Torpedoes in Anti-Submarine Warfare

Submariners hold to the saying, “sink a submarine before it fires its weapons”. The great battles of the World War II and the nerve-racking years of the Cold War has seen dominant forces race towards greater supremacy in this domain. Nazi U-boats and its predatory nature were among the most feared forces during the WWII. Moving in packs, they cruised the cold, dark water of the Atlantic Ocean, infusing fears among US sailors during the years. 

Later comes the Cold War. The tense relationship between the US and the Russian has put the world on high alert. The rivalry between the US and the Soviet Union took many forms; political, cultural as well as economic ideological. However, overshadowing all was the threat of nuclear war. War was imminent. Fortunately though, the war did not take place. Both nations managed to endure years of jittery relationship sensibly. However, in this article, it is important to stress on how submarines, during the years played its role as the nations’ most crucial offensive power – so crucial that nuclear powered submarine commanders were seen as the most powerful men on earth.

ASW – Questioning Its Significance

Post-Cold War, anxiety emerged from the West, questioning the relevance of underwater warfare, specifically pointing to the nuclear submarines. Elsewhere, blue-water operations are slowly but surely moving inland, towards shallower waters. The hide and seek game against deep-and-fast nuclear powered submarines are now replaced with the race against diesel/electric submarines. These diesel/electric submarines posses a distinct feature that puts them ahead of the nuclear submarines – they are stealth. Backed by its stealthy character, these submarines are able to lie motionless near the bottom while awaiting its prey.

Going diesel/electric, these submarines are able to minimise their noise projection hence enabling them to evade sonar detection. In addition, they can also manipulate waters with poor acoustic conditions, which are normally found in shallow or littoral waters. These conditions grant them tremendous strategic advantage in battle theatre. 

The significance of Anti-submarine Warfare (ASW) is furthermore highlighted with the equipment of soft-kill and hard-kill anti-torpedo defence suites onboard navy ships. ASW capabilities have today become the main focus among naval forces. Possessing a physically powerful edge in ASW equalises to the ability to project offensive and defensive power in the underwater domain.

In Asia specifically the East and Southeast Asia, the underwater arms race is rapidly taking place. Small nations with small and compact naval forces, such as the Indonesia, Malaysia, Singapore, Korea, China and Japan are arming themselves with submarines, ships with ASW capabilities as well as anti-submarine aircraft.

The Republic of Singapore Navy for example patrols the sea with six Formidable-class frigates. Each vessel sails along a Sikorsky S-70B helicopter equipped with anti-surface and anti-submarine combat systems. Surrounding waters are hostile hence the need of robust ASW capabilities not only for the island-nation of Singapore, but also for its neighbouring countries including Malaysia, Indonesia, Brunei and other ASEAN members.

Exercise Dynamic Mongoose 2014 was successfully conducted far north in February this year. Under the aegis of NATO, the exercise saw the participation of submarines from naval forces including France, Portugal and Norway. Additionally, other NATO members namely Germany, Norway, Poland and the UK dispatched a number of surface ships during the exercise while additional personnel from the US and Canada were present to provide assistance.

During the exercise, all participating members have staged various tactical ASW scenarios including submarines and aircraft detection, tracking and engagement as well as group escort against submarine threats.

Despite loud voices that are questioning the significance of the ASW in the 21^st century, procurement of submarines, equipment of ASW combat suites, added by exercises held in international waters have proven that ASW will remain significant in modern warfare. Submarines are becoming more and more lethal by continually undergoing enhancement and development thus stressing the point of having reliable ASW capabilities not only for big powers but also for small nations.

The Torpedo in ASW

Modern days torpedo is a mature weaponry technology that stretches back to 1866 when Robert Whitehead invented his infamous Whitehead torpedo. Torpedo technology has since undergone tremendous improvement – from random launch at sea to today’s modern torpedoes with self-guided tracking system.

As the ASW retains its significant existence in modern warfare, one cannot deny the importance of equipping torpedoes onto submarines and ships. As one of the most lethal offensive instrument at sea, torpedo, despite its long history has remained the choice of naval forces due to its efficiency. Naval forces today stress on the importance of having torpedoes in their inventory. The presence of submarines in regional waters has caused stirs among nations, especially in dealing with underwater threats.

Young nations such as Singapore, Malaysia and Brunei are newcomers in the ASW domain and all are currently beefing up their ASW capabilities. Other than procuring submarines and ships with ASW capabilities to deal with underwater threats, the development plans too include the purchase of torpedoes – both lightweight and heavyweight torpedoes.

This article discusses on arrays of latest lightweight torpedoes with a small proportion of heavyweight torpedoes as well. The torpedoes will consist of MK54, MU90, APR-3E as well as Blackshark and Spearfish heavyweight torpedoes to name a few. We will focus on some important parameters such as speed, range, guidance systems, propulsion as well as suitable launch platforms.

APR-3E

The intelligent innovation of the APR-3E is that it gives enemy forces no time to react. Its launch scenario is that it enters the water without starting the engine. It will first search for targets using its acoustic homing guidance system and the engine will only fire-up once target is identified. This innovation, according to its designer and manufacturer, Russian Tactical Missile Corporation JSC, is to increase the torpedo’s kill probability by providing targets no time to react.

The torpedo is made of turbo water jet propulsion system and a 74kg warhead for greater damage projection. Maximum speed is rated at 56 knots and its range, according to TMC, is approximated at 3km maximum. As an air-launched ASW lightweight torpedo, and being Russian, the APR-3E can be launched from a few Russian fixed and rotary wing aircraft including Tu-142, Il-38 and Ka-27 helicopter. However, the torpedo requires a minimum launching depth of 100 metres to allow airdrop.

