Military Technology – MILTECH - 8/2008
Anti-Submarine Weapons - The State of the Art
Massimo Annati
A Vertical Launch ASROC (VLA) at launch.
(All photos: via Author)
Among the different sectors of
naval warfare which underwent
major changes after the end of the
Cold War, Anti-Submarine Warfare
(ASW) is certainly the most
affected one. Nearly all the
potentially hostile submarines
belonged to Soviet Union, and
when the latter disappeared very
few boats were left in the
worldwide inventory to be dealt
with as potential threats. Moreover
are a very complex tool, and not
many navies belonging to
potentially hostile nations in the
so-called Third World were
considered capable to deploy -
both technically and operationally -
such a force with a significant
degree of effectiveness.
Nearly twenty years after the fall
of the Berlin Wall, what is the
current and prospective future
situation?
ASW In The 21st Century
Clearly enough, in the Atlantic Ocean and Mediterranean basins there no longer is
a submarine threat. Yet Russia increasingly appears to be indulging in sort of a
Cold-War nostalgia, and no longer looks very friendly and cooperative (if it really
ever had ...). Another important element of the strategic equation if the possible
future evolution of the political posture of some Middle East countries like Egypt
and Algeria. These are considered friendly and even allies to the West, yet are
struggling to maintain their route towards democracy and development against
instability caused by both domestic problems and foreign interferences.
Going eastwards Iran is the first (actually or potentially, make your choice)
hostile country with a submarine force, controlling the access to one of the most
sensitive areas of the world.
From the Arabic Sea and beyond, the situation is totally different. Regional
tensions and concerns involve countries with significant naval services, and quite
a few of these are engaged in a veritable "underwater arms race." New
submarine construction or procurement programmes are underway in Pakistan,
India, Indonesia, Malaysia, Singapore, Korea, China, Japan and, again, Russia.
Therefore any naval deployment and operation in that large slice of the planet's
waters must take into account, at least potentially, a robust ASW capability.
Military Technology – MILTECH - 8/2008
To conclude this very quick overview, also in the Caribbean there are local
tensions, with a loud-speaking Venezuela close to acquire a batch of Russian-built
KILO-class submarines.
The other main change following the end of the Cold War concerned the type of
hostile Submarines one could expect to face and their operational area.
It should be appreciated in this regard that submarines are an important factor of
both tactical and strategic equations, whose presence cannot and should not be
disregarded. While Western technological supremacy can be counted upon to
swiftly deal with attack craft, strike aircraft, coastal missile batteries and so on,
submarines are a completely different story and their suspected presence require
rather elaborate precautions. To underline this point with just two examples,
movement of surface warships during operations in the Gulf of Sidra (1986) and
the Adriatic Sea (1990s) were preceded and guarded by own submarines, just to
ensure that no hostile underwater boat was in the area. After, and only after, the
area was considered clear and safe, the big ships were allowed to enter it.
Yet another significant development following the end of the Cold War was the
evolution of the tactical and environmental scenarios. Blue-water encounters
against deep- and fast-running nuclear-powered boats were soon replaced by the
hide-and-seek game against slower but very quiet diesel/electric boats, operating
in shallow waters and littoral areas. Stealth - the submarine's main advantage -
was even increased, as diesel/electric boats can lie motionless near the bottom,
waiting for their potential preys while hidden in an environment characterised by
poor acoustic conditions (critical thermal gradients, environmental and man-made
background noise) and shallow waters (reverberation from both the bottom and
surface, difficult use of most ASW torpedoes).
While the US Navy withdrew its
SUBROC submarine-launched
ASW ballistic rocket system
immediately after the end of the
Cold War, the Russian Navy has
retained the conventional payload
versions of conceptually similar
weapons such as the RPK-2
TSAKRA (shown) and the RPK-7
VEDER.
