Mark 24 Tigerfish

Mark 24 Tigerfish

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The Mk 24 Tigerfish torpedo was a heavyweight acoustic homing
Acoustic homing
Acoustic homing is a system which uses sound to guide a moving object, such as a torpedo. Acoustic homing can be either Passive or Active in nature....

 torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

 used by the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 (RN) for several years. The early Mod0 and Mod1 variants were unreliable and unsuccessful, and were issued to the RN even though they failed Fleet Weapon Acceptance. Reliability was significantly improved in the Mod2 variant as a result of the Consolidation Programme which addressed the complete weapon system i.e. the on-board fire control system (TCSS10 and DCB) and the Mk24 torpedo. The Consolidation Programme was initiated following the torpedo's reliability failures during the Falklands War
Falklands War
The Falklands War , also called the Falklands Conflict or Falklands Crisis, was fought in 1982 between Argentina and the United Kingdom over the disputed Falkland Islands and South Georgia and the South Sandwich Islands...

 and was headed up by Marconi Underwater Systems Limited
Marconi Electronic Systems
Marconi Electronic Systems , or GEC-Marconi as it was until 1998, was the defence arm of The General Electric Company . It was demerged from GEC and acquired by British Aerospace on November 30, 1999 to form BAE Systems...

 as Prime Contractor with Ferranti Computer Systems Ltd
Ferranti
Ferranti or Ferranti International plc was a UK electrical engineering and equipment firm that operated for over a century from 1885 until it went bankrupt in 1993. Known primarily for defence electronics, the Company was once a constituent of the FTSE 100 Index but ceased trading in 1993.The...

 and Gresham Lion as major sub-contractors. Tigerfish was eventually replaced in-service by the much more capable Spearfish torpedo
Spearfish torpedo
The Spearfish torpedo is the heavy torpedo used by the submarines of the Royal Navy. It can be guided by wire or by autonomous active or passive sonar, and provides both anti-submarine warfare and anti-surface ship warfare capability.It replaces the unreliable Tigerfish torpedo, which was...

.

It is fitted with both active and passive sonar and can be remotely controlled through a thin wire which connects it to the launching submarine. Wire guidance permits a torpedo to be launched on-first-warning, i.e., when a target is first detected at long range. This permits the torpedo the time needed to close the range while target course and speed is being updated by the submarine's superior sensors and transmitted 'down-the-wire'; and also permits the torpedo to be re-assigned to another target or recalled. Typically, wire-guided torpedoes run at high speed to close the range (the approach speed) and slow down to minimise self-generated noise interference with on-board sensors during the attack phase (the attack speed).

Design and development


The initial concept developed in the mid-1950s was for a very fast (55 knot/100 km/h), deep-diving torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

 driven by an internal combustion engine, carrying high pressure oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 as oxidant, guided by a wire system developed from the Mackle wire-guidance study dated 1952 using data transmitted from the firing submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

s and using an autonomous active/passive sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

 developed from the abandoned 1950s UK PENTANE torpedo project.

The weapon was known as Project ONGAR because Ongar railway station was, until 1994, the last on the Central Line
Central Line
The Central line is a London Underground line, coloured red on the tube map. It is a deep-level "tube" line, running east-west across London, and, at , has the greatest total length of track of any line on the Underground. Of the 49 stations served, 20 are below ground...

 of the London Underground
London Underground
The London Underground is a rapid transit system serving a large part of Greater London and some parts of Buckinghamshire, Hertfordshire and Essex in England...

 system. The engineers developing this weapon
Weapon
A weapon, arm, or armament is a tool or instrument used with the aim of causing damage or harm to living beings or artificial structures or systems...

 were confident that it would be so advanced that it would be "...the end of the line for torpedo development".

The programme ran into serious problems in the late 1950s because the technology required was too advanced to meet an in-service target date of 1969. In addition, the closure of the Torpedo Experimental Establishment, Greenock
Greenock
Greenock is a town and administrative centre in the Inverclyde council area in United Kingdom, and a former burgh within the historic county of Renfrewshire, located in the west central Lowlands of Scotland...

, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

 in 1959 and the migration of its staff to Portland
Portland Harbour
Portland Harbour is located beside the Isle of Portland, off Dorset, on the south coast of England. It is one of the largest man-made harbours in the world. Grid reference: .-History:...

 in Dorset
Dorset
Dorset , is a county in South West England on the English Channel coast. The county town is Dorchester which is situated in the south. The Hampshire towns of Bournemouth and Christchurch joined the county with the reorganisation of local government in 1974...

 disrupted the pace of development.

In the early 1960s a series of wide-ranging reviews (one report was titled "Whither ONGAR?" - the pun being intentional) led to a greatly reduced performance specification which was realistically expected to achieve an in-service date of 1969.

The propulsion system was changed from an internal combustion engine to an electric motor with a silver zinc battery as the power source. This reduced the planned speed of the weapon from 55 knots to 24 knots (100 km/h to 44 km/h) with a short final attack phase capability at 35 knots (64 km/h).

