The littorals present a very complex environment in which the platform, weapon and the target interplay is dependent upon the real time and archival understanding of the medium parameters. The article aims to provide a perspective into the extent of the littoral underwater submarine threat and the constraints which hamper its successful prosecution. It also brings out the fact that the Blue water Navy would have to enhance its environmental understanding and modify its approach towards anti submarine operations to reduce likely attritions during littoral conflicts. The article brings out the imperative need to dove tail fundamental environmental research and Indian Naval requirements to tackle the threats in littorals.
By RADM Dr. S. Kulshrestha (Retd.), INDIAN NAVY
Abstract
The littorals
present a very complex environment in which the platform, weapon and the target
interplay is dependent upon the real time and archival understanding of the
medium parameters. The article aims to provide a perspective into the extent of
the littoral underwater submarine threat and the constraints which hamper its
successful prosecution. It also brings out the fact that the Blue water Navy
would have to enhance its environmental understanding and modify its approach
towards anti submarine operations to reduce likely attritions during littoral
conflicts. The article brings out the imperative need to dove tail fundamental
environmental research and Indian Naval requirements to tackle the threats in
littorals.
Introduction:
"...the
very shallow water (VSW) region is a critical point for our offensive forces
and can easily, quickly and cheaply be exploited by the enemy. The magnitude of
the current deficiency in reconnaissance and neutralization in these regions
and the impact on amphibious assault operations were demonstrated during Operation
Desert Storm." - Maj. Gen.
Edward J. Hanlon Jr., Director of Expeditionary Warfare, Sea Power, May 1997
A blue water
navy’s ability to execute maneuver in littorals is severely compromised due to
confined sea spaces, lesser depths, heavy traffic, threats due to lurking quiet
diesel submarines, coastal missile batteries, swarms of armed boats, deployed
mines and threats from the air. The definition of a littoral region encompasses
waters close to the shores as well as greater than 50 nm at sea. The Indian
Navy, like all the other blue water navies has not been fundamentally
positioned for close combat encounters. It is has generally been expected that
sea warfare would have standoff distances of at least 50/60 km if not more
between adversaries (outside range of
torpedoes and guns). If Carrier groups and anti ship cruise missile (ASCM)
cruisers are deployed, the standoff can be up to a couple of hundred kms (ASCM
and Air craft limits). However today littorals present an inevitable close
quarter engagement situation with CSG remaining well clear of coastal missile
batteries and aircraft operating from shore based airfields. In case of
countries like China, the CSG may even remain a thousand km away to save itself
from a barrage of carrier killer missile like the Don Feng 21 D with a range of
over 2000 kms .
Thus littorals
have withered away the advantage of the CSG and the big ships as manoeuvring in
close quarters is not feasible any more. The lighter ships would have to fight
in the littorals with a much larger risk of attrition from the diesel electric
submarine, mines, swarm of boats and shore based assets. The blue waters
represent large swaths of sea with adequate depths for operations, and much
less uncertainties in the sensor - weapon environment. The littorals are
confined zones with reducing depths and a very adverse sensor environment. This
has drastically compressed reaction times leading to requirements of great
agility for the men of war.
A worthy
defender is always considered to be in an advantageous position in the
littorals, fundamentally due to the intrinsic knowledge and experience in
operating in his home environment. It constitutes what the US DOD calls an
access denial area likely to impinge upon the US national interests in the Vision
2004 document this has been articulated as “To win on this 21st Century
battlefield, the U.S. Navy must be able to dominate the littorals, being out
and about, ready to strike on a moment’s notice, anywhere, anytime The Indian Navy has in all probability
identified areas in Arabian Sea, Bay of Bengal and Indian Ocean where it may
have to engage in littoral conflicts either singly or in concert with coalition
of navies, should such a contingency arise. On the other hand 26/11 had opened
the coasts to attack by terrorists and the Government of India has initiated
efforts to tighten its coastal security. As to the plans of defending own
littorals against a formidable expeditionary force, nothing much is known in
the open domain, in all likely hood it remains a simplistic defensive model due
to insufficient focus and the inevitable funding. The fact remains that ocean
rim state navies today are focussing more on littoral capability than building
a blue water navy. Indian Navy has to consider the littoral capability
seriously whilst modernising and achieve a balance, depending upon its current
and future threat perceptions. The blue water force has to have an embedded
littoral component force so that the IN can operate in littorals far away from
her home ports.
