British 21-inch torpedo

There have been a number of 21-inch (53.3cm) torpedoes in service with the Royal Navy of the United Kingdom.

Torpedoes of 21-inch caliber were the largest torpedoes in common use in the RN. They were used by surface ships and submarines; aircraft used smaller 18-inch torpedoes.

Mark I

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The first British 21-inch torpedo came in two lengths, "Short" at 17 ft 10.5 in (5.448 m), and "Long" at 23 ft 1.25 in (7.042 m). The explosive charge was 200 lb (91 kg) of gun cotton, increased later to 225 lb (102 kg).

Mark II

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21-inch Mark II
TypeHeavy Torpedo
Place of originUnited Kingdom
Service history
In servicec. 1914 – Second World War
Used byRN
WarsFirst World War, Second World War
Production history
Designedc. 1910
Specifications
Diameter21 in (530 mm)

WarheadTNT
Warhead weight400 to 515 lb (181 to 234 kg)

EngineWet Heater
Operational
range
8,000 yd (7,300 m) max depending on model
Maximum speed 29 to 35 kn (54 to 65 km/h)

The Mark II, chiefly used by destroyers, entered service in 1914. Apart from some older British ships, it was used with the old US (destroyers-for-bases deal) Town-class destroyers provided to the UK during the early part of the Second World War. The running speed was reduced from 45 kn (83 km/h) (over 3,000 yards) for better reliability.

The Mark II*, an improved Mark II, was used by battleships and battlecruisers. A wet heater design, it could run for 4,500 yd (4,100 m) at 45 knots (83 km/h).

Mark IV

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21-inch Mark IV
TypeTorpedo
Place of originUnited Kingdom
Service history
In servicec. 1916 – Second World War
Used byRN
WarsFirst World War, Second World War
Production history
Designedc. 1912
Specifications
Mass3,206 lb (1,454 kg)
Length22 ft 7.5 in (6.896 m)
Diameter21 in (530 mm)

WarheadTNT
Warhead weight515 lb (234 kg)

EngineWet Heater
Operational
range
8,000 to 13,500 yd (7,300 to 12,300 m)
Maximum speed 25 to 35 kn (46 to 65 km/h)

The Mark IV torpedo was the principal British torpedo of World War I. From 1912, used by destroyers, torpedo boats, and other surface ships equipped with 21-inch torpedo tubes, such as the Royal Sovereign class battleships. In the Second World War they were carried as auxiliary armament on submarines and various surface ships, including HMS Hood.

Mark V

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21-inch Mark V
TypeTorpedo
Place of originUnited Kingdom
Production history
Designed1917
Specifications
Length23 ft 4 in (7.1 m)
Diameter21 in (530 mm)

EngineWet Heater
Operational
range
5,000 to 13,600 yd (4,600 to 12,400 m)
Maximum speed 20 to 40 kn (37 to 74 km/h)

The Mark V was used by the A and B-class destroyers and, with modification, by the Kent-class heavy cruisers.

Mark VII

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21-inch Mark VII
TypeHeavy Torpedo
Place of originUnited Kingdom
Service history
In serviceSecond World War
Used byRN
Production history
Designed1920s
Specifications
Length25 ft 6 in (7.77 m)
Diameter21 in (530 mm)

WarheadTNT
Warhead weight740 lb (340 kg)

EngineOxygen enriched air
Operational
range
5,700 yd (5,200 m)
Maximum speed 35 kn (65 km/h)

The Mark VII was issued for use on the British heavy cruisers, i.e. cruisers with 8-inch guns. Designed in the mid-1920s the County-class cruisers were built at the same time in the post Washington Naval Treaty period.

The power came from the use of oxygen-enriched air, though torpedo stocks were converted to run on normal air at the start of the Second World War.

Mark VIII

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Mark VIII torpedoes being loaded onto the Polish Navy submarine ORP Sokół.

