Mark 46 torpedo explained

Mark 46 torpedo
Origin:	United States
Type:	Lightweight anti-submarine torpedo^[1]
Is Ranged:	y
Is Explosive:	y
Is Missile:	y
Service:	• Mod 0: 1963 • Mod 5: 1979
Used By:	See operators
Designer:	Naval Ordnance Test Station Pasadena Aerojet Alliant Techsystems
Design Date:	1960
Manufacturer:	Aerojet Naval Ordnance Station Forest Park Honeywell Raytheon^[2]
Variants:	Mod 0 Mod 1 Mod 2 Mod 5 Mod 5A Mod 5A(S) Mod 5A(SW)
Weight:	508lb
Length:	8feet
Diameter:	12.75abbr=on1abbr=on
Filling:	PBXN-103 high explosive (bulk charge)
Filling Weight:	96.8lb
Engine:	Two-speed, reciprocating external combustion
Propellant:	Otto fuel II
Vehicle Range:	12000abbr=onNaNabbr=on
Depth:	>1200feet
Speed:	>40abbr=onNaNabbr=on
Guidance:	Active or passive/active acoustic homing
Launch Platform:	Mark 32 Surface Vessel Torpedo Tubes, ASW Aircraft, RUM-139 VL-ASROC

The Mark 46 torpedo is the backbone of the United States Navy's lightweight anti-submarine warfare torpedo inventory and is the NATO standard. These aerial torpedoes are designed to attack high-performance submarines. In 1989, an improvement program for the Mod 5 to the Mod 5A and Mod 5A(S) increased its shallow-water performance. The Mark 46 was initially developed as Research Torpedo Concept I (RETORC I), one of several weapons recommended for implementation by Project Nobska, a 1956 summer study on submarine warfare.^[3]

Design details

Variants

• Mod 0: One of the original versions of 1960 (production started 1963). Solid propellent piston engine. Gyro/wire guidance with passive/active homing.^[1]
• Mod 1: Based on Mod 0. 1967. Uses liquid Otto fuel piston engine. Laminar search guidance.^[1] Phase 1 of 1968 uses stronger hull to resist deeper waters. Phase 2 of 1971 uses a new homing program able to detect submarines near the surface.
• Mod 2: Based on Mod 1 phase 2. More powerful Mk 103 Mod 1 warhead. Improved computer with snake search pattern capability. Known to have been captured by China in 1978.^[4]
• Mod 4: Version for use as Mark 60 CAPTOR mine payload.^{[5] [6]}
• Mod 5: 1979 upgrade kit for Mod 2, also known as NEARTIP (near-term improvement program). New passive/active sonar, liquid fuel and two speed engine for low speed search and high speed attack.^[7]
  • Mod 5A: Cheapter NEARTIP upgrade kit for Mod 1 and Mod 2 with improved shallow-water performance. 1980s.^[7]
  • Mod 5A(S): Variant of 5A that allows use in water as shallow as 40 m.^[7]
  • Mod 5A(SW): Latest variant from 1996 Service Life Extension Program.^[7] Boasts improved counter-countermeasure performance, enhanced target acquisition, provides a bottom-avoidance preset, and improved maintainability and reliability.^[2]
• Mod 6: Version for Mark 60 CAPTOR, with some NEARTIP components.^[5]
• Mod 7: Cancelled. Not funded by Congress.^[8]

For most variants there is also an inert REXTORP (recoverable exercise torpedo) version.

Specifications

Mark 46, Mod 5

• Primary Function: Air and ship-launched lightweight torpedo^[9]
• Contractor: Alliant Techsystems
• Power Plant: Two-speed, reciprocating external combustion; Mono-propellant (Otto fuel II)
• Length: 8feet tube launch configuration (from ship),^[10] 14feet with ASROC rocket booster^[9]
• Weight: 5080NaN0^[9] (warshot configuration)
• Diameter: 12.75inches^[10]
• Range: 12000yd^[9]
• Depth: > 1200feet
• Speed: > 40knots^[9]
• Guidance System: Homing mode: Active or passive/active acoustic homing^[10]
• Launch/search mode: Snake or circle search
• Warhead: 96.81NaN1^[9] of PBXN-103 high explosive (bulk charge)
• Date Deployed: 1967 (Mod 0);^[9] 1979 (Mod 5)

Yu-7 variant

The Chinese Yu-7 torpedo is said to be based on the Mk 46 Mod 2. The Chinese Navy used the Yu-7 ASW torpedo, deployed primarily on ships and ASW helicopters,^[11] but it started to be replaced by the Yu-11 in 2012.^[12]

Operators

• Australia
• Bahrain
• Belgium
• Brazil
• Canada
• Chile
• Colombia
• Croatia
• Ecuador
• Egypt
• France
• Germany
• Greece
• Indonesia
  • Israel
• Italy
• Japan
• Kuwait
• Mexico
• Morocco
• Netherlands
• New Zealand
• Norway
• Pakistan
• Peru
• Philippines^[13]
• Portugal
• Saudi Arabia
  • Spain
  • Thailand
• Turkey
• United Arab Emirates
• United Kingdom
• United States^[14]

See also

• Advanced Light Torpedo Shyena
• CAPTOR mine (a sea mine which incorporates a Mk 46 torpedo)
• MU90 Impact torpedo
• Mark 50 torpedo
• Mark 54 MAKO Lightweight Torpedo
• Stingray torpedo

External links

• DiGiulian, Tony, Navweaps.com: USA Torpedoes
• Unofficial U.S. Navy Site: MK-46 Torpedo
• FAS: MK-46 Torpedo

Notes and References

1. Web site: Jolie . E.W. . A Brief History of US Navy Torpedo Development: Torpedo Mk46 . 15 September 1978 . 24 June 2013.
2. Web site: The US Navy Fact File: Mark 46 Torpedo . 27 November 2012 . August 9, 2018 . 20 March 2019 . https://web.archive.org/web/20190320025704/https://www.navy.mil/navydata/fact_display.asp?cid=2100&tid=900&ct=2 . dead .
3. Book: Friedman, Norman . Norman Friedman . U.S. Submarines Since 1945: An Illustrated Design History . Naval Institute Press . 1994 . . 109-114 . limited . 1-55750-260-9 .
4. Web site: Undersea dragon: Chinese ASW capabilities advance . Jane's . 2017 . 25 October 2018.
5. Web site: Mark 60 CAPTOR . Weaponsystems.net . en.
6. Web site: Simeral . R. T. . Torpedo MK 46 Physical Characteristics. . Naval Ocean Systems Center, San Diego, CA.; Government-Industry Data Exchange Program . 1978. ADA081111.pdf
7. Web site: Mk 46 . Weaponsystems.net . en.
8. Web site: MK-46 Torpedo . www.navysite.de.
9. Thomas, Vincent C. The Almanac of Seapower 1987 Navy League of the United States (1987) pp.190-191
10. Polmar, Norman "The Ships and Aircraft of the U.S. Fleet: Torpedoes" United States Naval Institute Proceedings November 1978 p.160
11. http://mil.jschina.com.cn/huitong/missile1.htm (Chinese language)
12. Web site: Undersea dragon: Chinese ASW capabilities advance . Jane's . 2017 . 23 July 2019.
13. Web site: Frigate Lot 3A - Torpedoes Acquisition Project of the Philippine Navy . www.phdefenseresource.com . 3 April 2021.
14. Web site: Mk 46 torpedo - Weaponsystems.net. www.weaponsystems.net.