The Mark 48 and its improved Advanced Capability (ADCAP) variant are American heavyweight submarine-launched

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such ...

es. They were designed to sink deep-diving

nuclear-powered Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced b ...

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

s and high-performance surface ships.

History

The Mark 48 was initially developed as REsearch TORpedo Concept II (RETORC II), one of several weapons recommended for implementation by

Project Nobska Project Nobska was a 1956 summer study on anti-submarine warfare (ASW) for the United States Navy ordered by Chief of Naval Operations Admiral Arleigh Burke. It is also referred to as the Nobska Study, named for its location on Nobska Point near ...

, a 1956 summer study on

submarine warfare Submarine warfare is one of the four divisions of underwater warfare, the others being anti-submarine warfare, Naval mine, mine warfare and Naval mine, mine countermeasures. Submarine warfare consists primarily of Diesel engine, diesel and nu ...

. The Mk-48 torpedo was designed at the end of the 1960s to keep up with the advances in

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

technology. Operational since 1972, it replaced the Mk-37, Mk-14 and Mk-16 torpedoes as the principal weapon of U.S. Navy submarines. With the entry into service of the new Soviet in 1977, the decision was made to accelerate the ADCAP program, which would bring significant modifications to the torpedo. Tests were run to ensure that the weapon could keep up with the developments and the weapon was modified with improved acoustics and electronics. The new version of the weapon, also known as Mk-48 Mod 5, was extensively tested and production started in 1985, with entry into service in 1988. From then on, various upgrades have been added to the torpedo. the Mk-48 Mod 6 was in service; a Mod 7 version was test fired in 2008 in

Exercise RIMPAC The Rim of the Pacific Exercise (RIMPAC) is the world's largest international maritime warfare exercise. RIMPAC is held biennially during June and July of even-numbered years from Honolulu, Hawaii, with the exception of 2020 where it was held ...

. The inventory of the

U.S. Navy The United States Navy (USN) is the maritime service branch of the United States Department of Defense. It is the world's most powerful navy with the largest displacement, at 4.5 million tons in 2021. It has the world's largest aircraft ...

in 2001 was 1,046 Mk-48 torpedoes. In 2017 Lockheed's production was approximately 50 per year.

Deployment

The Mk-48 torpedo is designed to be launched from submarine torpedo tubes. The weapon is carried by all

submarines, including

ballistic missile submarines A ballistic missile submarine is a submarine capable of deploying submarine-launched ballistic missiles (SLBMs) with nuclear warheads. These submarines became a major weapon system in the Cold War because of their deterrence theory, nuclear ...

and -, -, and

attack submarine An attack submarine or hunter-killer submarine is a submarine specifically designed for the purpose of attacking and sinking other submarines, surface combatants, and merchant vessels. In the Soviet Navy, Soviet and Russian Navy, Russian navies ...

s. It is also used on Canadian, Australian, and Dutch

submarines A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or info ...

. Mk-48 and Mk-48 ADCAP torpedoes can be guided from a submarine by

wire file:Sample cross-section of high tension power (pylon) line.jpg, Overhead power cabling. The conductor consists of seven strands of steel (centre, high tensile strength), surrounded by four outer layers of aluminium (high conductivity). Sample d ...

s attached to the torpedo. They can also use their own active or passive sensors to execute programmed target search, acquisition, and attack procedures. The torpedo is designed to

detonate Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves wit ...

under the

keel The keel is the bottom-most longitudinal structural element of a watercraft, important for stability. On some sailboats, it may have a fluid dynamics, hydrodynamic and counterbalancing purpose as well. The keel laying, laying of the keel is often ...

of a surface ship, breaking the keel and destroying its structural integrity. In the event of a miss, it can circle back for another attempt.

Propulsion

The swashplate piston engine is fueled by

Otto fuel II Otto fuel II is a monopropellant mixture of chiefly propylene glycol dinitrate (an ester of nitric acid and propylene glycol, and structurally similar to nitroglycerin) that is used to drive torpedoes and other weapon systems. It was invented by ...

