By the mid-1960s, nuclear-powered ballistic missile submarines had become an important part of the US nuclear strategic forces. Due to the high secrecy and the ability to operate under the protection of ships of the surface fleet and aviation, SSBNs on combat patrol, unlike ballistic missiles deployed in silo launchers on American territory, were practically invulnerable to a sudden disarming strike. At the same time, the missile submarines themselves were almost ideal weapons of aggression. Already 15-20 minutes after receiving the appropriate command, the American SSBN located in the North Atlantic, Mediterranean or Sea of Japan could inflict a nuclear missile strike on targets in the territory of the USSR or the Warsaw Pact countries. Between 1960 and 1967, the US Navy received 41 nuclear-powered missile submarines. All of them were named after prominent American statesmen and received the nickname "41 on the guard of Liberty." In 1967, American SSBNs had 656 SLBMs. Thus, in terms of the number of deployed carriers, the fleet was on par with strategic bombers and was about a third inferior to ground-based strategic nuclear forces. Moreover, more than half of the American missile submarines were in constant readiness to launch their missiles.
However, the American strategists were not satisfied with the relatively short launch range of the Polaris SLBMs of the first modifications, which did not exceed 2,800 km. In addition, the accuracy of hitting monoblock warheads made it possible to effectively hit only large area targets - that is, in the 60s, SLBMs, like ICBMs due to their significant air defense, were typical “city killers”. Such weapons could carry out the policy of "nuclear deterrence", threatening the enemy with the destruction of many millions of civilians and the total destruction of political and economic centers. But it was not possible to win the war with missiles alone, albeit equipped with very powerful megaton-class warheads. The main part of Soviet divisions was stationed outside densely populated cities, and the bases of medium and long-range missiles "smeared" almost throughout the territory of the USSR were hardly vulnerable to SLBMs and ICBMs. Even with the most optimistic scenario for the development of a global conflict for the United States and NATO, a significant part of the Soviet nuclear potential was able to inflict unacceptable damage to the aggressor, and the multiple superiority of the USSR and the Warsaw Pact countries in conventional weapons did not allow the European allies of the United States to hope for victory in a land battle. In the event of a global conflict, the Americans, having suffered significant losses, still had a chance to sit out overseas, but the fate of NATO countries in Europe would not be enviable.
Although in the 60s American SSBNs and their weapon systems significantly surpassed their Soviet counterparts, the leadership of the US Department of Defense, in order to gain a total advantage over the USSR, required SLBMs with a launch range at least equal to the third modification of the Polaris, but with a large throw weight and many times improved accuracy hitting warheads with individual guidance. Working ahead of the curve, already in 1962, Lockheed Corporation specialists, based on their own technological capabilities, made the necessary calculations. In the materials submitted to the Department of Special Development of the US Navy, it was said that the creation of such a missile is possible within 5-7 years. At the same time, its starting weight relative to the Polaris A-3 rocket undergoing flight tests at that time will approximately double. Initially, the new missile was named Polaris B-3, but later, in order to justify the sharp increase in the cost of the program, it was renamed UGM-73 Poseidon C-3.
For the sake of fairness, it must be said that Poseidon had little in common with the third modification of the Polaris. If the length of the rocket did not increase much - from 9, 86 to 10, 36 m, then the diameter of the body increased from 1, 37 to 1, 88 mm. The mass has almost doubled - 29.5 tons versus 16.2 tons for the Polaris A-3. As on the Polaris, in the manufacture of Poseidon's engine cases, fiberglass was used with fiberglass winding and subsequent sizing with epoxy resin.
