SM-65 Atlas
The SM-65 Atlas was a missile designed by the Air Force Ballistic Missile Division and 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 United Launch Alliance. The Atlas rocket family is today used as a launch platform for commercial and military satellites, and other space vehicles.
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History
The Atlas, first flown in 1957, was the United States' first successful ICBM (Intercontinental Ballistic Missile). It was a "1.5 stage", liquid-fueled (LOX and RP-1) rocket, with two gimbaled 1,200 hp vernier guidance motors[1] and three engines producing 1,590 kN of thrust.
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 a full three engines and staging capability, as well as a true guidance system. 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. Finally, the Atlas D, the first operational model and the basis for all Atlas space launchers, debuted in 1959. The final variants of the Atlas ICBM were the E and F, introduced in 1960-1961.
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 late 1960s. Many of the retired Atlas E and F missiles were used for space launches into the '90s.
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 early 1950s after the thermonuclear weapon had been demonstrated and, because of an independent design breakthrough which 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 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.
Operational Atlas D were first deployed in "soft" sites featuring a "hardened" Launch Control Center and three soft launch pads. The guidance stations and antennas were also soft. Later Atlas D bases were in semi-hard coffin sites where the missile was stored in a concrete structure horizontally and erected before fueling and launch. The Atlas E missiles were deployed in buried semi-hardened coffins which functioned in the same fashion but each missile had its own LCC, allowing salvo launches. The Atlas F were deployed in 175-foot (53 m) deep underground missile silos that were hardened against all but a direct nuclear hit. Each silo had its own LCC. An Atlas F site could take an overpressure of 100 pounds per square inch (690 kPa) and lateral ground movement of one foot (30 cm). These silos were usually located together in groups of 12 silos throughout the Midwest.
The only exception to this deployment strategy was the Atlas squadron that was deployed around Plattsburgh AFB in upstate New York near the Canadian border. This location placed these Atlas missiles within striking range of soft targets located in the southern part of the Russian Federation and the Ukraine, of the then Union of Soviet Socialist Republics (USSR). This was the first and thus far the only instance where land-based ICBMs, loaded with live nuclear payloads, were deployed east of the Mississippi River.
The 551st Strategic Missile Squadron (551st SMS) located in Southeastern Nebraska is an example of the underground silo. From the mid-1960s, the Atlas were phased out in favor of the LGM-30 Minuteman and the LGM-25C Titan II. The newer weapons had storable fuel (solid for the Minuteman and liquid hypergolic propellant for the Titan II) so they could be launched immediately upon notification of a pending attack. The Atlas's requirement of a lengthy pre-launch fueling process with cryogenic fuel rendered it obsolete due to the sub 30 minute flight times of ICBMs and SLBMs. The Atlas would be destroyed before launch, making it useless as a deterrent.
The warhead of the Atlas D was originally the G.E. Mk 2 "heat sink" re-entry vehicle with a W-38 bomb. The Atlas E and F had an AVCO Mk 4 re-entry vehicle containing a W-38 thermonuclear bomb with a yield of 3.75 megatons which was fuzed for either air burst or contact burst. The Mk 4 RV also deployed penetration aids in the form of mylar balloons which replicated the radar signature of the Mk 4 RV.
Though never used for its original purpose as a weapon, 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.'s International Geophysical Year 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 art film Koyaanisqatsi, directed by Godfrey Reggio, in the penultimate shot. The vehicle shown in the movie was the first launch attempt of an Atlas-Centaur in May 1962.
Design
The Atlas A-D used radio guidance: the missile sent information from its inertial system to a ground station by radio, and received course correction information in return. The Atlas E and F had completely autonomous inertial guidance systems.
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 would collapse under its own weight if not kept pressurized, and had to have 5 psi nitrogen in the tank even when not fuelled[2]. 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 had two small rocket motors on the sides of the tank called vernier rockets. These provided fine adjustment of velocity and steering after the sustainer engine shut down.
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).
Sergey Korolyov made a similar choice for the same reason in the design of the R-7, the first Soviet ICBM and the launcher of Sputnik and Vostok. The R-7 had a central sustainer section, with four boosters attached to its sides. All engines were started before launch, eliminating the then unexplored task of igniting a large liquid fuel engine at high altitudes. Like the Atlas, the R-7 used cryogenic oxidizer and could not be kept in the state of flight readiness indefinitely. Unlike the Atlas, the R-7 had large side boosters, which required use of an expensive launch pad and prevented from launching the rocket from a silo.
