Aug 12, 2015

Submarine-Based Missiles -SOVIET SYSTEMS

On capturing German material in 1945, Soviet leaders were quick to see the potential importance of sea-borne long-range missiles, and their first attempt was to develop a towed-container system.2 Several hundred were built in the late 1940s, but the system does not appear to have become operational and attention soon switched to launching missiles from the submarine itself. Soviet army SS-1 (NATO = ‘Scud’) missiles were converted for naval use, and a Zulu-class diesel-electric submarine was adapted to house a single missile in a tube which stretched from the keel to the top of the sail. The first successful launch took place on 16 September 1955, and this system, designated SS-N-1 by NATO, entered service in 1959; its range was a meagre 150 km. Two missiles were carried in each of five converted Zulu-class submarines (Zulu V), and may also have been carried for a short time by the newly built Golf-class submarines, as well.

With a range of 150 km and an anti-ship role, SS-N-1 was not, however, a strategic missile; its significance here is as a ‘proof-of-concept’ system leading to strategic missiles.

Having proved the concept, the Soviet navy was quick to follow up with the more advanced SS-N-4 missile, which first went to sea in 1961. The system replaced the SS-N-1 aboard the Zulu V, but its principal platforms were the Golf-class diesel-electric and the Hotel-class nuclear (SSBN) submarines, which carried three missiles each. The SS-N-4 was a large missile for its time, with a launch weight of 13,750 kg, and carried a single 1 MT warhead, although contemporary reports credited it with a 5 MT warhead. Its range was 650 km. This was a surface-launched missile, and the submarine could travel at up to 15 knots and in conditions up to Sea State 5, although the submarine had to be on an even keel at the moment of launch.

The SS-N-5, ‘Sark’, which was deployed aboard later Golf- and Hotel-class submarines, was the first Soviet SLBM which could be launched while the submarine was submerged, the limits being a maximum depth of 60 m and surface conditions not exceeding Sea State 5. Of even greater significance was the SS-N-6, ‘Serb’, which enabled Soviet designers to switch from a few sail-mounted missiles to the same sixteen-tube, internally mounted layout as in Western SSBNs. It entered service in 1967 embarked aboard Yankee I-class SSBNs. The SS-N-6 had a relatively short range (2,400 km for Mod 1 and 3,000 km for Mods 2 and 3), which meant that the submarines had to deploy close to the Atlantic and Pacific coastlines of the USA. This made them vulnerable to US home-based anti-submarine measures, but, on the other hand, they threatened very rapid attacks on targets such as US ICBM fields – a threat which caused serious concern to US strategic planners.

The pace of Soviet naval missile development was maintained by the SS-N-8, ‘Sawfly’, which started test flights in 1971, demonstrating a range of 7,800 km. This caused considerable alarm in the West, as it exceeded, by a very considerable margin, the range of any other US or Soviet SLBM, and the alarm only increased when the Mod 2 version went on to demonstrate a range of 9,100 km. The long range was necessary because the SS-N-8 was designed for deployment aboard the new Delta-class submarines, which would operate from ‘SSBN bastions’ in Soviet-dominated waters. Accuracy was improved by using a stellar-inertial navigation system, although later reports suggested that this was frequently much less accurate than was believed in the West at the time.

The SS-N-17, ‘Snipe’, was embarked in one submarine only (the sole Yankee II), which was in service from 1977. It was the first Soviet navy SLBM to be powered by solid fuel, and also the first to carry a post-boost vehicle – in this case used for only a single re-entry vehicle. This system demonstrated a Soviet practice which tended to confuse Western observers, where a ‘one-off’ system was put into extended operational service – something which almost never happened in the West, as such a practice was very expensive in terms of procurement, training and logistic support. Even if, as was suggested at the time, the SS-N-17 might serve some special strategic purpose, there were inevitably protracted periods when the submarine was in refit, when the entire system was unavailable.

The SS-N-18, ‘Stingray’, which entered service in 1977, was a direct development of the SS-N-8 and was the first Soviet SLBM to carry MIRVs. It was installed in the Delta III-class SSBNs, which, owing to the missile’s greater length, had an even higher ‘hump’ abaft the sail than in the Delta I and II. The SS-N-18 continued the Soviet preference for storable-liquid propulsion.

The SS-N-20, ‘Sturgeon’, was specifically developed for use aboard the Typhoon-class SSBN and carried up to ten 100 kT MIRVs with a CEP of 500 m. This gave them a relatively low lethality (by nuclear standards), but was sufficient for the Typhoons’ wartime second-strike role (see below). Although it was the second Soviet SLBM to use solid fuel, it was the first such to be produced in quantity. The SS-N-20 entered service with the Typhoon in 1982, and was deployed only in that class of SSBN.