The Mark VIII was designed circa 1925 and was the first British burner cycle design torpedo. It was used from 1927 on all submarines, beginning with the later versions of the L class and the Odin class, as well as motor torpedo boats. The principal World War II version was the improved Mark VIII**, 3,732 being fired by September 1944 (56.4% of the total number). The torpedo is still in service with the Royal Navy albeit in a limited role,[citation needed] and was used by the Royal Norwegian Navy (Coastal Artillery: Kaholmen torpedo battery at Oscarsborg Fortress) until 1993.

Specifications:[1]

Mark VIII

  • Entered service: 1927
  • Weight: 3,452 lb (1,566 kg)
  • Length: 259 in (6.6 m)
  • Explosive charge: 750 lb (340 kg) TNT
  • Range and speed: 5,000 yd (4,600 m) at 40 kn (74 km/h)

Mark VIII**

  • Explosive charge: 722 lb (327 kg) Torpex, later increased to 805 lb (365 kg) Torpex
  • Range and speed: 5,000 yd (4,600 m) at 45.6 kn (84.5 km/h), 7,000 yd (6,400 m) at 41 kn (76 km/h)

The Mark VIII** was used in two particularly notable incidents:

Mark IX

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A Mark IX torpedo undergoing maintenance while loaded in a destroyer's triple tube mounting.

The Mark IX was designed circa 1928 and first deployed in 1930. The design was considerably improved by 1939. The Mark IX was a larger and longer-range sibling to the Mark VIII, employing a very similar four-cylinder radial kerosene-air burner-cycle propulsion system. Used on the Leander class cruisers and later cruisers, A and B class destroyers, and later destroyer classes. Also replaced the old Mark VII torpedo in some 8 in (200 mm) gun cruisers during the war. The Mark IX torpedo remained in service throughout the 1960s.[3]

Specifications:[4]

Mark IX

  • Entered service: 1930
  • Weight: 3,732 lb (1,693 kg)
  • Length: 286.5 in (7.28 m)
  • Explosive charge: 750 lb (340 kg) TNT
  • Range and speed: 10,500 yd (9,600 m) at 36 kn (67 km/h), 13,500 yd (12,300 m) at 30 kn (56 km/h)

Mark IX*

  • Explosive charge: 805 lb (365 kg) Torpex
  • Range and speed: 11,000 yd (10,000 m) at 36 kn (67 km/h), 14,000 yd (13,000 m) at 30 kn (56 km/h)

Mark IX**

  • Explosive charge: 805 lb (365 kg) Torpex
  • Range and speed: 11,000 yd (10,000 m) at 41 kn (76 km/h), 15,000 yd (14,000 m) at 35 kn (65 km/h)

Mark X

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From 1939, used by submarines, motor torpedo boats and destroyers from other navies such as the Grom-class destroyer.[citation needed]

Mark XI

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Electric battery-powered torpedo with a 710 lb (322 kg) TNT warhead. It entered service during the Second World War and was used by destroyers.

Mark 12

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At first codenamed Ferry, then Fancy, the Mark 12 never reached production. From 1952, it had a warhead of 750 lb (340 kg) Torpex.[citation needed] Using high test peroxide fuel, it attained a top speed of 28 kn (52 km/h) for 5,500 yd (5,000 m).[citation needed]

There were accidents during testing caused by the unstable nature of high test peroxide. One such engine explosion, after loading aboard the submarine HMS Sidon, caused enough damage to have the submarine taken permanently out of service.[citation needed]

Mark 12 torpedoes were out of service in 1959 and the programme was cancelled.[5]

Mark 20 Bidder

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21-inch Mark 20
TypeTorpedo
Place of originUnited Kingdom
Service history
In service1955–1980s
Used byRN
Production history
Designedc. 1950
Specifications
Mass1,810 lb (820 kg)
Length13.5 ft (4.11 m)
Diameter21 in (530 mm)

WarheadTorpex
Warhead weight196 lb (89 kg)

EngineElectric
PropellantBattery (perchloric acid)
Operational
range
12,000 yd (11,000 m)
Maximum speed 20 kn (37 km/h)
Guidance
system
Passive Sonar