The major
under water threats comprise of mines and undetected diesel submarines. However
as far as mines are concerned, they are every coastal country’s weapon of
choice as they are economic, easy to lay but very hard to detect and sweep.
They are the psycho sentinels of defence, since unless their existence is
proved it has to be assumed that waters are mine infested and have to be swept
before warships can attempt a foray in to the littorals . The clearing of mines
for safe passage is a very time consuming and intensive exercise which
introduces significant delays in any operation, while taking away element of
surprise and granting time to adversary to plan tactics. Therefore in case
delays are not acceptable, littoral operations would have to cater for some
attrition on account of mines as well as navigation hazards posed due to sunken
or damaged ships on the sea route.
The aim of
this article is to derive a perspective in to the fundamental dimensions of the
littoral medium, platform and weapon with respect to the underwater submarine
threat which constitutes the most potent hazard to a powerful navy.
Operating
Littoral Environment
The littorals comprise of different types of zones in which a Navy has to operate. These include continental shelf, surf zones, straits and archipelagos, harbors and estuaries. The main thrust of naval operations hinges upon the underwater acoustics (sonic ray plots) which provide not so accurate measure of effectiveness of Sonars. In the continental shelf not much is known about the tactical usage of bioluminescence, plankton or suspended particles and other non acoustic environmental information. Quantifiable effect on performance of different sensors and weapons under various conditions is also not available to the Commander to help him deploy them optimally. Further predictions about conditions for naval operations in continental shelf areas of interest are at best sketchy and no reliable database exists to provide correlation between various environmental conditions that may be encountered. In the surf zone region (within 10 m depth line till the beach), temporal and spatial environmental data is required for effective planning of naval operations however, there are large variations in acoustic data over short and long term. Archipelagos and straits are subject to; swift changes in currents and water masses due to restricted topography, dense shipping, fishing and human traffic which complicate planning. Most of the harbors are estuarine in nature and present a highly intricate and variable environment (tides, currents, wave amplitudes etc) warranting a holistic approach to understand the same.
Image Attribute: RADM Dr. S. Kulshrestha (Retd.), INDIAN NAVY
Thus it can be
seen that carrying out missions in littorals also involve other aspects of
environment in addition to the uncertain under water acoustics which have a
direct bearing on the missions. These aspects include real time and archival
data bases of; meteorological surface conditions required for efficient
operation of IR, Electro optical, and electromagnetic sensor and weapon
systems; under water topography, accurate bathymetry, bottom composition, and
detailed assessment of oceanographic water column environment for under water
sensors and weapons.
The
availability of overarching oceanic environmental knowledge would provide
insight into enemy submarine operating/hiding areas, location of mines and
underwater sea ward defences. Currently the Indian Navy does not have the
capability to carry out exhaustive littoral environmental scanning let alone
field any sensor or weapon system that can adapt to the dynamic littoral
environment and carry out missions with conviction. In fact, even for own littoral
zones this type of information is not available which would enable effective
deployment of static or dynamic defences.
Effect of
Environment on Propagation of Sound in Shallow Waters
A brief
description of the acoustic environment in shallow waters is relevant at this
stage. The main factor affecting acoustic propagation in deep oceans is the
increase in pressure of water column with increasing depth as the temperature
remains nearly constant. The speed of sound increases with depth and the sound
waves finally hit the bottom and reflect upwards. In shallow waters the rays
tend to refract, that is bend upward without going to the bottom. This
phenomenon takes place when the refracted sound velocity equals the sound
velocity emitted by the source. On reaching the region of the source they again
refract towards the depths and this process continues. In very shallow waters the sound rays are
reflected upwards from the bottom. The amount of sound energy reflected upwards
depends directly on the nature of the sea bottom. Harder the sea bottom better
is the reflection and vice versa. In shallow waters it is clear that the sound
speed depends mainly on the temperature which in turn depends upon the amount
incident solar radiation, wind speeds, wave action etc.
It can
therefore be inferred that the acoustic signal in shallow waters is dependent
upon factors like temperature, sea surface, nature of sea bottom, waves and
tides, in-homogeneities and moving water masses amongst others. These present a
very complex effect on the acoustic signal by altering its amplitude,
frequency, and correlation properties. Further, multi-path reflections from the
bottom, as well as surface put a severe constraint on signal processing. The
understanding of the underwater sound propagation remains unsatisfactory to
this day. The complex interplay of acoustics, oceanography, marine geophysics,
and electronics has bewildered Navies searching for submarines or mines in the
shallow waters. Two fundamental issues that of beam forming and lining up the
sonar are discussed in the subsequent paragraphs.