A further critical factor is related to the weaponry available to submarines. A
heavyweight torpedo can easily sink even a major vessel, breaking its back and,
most of all, there are very few effective countermeasures available and
deployable. Torpedoes can be covertly launched, providing no warning until too
late to react - which is in strong contrast with most warships being fitted with
electronic countermeasures and hard-kill defences supposedly capable to engage
and defeat an incoming anti-ship missile. In any case, many modern submarines
can launch either heavyweight torpedoes or anti-ship missiles, exploiting the best
of each solution, and extending their threat well beyond the detection range of
shipborne acoustic sensors.
In view of these considerations, ASW was considered out of fashion for a brief
period of time but is now coming back to its full importance. It is not by chance
that France is building eight FREMM frigates in the ASW variant [now down to six
under the new White Paper -Ed.], while four out of the first six FREMM frigates for
Military Technology – MILTECH - 8/2008
the Italian Navy will also be of the ASW variant. Eight of the UK Type-23 frigates
are being upgraded under the Task Force Escorts programme with the addition of
the Surface Ship Torpedo Defence suite and new improvements/replacements as
the Type 2070 active low-frequency bow-mounted sonar, Type 2087 lowfrequency
active sonar towed array, and the MERLIN HM1 ASW helicopter. The
German Navy is gradually upgrading its F123-class frigates and the 2009-2012
Phase 2 will include new MU-90 ASW torpedoes, MH-90 helicopters, upgrade of
the DSQS-23BZ bow-mounted sonar and fitting of a new low-frequency towed
active sonar.
The US Navy is equipping its most recent DDG-51 class destroyers with the SQQ-
89(V)15 ASW combat system, which is also being retrofitted to most of the earlier
destroyers and cruisers. This retains the SPS-53 bow sonar but replaces the old
SOR-19 towed array with the new Multi-Function Towed Array (MFTA), adding a
passive detection capability. The new ASW capacities will also include the MH-60R
helicopters with the AQS-22 ALFS sonar and the new Mk54 lightweight ASW
torpedoes. By the same token the Japanese Maritime Self Defence Force,
probably the world's most capable ASW force, is constantly adding new first-class
escorts, helicopters and patrol aircraft to its inventory.
Giving the relevant changes of tactical and environmental conditions experienced
over the last years, how are ASW weapons themselves being affected? The
following sections attempt at providing an answer.
The Atlas Elektronik DM2A4 heavyweight
torpedo equips most notably the German
Navy Type 212 submarines.
Heavy-Weight Torpedoes
Heavy-Weight Torpedoes (HWT) are the weapon of choice for all submarines not
only for use against surface vessels, but also enemy submarines under virtually
all tactical circumstances - ranging from the engagement of fast, deep-running
boats to the opposite scenario of an underwater target sitting on the bottom in
shallow waters. Needless to say, such a wide range of different and indeed
diverging engagement conditions create conflicting technological and performance
requirements. For instance, the US Mk48 Mod.6 AT - certainly one of the most
advanced heavyweight torpedo in the world - faces a severe limit in terms of
minimum depth at launch, as a 25m overshot is required because the significant
initial negative buoyancy (due to the weight of the propellant). In contrast the
WASS BLACK SHARK, designed much later for a different scenario requires only a
1.5m overshot, allowing it to be fired in very shallow waters or even from
bottom-sitting boats. Additionally some HWTs, like the Mk48 Mod.6 AT or the
German DM2A4, are fitted with a magnetic exploder for ASW engagements and
Military Technology – MILTECH - 8/2008
are therefore unable to cope with amagnetic hulls, whereas the BLACK SHARK
exploits a multi-frequency coded acoustic proximity exploder.
While all submarines can use 21-inch (533mm) torpedoes, some can also launch
smaller weapons for close encounter engagements. For instance, all modern
Swedish-built boats have four 533mm torpedo tubes and two 400mm tubes for
Type 432 ASW torpedoes.