The SS-N-23, ‘Skiff’, was the successor to the SS-N-18 and became operational with the Delta IV class in 1985. Unlike the solid-fuelled SS-N-20, it used storable-liquid propulsion, possibly because the Soviet navy had found such a system preferable to solid fuel over many years of service. The SS-N-23 was originally thought to be operating with ten MIRV warheads, but was later learned to have only four. The US also expected that it would be retrofitted into Delta IIIs, but this did not happen.

Zulu-class diesel-electric submarines were built in the early 1950s and, after one had been used to launch an SS-N-1 missile, five were converted and were then known to NATO as Zulu V, fitted first with two SS-N-1s and later with two SS-N-4s. The launching procedure was complicated, to say the least. The missile was fuelled and prepared while the submarine was submerged and, when all was ready, the submarine then surfaced and the two missiles were raised by lifts until they were clear of the sail, where they were held in position by four brackets. The missiles were then aligned with the target, the motors were started, and (presumably using nice judgement) the missiles were launched when the submarine was upright.

Golf, Hotel
The Zulu class was followed by two classes of purpose-built missile submarines, but, with typical Soviet caution, one class was diesel-electric-powered, while the other had nuclear propulsion. Fifteen of the diesel-electric boats – designated Golf class by NATO – entered service between 1959 and 1962 fitted with three sail-mounted SS-N-4s, using the same surface-launch techniques as the Zulu V. Thirteen of these were later converted to take the SS-N-5, which was launched submerged. The Hotel-class nuclear-powered submarines were developed concurrently with the Golf class and had very similar missile arrangements, with three SS-N-4s mounted vertically in the sail.

An important development came in 1967, when the Yankee I-class SSBNs entered service. These were the first Soviet SSBNs with sixteen missile tubes and the first to house the tubes in the pressure hull, as with the US Polaris submarines. Thirty-four were built between 1969 and 1972. Like the earlier classes, these boats patrolled off the US coast, but the greater range of the SS-N-6 missile enabled them to threaten targets much deeper inland. One boat, the sole Yankee II, was built to test the SS-N-17 missile, and a number of Yankee Is were converted as cruise-missile carriers.

The Delta class proved to be a very successful project for the Soviet navy, and the design remained in production from the late 1960s in four major versions: Delta I (eighteen built), Delta II (four built), Delta III (fourteen built) and Delta IV (seven built). The Delta I was built around the SS-N-8 missile and made maximum use of the well-proven Yankee design, enabling the Soviet navy to get it into service quickly, although, since the SS-N-8 was considerably larger than the SS-N-6, the ‘hump’ was higher and only twelve missiles could be accommodated. The Delta II, however, was longer, to enable the number of missiles to be increased to sixteen to match Western SSBNs. The fourteen Delta IIIs were the only Soviet SSBNs to carry the SS-N-18 missile, which was even longer than SS-N-8, thus requiring an even higher ‘hump’. Last of the class were the Delta IVs, commissioned between 1985 and 1992, which carried sixteen SS-N-23 SLBMs. All four Delta classes were designed to operate in the two Soviet ‘SSBN bastions’, their probable role being to deliver the first wave in a second strike.

The first Typhoon hull was laid down in 1977, and when it was first revealed in the West in the early 1980s it caused a greater stir than almost any other weapon system in the Cold War. Western intelligence had become aware of something unusual three years previously, when First Secretary Leonid Brezhnev told President Gerald Ford that he would go ahead with Project Typhoon if the US would not agree to drop the Trident programme. Later, US reconnaissance satellites took pictures of components being assembled at Severodvinsk which were so large that it was assumed that they were for another long-awaited project, an aircraft carrier. What eventually appeared, however, was the largest submarine the world has ever seen: its submerged displacement of 25,000 tonnes far exceeds that of the US navy’s Ohio-class SSBN (16,964 tonnes), while its length of 171 m is a little greater than that of a US navy Ticonderoga-class cruiser.

The Typhoon was innovative in many ways apart from its sheer size. The outer casing conceals no less than five interconnected pressure hulls, and the twenty SS-N-20 missiles are mounted forward of the sail – a feature unique among SSBNs.

The Typhoon was designed to provide a platform which would spend most of its very long patrols lying on the seabed beneath the Arctic ice cap. It would sit out a nuclear exchange and surface through the ice to launch its missiles only when the adversary was taking the first steps towards post-nuclear recovery. In the original concept it was planned that each Typhoon would spend as much as a year on patrol, and one of the reasons for its huge size was the need to provide good habitability and adequate recreation possibilities for the crew. Internally, the Typhoon is exceptionally spacious, with extensive facilities including saunas and a swimming pool, all designed to ease the burden of protracted periods at sea. Six of these unique submarines were built between 1977 and 1989.