Zurk et
al in their paper “Robust Adaptive
Processing in Littoral Regions with Environmental Uncertainty” have addressed a
real time problem in underwater, i.e. the dynamic nature of the sensor, target,
medium and the interfering element’s geometry. The moving sensor, target and
medium causes difficulties for adaptive beam former sonars which are designed
to assume a certain level of stationary conduct over a specified time period .
The time period required is dependent upon the number of elements in the array
and the coherent integration time. Since large arrays give much better
resolution they have a larger number of
elements, leading to a moving source transiting more beams during a given
observation period. If target is in motion, the target energy is distributed
over many beams weakening the signal and degrading the accuracy of targets
location. The arrays with larger volumes thus have larger probability of motion
losses. Some techniques to reduce these errors include sub-aperture processing,
time-varying pre-filtering of the data, and reduced-dimension processing.
Naval sonar
systems have become more and more complex over time and require expert
operators. Optimizing sonar line ups has become essential in a littoral
environment where the acoustic properties change rapidly over time and space
domains. With the sonar automatically determining the optimal line up based
upon desired inputs from the operator and the sensor feeds of operating environment,
the sonar operator would be able to give his full attention to the task of
detection, identification and classification of the targets. The necessity
of autonomous environmentally adaptive
sonar control is imperative in littorals because of the tremendously large
number of objects which may be present below the water line and skills of the
operator would be put to test to sieve out the elusive submarines.
Warren L.J.
Fox et al. “Environmental Adaptive Sonar Control in a Tactical Setting.” Have addressed the issue of sonar line up
and have recommended neural networks for generating acoustic model simulations
required. Control schemes for Sonars are
of two types, namely acoustic model-based and rule-based. Model-based
controllers embed an acoustic model in the real-time controller. In acoustic
model based controllers, acoustic performance predictions are inputted in to
the controller, based upon available estimates of the existing environment,
which in turn, gives the feasible sonar line ups. The choice of line up depends
upon the chosen parameters for the operation. In the rule based controller, a
generic set of operating environmental conditions are defined by the sonar and
acoustic experts, which are then subjected to acoustic modeling and the sonar
equations to generate the best possible line up. The existing environmental
conditions would have to be assessed in real time prior to selection of the
best line up available as per design. This approach however may not account for
the large number of varying environments that are the hallmark of different
littorals, and lead to discrepancies in results. Thus it appears that acoustic
model based controller may be a better choice, as it largely takes care of the
prevailing conditions at sea, than the rule based one, but it requires much
more computational power and time to assess the situation prior to lining up
the sonars. Warren L.J. Fox et al have
recommended a method of training artificial neural networks for use in a sonar
controller for ships as well as unmanned under water vehicles, to emulate the
input/output relations of a computationally intensive acoustic model.
Artificial neural networks are much faster and utilize far lesser computational
capacity.
The Submarine
Threat in Littorals
The shallow
waters pose a serious problem for under water acoustics, they remain unfriendly
to current sensors like towed arrays, variable depth sonars and air dropped
sonobuoys due to depth limitations, deployment of torpedoes ( both ship and air
launched) and depth charges. Shallow waters with close proximity to land also
pose difficulties for radars and magnetic anomaly detectors thus providing a
relatively safe operating area for small diesel electric submarines. Detection
of surface craft by submarines in passive sonar mode is much easier because of
their higher acoustic signatures. The surface ships would perforce resort to
active sonar transmission as their passive capabilities are degraded in
littorals. This in turn makes them more acoustically visible.
The littoral submarine however has a limited period of quiet operation under water of a couple of days, as it has to either surface or snorkel for recharging its batteries by running its diesel generator sets. The battery capacity drainage is directly proportional to the running speeds, faster the submarine travels quicker is the discharge and hence larger is the discretion rate, which is the charging time required. Interestingly it is this discretion rate, which allows the submarine to be vulnerable to detection. During charging, the radiated noise of diesel generators, the IR signatures and the likely visibility of the snorkel make it susceptible to observation by trained crews. The submarine therefore prefers to lie in wait, barely moving or just sitting at the bottom for the prey to arrive.