HWTs can also be fitted to ASW-oriented surface warships, providing an
additional capability for longer-range ASW attacks. This practice, once quite
common has been progressively abandoned in view of the improved performance
offered by modern light-weight torpedoes, and is nowadays only in use with some
Russian-designed vessels operated by the Russian, Chinese, and Indian navies.
This old-fashioned approach would admittedly still offer a potential advantage in
terms of single-shot lethality, but other factors such as target detection capability
or countermeasures rejection also play an important role.
Heavyweight torpedoes such as this Chinese
Yu-6 remain the main weapon of submarines
for use against other submarines.
Light-Weight Torpedoes
LWTs represent certainly the main and most common type of ASW weapons. They
are used by surface ships, helicopters and maritime patrol aircraft, and can
further be carried as payload by long-range ASW missiles (see below) or even by
moored ASW continental-shelf mines.
The evolution of the tactical scenarios, as described above did also have an
impact on the required characteristics and performance of LWTs. However, the
time, cost and technical risks related to the development of a new weapon are so
high, that this process is mostly reflected in the progressive upgrade and
modernisation of existing weapons rather than the introduction of completely new
models. This is further compounded by powerful financial incentives for the large
stocks of LWTs dating back to the Cold War era to be kept in service as long as
possible, even when they are not up to contemporary operational needs.
The advanced features of modern/upgraded LWTs are reflected in the evolution of
operational tactics. In the past such tactics foresaw e.g. the near simultaneous
launch of two Mk44 torpedoes in order to increase the chances of success against
a submarine, that was trying to exploit the bathy-thermal layers to hide itself.
The limited sonar power and thus reduced detection range of the torpedoes made
this mode of operation possible, without excessive risks of mutual interference.
The higher power available to 2nd generation torpedoes (Mk46, STINGRAY, A244)
forced this practice to be discontinued - but the growing availability of torpedo
countermeasures available to submarines is now again changing the terms of the
equation. In fact, the nearly simultaneous launch of two LWTs degrades the
survival chances of a boat protected by countermeasures by a factor of three to
Military Technology – MILTECH - 8/2008
four. On the other hand, there is a significant risk of mutual interference between
the torpedoes, especially because the reciprocal Doppler effect is relevant due to
the wide array of possible relative speeds.
The solution could lay in the use of IFF-like sound codes injected within the active
sonar pulses, allowing the torpedoes to reject the acquisition of friendly torpedoes
and widening the operational chances, while eliminating firing restrictions (i.e., it
would even be possible to locate two torpedoes at the same search depth). The
A244S Mod3 is the very first LWT with embedded IFF code technique.
The traditional triple torpedo tubes mounts for lightweight ASW torpedoes onboard surface
vessels (left, showing a Mk46 at launch) are increasingly being replaced by internal
arrangement (right, the MU90 torpedo room onboard an "Horizon" class DDG).
US Models
The US Mk46 is certainly the most common and widespread LWT since the 70s. It
was initially designed to operate only in deep waters, as all the versions up to the
Mk46 Mod5 (included) required a minimal depth to at least 60rn for shipborne
launches and 90m for air launches. The self-evident need for a shallow water
performance improvement led to development of the Mk46 Mod5A(SW), suitable
for use with a minimum depth of 45m for ship-borne launches. Some 1000 US
Navy Mk46 warshots were converted to the Mod5A(SW) standard during 1996-
1998, achieving better bottom avoidance and resistance to countermeasures.
While the Mk46 Mod5A(SW) will remain in US service until 2014, there is a
significant lack of shallow water capability for most allied navies, which
additionally will be soon left without support for all Mk46 models. In 1996 the US
Navy prematurely terminated the production of the ill-fated Mk50 torpedo after
just 1065 units (versus 8000 as initially planned), due to cost reasons. The Mk50
was designed to counter the fast, deep-diving, blue-water Soviet threat, although
the Mod1 variant and the Software Block Upgrade I provide improved countercounter
measures and better shallow water performances than any conceivable
Mk46 evolution. The Mk50 is anyway planned to end its short service life by
2014.
