Torpedoes are self-propelled guided projectiles that operate underwater and are designed to detonate on contact or in proximity to a target. For the U.S. Navy, the modern torpedo enables submarines to defeat surface and undersea threats and gives surface ships and aircraft the means to reach beneath the surface and attack submarines.
During World War II, submarine and aircraft-dropped torpedoes sank hundreds of merchant ships and warships. Unlike the numerous aerial bombs or cannon shells required to sink large warships, just one or two torpedo hits could and sometimes did suffice to sink huge aircraft carriers and battleships.
Torpedoes are the primary weapons of most submarines and anti-submarine warfare platforms. They are typically classified as being either lightweight (air dropped or rocket-delivered) or heavyweight (submarine or ship launched); with lightweight torpedoes carrying smaller warheads and having reduced range and endurance;; the primary distinction being not a particular weight but the mode of delivery, warhead and endurance. Lightweight torpedoes are designed to be delivered by aircraft or rocket, and typically have a warhead in the 40kg range. A lightweight torpedo is designed to be dropped very close to the target, and therefore has no wire guidance and frequently begins a programmed search pattern on entering the water. Lightweight torpedoes are typically ASW-only weapons with no ability to engage surface targets. Torpedoes primarily vary in their guidance mode and performance characteristics such as maximum depth, maximum speed and sensor performance. Torpedoes can be countered with acoustic countermeasures, decoys and even anti-torpedo torpedoes.
A heavyweight torpedo is typically fired from a submarine or surface ship and may have wire guidance. Compared to a lightweight torpedo a heavyweight torpedo will usually be much larger and have a warhead in the 300kg range. A heavyweight torpedo is designed to be launched from its firing platform and then travel to the target at high speed before acquiring the target and homing in on it (with the exception of WW2 era ‘straight runners’). Heavyweight torpedoes tend to be dual purpose ASW and ASuW weapons, however some older types are clearly more suitable for one type of target than any others (e.g. the Mk 36 is able to outrun submarines of its era but is unlikely to catch up to a surface ship). Submarine launched heavyweight torpedoes may be guided with a wire that connects them to their firing platform. This allows the firing platform to retain control over the torpedo, setting waypoints, changing speed and depth and even selecting a different target after launch.
Torpedoes are the most preferred lethal underwater weapons for naval platforms such as submarines, surface vessels, aircraft and helicopters. But limited range has long been the torpedo’s major drawback. Unlike a missile which travels through the thin atmosphere, a torpedo must fight harder to reach its target. Countries are in race to develop long range lethal torpedoes with unlimited range.
Belgorod will be the first vessel armed with Russia’s Poseidon intercontinental nuclear-powered nuclear-armed autonomous torpedo. Putin alluded to the upcoming launch of Belgorod in his address to the Federal Assembly on 20 February 2019, saying, “In this connection, I would like to make one important remark. Nothing has been said about this so far, but it is possible to do so today. In the spring of this year the first nuclear-powered submarine armed with this unmanned vehicle [Poseidon] will be launched.” In the November 2015 ‘leak’, a profile illustration of Belgorod was shown on the leaked slide, together with the Khabarovsk and Sarov . The slide indicated that Belgorod will carry six Poseidon torpedoes. Jane’s assesses that Poseidon is likely to be a very large torpedo-like vehicle that can travel at great depth, at torpedo-like speeds of approximately 50–60 knots, and for an effectively unlimited range, to deliver a nuclear warhead.
Russia is seeking to further bolster its sub-surface capabilities, with new generations of conventional and nuclear propulsion submarines, which promise to be significantly more difficult to detect and track for western naval forces. This includes the Yasen, Lada, and Kalina classes of submarines. In recent times, Russia has also demonstrated its growing capability to perform land attack missions with submarines. In December of 2015, a Russian submarine in the Mediterranean fired Kalibr missiles against land targets in Syria.
The U.S. Navy is now prototyping a new, longer range and more lethal submarine-launched heavyweight Mk 48 that can better destroy enemy ships, subs and incoming weapons at longer ranges, service officials said. The Mk-48 torpedo is designed to be launched from submarine torpedo tubes. The weapon is carried by all U.S. Navy submarines, including Ohio-class ballistic missile submarines and Seawolf-, Los Angeles-, and Virginia-class attack submarines. It is also used on Canadian, Australian, Brazilian and Dutch submarines.
