Author: Zhang Yi Chi
In recent years, the Air Force is working to develop a new generation of intercontinental ballistic missiles to replace the "militia" III intercontinental ballistic missile. An important part of this is the development of the W87-1 warhead and the MK-21A reentry aircraft. We use this article to understand the warheads of the US Air Force "Minuteman" series ballistic missiles. From this, we can also roughly understand W87-1 and MK. -21A technical route.
The earliest "Minuteman" I missile and "Minuteman" 1A missile used W59 Mk 5 warhead/reentry vehicle. Let's explain the number first, where W59 refers to the nuclear warhead, and the term Mk 5 refers to the reentry vehicle used with that particular warhead. The "Minuteman" IA is only deployed at Malmstrom Air Force Base in Montana. A total of 150 W59 Mk-5 warheads/reentry vehicles were deployed by the "Minuteman" IA missiles.
The combined nuclear warhead and reentry vehicle has a diameter of 16.3 inches, a height of 47.8 inches, and a weight of 550 pounds. . The equivalent of W59 is 1 million tons . From 1962 to 1969, a total of 175 W59 Mk-5 warheads were produced. The W59 warhead was designed and developed by Los Alamos National Laboratory.
Started production of W56 warhead in 1963. The warhead was developed by Lawrence Livermore National Laboratory (Lawrence Livermore National Laboratory), including 4 subtypes, each with an equivalent of 1.2 million tons. They are basically the same size, the bottom diameter of is 17.4 inches, and the length is 47.3 inches. Models 1 to 3 each weigh 600 pounds, and Model 4 weighs 680 pounds. W56 warhead is used for "Minuteman I" missiles and "Minuteman II". The earlier Type 1 to Type 3 warheads were produced in 1963. This model was phased out in September 1966. A total of 545 Model 1 to 3 warheads were produced. 455 Model 4 warheads were produced until 1969 and used until 1993. The Mk-11 reentry aircraft is matched with the W56 warhead. This combination is equipped with 650 "Minuteman" IB missiles and 450 "Minuteman" II missiles. According to public information, W56 is one of the most efficient nuclear warheads ever manufactured. Its warhead has an equivalent of 1.2 million tons, which produces 4.9 kilotons of equivalent per kilogram of weight.
Lawrence Livermore National Laboratory engineers began to design the W62 Mk-12 warhead/reentry vehicle in June 1964. The W62 production engineering project started in March 1967, and the actual production started in March 1970. W62 Mk-12 is equipped with the first combat-capable "Minuteman" III intercontinental ballistic missile squadron. The squadron began its combat readiness on December 29, 1970. The 741 Strategic Missile Squadron at Minot Air Force Base in North Dakota was the first squadron to equip and deploy the Minuteman III missile.
The deployment of the "Minuteman" III missile realized for the first time an intercontinental ballistic missile carrying three "multi-target independent reentry vehicles" (separate-guided multiple warheads), which can carry three MIRV warheads Ability. Before the "Minuteman III" missile, each of the "Minuteman I" and "Minuteman II" missiles could only carry one warhead. The
technological advancement enables the US Air Force to design the payload mother bay so that it can maneuver to the correct position by itself so as to provide the best trajectory for each warhead of the three Mk-12 reentry vehicles. The explosive bolts that secure each individual warhead are exploded, and then released from the mother compartment. The computer system of the payload mother bay can then navigate to the next position to release the second and finally the third W62 warhead.
Lawrence Livermore National Laboratory) began to manufacture the W62 warhead in March 1970 and continued production until June 1976. W62 Mk-12 warhead/reentry vehicle has a diameter of 21 inches and a height of 72 inches. The warhead has an equivalent weight of 170 kilotons and weighs approximately 700 to 800 pounds. Some sources said that a total of 1,800 W62 warheads were produced, and some sources said that a total of 1,725 W62s were produced.
Warhead accuracy has always been the focus of the US Air Force. The circular probability error (CEP) of W62 is 900 feet. Later, the W78 Mk-12A warhead/reentry vehicle replaced the W62 Mk-12. The source said that by 2009, all W62 nuclear warheads had been decommissioned. The W78 warhead was designed and manufactured by Los Alamos National Laboratory. It is based on the W50 warhead design, is 21.3 inches in diameter, 67.7 inches in height, and weighs about 700 to 800 pounds. The equivalent of W78 is 335 kilotons. The engineering design of W78 began in November 1975, and then the first production warheads were put into use in August 1979. This warhead was produced until October 1982. A source said that a total of 1083 W78s were produced. The second source is believed to be 1,000. Compared with the W62 warhead, the CEP of W78 has been improved. The CEP of W78 is 720 feet . In the early stages of designing the W78, the Air Force initially thought that the warhead could also be used for the MX missile ("Peace Guardian" missile). After the "Peace Guardian" was successfully developed, the W87 warhead was used in the missile, which is also known as LGM-118A.
W87 warhead is a relatively new warhead in the Air Force intercontinental ballistic missile weapon system. W87 was developed by Lawrence Livermore National Laboratory. The design of W87 began in February 1982. The first batch of warheads was produced in April 1986, and by July 1986, W87 reached full capacity. Lawrence Livermore National Laboratory continued to produce this warhead until December 1988.
By December 22, 1986, 10 MX missiles at Warren Air Force Base in Wyoming reached operational capability. Warren Air Force Base (FE Warren AFB) has reserved 50 "Minuteman" III silos for MX missiles. The base reached a fully deployed state of 50 "Guardian of Peace" missiles in December 1988. According to a source, the "Peace Guardian" missile is capable of carrying 11 W87 Mk-21 warheads/reentry vehicles. According to the START treaty agreement, "Peace Guardian" can only be equipped with 10 W87 warheads. An interesting feature of the "Peace Guardian" missile is that the space of the payload mother bay carrying the W87 warhead is said to be able to accommodate 12 W87 Mk-21 warheads. This resource comes from page 121 of Volume I of the Nuclear Weapons Data Handbook.
The assembled W87 Mk-21 warhead/reentry vehicle has a diameter of 21.8 inches and a height of 68.9 inches. Some sources claim that the W87 Mk-21 warhead/reentry vehicle is heavier than the W78 warhead. The weight of the W87 warhead and loading aircraft is approximately 800 pounds. The CEP of W87 is 400 feet and the equivalent is 300 kilotons. With W87, this warhead can increase its equivalent weight by adding additional high-concentration uranium alloy rings in the second stage. This can increase the warhead's equivalent to 475 kilotons.
The United States has also conducted related research, using W87 for small intercontinental ballistic missile MMG-134A (also known as midget missile). Some early MGM-134A models were manufactured, but the Air Force never approved mass production of this missile. MGM-134A will carry a W87 Mod 1 warhead, carrying a more efficient warhead of 475 kilotons.
The Mk-21 reentry vehicle (RV) used by the W87 warhead was formerly known as ABRV, "Advanced Ballistic Reentry Vehicle" and was created by AVRV Systems Division design. This RV makes the warhead more accurate. The AVCO reentry vehicle is designed to be heavier, but the Air Force is indeed fascinated by its higher accuracy, with a CEP of 400 feet. Part of the strategy that incorporates higher precision is to be able to hit nuclear hardened targets with higher precision, and the goal is to eliminate the target more likely.
A source stated that a total of 560 W87 warheads were produced. The second source stated that a total of 525 nuclear warheads were manufactured. After the Peace Guardian missile was retired, the W87 MK-21 combination is currently used to equip the Minuteman III intercontinental ballistic missiles deployed at Warren Air Force Base and Minot Air Force Base.