The Mk54 Lightweight Hybrid Torpedo (LHT), which achieved Initial Operational
Capability in 2004, finally offers a credible shallow water capability being cleared
for surface launches in water as shallow as 25m and air launches in 35m. The
LHT is the fusion of a number of Non-Developmental Items, like the warhead, fuel
tank and afterbody of the Mk46, sonar and thermal battery of the Mk50, signal
processing and speed control valve of the Mk48 Mod6, and software components
from both the Mk50 and Mk48 ADCAP. However it must be underlined that the
fuel used in the Mk54 poses some not insignificant operational limitations, e.g.
the torpedo can be carried at high altitude only within a heated bomb-bay.
Military Technology – MILTECH - 8/2008
By 2014 the Mk54 Mod0 is scheduled to replace the entire inventory of Mk46s
and Mk50s, with even a slight increase in warshot numbers.
In order to be ready to face the increasingly complex threats, the Mk54 is
entering a spiral Pre-Planned Product Improvement (P3I) programme including
new software, an improved sonar array (both leveraging from the Mk48 CBASS
programme) and additional operational features, like integration with the Vertical
Launched ASROC (VLA) and the High-Altitude ASW Weapon Concept (HAAWC).
The latter idea, financed in June 2006 through a contract with Lockheed Martin,
foresees torpedo release form an altitude of some 20,000ft while still achieving a
precise water-entering point. This would allow selected MPA (P-3C or, in
perspective, P-8A) to attack a submarine while remaining well outside the
possible envelope of future submarine-launched anti-aircraft missiles such as the
German IDAS. Additionally, this feature would reduce the stress on the aircraft
airframe due to the frequent changes of altitude, and enable off-axis attacks thus
widening operational capabilities. Further, sonobuoys and distributed sensors will
also be fitted with GPS, providing a precise information on target position.
HAAWC will enable the patrol aircraft to exploit the full sensor field, allowing highaltitude
surveillance and attack.
HAAWC includes a Long-Shot wing adaptor kit with self-contained GPS guidance,
enabling a long and precise glide of the aircraft-released torpedo. Once the
HAAWC reaches the desired release point at the normal altitude (usually 500-
600ft), Long-Shot is jettisoned and the Mk54 torpedo enters the water with a
normal profile with a traditional parachute brake.
Another interesting sets of development, to be carried out during 2010-2012,
include the demonstration of the integration of the Mk54 into USV, transforming
the latter (a 7m RHIB) into an ASW weapon delivery system.
Turkey is the first (and for the moment, the only) foreign service to have asked
to purchase the Mk54 Mod0 (under the form of conversion kits for the Mk46s on
stock) and have received approval from the US Congress. However as indicated
the Mk54 can only be carried by fixed-wing aircraft fitted with a heated bomb bay
(which are not in Turkish service), and therefore at least two LWT models will be
needed.
All the rest of the wide community of foreign Mk46 users will have to decide quite
soon whether to adopt the Mk54. or to select a different LWT,... or to be left
without torpedoes.
Military Technology – MILTECH - 8/2008
The Chinese Yu-7 LWT is
understood to be a copy of
the Mk46Mod.2.
European Programmes
Cold War requirements are also evident in electric-powered European-made
LWTs. For instance, the BAE Systems STINGRAY was designed to operate down to
a 900rri depth in order to catch the deep-running ALPHA-class Soviet boats -
which however soon disappeared from the order of battle. By the same token,
features of the MU90 IMPACT such as the shaped charge warhead and precision
attack software were intended to defeat the large double-hull spacing of the
OSCAR-class submarines. However these features, though probably not anymore
so important, would be of some use even in today's encounters.