The Mark 20 was a passive-seeker battery-powered torpedo which was developed alongside the 18-inch Mark 30 Dealer B and shared elements of its design.[6] Two variants were developed: the Mark 20S ("Submarine") for use by submarines, and a larger Mark 20E ("Escort") for use by surface ships. The S variant had a single speed of 20 knots, and the E variant had a dual-speed mode of 15 knots and 24 knots, for target search and subsequent autonomously-switched attack run.[7] In the E configuration, the torpedo was designed to have a total endurance of 20,000 yd (18,000 m) at the 15 knot speed, and 6,000 yd (5,500 m) upon switching to the 24 knot speed.[8] As of 1958, The E variant was still not ready for service due to problems with its programming, and the prospect of a medium-range ASW torpedo being carried by the upcoming Westland Wasp helicopter was deemed more desirable. As a result, the E variant project was eliminated, leaving only the S variant. This led to several of the frigates that were intended to have used them (Rothesay and Whitby classes) never being fitted with torpedo tubes or having them removed. As of 1959, the only destroyer class projected to carry the Mark 20 was the Leander,[9] but as of 1963, this design consideration would also be eliminated.[10] The final version of the Mark 20 Bidder was also referred to in literature as the Mark 20 Improved.[11]

It remained in the submarine service until the 1980s, whereupon it was replaced by the Mark 24 Tigerfish.

Mark 21 Pentane

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A project for an autonomous active/passive sonar ASW torpedo to be carried by the Short Sturgeon and Fairey Gannet anti-submarine aircraft.[12] Development commenced in 1949 and delivered functional prototypes with a speed of 30 knots. Following the 1957 Defence White Paper, which de-emphasized the role of aircraft carriers, the RAF Coastal Command was left as the sole operator and the project was cancelled in 1958 due to cost considerations. The seeker head development was transferred to Project Ongar, which would later become the Mark 24 Tigerfish.[13]

Mark 22 Mackle

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A wire-guided version of the Mark 20 separately developed by Vickers Shipbuilding and Engineering (VSEL) as a private venture. The project was cancelled in 1956, but the wire guidance technology was transferred to the Mark 20 Bidder, contributing to the development of the Mark 23 Grog.[14]

Mark 23 Grog

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21-inch Mark 23
TypeTorpedo
Place of originUnited Kingdom
Service history
In service1966–1980s
Used byRN
Production history
Designedc. 1959
Specifications
Mass2,000 lb (907 kg)
Length14.9 ft (4.54 m)
Diameter21 in (530 mm)

WarheadTorpex
Warhead weight196 lb (89 kg)

EngineElectric
PropellantBattery (perchloric acid)
Operational
range
12,000 yd (11,000 m) low-speed, 8,900 yd (8,100 m) high-speed
Maximum speed 20 kn (37 km/h) low-speed, 28 kn (52 km/h) high-speed
Guidance
system
Passive Sonar, Wire-Guided

A wire-guided version of the Mark 20 with a dual-speed mode, for target approach and attack run.[15][16] The Mark 23 was fitted with a 10,000 m (11,000 yd) outboard dispenser that contained a control wire to guide the weapon. Entered service in 1966 although already obsolescent, and did not become fully operational until 1971, serving only as an interim before the Mark 24 Tigerfish entered service.

During 1973, all of the RN torpedoes had to be taken out of service as the control system was failing at extreme range.[citation needed]

After months of investigation, it was discovered that the fault lay in the Guidance Unit made by GEC. A germanium diode in the automatic gain control (AGC) circuit had been replaced by a silicon diode, following an instruction by RN stores that all germanium diodes had to be replaced by more modern silicon diodes. The silicon diode's different characteristics caused the AGC circuit to fail. Once the mistake was found, replacing the diode with the original type cured the problem.

Mark 24 Tigerfish

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The Mark 24 Tigerfish was a high-speed, long-range, wire-guided torpedo originally developed under Project Ongar. The staff requirement for this weapon was written in 1959[17] and the weapon was expected to enter service in the mid-1960s, with an in-service target date of 1969.[18] Initial production rounds were delivered in 1974, and a production order was made in 1977. Affected by the budgetary constraints of the 1966 Defence White Paper, the first Tigerfish (Mod 0) entered deployment in 1983. All variants of the Tigerfish were removed from service in 2004.