The first stage solid propellant engine developed by Hercules had an original design. It was controlled by a nozzle that was deflected by hydraulic drives. The nozzle itself, made of aluminum alloy, to reduce the overall length of the rocket, was recessed into the fuel charge and extended after launch. In flight, to provide a turn in the angle of rotation, a system of micro nozzles was used, using gas produced by a gas generator. The second stage engine from Thiokol Chemical Corp. was shorter and featured a graphite-lined fiberglass nozzle. The same fuel was used in the engines of the first and second stages: a mixture of artificial rubber with ammonium perchlorate and the addition of aluminum powder. The instrument compartment was located behind the second-stage engine. Thanks to the use of a new three-axis gyro-stabilized platform, the control equipment provided the KVO about 800 m. The fundamental innovation implemented in the UGM-73 Poseidon C-3 SLBM was the use of warheads with individual targeting. In addition to warheads, the missile carried a wide range of missile defense breakthroughs: decoys, dipole reflectors and jammers. Initially, in order to unify and save money, the military insisted on the use of a guidance system and Mk.12 warheads created for a silo-based intercontinental ballistic missile LGM-30G Minuteman-III in a new missile intended for deployment on submarine missile carriers. ICBMs in service with the strategic missile wings of the US Air Force carried three W62 warheads with a capacity of 170 kt. However, the command of the fleet, wishing to increase the striking power of its SLBMs, was able to prove the need to equip new missiles with a large number of individually guided warheads. As a result, the Poseidon missiles were equipped with Mk.3 blocks with W68 thermonuclear warheads with a power of 50 kt, in an amount from 6 to 14 units. Subsequently, SLBMs with 6-10 warheads became the standard options.
The maximum throw weight was 2000 kg, but depending on the weight of the combat load and the number of warheads, the range could change significantly. So, when the rocket was equipped with 14 warheads, the launch range did not exceed 3400 km, from 10 to 4600 km, from 6 to 5600 km. The warhead disengagement system provided guidance to targets located on an area of 10,000 km ².
The launch was carried out from a depth of up to 30 m. All 16 missiles could be fired off in 15 minutes. The preparation time for the launch of the first rocket was 12-15 minutes. After the rocket came out of the water and at an altitude of 10-30 m, the first stage engine was started. At an altitude of about 20 km, the first stage was shot and the second stage engine was started. The missile control at these stages was carried out using deflected nozzles. After detaching from the second stage, the warhead continued its flight, following a given trajectory, sequentially firing warheads. The body of the Mk.3 warhead was made of a thermal-protective beryllium alloy with an ablative graphite toe. The graphite nose was also asymmetrical in flight in dense layers of the atmosphere, which gave the block rotation to prevent uneven burning. Particular attention was paid to protection against penetrating radiation, which could disable the control equipment and the plutonium charge. As you know, the first Soviet and American interceptor missiles were equipped with thermonuclear warheads with an increased yield of neutron radiation. Which was supposed to "neutralize" the electronics and start a nuclear reaction in the plutonium core, causing the warhead to fail.
Flight tests of the prototypes began in August 1966. The missiles were launched from ground-based launchers at the Eastern Proving Grounds in Florida. The first launch from the USS James Madison submarine missile carrier (SSBN-627) took place on July 17, 1970. On March 31, 1971, this boat went on combat patrol for the first time.
The James Madison-class nuclear-powered submarines are in fact improved Lafayette-class submarines. Structurally, externally and in terms of running data, they almost did not differ from their predecessors, but at the same time they were quieter and had improved hydroacoustic equipment.
However, after the rearmament of the Poseidon missiles in the United States, they began to be considered a separate type of SSBN. In total, the US Navy received a series of 10 James Madison-class missile carriers. Between March 1971 and April 1972, all 10 boats were rearmed with Poseidon missiles. At the same time, the diameter of the missile silos was increased and a new fire control system was installed.
The UGM-73 Poseidon C-3 SLBM was also installed on Lafayette and Benjamin Franklin-class SSBNs. The lead boat Benjamin Franklin (SSBN-640) entered service on October 22, 1965.
From SSBN Lafayette and James Madison boats of the type Benjamin Franklin, in addition to more advanced equipment, differed in the main turbo-gear unit with sound-absorbing material and a new propeller design, which made it possible to reduce noise.