The STINGRAY entered service with the UK Royal Navy and Royal Air Force in
1983, and is expected to remain in use until 2030. Export users include Brazil,
Thailand, Egypt, Romania and Norway. The Mod.1 upgrade, aimed to improve
shallow water performances began development in 1996 and achieved
operational capability in June 2006, with production expected to be concluded by
2010. Major improvements affect the guidance and homing system, the front-end
array, a new SAFT Magnesium-Silver Chloride salt-water battery, new tactical and
signal processing software, and a new warhead (though the two latter
components are being developed under different and parallel programmes, and
will be added to already delivered Mod.1 torpedoes from late 2008 onwards). Part
of the Mod.1 improvements are also being made available to some export users.
The Franco-Italian MU90 IMPACT is claimed to be the best LWT on the market,
having been developed from scratch with the littoral threats in mind. For
instance, it can be launched in depths limited to just 20m (shipborne) or 25m
(airborne), with a further improvement over the previous A244S (30m from
ships). The MU90 further offers speeds variable from 29 to over 50 knots with
continuous adjustment via step-less regulation according to the tactical
requirements, with corresponding ranges from 25,000m to 15,000m. With its
insensitive munition warhead, broadband sonar processing and tactical computer,
high immunity to acoustic countermeasures, propulsion quietness and lack of
wake, the MU90 provides today the performance envisaged for the future Mk54
P3I. MU90 users included France, Italy, Germany, Poland, Denmark and Australia,
with two South American and South-East Asian countries likely to follow soon.
Possible future growth includes a Li-ion rechargeable battery for exercise
torpedoes (further decreasing the cost of training/qualification and enhancing the
performances to full warshot levels) and a large series of tactical applications.
Military Technology – MILTECH - 8/2008
These would include e.g. the launch from a continental shelf mine, the use as a
low-lethality weapon against large surface targets in specific conditions (i.e.
stopping a vessel destroying its propeller, without having to sink it), the launch
from midget submarines, or even the use as a hard-kill anti-torpedo torpedo. Any
standard MU90 would be capable to fulfil either ASW or ATT roles thanks to a
specific resident software to be activated at the moment of the launch.
Roketsan of Turkey, in cooperation with Aselsan,
is developing an indigenous Anti Submarine
Warfare (ASW) rocket under a R&D contract for
the Turkish Navy. The depth of the underwater
explosion of the rocket's HE warhead will be able
to be adjusted digitally before launch, using a
fire control system. Under the project a two-axis,
6-8 cell stabilised rocket launcher (ASRLS) will
also be designed and manufactured by Aselsan.
The new ASW system is expected to be installed
on the MILGEM Patrol/ASW corvettes as well as
other existing and future platforms of the Turkish
Navy.
(Photo: Ibrahim Sünnetçi)
The Otto-fuel engine of torpedoes such as the Mk46 does
pose a significant risk for leakages.
Asian Developments
While the LWT world market is nearly completely
covered by the US Mk46, the UK STINGRAY and the
Franco-Italian MU90, some models were developed in
Asia, tough only for domestic use (at least for the
moment).
The Korean BLUE SHARK is considered from many points of view a tentative
cloning of the MU90, especially as regards the brushless motor and propellers.
Even the technology of the AI-AgO battery was probably derived from the MU90,
though its development appears not yet completed.
Japan developed a domestic version of the Mk50 (GRX-4), with a number of
national components. As usual for most Japanese weapon system, no information
is available on performances, quantity procured, etc. A further LWT model is now
under development.
The Indian NSTL was inspired by the A244S torpedo when developing the NST58
TAL, a rather similar LWT with a modified acoustic head and guidance system,
exploiting a copy of the SAFT Mg-AgCI sea water battery.
Military Technology – MILTECH - 8/2008
Finally, the Chinese operate reverse engineering copies of both the Mk46 Mod2
(Yu-7) and more recently the A244S (ET52).
Cutaway drawing of the Mk54 torpedo, evidencing the NSDI components sourced from
other programmes.