The Mark 24 Tigerfish had a protracted development program, beginning with the initial two models, then studies to tackle its deficiencies, and finally a Marconi Consolidation Program (nicknamed "Get Well") undertaken in the late 1980s to convert existing units to the Mod 2 standard.

  • Mark 24 Mod 0 Tigerfish (1974)
  • Mark 24 Mod 1 Tigerfish (1978)
  • Mark 24(N) Tigerfish (nuclear payload variant, paper study only)
  • Mark 24 Mod 2 Tigerfish (1987)
  • Mark 24 Mod 3 Tigerfish (simplified inexpensive version, paper study only)

Spearfish

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Much more capable than Tigerfish. Deployed from 1992, and replacing all Tigerfish by 2004.

See also

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Notes

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  1. ^ DiGiulian, Tony. "World War II Torpedoes of the United Kingdom/Britain – NavWeaps". www.navweaps.com. Archived from the original on 21 February 2009.
  2. ^ Brown, Colin; Kim Sengupta (3 April 2012). "Sinking the Belgrano: the Pinochet connection". The Independent. London. Archived from the original on 23 June 2015. Retrieved 2 May 2012.
  3. ^ Andrew, Doty (2013). White Ensign (2nd ed.). Admiralty Trilogy Group. p. 67.
  4. ^ DiGiulian, Tony. "World War II Torpedoes of the United Kingdom/Britain – NavWeaps". www.navweaps.com. Archived from the original on 21 February 2009.
  5. ^ DiGiulian, Tony. "Post-World War II Torpedoes of the United Kingdom/Britain – NavWeaps". www.navweaps.com. Archived from the original on 4 December 2009.
  6. ^ Friedman, Norman (1986). The Postwar Naval Revolution. Naval Institute Press. p. 79. ISBN 0-87021-952-9.
  7. ^ Llewelyn-Jones, Malcolm (2005). The Royal Navy, 1930-2000; excerpt, The Royal Navy and the Challenge of the Fast Submarine, 1944-1954. Frank Cass. p. 168. ISBN 0-714-65710-7.
  8. ^ Llewelyn-Jones, Malcolm (2005). The Royal Navy, 1930-2000; excerpt, The Royal Navy and the Challenge of the Fast Submarine, 1944-1954. Frank Cass. p. 169. ISBN 0-714-65710-7.
  9. ^ Friedman, Norman (2006). British Destroyers & Frigates. Chatham Publishing. p. 250. ISBN 1-86176-137-6.
  10. ^ Friedman, Norman (2006). British Destroyers & Frigates. Chatham Publishing. p. 268. ISBN 1-86176-137-6.
  11. ^ Richardson, Douglas (1986). Naval Armament. Naval Institute Press. p. 120. ISBN 0-531-03738-X.
  12. ^ Friedman, Norman (1986). The Postwar Naval Revolution. Naval Institute Press. p. 79. ISBN 0-87021-952-9.
  13. ^ "United Kingdom Aerospace and Weapons Projects - Guided Weapons". n.d. Archived from the original on 1 June 2009.
  14. ^ Friedman, Norman (1986). The Postwar Naval Revolution. Naval Institute Press. p. 200. ISBN 0-87021-952-9.
  15. ^ Andrew, Doty (2013). White Ensign (2nd ed.). Admiralty Trilogy Group. p. 67.
  16. ^ Richardson, Douglas (1986). Naval Armament. Naval Institute Press. p. 120. ISBN 0-531-03738-X.
  17. ^ Friedman, Norman (1986). The Postwar Naval Revolution. Naval Institute Press. p. 79. ISBN 0-87021-952-9.
  18. ^ Richardson, Douglas (1986). Naval Armament. Naval Institute Press. p. 120. ISBN 0-531-03738-X.

References

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