Availability
Availability of the later missiles aboard SSBNs remains classified, but in a US navy Polaris submarine fourteen missiles were available for 100 per cent of the time, while all sixteen were available for 95 per cent of the time.
Typical of its generation, the US navy’s Lafayette class usually spent sixty-eight days on patrol with the Blue crew, followed by a thirty-two-day refit before starting the next patrol with the Gold crew. There was also a sixteen-month yard overhaul every six years, giving an overall availability for each hull of 55 per cent. The Ohio class, however, offered a considerable increase in availability, with seventy-day patrols, followed by twenty-five-day refits, and with a twelve-month yard refit every nine years, increasing overall availability to 66 per cent.
ALTERNATIVE US SEA SYSTEMS
As with land-based missiles, there were repeated attempts in the USA to discover a form of sea-borne basing that was either less expensive or more survivable – or, preferably, both. Designs took a variety of forms.
In the immediate post-war period the USA examined the German plan to launch A-4s from submersible barges, and carried out some tests, using ex-German A-4s and US-built barges. The result was always that the rocket efflux destroyed the barge, resulting in a somewhat erratic launch. Nevertheless, the idea was re-examined in 1961–5 as a possible alternative to Polaris, under the code-name Project Hydra, and was looked at yet again in the early 1980s as an alternative to both Trident and the Peacekeeper (MX) ICBM. Project Hydra showed that the technique was perfectly feasible, although it found that the most effective way of launching was simply to put the missile in the water without any form of protective container. The missiles needed to be waterproofed, and those with a specific gravity greater than 1.0 needed a flotation collar to make them float, the collar being shed on launch. The plan was for such missiles to be taken to sea aboard a converted merchant ship and lowered into the water, where they would be left until they were activated and the launch command was signalled from a headquarters ashore.
The 1970s plan was for thirty fast merchant ships, each capable of rapid changes in appearance, to operate out of two bases, one on the Atlantic and one on the Pacific. Each ship would have carried ten missiles, and two plans were considered: one to offload the missiles into the sea in peacetime, the other to offload them only in a crisis. In fact the project foundered on the deployment issue, as the system was judged to be far too vulnerable and susceptible to accidents, but there was never any doubt as to its technical feasibility.
fn3
There were a number of proposals in the late 1970s to use small diesel-electric submarines, operating on or near the continental shelf. One proposal involved a design displacing some 450 tonnes, based on the West German-designed Type 209; another was for a larger boat displacing between 500 and 1,000 tonnes. Such submarines would have carried two (or, in some proposals, three) Minuteman III missiles in external, horizontally mounted containers, from which the missile would have been floated out, brought upright by its ballasted rear end, and then ‘wet launched’ as with Project Hydra. Force levels varied between 100 and 138, with manning figures ranging between five and fifteen men per submarine. The most serious drawbacks were that, being diesel-electric powered, slow and with relatively short range, the submarines would have needed protection by a strong ASW force, while if they operated within the limits of the continental shelf they were vulnerable to attack by a relatively small number of Soviet missiles.
The Hydra plan was for surface ships to place missiles in the sea for a water launch, but there were other plans to use the surface ships themselves as launch platforms. The most serious of these was the ‘Multi-Lateral Force’ (MLF) proposed by President John F. Kennedy in 1961. This proposal was for a fleet of twenty-five surface ships to be built in west-European yards, each armed with eight Polaris A-3 missiles, supplied by the United States. Both ships and missiles would have been jointly owned by the nations concerned and jointly manned (as, for example, happened later for the E-3 Airborne Warning and Control System (AWACS) force).
One curious event, possibly linked to the MLF proposal, was associated with the Italian cruiser
Giuseppe Garibaldi
. This ship underwent a major refit in the early 1960s and emerged in 1962 as a guided-missile cruiser, its principal weapons being US-supplied Terrier anti-aircraft missiles. It was, however, also equipped with four vertical launch tubes for Polaris A-3 missiles. Dummies were successfully tested, but real missiles were never
embarked
, nor were live Polaris missiles ever made available to the Italian navy.
1
The most significant feature of the MLF proposal was that the warheads would have been under NATO control, with release authorized by a NATO body to be set up for that purpose, and signalled over a NATO-owned ‘permissive link’ to the ships. The MLF never came about, but the question of NATO control over nuclear weapons led to the setting up of the Nuclear Planning Group.
There was also a proposal for a NATO-operated ballistic-missile submarine force. This was, however, quickly scotched, since the US would not reveal its nuclear-propulsion secrets and a diesel-electric submarine would have lacked the essential stealth.
SOVIET SYSTEMS
SS-N-1
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.
SS-N-4
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.
SS-N-5/SS-N-6
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.
SS-N-8
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 (
see here
). 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.
SS-N-17
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.
SS-N-18
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.
SS-N-20
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.
SS-N-23
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.
SOVIET SUBMARINES
Zulu
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.
Yankee
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.
Delta
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.