Long-Range Torpedo Carriers
The use of ballistic rockets and guided missiles to carry ASW torpedoes arises
from the need to deliver the payload at ranges longer than the ship launch would
allow. Their use is mostly alternative to ASW helicopters and offers some clear
advantages. First of all no aircrew or expensive aircraft are required or put at risk
for delivering the ASW ordnance on top of the target submarine. While this risk is
admittedly relatively minor under the current operational conditions, things may
well take a distinct shift for worse should submarine-launched anti-aircraft
weapons become available. Second, once the boat is positively detected and
classified, the time of reaction is definitely shorter than the flight of a helicopter
to the launching point, and, third, the operation is not affected by adverse
environmental conditions.
On the other hand, a missile is just a weapon delivery system and doesn't offer
the same operational flexibility of a helicopter. Also, the ASW helicopter with its
dipping sonar would often be anyway indispensable to reconfirm the target as
first discovered by the ship's sonar, and thus it makes much practical sense to
have the helicopter also acting as the platform for immediate LWT delivery.
The most common ASW rocket is the US ASROC. The venerable Mk112 eight-cell
"pepperbox" ASROC launcher is now fitted to just some second-hand ex-US Navy
frigates serving into allied navies - with one important exception, though,
because all JMSDF destroyers are fitted with either the Mk112 or a Vertical
Launched ASROC (VLA) capability for their Mk41 VLS. The VLA features a
maximum range of 10km and carries a Mk46 Mod-5A(SW), while the Mk54-
carrying version should achieve IOC later this year and progressively replace the
previous model over the next ten years although in sharply reduced numbers
(nearly half the current inventory).
Military Technology – MILTECH - 8/2008
Lockheed Martin is currently developing the VLA-ER extended range version,
which will maintain 90% commonality with the existing weapons but will be
capable of four-five times the ranges through the addition of a wing glide kit (a
further increase to up to some 100km could be reached through spiral
developments). The VLA-ER is a potential weapon of choice for net-centric
warfare operations, in that it can exchange data during its flight and receive
target position updates. A VLA-ER variant without booster, called Common
Launch Anti-submarine Weapon (CLAW) is also being proposed for arming the P-
8A patrol aircraft, as a possible alternative to the HAAWC concept.
Copies of the VLA, or at least very similar weapons, are also being locally built in
Japan (N-ASROC) and South Korea (K-ASROC, a.k.a. RED SHARK).
Artist's impression of the High-Altitude ASW
Weapon Concept (HAAWC) for an air-launched
Mk54 lightweight torpedo fitted with a Long-
Shot wing adaptor kit with self-contained GPS
guidance.
A STINGRAY lightweight torpedo equips a
Royal Navy LYNX helicopter.
The only Western counterpart to ASROC is the Italian MILAS, i.e. an
OTOMAT/TESEO anti-ship missile airframe modified to carry an LWT (either the
Mk46 Mod-5, the A244S, or the MU90). The system, with a range of 55km, can
be controlled in flight from the very same consoles used for the OTOMAT. MILAS
was jointly developed by Italy and France, but is has been procured only by the
Italian Navy in very small numbers Oust twelve warshots).
Other conceptually Western similar systems such as the French MALAFON or the
British-Australian IKARA have since been withdrawn in light of the increasing
availability of helicopters and the comparably short detection ranges offered by
shipborne acoustic sensors against modern submarines in coastal waters.
The Russian Navy however still operates a number of similar weapons. The
submarine-launched RPK-7 VEDER (SS-N-16B STALLION) has a 650mm calibre
and carries a Type 40 torpedo to a range of up to 100km, while the 533mm RPK-
2 TSAKRA (SS-N-15 STARFISH) has a range of 45km and can be launched either
by submarines or surface ships. Other Russian surface-launch systems include
the obsolescent RASTRUB (SS-N14 SILEX) with a E53-72 torpedo and a range of
55km, and the new RPK-9 MEDVEDKA (SS-N-29) with a Type 40 torpedo and a
range of 25km.
