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Mk 46



Overview


Mk 46 torpedo

A Mk 46 torpedo being launched from a Mk 32 three round launcher.
Source: US Navy (hotographer's Mate 3rd Class Ramon Preciado) - © public domain

Origin
United States
Type
Lightweight torpedo
Entered service
1967 for Mod 0
1979 for Mod 5
1989 for Mod 5A
Status
In service
Development
1960 - 1963
Developer
United States - Aerojet-General
Production
1966 - ?
Producer
United States - Aerojet-General (Mod 0)
United States - Honeywell (main producer)
Japan - Mitsubishi Heavy Industries
Number produced
Over 26.000 Mk 46 produced, including:
6.608 Mod 1
3.344 Mod 2
4.922 NEARTIP upgrade kits
6.058 Mod 5
Designations
NEARTIP (improvement program)
Notable users
United States
Japan
United Kingdom
Australia
Germany
France

Description


Introduction


The Mk 46 is a lightweight torpedo of US origin. It was developed in the early 1960's to replace the successful Mk 44 torpedo. It was the first high performance thermal powered torpedo in US service. The complex but powerful propulsion system was chosen to keep up with Soviet submarine developments. The Mk 46 is the most common lightweight torpedo in the world and remains in widespread use.

Layout

The Mk 46 has a conventional layout with the homing section and warhead in the nose, the fuel in the middle and the engine and control fins at the rear. Apart from the original production version all Mk 46 use an Otto fuel engine. Over time the design was improved with improved guidance, stronger body, new fuel and two speed engine.

Guidance

The Mk 46 uses a passive and active sonar guidance system. Over time the quality of the seeker has been improved. The seeker on the Mk 46 Mod 2 reportedly has a detection range of 460 meters. The latest models received various upgrades to improve performance in shallow water.

Firepower


The Mk 46 has a range of 8 km and a speed of 40 to 45 kt. The NEARTIP improvement includes a two speed motor which extends the range up to 11 km. The Mk 46 can engage targets ranging from 15 to over 400 meters below sea level. The 45 kg warhead is more powerful than those used on many other lightweight torpedoes.

Launch platforms

The Mk 46 is found on many surface vessels ranging from frigates to cruisers. The Mk 46 can also be air launched and is used on various helicopters such as the SH-60 Seahawk, the Sea King and the Lynx. The Mk 46 is also deployed by more unconventional means such as the Mk 60 CAPTOR mine and ASROC anti-submarine rocket.

Users

The main user of the Mk 46 is the US navy. Subsequent upgrades ensure that the Mk 46 remains a capable weapon, although the very latest lightweight torpedo designs feature both better guidance and propulsion. The Mk 46 is in use with many NATO partners and various other US allies, making it the most numerous lightweight torpedo in the world.

Variants


Mk 46 torpedo

A Mk 46 torpedo being launched from a surface vessel.
Source: US Navy (photographer unknown) - © public domain

Variants of the Mk 46 torpedo

Mk 46 Mod 0
Original production version with unreliable solid fuel turbine motor introduced in 1963.
Mk 46 Mod 1
Extensively upgraded Mod 0 with original engine replaced by Otto fuel engine. The 1968 phase 1 upgrade included a stronger hull that increased maximum operating depth from 350 to over 400 meters. The 1971 phase 2 upgrade allowed the homing system to detect submarines near the surface.
Mk 46 Mod 2
Mod 1 phase 2 with more powerful Mk 103 Mod 1 warhead and improved computer with snake search pattern capability. Introduced in 1972.
Mk 46 Mod 5 NEARTIP
Upgrade kit for the Mod 2 with new passive/active sonar, liquid fuel and two speed engine for low speed search and high speed attack. Introduced in 1979. NEARTIP stands for Near Term Improvement Program.
Mk 46 Mod 5A
Cheaper NEARTIP upgrade kit for Mod 1 or Mod 2. Developed in the mid-1980's specifically for use in shallow water. The Mod 5 A(S) can be used in water as shallow as 40 meters and the Mod 5A(SW) is the latest version introduced in 1996.

Details


Facts Mk 46 Mod 0 Mk 46 Mod 1 Mk 46 Mod 5 NEARTIP
General
Origin
United States
Type
Lightweight torpedo
Launch platform
Aircraft, surface ships, ASROC
Target platform
Submarines
Dimensions
Diameter
324 mm
Length
2.59 m
Weight
259 kg
Warhead
Type
45 kg Mk 103 Mod 0 warhead with PBX filling
Guidance
Homing
Active/passive acoustic seeker
Homing range
460 m
Wire guidance
No
Propulsion
Power source
Solid fuel turbine motor
Propulsion
Twin propeller
Speed
35 kt
Range
7.5 km
Depth
15 to 350 m below sea level

Media


Related articles


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Yu-7

The Chinese Yu-7 lightweight torpedo uses an Otto fuel engine reverse engineered using a Mk 46 Mod 2 torpedo.