, a

monopropellant Monopropellants are propellants consisting of chemicals that release energy through exothermic chemical decomposition. The molecular bond energy of the monopropellant is released usually through use of a catalyst. This can be contrasted with biprop ...

which combusts to drive the engine. The thrust is generated by a

propulsor {{short description, Mechanical device to propel a vessel A propulsor is a mechanical device that gives propulsion. The word is commonly used in the marine vernacular, and implies a mechanical assembly that is more complicated than a propeller. The ...

assembly, which is an axial-flow pump-jet with approximately 15 rotor blades and 12 stator blades based on US Navy computer graphics from 2011.

Sensors and improvements

The torpedo's seeker has an active electronically steered "pinger" (2D

phased array In antenna (radio), antenna theory, a phased array usually means an electronically scanned array, a computer-controlled Antenna array, array of antennas which creates a radio beam, beam of radio waves that can be electronically steered to point ...

sonar) that helps avoid having to maneuver as it approaches the target. Unconfirmed reports indicate that the torpedo's sensors can monitor surrounding electrical and magnetic fields. This may refer to the

electromagnetic coil An electromagnetic coil is an electrical Electrical conductivity, conductor such as a wire in the shape of a wiktionary:coil, coil (spiral or helix). Electromagnetic coils are used in electrical engineering, in applications where electric curre ...

s on the warhead (at least from 1977 to 1981), used to sense the metallic mass of the ship's hull and detonate at the proper stand-off distance. The torpedo has been the subject of continued improvement over its service lifetime. In the 1990s, a Mod 6 variant of the ADCAP provided much improved

noise Noise is sound, chiefly unwanted, unintentional, or harmful sound considered unpleasant, loud, or disruptive to mental or hearing faculties. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrat ...

isolation for the engine, which makes this torpedo more difficult to detect for a potential target. 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. The MK48 ADCAP Mod 7 (CBASS) torpedo is the result of a Joint Development Program with the Royal Australian Navy and reached Initial Operational Capability in 2006. The modular Mod 7 variant increases sonar bandwidth, enabling it to transmit and receive pings over a wider frequency band, taking advantage of broadband signal processing techniques to greatly improve search, acquisition, and attack effectiveness. This version is much more resistant to enemy countermeasures. On July 25, 2008 a MK 48 Mod 7 CBASS torpedo fired by an Australian , , successfully sank a test target during the Rim of the Pacific 2008 (

RIMPAC The Rim of the Pacific Exercise (RIMPAC) is the world's largest international maritime warfare exercise. RIMPAC is held biennially during June and July of even-numbered years from Honolulu, Hawaii, with the exception of 2020 where it was held ...

) exercises. In 2015 the USN announced plans to restart production and seek a more modular design.

Lockheed Martin The Lockheed Martin Corporation is an American Arms industry, defense and aerospace manufacturer with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta on March 15, 1995. It is headquartered in North ...

is to upgrade existing Mark 48s to include a new guidance-control system known as the Common Broadband Advanced Sonar System (CBASS), in addition to improving propulsion and resistance to

electronic countermeasures An electronic countermeasure (ECM) is an electrical or electronic device designed to countermeasure, trick or deceive radar, sonar, or other detection systems, like infrared (IR) or lasers. It may be used both offensively and defensively to deny ...

. Starting in 2003, the US Navy began the Stealth Torpedo Enhancement Program which aims to upgrade the capability of the existing Mk 48 design by implementing alternative fuel sources including electric fuel cells, and a "swim out" capability, a capability that allows a torpedo to leave the tube under its own power without using a torpedo tube's noisier compressed air-launch system. The program is ongoing, with many details yet classified. Torpedo Mark 48 Evolution

Operators

Current operators

* * * * * *

References

External links

Mk 48 at Raytheon CompanyUS Navy Fact File
{{DEFAULTSORT:Mark 48 Torpedo Cold War anti-submarine weapons of the United States Military equipment introduced in the 1970s Raytheon Company products Torpedoes of the United States