The most recent addition is represented by the 91 RE1 12 members of the KLUB
(SS-N-27) family. These are ballistic anti-submarine missiles whose payload is an
underwater rocket-propelled homing torpedo. The 91RE1 is designed for surface
Military Technology – MILTECH - 8/2008
ship launch tubes, while the 91RE2 is designed for submarine torpedo tubes. The
maximum range is 50 and 40km, respectively. Is not clear whether the system is
already installed on operational submarines, and if it has been exported to China
or/and India together with the other anti-ship and land-attack variants of the
KLUB family. In any case, the expected detection ranges would not allow a full
exploitation of the range of the torpedo-carrying missiles, especially in case of
littoral encounters.
An air-launched STINGRAY
lightweight torpedo about
to enter water being
slowed down by its
parachute.
This is the procedure for
virtually all air-launched
LWTs.
The RBU6000 is one in a range of Russian "brute force" ASW
weapons, that are still being used for contemporary naval
designs.
Small & Smart
Another way to extend the delivery range of an LWT is to use an UAV. Back in the
sixties the US Navy established the Q-50C DASH as a long-range ASW weapon
carrier. As many as 750 drones were built for the US Navy and the Japanese
MSDF, but the revolutionary approach was soon abandoned after a great number
of drones were lost due to both technical problems and human mistakes.
Now, over forty years later the same concept has been resurrected, as the MQ-8B
FIRE SCOUT VTUAV will also be fitted with the Compact Rapid Attack Weapon
(CRAW). In turn, this is a derivative of the developmental 6.75" (171.5mm)
Common Very Lightweight Torpedo (CVLWT), suitable for use as hard-kill antitorpedo
torpedo onboard both surface ships and submarines. The demonstration
of CRAW will begin in 2009 and should extend to 2013, with air-drop homing and
engagement demonstrations planned for 2010 and 2011, respectively. CRAW will
be the main ASW armament of the MQ-8B VTUAVs operating from the Littoral
Combat Ships. It will offer a reduction factor in weapon size and weight of twothree
times compared to the present lightweight weapons, while still offering a
very high lethality versus most existing submarines.
The three most significant technology challenges for such a revolutionary change
are represented by the development of a single-crystal, high-power broadband
transducer capable to be fitted into the "needle nosed" torpedo; the production of
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a very compact battery with high rate power, suitable for weapon applications;
and, finally, a compact and effective warhead.
A new specific sonobuoy-like communication device will be used to ensure
guidance of the CRAW towards the target, before stepping into the small torpedo
autonomous terminal homing.
The RPK-9 MEDVEDKA
(picture shows the
launch tubes) is the
latest development in
Russian series of longrange
carriers for
lightweight torpedoes. It
carries a Type 40 torpedo
to a max. range of 25kin.
Some Russian-designed or
Russian-inspired surface
combatants still carry
torpedo tubes for
heavyweight ASW
weapons. Picture shows a
mid-ship detail of the
Indian Navy destroyer INS
MYSORE.
"Dumb" Weapons With Massive Punch
At the opposite extreme, the last category of ASW weapons to be summarised is
represented by multiple rocket launchers.
These weapons trace their origin back to an US WW2 concept ("Hedgehog"), and
can still be found on nearly all Russian, Indian, and Chinese surface warships.
Different models are available: RBU 1000 (1 km range, 6 tubes, 55kg warhead),
RBU 6000 (6 km range, 12 tubes, 31kg warhead), RBU 12000 (12km range, 10
tubes, 80kg warhead). China also built a local variant, though is more and more
relying on LWTs as its primary ASW weaponry. In all of these weapons, the
rockets are unguided and their depth charges are comparably dumb - yet for this
very reason they can't be jammed or deceived and deliver a brute slamming force
against the submarine. The RBUs are also being used as torpedo defence, both as
hard-kill effectors and as launchers for acoustic decoys, and can easily be
employed also against combat divers and underwater intruders.
