas F)
• CEP: 4,600 ft (1,400 m)

[edit] References

• Gunston, Bill (1979). Illustrated Encyclopedia of the World's Rockets & Missiles. London: Salamander Books. ISBN 0-517-26870-1

[edit] External links

• bio Karel J. Bossart
• Karel Jan Bossart, Ir.
• Atlas launch vehicle profile
• 1958 Video of "Atlas in Orbit" Newsreel
• Atlas D from Encyclopedia Astronautica
• Atlas ICBM History site
• Atlas ICBM Launch on 5/23/1960 Video
• Atlas ICBM Information/History

[edit] Related content

Comparable missiles

• SM-68 Titan I
• SM-68 Titan II

Designation sequence

• M- sequence: MGM-13 Mace - MIM-14 - RGM-15 - CGM-16/HGM-16 - PGM-17 - MGM-18 - PGM-19

B- sequence: SM-62 - XGAM-63 - SM-64 - SM-65 - B-66 - GAM-67 -	XB-68
	SM-68 I
	SM-68 II

Related lists

• List of military aircraft of the United States
• List of missiles

See also

• Strategic Air Command