Mark 46 torpedo

Mark 46 torpedo
A Mk 46 exercise torpedo launched from USS Moosbrugger.
Type	Lightweight anti-submarine torpedo[1]
Place of origin	United States
Service history
In service	• Mod 0: 1963[1] • Mod 5: 1979
Used by	See operators
Production history
Designer	Naval Ordnance Test Station Pasadena[1] Aerojet[1] Alliant Techsystems
Designed	1960[1]
Manufacturer	Aerojet[1] Naval Ordnance Station Forest Park Honeywell Raytheon[2]
Variants	Mod 0[1] Mod 1 Mod 2 Mod 5 Mod 5A Mod 5A(S) Mod 5A(SW)[2]
Specifications
Mass	508 lb (230 kg)
Length	8 ft 6 in (2.59 m)
Diameter	12.75 in (323.8 mm)
Warhead	PBXN-103 high explosive (bulk charge)
Warhead weight	96.8 lb (43.9 kg)
Engine	Two-speed, reciprocating external combustion
Propellant	Otto fuel II
Operational range	12,000 yd (11,000 m)
Maximum depth	>1,200 ft (370 m)
Maximum speed	>40 kn (74 km/h; 46 mph)
Guidance system	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]

• 
  A Mark 46 Mod 5A torpedo is inspected aboard the guided missile destroyer USS Mustin.
• 
  A French Lynx helicopter carrying a Mk 46 torpedo.
• 
  A P-8A Poseidon of VP-16 dropping a Mark 46 torpedo

• 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.^[4]
• Mod 2: Based on Mod 1 phase 2. More powerful Mk 103 Mod 1 warhead. Improved computer with snake search pattern capability.^[4] Known to have been captured by China in 1978.^[5]
• Mod 4: Version for use as Mark 60 CAPTOR mine payload.^[6][7]
• 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.^[4]
  • Mod 5A: Cheapter NEARTIP upgrade kit for Mod 1 and Mod 2 with improved shallow-water performance. 1980s.^[4]
  • Mod 5A(S): Variant of 5A that allows use in water as shallow as 40 m.^[4]
  • Mod 5A(SW): Latest variant from 1996 Service Life Extension Program.^[4] 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.^[6]
• Mod 7: Cancelled. Not funded by Congress.^[8]

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

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: 8 ft 6 in (2.59 m) tube launch configuration (from ship),^[10] 14 ft 9 in (4.50 m) with ASROC rocket booster^[9]
• Weight: 508 lb (230 kg)^[9] (warshot configuration)
• Diameter: 12.75 in (324 mm)^[10]
• Range: 12,000 yd (11,000 m)^[9]
• Depth: > 1,200 ft (370 m)
• Speed: > 40 kn (74 km/h; 46 mph)^[9]
• Guidance System: Homing mode: Active or passive/active acoustic homing^[10]
• Launch/search mode: Snake or circle search
• Warhead: 96.8 lb (43.9 kg)^[9] of PBXN-103 high explosive (bulk charge)
• Date Deployed: 1967 (Mod 0);^[9] 1979 (Mod 5)

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.^[5]

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• 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

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