The U.S. Navy, aiming to make its attack submarines even more stealthy and lethal at extended ranges, took a big step forward with a contract announcement in June 2018. The Office of Naval Research awarded Aerojet Rocketdyne a contract that aims to increase the efficiency of the engine of its Mark 48 heavyweight torpedo, a weapon designed to kill deep-diving Soviet submarines and advanced surface ships, according to a release from the company.
The idea behind extending the range of the torpedo is to keep valuable submarines away from potential targets and allow a third party (a P-8 Poseidon overhead, for example) to relay the targeting data, Clark said. “Through third-party targeting, you can use it as a standoff weapon,” he said. “If you can extend that range to 50 or more miles, you can attack submarines without your sub having to hold that target organically with its sensors.” At those ranges, it’s unlikely the submarine would give away its position by firing a torpedo, he said. Using this method, he added, the service can get the most out of the weapons packed on the attack boat.
“If you have 30 torpedoes onboard, you may only have one or two targets within range of your sensors and weapons,” Clark said, arguing that with third-party targeting, one could conceivably use the submarine as a submerged arsenal. The concept is similar to the cooperative engagement technology that the surface navy is developing, where an aircraft such as an F-35 or E-2D detects an incoming hostile track and relays kill-quality target data to the ship for engagement with a long-range missile, such as an SM-6. Applying the same concept to the submarine world still has some issues, however, because torpedoes fired at long ranges take a good long while to reach their targets, Clark said.
World’s deadliest Torpedoes
Black Shark Advanced (BSA)
The Black Shark Advanced (BSA), a new generation multi-role heavyweight torpedo fired from submarines or surface ships, is designed to counter threats from all surface and underwater platforms. The Black Shark is currently being produced by Whitehead Alenia Sistemi Subacquei (WASS) for several major naval forces and has been integrated into Scorpene, U209, U214 and U212 submarines.
The wire guided, self-homing torpedo has 21-inch diameter and integrates an ASTRA (Advanced Sonar Transmitting and Receiving Architecture) and high explosive warhead. The propulsion system with Al-AgO battery, contra-rotating brushless motor and skewed propellers ensures a maximum speed of 50kt and range of 50km.
F21 Heavyweight Torpedo
The F21 heavyweight torpedo from DCNS is a dual-purpose torpedo that is effective against submarines and surface vessels. The 1.3t F21 can be integrated into all types of submarines including nuclear-powered SSBNs and SNs as well as diesel-electric types, and can be launched in swim-out or push-out modes. It incorporates a new-generation acoustic head from Thales Underwater System, in addition to an impact/acoustic fuse warhead.
The F21 can be operated in depth ranging from 10m to 500m and is driven by electric propulsion based on the silver oxide-aluminium (AgO-Al) primary battery providing a speed of 25kt to 50kt, range of over 50km and endurance of one hour.
Spearfish Heavyweight Torpedo
The Spearfish advanced heavy weight torpedo from BAE Systems is effective against submarine and surface threats in oceanic and coastal waters. The 1.85t torpedo is in service with the submarine fleet of the UK Royal Navy. The Spearfish carries Aluminised PBX explosive warhead of 300kg and is directed towards the target by high-capacity guide wire system and passive and active sonar.
Its power plant is composed of a gas turbine engine using Otto Fuel as a liquid monopropellant, and Hydroxyl Ammonium Perchlorate (HAP) as oxidant. The propulsion system allows the Spearfish to engage targets within 48km at low speed.
Torpedo 62 (Torpedo 2000)
The Torpedo 62 (Export designation: Torpedo 2000) from Saab is a dual-purpose heavy weight torpedo system in use with the submarine fleet of the Royal Swedish Navy. It can be effectively launched against all types of submarines and surface ships. The Torpedo 62 has a launch weight of 1,450kg and can carry high explosive warhead. The torpedo operates at depths of 500m and is guided by active/passive homing system. The torpedo is propelled by an advanced pump jet engine and can engage targets within the range of over 40km, at a maximum speed of 40kt.
DM2A4/SeaHake mod 4
The DM2A4 Seehecht (Export Name: SeaHake mod 4) is the main under water weapon of the German Navy’s Type 212 submarines. The heavyweight torpedo, weighing 1.37t, can be launched from both submarines and surface ships. Developed by Atlas Elektronik, the SeaHake mod 4 torpedo employs fibre optic wire guidance to accurately engage underwater and above-water targets, and carries a 255kg warhead.
The torpedo is equipped with a high frequency permanent magnet motor and silver zinc battery modules ensuring a maximum speed of 50kt and a range of over 50km (27nmi).
