During the Second World War German submarines in the
Atlantic brought the United Kingdom very close to collapse before they were
ultimately defeated, while US submarines in the Pacific achieved a mastery
which played a significant part in Japan’s defeat. However, only a tiny handful
of people foresaw a potential marriage between submarines and the newly
developed missiles, and once again this occurred in Germany. The original
suggestion came from a visitor to the German rocket-development site at
Peenemünde, who proposed that the A-4 (V-2) missile, in addition to being
launched from land, might also be launched from a submersible barge towed by a
submarine. With such a device, he suggested, the Germans would be able to
bombard New York. The suggestion was seized upon by the staff at Peenemünde,
but the land-based missile was given higher priority and only one barge was
completed before the surrender in May 1945. A separate proposal to mount V-1
cruise missiles in submarines for use against New York was considered in 1943,
but was rejected due to a lack of suitable submarines.
The nuclear-powered missile submarine (submarine, ballistic,
nuclear – SSBN) and its weapon, the submarine-launched ballistic missile
(SLBM), formed a truly innovative weapon system. It was in essence a missile
base, but with the immense advantage over land-based ICBMs that not only was it
mobile, but it could use that mobility to hide in the vastness of the oceans.
US SYSTEMS
Regulus
Some of the V-1 and A-4 missiles obtained by the US forces
in 1945 were allocated to the US navy, together with a number of the German
scientists who had been involved in their development. These missiles were
immediately seen as having a seaborne role against land targets, and, of the
two, the V-1 cruise missile seemed to offer the greater promise in the short
term. As a result, two fleet submarines were converted by installing a
watertight hangar abaft the sail with a stern-facing take-off ramp – an
installation similar to that used by the Japanese navy for its
aircraft-carrying submarines, of which the US navy captured a number in 1945.
The submarines had to surface to launch the missiles, and the first of many
test flights took place in February 1947. The navy also conducted trials with
the A-4, including the first launch of a ballistic missile at sea, from the
flight deck of the aircraft carrier USS Midway on 6 September 1947. Numerous
tests were conducted with both types of missile until the programme ended in
1950, but it was a start.
Meanwhile, two exceptionally far-sighted submarine-launched
cruise-missile programmes were initiated, one for Rigel in 1947 and the second
for Triton in 1952, although both were eventually cancelled. A less ambitious
cruise-missile programme named Regulus did, however, reach service. Powered by
a turbojet, the subsonic Regulus I had swept wings, and served operationally
aboard submarines from 1954 to 1964. It was armed with a nuclear warhead, but
was relatively inaccurate and was targeted against large cities within 650 km
of its submarine launch position, such as Beijing. A second cruise missile, Regulus
II, was greatly superior to Regulus I and carried a nuclear warhead at speeds
in excess of Mach 2 to ranges of 1,610 km. Although it was proving very
successful, the programme was cancelled in 1959, as the concurrent Polaris
programme held out greater promise.
Polaris
The United States’ first SLBM and SSBN programme – known
collectively by the missile’s name, Polaris – was one of the most successful
defence projects ever undertaken. It was a huge undertaking, which incorporated
an astonishing range of innovations in two parallel but interlocking
programmes. On the missile side, these included solid-fuel propulsion, cold-gas
launch from a submerged submarine, lightweight ablative re-entry vehicles, and
small nuclear warheads. Alongside this was the submarine programme, which
involved cutting a nuclear-propelled attack submarine under construction in two
and inserting a 39.6 m ‘plug’ containing sixteen vertical missile tubes. The
submarine system also involved new launch-control and communications systems,
as well as novel systems for submarine navigation. This very ambitious
programme was steered to completion by Rear-Admiral William Raborn of the US
navy.
When the first Polaris submarine entered service, in 1960,
it revolutionized strategic warfare. The Polaris A-1 missile carried a single
500 kT warhead over a range of 2,600 km and, using inertial guidance, achieved
a CEP of some 1,830 m. Polaris A-2 also had single warhead, but this was both
more powerful (800 kT) and more accurate (CEP = 1.2 km), while Polaris A-3
carried three RVs, each with a 200 kT yield and a CEP of 850 m. The Polaris A-3
also became the first (and so far the only) SLBM to be supplied to a foreign
nation, when it was sold to the United Kingdom to arm that country’s
Resolution-class SSBNs.
Poseidon
The Poseidon C-3 two-stage missile started life as an
evolutionary development of the earlier missile (its initial designation was
Polaris B-3) and, although having a greater diameter, it was able to use the
same launch tubes by eliminating the guide-rings used on Polaris. The first
Poseidon was launched in August 1968, and the system entered service in 1971.
The most important innovation was that it was armed with MIRV warheads, of
which a maximum of fourteen could be carried, though this was limited to ten
100 kT warheads under the SALT I agreement with the USSR. The potential
accuracy of the MIRVs could have given them a counter-force (hard-target)
capability, but, since this ran counter to contemporary US strategists’ view of
SLBMs as a survivable, second-strike, counter-value (i.e. anti-city) system,
the proposed high-precision stellar-inertial navigation system was not
authorized by the Department of Defense.
At its peak Poseidon armed thirty-one SSBNs. Conversion of
twelve of these boats to carry the Trident missile started in 1984, however,
and by 1990 only ten Poseidon boats remained in service.
Trident
Development of Trident I began in 1972, the missile being
essentially a Poseidon C-3 with a third-stage motor added to give a greatly
increased range of 7,400 km – that range enabling the SSBNs to obtain more sea
room. The Trident design was a much more efficient design than earlier SLBMs,
maximising its use of the volume available, and making use of all the fuel. The
designers were also able to include the stellar navigation package which had
been forbidden Poseidon, thus enabling the warhead to be extremely accurate,
with a CEP of 463 m. Trident I (C-4) was put into production even though it was
known that Trident II (D-5) would become the definitive system, and it armed
twelve SSBNs which had originally carried Poseidon as well as the first eight
Ohio-class SSBNs.
