Mark 46

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.

• Name — Mark 46 torpedo • Origin — United States • Type — Lightweight anti-submarine torpedo • 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 • Variants — Mod 0 Mod 1 Mod 2 Mod 5 Mod 5A Mod 5A(S) Mod 5A(SW) • Weight — 508 lb • Length — 8 ft • Diameter — 12.75 in • Filling — PBXN-103 high explosive (bulk charge) • Filling Weight — 96.8 lb • Engine — Two-speed, reciprocating external combustion • Propellant — Otto fuel II • Vehicle Range — 12000 yd • Depth — >1200 ft • Speed — >40 kn • Guidance — Active or passive/active acoustic homing • Launch Platform — Mark 32 Surface Vessel Torpedo Tubes, ASW Aircraft, RUM-139 VL-ASROC

• Mod 0: One of the original versions of 1960 (production started 1963). Solid propellent piston engine. Gyro/wire guidance with passive/active homing. • Mod 1: Based on Mod 0. 1967. Uses liquid Otto fuel piston engine. Laminar search guidance. 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. • Mod 4: Version for use as Mark 60 CAPTOR mine payload. • 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. • Mod 5A: Cheaper NEARTIP upgrade kit for Mod 1 and Mod 2 with improved shallow-water performance. 1980s. • Mod 5A(S): Variant of 5A that allows use in water as shallow as 40 m. • Mod 5A(SW): Latest variant from 1996 Service Life Extension Program. Boasts improved counter-countermeasure performance, enhanced target acquisition, provides a bottom-avoidance preset, and improved maintainability and reliability. • Mod 6: Version for Mark 60 CAPTOR, with some NEARTIP components. • Mod 7: canceled. Not funded by Congress. 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 • Contractor: Alliant Techsystems • Power Plant: Two-speed, reciprocating external combustion; Mono-propellant (Otto fuel II) • Length: 8 ft tube launch configuration (from ship), 14 ft with ASROC rocket booster • Weight: 508 lb (warshot configuration) • Diameter: 12.75 in • Range: 12,000 yd • Depth: > 1200 ft • Speed: > 40 knots • Guidance System: Homing mode: Active or passive/active acoustic homing • Launch/search mode: Snake or circle search • Warhead: 96.8 lb of PBXN-103 high explosive (bulk charge) • Date Deployed: 1967 (Mod 0); 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, but it started to be replaced by the Yu-11 in 2012.

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

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