The boats were rearmed during scheduled overhauls. SSBN type "Lafayette", before that carried the complex "Polaris A-2", the rest - "Polaris A-3". Rearmament from Polaris to Poseidon began in 1968 and ended in 1978. Ten early-built missile carriers of the George Washington and Aten Allen class retained the Polaris A-3 missiles. It was not possible to re-equip them on the Poseidon due to the small diameter of the missile silos. In addition, a number of experts expressed the opinion that SSBNs of the "George Washington" type, due to problems with maintaining a given depth caused by design features, during missile launches would not be able to shoot SLBMs with a launch mass of more than 20 tons at a high rate and relatively safely.
Boats armed with "Polaris" served in the Pacific Ocean, patrolling along the eastern coast of the USSR. Missile carriers with Poseidons operated in the Atlantic and Mediterranean. For them, forward bases in Scotland and Spain were equipped. The adoption of the Poseidon C-3 missiles has significantly increased the combat capabilities of the US Navy. While the number of submarines and missiles remained unchanged, the number of warheads deployed on them increased 2, 6 times. If in 1967, 656 Polaris missiles were equipped with 2016 warheads, then in 1978, 496 Poseidon missiles accommodated up to 4960 (in reality, somewhat less, since some of the missiles had 6 warheads) thermonuclear warheads, plus another 480 on missiles "Polaris A-3". Thus, about 5,200 thermonuclear warheads were deployed on submarine ballistic missiles, which increased the contribution to the US nuclear arsenal to 50%. Already in the late 70s, the naval component of the American strategic nuclear forces came out on top in terms of the number of warheads placed on carriers and continues to hold it to this day.
At the same time, the process of combat service of UGM-73 Poseidon C-3 missiles was not cloudless. Although the Poseidon's launch reliability was approximately 84%, this rocket earned a reputation for being capricious and difficult to operate, which was not a little helped by the need for careful debugging of onboard control equipment.
Information concerning various incidents with nuclear weapons that occurred on board missile submarines and naval arsenals during the Cold War was carefully classified. But, nevertheless, in the media all the same something leaked. Sometime in 1978, it turned out that the W68 warheads did not meet safety requirements. So American experts in the field of nuclear weapons write about their "high fire hazard". As a result, 3,200 warheads underwent revision until 1983, and the rest were sent for disposal. In addition, during the control and verification launches of inert warheads, a manufacturing defect in the graphite nose of the Mk.3 warhead was revealed, which led to the need to replace them on all warheads.
But, despite some shortcomings, it should be recognized that the Poseidon missile significantly increased the striking power of American SSBNs. And it's not just a sharp increase in the number of deployed warheads. Even during the design process, it was planned to install an astrocorrection guidance system on the UGM-73 Poseidon C-3 SLBM, which was supposed to radically improve the accuracy of aiming warheads at the target. However, at the request of the military, in order to reduce the development time and minimize the technical risk, an already mastered inertial navigation system was adopted. As already mentioned in the KVO warheads SLBM "Poseidon" initially was about 800 m, which was not very bad for the INS. In the second half of the 70s, as a result of several stages of modernization of the navigation system NAVSAT (English Navy Navigation Satellite Syste), which increased the accuracy of determining the coordinates of submarine missile carriers and the rocket computing unit using a new element base and gyroscopes with an electrostatic suspension, KVO managed to bring it up to 480 m. As a result of increasing the accuracy of shooting, American nuclear submarines with Poseidon missiles were no longer only “city killers”. According to American data, the probability of hitting a target such as command bunkers and missile silos that withstand an overpressure of 70 kg / cm² with one W68 thermonuclear warhead with a capacity of 50 kt was slightly higher than 0.1. consecutive strikes by alternately launched missiles, the American strategic nuclear forces for the first time received the possibility of practically guaranteed destruction of especially important targets.