Next came Trident II (D-5), which was the same diameter as
Trident I but 3.6 m longer, giving it a range of 12,000 km and nearly double
the throw weight of the earlier missile. As the Cold War ended, Trident II was
coming into service aboard the twenty-four-missile Ohio-class SSBNs. Trident II
was fitted with NAVSTAR satellite receivers, giving mid-course navigational
updates to the inertial system, resulting in a CEP of 90 m, making this a
genuine hard-target attack system, with a range enabling it to hit any target
in the world from anywhere in any ocean.
Tomahawk
In the late 1980s the US navy introduced the Tomahawk cruise
missile into service, thus turning the wheel full circle, since the navy had
started its Cold War development with a cruise missile – the Regulus – some
forty years earlier. This missile was, however, much superior in performance,
range and accuracy, delivering a 200 kT warhead to a maximum range of 2,500 km
with an accuracy of 280 m. It was also smaller and lighter, being capable of
being launched from a standard 533 mm diameter torpedo tube.
SLBM Launching
One of the keys to success of the US SLBMs was the use of a
gas-operated system which blew the missile out of the launch tube towards the
surface, thus avoiding the rocket-motor ignition taking place in the tube, with
its attendant dangers to the submarine. In some missiles the first-stage motor
to drive the missile up into the atmosphere fired below the surface, while in
others (e.g. Trident) it fired when clear of the surface. The missiles were
launched in sequence, Poseidon missiles being launched at a rate of one every
fifty seconds.
US SUBMARINES
The original submarines used by the US navy in the 1946–7
V-1 programme were standard Second World War diesel-electric fleet submarines
with large cylindrical hangars abaft the sail, with a short, sloping launching
rail. The next step was the Regulus I and II programmes, which involved five
submarines. The first two of these were converted fleet submarines with
cylindrical aft-facing hangars, but the other three were purpose-built, with
the missiles stored in a large hangar in the bows, two of them being diesel-electric-powered
and the third, Halibut, nuclear-powered. All ceased to operate Regulus when the
system was discontinued in 1964 and were then employed on different missions.
Led by Rear-Admiral Raborn, the Fleet Ballistic Missile
System (FBMS) programme started in the mid-1950s, and the first submarine,
George Washington, complete with sixteen operational Polaris A-1 missiles,
entered service on 15 November 1960 – an astonishing technical, manufacturing
and managerial achievement.
To save time, the George Washington class was created by
taking five Skipjack-class attack-submarine hulls currently under construction,
cutting them in two, and adding a missile section containing sixteen vertical
tubes abaft the sail. There were, of course, many minor changes, including the
addition of missile control and launch systems, special navigation systems, and
new communications. The system introduced many new concepts which subsequently
became standard practice, including the sixty-day operational cycle, using two
crews, designated Blue and Gold, one of which was at sea, the other ashore on
rest, leave, training and, finally, preparing to take over for the next
operational cruise.
The George Washington class was very quickly followed by
five Ethan Allen-class boats, completed between 1961 and 1963, which were very
similar to the George Washington class, but with the advantage of being
designed as SSBNs from the start.
The range of Polaris (A-1 – 2,600 km; A-2 – 2,800 km; A-3 –
4,630 km) meant that all these SSBNs had to operate relatively close to Russian
shores to meet the requirement to hit Moscow. So, in order to reduce transit
times, the boats were forward based at Holy Loch (Scotland), Rota (Spain) and
Apra Harbor (Guam). None of these ten SSBNs could be converted to take the
Poseidon missile, and in 1980–81 all were either converted to nuclear-powered
attack submarines (SSNs) by deactivating the missile tubes or were
decommissioned.
The first of the Ethan Allen class had not even been
completed before the next class was being laid down, and thirty-one
Lafayette-class SSBNs joined the fleet between 1963 and 1967. All thirty-one
entered service with Polaris missiles (the first eight with Polaris A-2, the
remainder with A-3), and a further four were planned to bring the grand total
of Polaris-armed boats to forty-five. These last boats were never built, and
the thirty-one Lafayette-class were converted in 1970–78 to take the Poseidon
missile. Twelve were later converted yet again to take Trident C-4 (1978–83),
with the first of these, Francis Scott Key, sailing on its first patrol on 20
October 1979.
Finally came the Ohio class, the largest US submarine and
the most powerful single weapons platform ever built – 171 m long, displacing
16,964 tonnes and carrying twenty-four missiles. Like most other strategic
programmes, the Ohio-class programme was surrounded by doubts, and in
particular by concern over its costs, but eventually the first submarine sailed
on its initial patrol on 11 November 1981. The first eight, which entered
service between 1981 and 1986, were armed with Trident I (C-4) missiles, and
the remaining ten (completed in 1988–97) with Trident II (D-5).
Missile Numbers
When the first SSBN was being designed there was a major
investigation into the optimum number of missiles. The minimum cost-effective
number was twelve, but the maximum depended on the money available. The number
of sixteen was simply the number that fitted in the largest submarine the US
navy felt that it could persuade the Pentagon and Congress to pay for, and the
majority of SSBNs subsequently built for both the US and foreign navies have
been equipped with this number of tubes. There is, however, nothing magic about
the figure of sixteen, and SSBNs have been built with twelve tubes (Soviet Yankee
class), twenty tubes (Soviet Typhoon class) and twenty-four tubes (US Ohio
class).
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.
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.
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.
SLBM family: UGM-27A, UGM-27A, UGM-27C, UGM-73A, UGM-96A, UGM-133A
