The US Nuclear Arsenal: A-88, Polaris, Pershing, and the Race Results
W58/Mk2 Warhead: Purpose and Characteristics
Nuclear charger (NCR) W58 — a thermonuclear warhead used in the Mk2 warhead of the UGM-27C submarine-launched ballistic missile Polaris A-3Each missile carried three W58/Mk2 warheads. The total throw weight of the new modification (less than 1,000 pounds, 450 kg) did not exceed that of the first modifications, the UGM-27A. Polaris A-1 and UGM-27B Polaris A-2, with single-block warheads (WB).
The W58 nuclear warhead had a cylindrical body with a diameter of 15,6 inches (400 mm) and a length of 40,3 inches (1020 mm) and a mass of 257 pounds (117 kg). The yield was 200 kilotons of TNT (840 TJ). The warhead used a primary module Kinglet, the main part, common with charges W55 and W47.
The W58/Mk2 warhead entered service in 1964, and the last examples of this type were retired in 1982, along with the last Polaris A-3T missiles.
UGM-27C Polaris A-3 submarine-launched ballistic missile
Launching the program and choosing a concept
The W58 program began in mid-1959 amid concerns that improved enemy detection capabilities would allow them to more effectively intercept warheads, thereby increasing their defenses. To overcome such defenses, it was necessary to disperse the warheads across several warheads. A study of the problem resulted in a report published in August 1959 recommending the development of a dispersive cluster warhead system for ballistic missiles (Multiple Re-entry Vehicle, MRV). In November 1959, a study began on the feasibility of developing such a warhead for the Polaris missile, and a report was submitted in January 1960. It recommended developing a missile with three warheads, equipped with an ejection system for their dispersal. The warheads were to separate from the platform at an altitude of approximately 200,000 feet (61,000 m). A protective fairing would protect them during underwater launch and during the boost phase of the trajectory.
Initially, two warhead variants were considered. They were similar in appearance, consisting of the same cylinder slightly flared at the bottom, but the first had a hemispherical nose made of pyrolytic graphite, while the second had an elliptical nose made of pyrolytic graphite or beryllium. In both cases, the internal surface temperature of the warhead body was not to exceed 1500°F (820°C), and internal thermal insulation limited the temperature of the nuclear warhead to 300°F (149°C). Ultimately, the first variant, with a hemispherical nose cone, was chosen.
Fuze system and safety devices
In July 1960, a decision was made to develop new types of fuses, one for airburst and one for ground burst. The airburst fuse was inertial and consisted of a range-corrected timer triggered by a decelerometer. It was suitable for defeating 95% of the targets designated for the Polaris. Highly hardened point targets remained outside its kill zone, as the minimum detonation altitude was 500 yards (460 m), which was insufficient. Such targets were planned to be destroyed by a ground burst fuse. The ability to select a contact fuse for any target was also added.
The primary safety device was to be a decelerometer, triggered if a deceleration of at least 10 g (98 m/s²) was maintained for five seconds. Additionally, a lockout device was included to prevent the warhead from being armed if it had not separated from the missile. The thermal battery, which supplied the warhead with electrical power, was designed to be triggered by the high temperatures generated upon reentry.
Development and distribution of works
Official approval for the warhead's development was received in July 1960, and its military specifications were approved in August of that year. Development was assigned to the Lawrence Livermore National Laboratory (now Lawrence Livermore National Laboratory). Despite the laboratory's extreme workload at the time, it was believed that extending the development period from three to four years reduced the laboratory's peak workload and therefore allowed it to continue its other programs.
The nuclear payload was initially designated XW-59, but in October 1960, it was redesignated XW-58. Previously, the XW-58 designation belonged to a version of the special primary module of the nuclear device, which was later redesignated W54. The Ministry of Defense was responsible for all financial and material aspects of the development, but the military had no authority to interfere with the design of the nuclear payload itself or make adjustments. The company's Missiles and Space Systems Division Lockheed was responsible for developing the warhead casing, missile, and test equipment, while the Naval Weapons Laboratory was responsible for the fuse and launch system. A flight test program of 14 tests was scheduled for October 1962, with production commencing in January 1964 and operational entry in June 1964.
The fuse system was to include a barometric airburst fuse with three altitude settings and a contact fuse for surface detonation. The actuation system was to be of the electric detonation type, the warhead was designed to be hermetically sealed, and the capsule containing the gaseous mixture of deuterium and tritium was to be housed in a well that allowed for its removal and replacement without compromising the charge's seal. In March 1961, a magnesium alloy was chosen for the supporting hull instead of the originally planned titanium, as it offered minimal weight, low cost, ease of machining, and moderate heat resistance. The radiation compartment was equipped with a protective casing as a temporary measure, as a reliable method of protecting it from environmental influences had not yet been found. The explosive-electric converter was later replaced with a ferromagnetic one, as the previous technology was not sufficiently proven.