The littoral submarine however has a limited period of quiet operation under water of a couple of days, as it has to either surface or snorkel for recharging its batteries by running its diesel generator sets. The battery capacity drainage is directly proportional to the running speeds, faster the submarine travels quicker is the discharge and hence larger is the discretion rate, which is the charging time required. Interestingly it is this discretion rate, which allows the submarine to be vulnerable to detection. During charging, the radiated noise of diesel generators, the IR signatures and the likely visibility of the snorkel make it susceptible to observation by trained crews. The submarine therefore prefers to lie in wait, barely moving or just sitting at the bottom for the prey to arrive.
Image Attribute: A typical Littoral Warfare Submarine Concept - Andrasta SSK by DCNS
Development of
Air independent propulsion technology (AIP) has enhanced the submerged time of
submarines by a great extent (from a couple of days to about two weeks). The
AIP is dependent upon availability of oxygen on board. The AIP while granting
more submerged time to a submarine unfortunately provides the same level of
acoustic signature as a snorkelling submarine, thus making it prone to
detection.
Fuel cell
technology has been successfully interfaced with AIP and Siemens 30-50 KW fuel
cell units have been fitted in the German Type 212A submarines since 2009, it
is said to be much quieter , provides higher speeds and greater submerged time.
The weapons
for the submarines include mines, torpedoes and the submarine launched
missiles. The technology ingress in computing, signal processing, hull design
and materials have benefitted the submarine, its sensors, weapons and fire
control systems. These advances coupled with vagaries of the acoustics in
shallow waters have made the diesel submarine a very potent and lethal
platform. While many countries have AIP submarines, of interest to India is the
acquisition of these submarines by Pakistan
since the Indian Navy does not operate an AIP submarine. The Indian Navy
today even lacks the adequate numbers of diesel electric submarines required.
The Unmanned
Submarine (Unmanned Underwater Vehicle; UUV)
An UUV
generally is a machine that uses a propulsion system to transit through the
water. It can maneuver in three dimensions (azimuth plane and depth), and
control its speed by the use of sophisticated computerized systems on-board the
vehicle itself. The term Unmanned underwater vehicle includes, remotely
operated vehicles, Paravane, sea gliders and autonomous underwater vehicles.
It can be pre
programmed to adhere to course, speed and depths as desired by the operator, at
a remote location and carry out specific tasks utilizing a bank of sensors on
the UUV. The data collection can be both time and space based and is referenced
with respect to coordinates of the place of operation. It can operate under
most environmental conditions and because of this, they are used for accurate
bathymetric survey and also for sea floor mapping prior to commencing
construction of sub-sea structures. The Navies use them for detecting enemy
submarines, mines, ISR and area monitoring purposes etc.
Image Attribute: REMUS 600 AUV/UUV by Kongsberg
Maritime AS
The
UUVs carry out their routine tasks unattended, meaning there by that once
deployed the operator is relatively free to attend to other tasks as the UUV
reaches its designated area of operation and starts carrying out its mission,
be it survey, search, or surveillance.
Compared with
many other systems, UUVs are relatively straightforward, with fewer
inter-operable systems and component parts, facilitating reverse-engineering of
any components that might be restricted in the commercial market place. All of
these factors, however also increase the likelihood that even a low tech
littoral adversary could easily field offensive, autonomous UUVs, this in turn
leads to seeking rapid developments in UUVs by major navies.
UUVs are on
the verge of three developments which would accelerate their induction into
modern navies. First is the arming of UUVs to create Unmanned Combat Undersea
Vehicles (UCUVs). This is virtually accomplished with UUV designs incorporating
light weight torpedoes as weapons of choice. Heavier UUVs are contemplating missile
launchers and/or heavy weight torpedoes as weapons in their kitty. However
these appear to be interim measures, as a new class of weapons specific to
unmanned vehicles are already under advanced development. These include much
smaller and lighter missiles, torpedoes and guns firing super-cavitating
ammunition.
A second
potential technology development is radically extended operational ranges for
these armed UUVs. Already, the developed countries have invested in programs to
create long-range underwater “sea gliders” to conduct long-range Intelligence
Preparation of the Operational Environment (IPOE) missions . While the
technologies enabling the “sea glider” approach probably do not provide the
flexibility and propulsion power to enable armed UUVs, such programs will
significantly advance the state of UUV navigation and communications
technologies. Leveraging these advancements, other nascent technologies such as
Air-independent-propulsion (AIP) or Fuel Cell propulsion or perhaps
Aluminium/Vortex Combustors, could provide the propulsion power necessary to
effectively deploy armed UUVs even well outside of the operating area
limitations of conventionally powered submarines.