The homing system was simplified by the exclusion of the anti-surface ship capability in the Mod 0 weapon.

Only the wire-guidance system was retained relatively unchanged. This was similar to the system used on the earlier Mk 23 torpedo.

The original requirement for a crush depth of 1,000 ft (300 m) was overtaken by rapid advances in SSN deep-diving performance, and the requirement was progressively increased to 1,600 ft (490 m) and then 2,000 ft (600 m). Tigerfish never met these requirements and the best that could be achieved was 1,150 ft (350 m) and later 1,450 ft (440 m); the structure was incapable of further crush-depth development.

In-service performance


Early models suffered from poor reliability: only 40% of the Mod 0 ASW model performed as designed. The torpedo depended in large part on the remote-control system, but the weapon tended to dip during launch, severing the control wire. The Mod 0 failed its initial fleet acceptance trials in 1979 but was nevertheless issued to the fleet in 1980. The Mod 1 DP (dual purpose) anti-submarine and anti-ship model also experienced problems, though a redesigned version (Mod 2) passed sea trials in 1978 and was issued the following year. When HMS Conqueror
HMS Conqueror (S48)
HMS Conqueror was a nuclear-powered fleet submarine that served in the Royal Navy from 1971 to 1990. She was built by Cammell Laird in Birkenhead...

 sank the ARA General Belgrano
ARA General Belgrano
The ARA General Belgrano was an Argentine Navy light cruiser in service from 1951 until 1982. Formerly the , she saw action in the Pacific theater of World War II before being sold to Argentina. After almost 31 years of service, she was sunk during the Falklands War by the Royal Navy submarine ...

 during the 1982 Falklands war
Falklands War
The Falklands War , also called the Falklands Conflict or Falklands Crisis, was fought in 1982 between Argentina and the United Kingdom over the disputed Falkland Islands and South Georgia and the South Sandwich Islands...

 she used the "point and shoot" Mark 8 torpedoes rather than her Tigerfish. The Mark VIII had no homing system but, despite the design being over 50 years old at the time, were far more reliable and carried a greater high explosive payload. In a test carried out by submarines returning to the UK after the war two of five Mod 1 Tigerfish fired at a target hulk failed to function at all and the remaining three failed to hit the target

A measure of the Royal Navy's desperation for a reliable means of dealing with fast, deep-diving time-urgent targets at long range resulted in a project to arm Tigerfish with a nuclear warhead to offset its poor diving depth and homing performance and to increase kill probability close to 90%. Various other measures were proposed in mid-1969, including purchase of the U.S. Mark 45 ASTOR nuclear torpedo, or the U.S. Mark 48 Mod-1
Mark 48 torpedo
The Mark 48 and its improved ADCAP variant are heavyweight submarine-launched torpedoes. They were designed to sink fast, deep-diving nuclear-powered submarines and high-performance surface ships.-History:...

, or Subroc from the United States, or at the initiative of Flag Officer Submarines (FOSM), fitting a nuclear warhead to the unguided, shallow-running and short-ranged, but reliable 21" Mark 8 torpedo. Flag Officer Submarines minuted that the proposal to arm the Mark 8 with the WE.177
WE.177
WE.177 was the last air-delivered tactical nuclear weapon of the British Armed Forces. There were three versions; WE.177A was a boosted fission weapon, while WE.177B and WE.177C were thermonuclear weapons...

A warhead would, despite the torpedo's performance shortcomings, be "much superior to any present British submarine weapon ..." However, the short range of the Mark 8 put the firing submarine within damage range of the nuclear warhead of its torpedo.

The Marconi
Marconi Company
The Marconi Company Ltd. was founded by Guglielmo Marconi in 1897 as The Wireless Telegraph & Signal Company...

 Consolidation Programme of the early 1980s finally produced the Mod 2 with reliability improved to 80%, which the Royal Navy accepted as the best that could be achieved with a basic design that was incapable of further development. By 1987 all 600 Tigerfish had been modified to the Mod 2 standard.

The tribulations with the Tigerfish torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

 development, from its concept in the mid-1950s to the introduction of the unsuccessful Mod 0 variant into Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 service in 1980, were responsible for the decision to purchase cruise missiles to attack ships from Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

submarines.

Versions were:
Mark 24-Mod-0 for ASW use. Dive depth 1,150 ft (350 m).
Mark 24-Mod-1 (or Mark 24 DP) for ASW and ASV use. Dive depth 1,450 ft (442 m).
Mark 24-Mod-1-N for ASW and ASV use. Dive depth 1,450 ft (440 m). The nuclear version - paper study only.
Mark 24-Mod-2 for ASW and ASV use. Dive depth 1,450 ft (440 m). The Marconi upgrade.


In 1990 Cardoen of Chile was granted a license to manufacture Tigerfish for the Chilean, Brazilian and Venezuelan navies.

The Royal Navy retired the last of the Tigerfish torpedoes from service in February 2004.