Current Atlas family
- Atlas II
- Atlas III
- Atlas V
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 NPO Energomash RD-180 engines. These engines are now prepared for license production by Pratt and Whitney company in the US.
Operational units
Strategic Air Command deployed Atlas models D, E, and F
As an emergency measure, in September 1959 the Air Force deployed three SM-65D Atlas missiles on open launch pads at Vandenberg AFB, California, under the operational control of the 576th Strategic Missile Squadron, 704th Strategic Missile Wing. Completely exposed to the elements, the three missiles were serviced by a gantry crane. One missile was on operational alert at all times. They remained on alert until 1 May 1954
Operational SM-65D Atlas missiles were deployed to the following units:
- 389th Strategic Missile Wing
- Francis E. Warren AFB, Wyoming (2 September 1960-1 Jul 1964)
- 564th Strategic Missile Squadron (6 missiles)
- 565th Strategic Missile Squadron (9 missiles)
- 385th Bombardment (later Strategic Aerospace) Wing
- Offut AFB, Nebraska (30 March 1961-1 Oct 1964)
- 549th Strategic Missile Squadron (9 missiles)
Operational SM-65E Atlas missiles were deployed to the following units:
- 92nd Bombardment (later Strategic Aerospace) Wing
- Fairchild Air Force Base, Washington (28 September 1961-17 February 1965)
- 567th Strategic Missile Squadron, (9 missiles)
- 40th Strategic Aerospace Wing
- Forbes AFB, Kansas (10 October 1961-4 January 1965)
- 548th Strategic Missile Squadron, (9 missiles)
- 389th Strategic Missile Wing
- Francis E. Warren AFB, Wyoming (20 November 1961-4 January 1965)
- 566th Strategic Missile Squadron (9 missiles)
Operational SM-65F Atlas missiles were deployed to the following units:
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See squadron articles for further information about the dispersed Atlas missile launch sites
Service history
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
Survivors
- HGM-16F Atlas is on display at the National Museum of the United States Air Force in Dayton, Ohio. For years the missile was displayed outside the Museum. In 1998 it was removed from display. It was restored by the Museum's restoration staff and returned to display in the Museum's new Missile Silo Gallery in 2007. The white nose cone atop the Museum's Atlas is an AVCO IV re-entry vehicle built to contain a nuclear warhead. This nose cone actually stood alert in defense of the United States, as it was initially installed on an Atlas on 2 October 1962 at a launch site near Denton Valley, Texas.
- Atlas 5A (56-6742) is on display on the lawn in front of the Canada Science and Technology Museum in Ottawa, Canada.
- Atlas 2E is on display in front of the San Diego Aerospace Museum at Gillespie Field, El Cajon, California.
- Atlas 2D mounted with a Mercury Capsule is on display in the Missile Garden at Kennedy Space Center, Titusville, FL.
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
- Fin length: 6 ft 1 in
- 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)
See also
- Strategic Air Command
- WD-40
Comparable aircraft
- SM-68 Titan I
- SM-68 Titan II
Related lists
- List of military aircraft of the United States
- List of missiles
References
- ↑ See inset launch photo.
- ↑ SM-65 Atlas - United States Nuclear Forces
- Gunston, Bill (1979). Illustrated Encyclopedia of the World's Rockets & Missiles. London: Salamander Books. ISBN 0-517-26870-1.
- Walker, Chuck, & Powell, Joel (2005). Atlas The Ultimate Weapon. Burlington, Ontario, Canada: Apogee Books. ISBN 1-894959-18-3.
External links
- bio Karel J. Bossart
- Karel Jan Bossart, Ir.
- Atlas SM-65, from the FEW Museum
- Atlas launch vehicle profile
- Atlas D from Encyclopedia Astronautica
- Atlas ICBM Information/History
- Video of an early Atlas launch in 1960
- 1958 Video of "Atlas in Orbit" Newsreel
- Atlas ICBM Launch on 5/23/1960 Video
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