Finally,
“autonomy” for these armed, long range UUVs will allow them the flexibility to
conduct operations far away from the home port. Artificial intelligence (AI)
based autonomous control systems are being developed at a frenetic pace,
fuelled principally by demand for improved UAVs. Such developments will
directly contribute to UUV autonomy, but in fact, are not actually necessary
for the majority of “sea denial” missions envisioned for UCUVs. Even with
current state of missile seeker technology, UCUVs would only need enough
autonomy to navigate to a known area of operations (a port, choke point, or
coastal location) and launch, and the missile would do the rest. For more
complex missions, weapons could be guided by an on-site observer, for instance
on a trawler or even ashore, in real-time or near-real-time. In short, there
are a remarkably small number of “hard” technology barriers standing in the way
of the long range, autonomous, armed and capable UUVs. There is little reason
to think that this capability will be limited to high end, navies only. Thus
networked operations of unmanned vehicles with PGMs are going to become the
lethal weapon combo for the future.
A request for
information has been floated by the Indian Navy to meet its requirement for at
least 10 autonomous underwater vehicles (AUVs). These AUVs are to be developed and
productionised within four years of contract finalisation. The Navy has opted
for a special category MAKE for the armed forces under the Indian Defence
Procurement Procedure for high technology complex systems designed, developed
and produced indigenously .Modular payload capability of the AUVs have been
asked for, where in payloads like
underwater cameras for surveillance reconnaissance and high definition sonars
can be mounted.
UUVs in various configurations
and roles such as communication and navigation nodes, environmental sensors in
real time or lie in wait weapon carriers are going to be the choice platform in
the littorals. These are expendable if required, economically viable, and offer
flexibility in design as being unmanned they can have much lesser degree of
safeties.
Weapons
“The Navy’s
defensive MCM capabilities in deep water are considered fair today, but they
are still very poor in very shallow water (VSW) – not much better in fact than
they were some 50 years ago.”
Milan Vego.
The naval mine
is a relatively cheap, easy to employ, highly effective weapon that affords
weaker navies the ability to oppose larger, more technologically advanced
adversaries. The mere existence of mines poses enough psychological threat to
practically stop maritime operations, and thus deny access to a desired area at
sea. Further they can be used as barricades to deter amphibious forces and
cause delays in any naval operation in the littoral. Thus, a mine doesn’t have
to actually explode to achieve its mission of access denial. North Koreans were
able to deter and delay arrival of U.S Marines sufficiently to escape safely,
by mining Wonsan Harbour in October of 1950 with about 3000 mines.
Mines are
classified based upon their depth of operation, methods of deployment or the
way they are actuated. The versatility of deployment can be gauged by the fact
that mines can be laid by majority of surface craft, submarines, crafts of
opportunity and aircrafts/ helicopters. Mines have been used by countries and non
state actors alike with dangerous effects and thus continue to pose a credible
threat to Navies as well as merchant marine.
Types of mines are based upon
the depth at which they are deployed. As per the 21ST Century U.S. Navy Mine Warfare
document the underwater battle space has
been divided into five depth zones of, Deep Water (deeper than 300 feet),
Shallow Water (40-300 feet), Very Shallow Water (10-40 feet), the Surf Zone
(from the beach to 10 feet) and the Craft Landing Zone (the actual beach). Mines
are of three basic types namely, floating or drifting mines, moored or buoyant
mines and bottom or ground mines.
Drifting mines
float on surface and are difficult to detect and identify because of factors
like visibility, sea state and marine growth etc. Moored mines are tethered
mines using anchoring cables to adjust their depths. These can be contact or
influenced based mines. Bottom mines are most difficult to locate as they can
also get buried under sediment layer which cannot be penetrated by normal
sonars.
Mines can be
actuated by contact, influence, and by remote or a combination thereof. With
modular Target Detection Device (TDD) upgrade kits, the older contact mines can
be easily upgraded to actuate by influence methods. The influence needed for
actuation could be pressure, acoustic or magnetic or a desired combination. In
addition ship counters and anti mine counter systems are also being
incorporated in to the mines to make them much more potent and lethal.