Design refinement and serial production
In August 1961, the developer's proposed warhead specifications were deemed satisfactory to the U.S. Navy. The cone-shaped casing had a base diameter of 23,5 inches (600 mm) and a length (height) of 54 inches (1400 mm), with a loaded weight of 300 pounds (140 kg); a squib was installed in the center of the platform cell. Instead of the pyrolytic graphite that was planned to coat the casing, an ablative heat shield, integrated into the design, was installed over the warhead. The warhead was designated W-58/Mark 2.
In March 1962, the nuclear warhead was upgraded and designated XW-58-X1. The upgrade included a more compact reconfiguration of the automatics unit, a modified hull with a new heat shield, and the integration of the fuse and automatics into a single unit. This work delayed the development by three months. Work on the Mk 58 Mod 0 charge was completed, and the first production unit was produced in May 1963. Primary module Kinglet They were not produced anew, but were taken from W-47/Mk1s that had been decommissioned; a total of 300 modules were obtained in this way.
In June 1963, after an interim technical analysis, the primary module was replaced. The new version of the module eliminated the mechanical safety system that had raised concerns about the warhead's reliability in the Navy. In March 1964, full-scale serial production of the Mk 58 Mod 1 warheads began, and in October of that year, the first submarine armed with these warheads entered combat duty.
In December 1965, it was proposed to equip the Mk 58 Mod 2 device with high-energy X-ray protection, but the program was never approved.
Around 1975, problems related to electrical wiring corrosion were discovered in some W58/Mk2 warheads. These were studied using computer modeling, without nuclear testing. The modeling showed that the problem could be resolved with minor maintenance changes, but the already scheduled decommissioning date could limit the implementation of these measures. weapons from service, since it was considered impractical to modify the warheads being removed from service.
Warhead design
The warhead body is made of magnesium alloy, and the bottom of the conical body is made of ordinary aviation Aluminum alloy. A nylon-phenolic heat shield was bonded to the magnesium casing. The cover had two openings for the radar altimeter antennas, a pressure port for measuring pressure, and a valve for filling the warhead with dry air. The radio-controlled fuse was single-channel. The thermal battery and radar antennas were mounted on the diffuser section. The backup air fuse was controlled by a timer and a barosensor with three detonation altitude settings; in case of failure of the primary systems, the warhead was equipped with a backup contact fuse for detonation on the surface.
A modified American W58/Mk2 warhead inside a British-designed MIRV dispensing unit. Horse
The detonation system had two channels, and the primary charge module used an external neutron generator. The safety system was designed to withstand the event of the plutonium core being subjected to an unauthorized (accidental) pinpoint detonation by a conventional explosive charge with a yield of up to 4 pounds (1,8 kg) in TNT equivalent—that is, a detonation not initiated by the standard nuclear charge detonation system. In this case, a nuclear explosion should not occur. The protection against unauthorized tampering included a device activated by an accelerometer. Approximately 55 seconds after the SLBM launch (the operating time of the first stage) at an altitude of 65,000 feet (20,000 m), it closed contacts, connecting the warhead's electrical circuit to the thermopile and programmer. The warhead used a primary module Kinglet with a calculated boosted fuse yield of 18 kt.
The warhead was removed from US Navy service in April 1982, along with its carrier.
A Pershing ballistic missile (likely a Pershing 1B) on its launcher. Photo taken in January 1986 at White Sands Missile Range.
NATO's "Dual Decision" and the Deployment of Pershing II
On December 12, 1979, at a special meeting of NATO foreign and defense ministers in Brussels, it was decided NATO's "double solution"The ministers decided to deploy 108 MGM-31B launchers in Western Europe. Pershing II to replace existing PU Pershing 1a and 464 BGM-109G ground-launched cruise missiles. In addition, the German Air Force planned to replace its 72 aging MGM-31A missiles. Pershing 1a to the latest Pershing 1b short-range, but this never happened. On August 26, 1987, West German Chancellor Helmut Kohl promised to unilaterally dismantle the existing Pershing 1a, if the United States and the Soviet Union destroyed all their intermediate- and shorter-range missiles. By 1991, the missiles had been decommissioned in accordance with the Intermediate-Range Nuclear Forces Treaty.
On November 22, 1983, the German Bundestag, by a small majority, adopted a resolution on the beginning of the deployment of medium-range ballistic missiles (IRBMs). Pershing II on the territory of the country. The first launchers were deployed in West Germany at the end of November 1983, and full deployment was completed by the end of 1985, bringing the number of launchers to 108. Initial operational readiness (IOS) was achieved on December 15, 1983, when a battery (9 launchers) of the 1st Battalion (Division) of the 41st Field Regiment artillery entered combat duty with new missiles Pershing II at the positional area in Mutlangen.
On December 13, 1985, the West German government announced the rearmament of the US Army's 56th Field Artillery Brigade Pershing II consisting of three missile divisions stationed in Neu-Ulm, Mutlangen, and Neckarsulm. A total of 108 launchers and 120 missiles with W-85 nuclear warheads (including reserve ammunition) were deployed at three missile operating bases in West Germany for Pershing IIDuring peacetime, all missiles and equipment were typically stored in permanent hangars. When elevated to the highest levels of combat readiness, they were supposed to be moved to the wooded areas of Bavaria, where missile batteries would take up launch sites and prepare for combat missions.
To be continued
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