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The planned engagement sequence of the extended-range version of the Vertical Launch
ASROC (VLA-ER).
It is worth to note that most of their western Counterparts (the Bofors 375mm
rocket launchers, the British LIMBO ASW mortar, the Norwegian TERNE and so
on) were progressively withdrawn from service as soon as LWT became available
and reliable. By contrast, the Russian attitude indicates a continued confidence in
the effects of delivering a real shower of explosive around a given area to
saturate the likely target position, rather than achieving a precise kill as an LWT
would be expected to do. As a result, the Russian Navy doesn't operate real
lightweight torpedoes beyond the 400mm weapons intended only as payload for
missiles or as helicopter armament, and the RBU rockets represent a sort of antisubmarine
CIWS. China operates alternatively either RBUs or LWTs, yet not
together on the same platform.
The MILAS long-range ASW
missile was developed in
Franco-Italian cooperation
based on the OTOMAT/TESEO
anti-ship/land-attack missile,
but it has entered limited
procurement only with the
Italian Navy.
The only recent western counterpart is the small ASW grenade launchers fitted to
some Swedish and Finnish vessels, like the Saab ALECTO and ASW-601 (1200m
range). Also in this case the launchers are being used also for different payloads
Military Technology – MILTECH - 8/2008
(chaffs, decoys) and the relevant vessels aren't fitted with LWTs (or, in a case,
limited to 400mm torpedoes) as the ASW rocket-propelled grenades are
considered especially useful in the extreme littoral waters of the archipelago, as
well as during intrusion incidents when the ASW action would be intended to force
the intruding submarine to surface with minor damages rather than sinking it.
Thus, yet another adaptation of traditional ASW weaponry to specific operational
needs.
New Heavyweight Torpedoes for the French Navy
The French Defence Procurement Agency (DGA) has selected DCNS as prime
contractor to deliver, integrate and maintain a new-generation heavyweight
torpedo to replace the F17Mod2 model currently carried by the French Navy
SSNs and SSBNs.
In detail, the €420 million contract covers the manufacture of about 100
torpedoes, an initial six-year period of post-delivery through-life support for the
proposed weapons and crew training, integration studies with French nuclearpowered
submarines as well as the validation and integration of the new
weapon with the submarine that will carry the first batch. Deliveries will start in
2015. Options include additional batches of production torpedoes that will be
ordered for successive submarines as each comes due for scheduled refit.
The French Navy's new torpedo will be derived from the BLACK SHARK torpedo
developed and marketed jointly by Finmeccanica subsidiary WASS (Whitehead
Alenia Sistemi Subacquei) of Italy in cooperation with DCNS, which will act as
prime contractor, design authority and lead integrator for the proposed weapon
system.
DCNS and WASS will supply complete torpedo subassemblies in line with their
respective areas of expertise, while DCNS will subcontract the manufacture of
the acoustic head to Thales Underwater Systems (TUS). The programme will be
led and managed by the Saint-Tropez plant with contributions by other DCNS
centres. The contract will represent some 50% of the Saint-Tropez plant's
workload.
With a range of over 50km and a top speed in excess of 50 knots, the new
heavyweight torpedo is designed to knock out enemy surface combatants and
submarines. Both the torpedo and its warhead, which is sized to destroy all
types of ships, comply with the demanding safety requirements laid down for
French nuclear-powered submarines. The 6m-long torpedo features electric
propulsion and wire guidance combined with final-phase autonomous homing
and counter-countermeasure capabilities. Like the BLACK SHARK, the new
torpedo will offer far higher performance than heavyweight types currently in
service.
The new torpedo, which will be fully compatible with the latest combat systems
carried by French submarines, opens up new development prospects for DCNS,
including international orders for heavyweight torpedoes for new-build
submarines or for the modernisation of complete submarine combat systems or
their weapon systems.
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