The three major torpedoes in the Navy inventory are the Mark 48 heavyweight torpedo, the Mark 46 lightweight and the Mark 50 advanced lightweight. The lightweight torpedo gives surface ships, airplanes, and helicopters the means to destroy threat submarines.
A Mk 48 torpedo is 21 inches in diameter and weighs 3,520 pounds; it can destroy targets at ranges out to five miles and travels at speeds greater than 28 knots. The weapon can operate at depths greater than 1,200 feet and fires a 650-pound high-explosive warhead. The MK 48 is propelled by a piston engine with twin, contra-rotating propellers in a pump jet or shrouded configuration. The engine uses Otto fuel propulsion system, a liquid monopropellant fuel,that decomposes into hot gas when ignited, which drives the engine. The thrust is generated by a propulsor assembly
The MK 48 has a sophisticated guidance system permitting a variety of attack options. As the torpedo leaves the submarine’s launch tube a thin wire spins out, electronically linking the submarine and torpedo. This enables an operator in the submarine, with access to the submarine’s sensitive sonar systems, initially to guide the torpedo toward the target. This helps the torpedo avoid decoys and jamming devices that might be deployed by the target. The wire is severed and the torpedo’s high-powered active/passive sonar guides the torpedo during the final attack. The MK48 Mod 5, with its improved guidance system, and the MK48 Mod 6 with low noise propulsion, provide the fleet with torpedoes whose performance is unmatched in deepwater scenarios.
Lockheed Martin developed the new version of the Mk-48 under a five-year $425 million contract that was awarded in 2011. The new Mod 7 is also resistant to advanced enemy countermeasures. Modifications to the weapon improves the acoustic receiver, replaces the guidance-and-control hardware with updated technology, increases memory, and improves processor throughput to handle the expanded software demands required to improve torpedo performance against evolving threats, according to Navy information on the weapon. The Mod also provides a significant reduction in torpedo radiated-noise signatures, a Navy statement said.
The Mk48 Mod 7 Common Broadband Advanced Sonar System (CBASS) torpedo is optimized for both the deep and littoral waters and has advanced counter-countermeasure capabilities. Compared to older versions of the venerable Mk-48, the new modular Mod 7 variant increases sonar bandwidth. It can transmit and receive pings over a wider frequency band and it takes advantage of broadband signal processing techniques to greatly improve the weapon’s search, acquisition and attack effectiveness. The torpedo’s seeker has an active electronically steered “pinger” (2D phased array sonar) that helps avoid having to maneuver as it closes with the target. The earlier version, the Mk 48 Mod 6, has been operational since 1997 – and the more recent Mod 7 has been in service since 2006.
The Common Broadband Advanced Sonar System (CBASS) upgrades to ADCAP will extend the current sonar array on the weapon into a broadband mode and improve the onboard signal processing to provide enhanced operation against countermeasures and diesel submarines operating in the littorals. “This provides streamlined targeting and allows the torpedo to transmit and receive over a wider frequency band,” Tom Jarbeau, Director and General Manager of Targets, Torpedoes and Sensors, Lockheed Martin, said.
The submarine missions now increasingly take place in shallow-water littoral areas. The Chief of Naval Operations continues to stress shallow water (less than 600 feet) as a critical operating area to counter third world diesel electric submarines. Acoustic reverberation, poor sound propagation, local ship traffic, false targets, and bottom clutter all make torpedo operations more difficult in this noisy operating environment.
MK-48 and MK-48 ADCAP torpedoes can operate with or without wire guidance and use active and/or passive homing. When launched they execute programmed target search, acquisition and attack procedures. Both can conduct multiple reattacks if they miss the target.
The earlier MK 48 Mod 5 ADCAP torpedo was an improvement to the MK 48 submarine launched torpedo. The ADCAP enhancement included all digital guidance and control systems, digital fuzing systems, and pro-pulsion improvements which add speed, depth, and range capability. The ADCAP version, in comparison with earlier MK 48 torpedoes, has improved target acquisition range, reduced vulnerability to enemy countermeasures, reduced shipboard constraints such as warmup and reactivation time, and enhanced effectiveness against surface ships.
In 2015 the USN announced plans to restart production and seek a more modular design. “ In the torpedo restart, we are going to be making this a truly modular design that you can pull out a section and plug in different payloads or different propulsion systems or different fuel supplies, and so as you’re developing the payloads you ought to be thinking about how you integrate with the modular Mk 48 some new capabilities and the like,” Program Executive Office for Submarines Executive Director George Drakeley said.
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