The development of the Soviet strategic nuclear forces took a different path. The USSR also built nuclear submarine missile carriers. But unlike the United States, our main focus in the 60-70s was on heavy silo-based ICBMs. The Soviet strategic missile submarines, in comparison with American submarines, went on combat patrols 3-4 times less often. This was due to the lack of repair capacity in the places where SSBNs were based and to the shortcomings of missile systems with liquid-propellant missiles. The Soviet response to the sharp increase in the number of warheads on American SLBMs was the development of anti-submarine forces capable of operating in the oceans, far from their shores. Now the main task of Soviet nuclear-powered torpedo submarines in the event of a full-scale conflict, in addition to actions on communications and the destruction of aircraft carrier strike groups, was the fight against American SSBNs. In November 1967, the first nuclear-powered torpedo submarine, project 671, was introduced to the USSR Navy. Later, on the basis of this very successful project, large series of boats were created and built: project 671RT and 671RTM. In terms of noise level, the Soviet nuclear submarines of these projects were close to the American nuclear submarines of the Los Angeles type, which allowed them in peacetime to covertly monitor the US Navy's SSBNs. In addition, in May 1966, by order of the USSR Navy High Command, a class of large anti-submarine ships (BOD) was introduced. In the 60-70s, ships of special construction were being built: projects 61, 1134A and 1134B, and during the overhaul, the destroyers of the project 56 were re-equipped into the anti-submarine project 56-PLO. In addition to anti-submarine torpedoes and rocket launchers, the armament of the BPK pr. 1134A and 1134B included guided missile-torpedoes, which could be equipped with conventional and "special" warheads. Special anti-submarine helicopters with hydroacoustic buoys and submersible hydrophones could increase the effectiveness of the fight against submarines. In December 1967, a large anti-submarine cruiser (helicopter carrier) "Moskva" pr.1123, specially designed for the search and destruction of enemy strategic nuclear submarines in remote areas of the World Ocean, entered service. Its aviation group consisted of 12 Ka-25PL anti-submarine helicopters. In January 1969, the Il-38 anti-submarine aircraft was adopted by the naval aviation, which was a functional analogue of the American P-3 Orion. The Il-38 supplemented the Be-12 amphibious aircraft, the operation of which began in 1965. Specially modified Be-12 and Il-38 could carry nuclear depth charges 5F48 "Scalp" and 8F59 ("Skat"). In the 70s, helicopters were modified to use "special munitions". But, despite significant financial investments and a variety of anti-submarine weapons, the USSR Navy was not able to destroy most of the American SSBNs before they launched missiles. The main deterrent was not anti-submarine ships, aircraft and helicopters, but ballistic missiles deployed deep in Soviet territory.
Thus, against the background of an increase in the number of Soviet ICBMs, an improvement in their characteristics and the appearance in the USSR of ocean-class anti-submarine ships, the deployed Poseidon SLBMs no longer seemed such a perfect weapon and could not provide guaranteed superiority in a global conflict. Wishing to increase the importance of nuclear missile submarines in the structure of the American strategic nuclear forces and to consolidate the success achieved in the eternal rivalry with the Air Force, American admirals in the late 60s, even before the adoption of the UGM-73 Poseidon C-3 missile, initiated the development of an SLBM with an intercontinental range of fire. This, in turn, was supposed to further increase the combat stability of American SSBNs, allowing them to strike at the territory of the USSR while on patrol in areas inaccessible to Soviet anti-submarine forces.
Nevertheless, the combat service of the UGM-73 Poseidon C-3 was quite long, which indicates the high perfection of the missile. From June 1970 to June 1975, 5250 W68 warheads were assembled to equip Poseidon SLBMs. According to the data published on the website of the Lockheed corporation, 619 missiles were delivered to the customer. The last Poseidon boat was decommissioned in 1992, but the missiles and warheads were in storage until 1996.