Mine
technology has kept a step ahead of the ships designs for low acoustic and
magnetic signatures, and many countries are engaged in development and
production of naval mines. Non metallic casings, anechoic coatings, modern
electronics and finally reasonable costs have made mines a choice weapon for
poor and rich nations alike. It is estimated that about 20 countries export
mines while about 30 produce them. Sweden Russia, China and Italy are the
leading exporters. Mine MN 103 Manta from SEI SpA of Italy is one of the most
exported mines in the world with about 5,000 Mantas in inventories throughout
the world.
It is
estimated that China has in its inventory about a hundred thousand mines of
various vintages and from the WWI simple moored contact mines to modern
rocket-propelled mines with advanced electronic systems for detection and
signal processing.
The submarine torpedoes are an embodiment of a synergetic mix of engineering disciplines ranging from mechanics, hydraulics, electronics, acoustics, explosive chemistry etc. to sophisticated software and computing. Their development has therefore involved differences in propulsion designs from steam engines to electrical motors to thermal engines and rocket motors. The control and guidance systems have also evolved from simplistic mechanical/ hydraulic to sophisticated electronic and onboard computer based systems. The guidance has further diversified in to self guided and wire guided varieties. The simple straight runners have given way to active passive homers and wake homers to attack moving targets. The warheads have moved from minol based to TNT/RDX/Al and now on to insensitive explosives with a life of over 40 years. The warheads over the years have been fitted with simple contact exploders, to acoustic influence and magnetic influence proximity fuses. The diameter of the torpedoes has ranged from 324mm to 483mm to 650mm, and before settling for internationally acceptable 533mm. Interestingly with the advent of microelectronics space has never been a constraint for the torpedo and electronic/ software updates always get comfortably accommodated in the torpedo.
The submarine torpedoes are an embodiment of a synergetic mix of engineering disciplines ranging from mechanics, hydraulics, electronics, acoustics, explosive chemistry etc. to sophisticated software and computing. Their development has therefore involved differences in propulsion designs from steam engines to electrical motors to thermal engines and rocket motors. The control and guidance systems have also evolved from simplistic mechanical/ hydraulic to sophisticated electronic and onboard computer based systems. The guidance has further diversified in to self guided and wire guided varieties. The simple straight runners have given way to active passive homers and wake homers to attack moving targets. The warheads have moved from minol based to TNT/RDX/Al and now on to insensitive explosives with a life of over 40 years. The warheads over the years have been fitted with simple contact exploders, to acoustic influence and magnetic influence proximity fuses. The diameter of the torpedoes has ranged from 324mm to 483mm to 650mm, and before settling for internationally acceptable 533mm. Interestingly with the advent of microelectronics space has never been a constraint for the torpedo and electronic/ software updates always get comfortably accommodated in the torpedo.
Image Attribute: Loading of Mk 48 Adcap Torpedo in HMAS Rankin / Source: Wikimedia Commons
A major
technical feature that sets apart a torpedo from a missile is the fact that a
practice torpedo is recoverable for reuse; this enables excellent weapon
capability assessment, crew training as well as analysis of vital firing
geometry. Some of the noteworthy heavy weight torpedoes are the American Mk 48
Adcap, the Italian Blackshark, the German DM2A4 and the Russian 53-65 K oxygen
torpedo.
The torpedo
has been evolving with leaps in technology but some characteristics towards
which the heavy weight torpedoes are headed include; faster speeds (~over 60
Kts), Quieter signature, better reliability in detection, enhanced ranges of
operation (>100 Kms),smarter electronics, and increased lethality.
The cruise
missile owes it origins to the German V1/V2 rockets and mainly to the fact that
manned aircraft missions had proved to be very expensive during the wars (loss
of trained fighter pilots as well as expensive aircraft). Unfortunately the
cruise missile development until the 1970s resulted only in unreliable and
inaccurate outcomes which were not acceptable to the armed forces. Cruise
missiles overcame their inherent technical difficulties and owe their
tremendous success and popularity to some of the technological advances in the
fields of; firstly, propulsion, namely small turbofan jet engines which
resulted in smaller and lighter airframes; secondly miniaturization of
electronic components, which led to much smaller on board computers thus to
much better guidance and control abilities and finally, high density fuels and much better explosives
and smaller warheads.