As far as is known, the sole Soviet alternative to SLBMs was a 1.5 m diameter torpedo developed in the late 1940s, which would have been launched from a single bow tube at a range of some 30–40 km from the target, usually a port. The missile travelled at approximately 55 km/h, and with a payload of some 3.6 tonnes it would have delivered a nuclear warhead with a yield of approximately 1 MT.

In the early years of the Cold War the Soviet Union found itself in a position where US missile and airbases, some operated by the USA and others by NATO allies, directly threatened the Soviet land mass. On the other hand, the Soviet Union did not have a long-range air capability equivalent to the USAF’s Strategic Air Command with which to pose a corresponding threat to the USA, and it thus turned to missile-armed submarines as the quickest way of obtaining such a capability. The early missiles had a short range (650 km for the SS-N-4, for example) and the submarines would have been vulnerable to very active ASW activity by the USA. In particular, submarines armed with the surface-launched missiles (SS-N-1 and SS-N-4) would have been extremely vulnerable during their lengthy launch preparations.

At that time the primary purpose of the nuclear force was to pose an anti-city threat, and there were large numbers of important urban concentrations down the east and west coasts of the USA within the range of those missiles. When the Yankee SSBNs first started to patrol off the US Pacific and Atlantic coasts in the late 1960s, armed with their counter-value SS-N-6s, they too were targeted at large area targets, such as cities, government facilities, military bases and airfields. All these early SSBNs – including the Yankees – also brought another factor to the threat to the USA, since their missiles would have had a very short time of flight (possibly between four and five minutes), compared to the thirty minutes’ warning the USA expected to receive of a trans-polar missile attack. For the Soviet navy, these new types of submarine and missile also had the advantage that, apart from increasing the capability of the navy, they also helped to increase the experience of its officers and ratings.

The Delta-I/SS-N-8 combination, however, represented a complete change in strategy, since the long range of the missiles enabled the submarines to operate in what came to be known as the ‘SSBN bastions’. There were two of these – the Barents Sea in the west and the Sea of Okhotsk in the east – where the SSBNs had plenty of room for submerged patrols, while the sea around them and the airspace above them were patrolled and defended by Soviet naval and air forces. In particular, the Soviet SSBNs were defended against attacks by US and British SSNs, one of whose primary roles was to try to destroy Soviet SSBNs before they could launch their missiles. One consequence of this strategy was that Soviet war plans allocated increasing surface and air forces to the defence of the bastions, which reduced the assets they could assign to attacking NATO naval forces elsewhere.
Delta-II/SS-N-8 and Delta-III/SS-N-18 continued this pattern, but the Delta-IV/SS-N-23 and Typhoon/SS-N-20 combinations, which were produced simultaneously in the 1980s, introduced a new dimension. They were intended for different missions, the Delta IV being intended for use early in a nuclear campaign, possibly even in the first strike, but from the Arctic region, rising though relatively thin ice to fire its missiles from the surface. Typhoon, on the other hand, was intended to submerge under the deep ice cap for a protracted period, possibly as long as a year, and then break through thicker ice in order to carry out a final strike on the USA as it attempted to recover from the effects of a nuclear war.

Both sides considered it necessary to be aware of the movements of the other side’s SSBNs, first to establish routine patterns and then to detect any variations from the routine – such as, for example, an increase in the number of SSBNs at sea, which might indicate possible preparation for war. The start points for all SSBN missions – their bases – were well known to both sides, and the most vulnerable part of an SSBN’s voyage was its departure from its base.

The bases were closely monitored by satellite and, at least in the case of the Western bases, visually as well, but there were also more covert means of surveillance. Knowledge of the submarines’ operational cycles enabled the sailing and return dates of SSBNs to be predicted with a fair degree of accuracy, and in the early days the other side’s SSNs would wait outside bases to monitor SSBN movements using their on-board sensors. This was countered by giving departing SSBNs an ASW escort of aircraft, surface ships and SSNs, which in its turn was countered by using attack submarines to place sensors on the seabed. The British, for example, built a specialized and very complex ship, Challenger, at very considerable expense, specifically to locate and remove such devices from the approaches to the nuclear-submarine base in the Clyde.

Once at sea, the SSBNs would make fairly rapid, but careful, transits to their operational area, where they would then cruise at about 3 knots, varying their depth to take maximum advantage of oceanic conditions, to make detection as difficult as possible.