AS244/S

AS244/S is a lightweight torpedo with 32.7kg warhead developed by the French/Italian EuroTorp consortium. The torpedo features a fire-and-forget, active/passive acoustic homing guidance system and can be deployed from surface or airborne platforms. It has a maximum range of approximately 23km while capable of attaining to a top speed of 50 knots.  The latest version of the torpedo is the AS244/S mod 3 and the torpedo is widely used by many of the Asian navies. Among the navies that posses the AS244/S torpedo in their inventory include the Royal Malaysian Navy, Republic of Singapore Navy, Indonesian Navy, and Indian Navy.

MK54

Raytheon’s MK54 lightweight torpedo remains as one of the most successful torpedo ever in production today. The US, Australia and India are currently cruising the oceans armed with the MK54 torpedo as their main lightweight torpedo. MK54 torpedo has an engagement range of around 10km and thanks to its Otto II propellant, is capable of achieving a top speed of more than 40 knots. MK54 guidance system consists of active/passive acoustic homing devices and its warhead weighs approximately 44kg. India becomes the torpedo’s latest user in June 2011 when they made the purchase of 32 MK54 torpedoes, amounted to a total of $86million. Latest update saw the P-8A Poseidon becoming the torpedo’s latest launch platform. The aircraft has successfully launched the torpedo during a flight test and as the replacement of the P-3C Orion, the P-8A Poseidon is now regarded as the US Navy’s latest addition of submarine adversary.

MU90/Impact

As a fire and forget torpedo, the MU90 can be launched from all three domains-from underwater, surface and airborne platforms. Its history began out of the join venture effort of Thomson Sintra’s Murène and Whitehead’s A290 torpedo, a replacement of their A244 torpedo. Its introduction in 1993 after the successful formation of EuroTorp Consortium has put the MU90 as one of the leading lightweight torpedoes among European navies.

The torpedo is designed to encounter variety of threats including nuclear and the more modern diesel/electric submarines with deployment relies heavily on its active/passive acoustic homing guidance system. The torpedo has a maximum engagement range of approximately 23km at its minimum speed while capable of cruising the water at a speed of 50 knots propelled by its pump-jet/electric propulsion system. Its long range and high-speed engagement capabilities are furthermore enhanced with the delivery of a 32.7kg warhead to its target, boosting its fear factor among enemy forces.

Currently, over 1000 rounds of the MU90 torpedo have been ordered by the navy of France, Italy, Germany, Denmark and Poland. Australia in August last year has successfully conducted a series of test-fire of the MU90 torpedo, after years of delay. The commissioning of the torpedo into the Australian navy in late last year marked the near success of the $639 million project.

YU-7/MK46

The Chinese is the best reverse-engineers in the world. No one can deny this fact. They are a group of people capable of reproducing anything out of something. While the reverse engineering is nothing but uncommon among the Chinese, little knows that they too have put their skills in the defence sector. The production of the YU-7 torpedo is a great symbol of a successful reverse engineering effort in China’s booming defence industry. The history of YU-7 leaps back in to the 1970’s when a number of US-made MK46 torpedoes were recovered by a group of Chinese fishermen. The Chinese government approved the development effort and a full-scale process began in 1984. The Chinese lack of knowledge in torpedo development was covered-up when they, in 1985 sealed an $8 million deal with the US to purchase a number of MK46 Mod 2 torpedoes including its technological support. Development of the YU-7 torpedo continues until late 1990’s when it successfully went into full production.

Looking at its specification, one will identify that the torpedo, more or less resemble the MK46 torpedo. Its guidance system is made of active/passive homing acoustic system, and its propulsion system consists of the more conventional Otto II fuel. While its maximum engagement speed may reach an astounding 65 knots, it has a limited range of 7km. Among other torpedoes mentioned in this article, the YU-7 stands as the second most lethal torpedo after the Russian APR-3E, with the arming of a 45kg warhead.

Heavyweight Torpedoes Go Faster, Further and Stronger 

Though the lightweight torpedo is gradually becoming more efficient, heavyweight torpedoes remain as naval forces’ number one choice to ensure more promising striking damage over enemy threats. Today’s lightweight torpedo capabilities are nowhere near the capabilities of the heavyweights. Heavyweight torpedoes possess greater range, higher speed and most importantly superior  explosive power.

Spearfish heavyweight torpedo developed by BAE Systems is currently in service with the Royal Navy. BAE Systems was responsible for development and manufacturing process of the torpedo. The torpedo is designed to engage submarines and surface targets, and it was first declared operational onboard HMS Vanguard ballistic missile submarine in 1994.

Its guidance system consists of two systems, either the autonomous active/passive homing guidance or wire-guided. Meanwhile, its propulsion system is made of a Sunstrand gas turbine engine coupled to a pump jet. This propulsion system enables the torpedo to strike targets at a maximum speed of 80 knots and at a range of approximately 23km to 54km.

Meanwhile, Whitehead Alenia Sistemi Subacquei (WASS) Black Shark torpedo features a silent electrically powered brushless motor propulsion system, and can be deployed from both submarines and surface platforms. Black Shark torpedo has an estimated engagement range of 50km with a maximum speed of approximately 50 knots.

Royal Malaysian Navy Scorpene-class submarines are armed with the Black Shark torpedo.

Its sensing capabilities is enhanced through the introduction of the Advanced Sonar Transmitting and Receiving Architecture (ASTRA) an active/passive acoustic homing guidance system introduced by WASS. Apart from acting as a torpedo guidance system, WASS too has admitted that the ASTRA system is potentially capable to operate as submarine’s additional sensor system.

Currently, the heavyweight torpedo is in service with the French, Italian and Chilean navies. The torpedo is currently arming the Scorpene submarines of the Malaysian and Indian navy to name a few.