Cruise missiles have become
weapons of choice at sea because of their ability to fly close to the sea
surface at very high speeds (sub-sonic/supersonic), formidable wave point
programming and lethal explosive capabilities. These make the missiles very
difficult to detect and counter at sea. Some of the naval cruise missiles worth
mentioning are the Brahmos, the Tomahawk, the Club and the Exocet family.
It appears
that the trend towards hypersonic scramjet cruise missiles will continue to
gather momentum and such missiles could be in the naval inventories by 2020.
Coupled with hypersonic missiles would be real time target data updating and
guidance by extremely fast computers and satellite based systems. The kinetic
energy of hypersonic cruise missiles would be a lethality multiplier against
targets at sea and therefore such a missile would be a formidable weapon
without a credible countermeasure as on date. The costs continue to increase with
new developments; however maintenance requirements appear to be reducing with
canistered missiles.
As Far as
weapons are concerned the Indian Navy has a fairly reliable capability in
mines, torpedoes and cruise missiles, however the numbers appear deficient for
the defensive role in own littorals.
The submarines
today can launch such missiles from their torpedo tubes or from vertical
launchers which can also be retrofitted. In fact the submarines can launch
torpedoes, missiles, UUVs and also lay mines comfortably. Thus making them, the
toughest of platforms to counter.
Conclusion
“The marriage
of air independent, nonnuclear submarines with over-the-horizon, fire and
forget antiship cruise missiles and high endurance, wake homing torpedoes . . .
[means that] traditional ASW approaches, employing radar flooding and speed,
are not likely to be successful against this threat.” -
The dimensions
of submarine threat in the littorals, discussed briefly above encompass the
underwater acoustic environment, the developments in submarine technology, the
underwater unmanned vehicle, and the weapons. The discussion has brought out
the potent danger an undetected submarine in littorals presents to the
aggressor.
The Navy today
faces a deficiency in an all inclusive understanding of the undersea
environment in the coastal areas due to which it is difficult to counter the
diesel electric submarine threat in the littorals. This deficit would not allow
correct positioning and deployment of sensors for timely detection of the
underwater peril. Research and development is also needed in the quality of
sensors such that they are embedded with real time environmental information
and can calibrate themselves accordingly for best results. As far as other
environmental sensors are concerned, like those dependent on zoo plankton
behaviour or bioluminescence fundamental research needs to be initiated with
naval needs in focus. The acquisition of submarines and UUVs should be fast
tracked if Indian Navy wants to be a credible littoral force.
About The Author:
The author RADM Dr. S. Kulshrestha (Retd.), INDIAN NAVY, holds expertise in quality assurance of naval armament and ammunition. He is an alumnus of the NDC and a PhD from JNU. He superannuated from the post of Dir General Naval Armament Inspection in 2011. He is unaffiliated and writes in defence journals on issues related to Armament technology and indigenisation.
Note:
1. The speed of sound
is given by the equation (available in text books):-C(T,P,S)=1449.2+4.6 T+0.055
T2+1.39 (S−35)+0.016 D(1) / Where: C is in m/sec, T in ° Celsius, D in metres and
embodies density and static pressure effects. S in parts per thousand.
The speed of
sound is dependent upon temperature and depth because the S, the salinity is
nearly constant at 35 ppt for sea water.
References:
[i] G D Bakshi
China - Dong Feng 21-D: A Game Changer?
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[ii] VISION |
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[iii] US Navy
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[iv]Robert J.
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[v] Lisa M.
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[vi] Warren L.J. Fox et al. “Environmental
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[1] Benedict,
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[viii] Rajat Pandit, Pak adding submarine muscle as
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[ix] K. L.
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[x] Milan
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[xi] 21ST Century U.S. Navy Mine Warfare,
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[xii] Scott C. Truver. TAKING MINES SERIOUSLY Mine
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[xiii] Malcolm I.
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as published in Submarine Review (October 2000), p. 34.
_________________________________________
Publication Details:
Kulshrestha,
Sanatan. "FEATURED | Dimensions of Submarine Threat in the Littorals –A Perspective
by RADM Dr. S. Kulshrestha (Retd.), INDIAN NAVY." IndraStra Global 01, no.
11 (2015): 0408. http://www.indrastra.com/2015/11/FEATURED-Dimensions-of-Submarine-Threat-in-the-Littorals-by-RADM-Dr-S-Kulshrestha-Retd-INDIAN-NAVY-0408.html.
|ISSN 2381-3652| https://dx.doi.org/10.6084/m9.figshare.2064207
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