The Mark 50 torpedo is a U.S. Navy advanced lightweight

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such ...

for use against fast, deep-diving

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

s. The Mk 50 can be launched from all anti-submarine aircraft and from torpedo tubes aboard surface combatant ships. The Mk 50 was intended to replace the Mk 46 as the fleet's lightweight torpedo. Instead the Mark 46 will be replaced with the Mark 54 LHT.

Propulsion system

The torpedo's stored chemical energy propulsion system uses a small tank of

sulfur hexafluoride Sulfur hexafluoride or sulphur hexafluoride ( British spelling) is an inorganic compound with the formula SF6. It is a colorless, odorless, non-flammable, and non-toxic gas. has an octahedral geometry, consisting of six fluorine atoms attache ...

gas, which is sprayed over a block of

solid Solid is a state of matter where molecules are closely packed and can not slide past each other. Solids resist compression, expansion, or external forces that would alter its shape, with the degree to which they are resisted dependent upon the ...

lithium Lithium (from , , ) is a chemical element; it has chemical symbol, symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperature and pressure, standard conditions, it is the least dense metal and the ...

, which generates enormous quantities of

heat In thermodynamics, heat is energy in transfer between a thermodynamic system and its surroundings by such mechanisms as thermal conduction, electromagnetic radiation, and friction, which are microscopic in nature, involving sub-atomic, ato ...

, which generates

steam Steam is water vapor, often mixed with air or an aerosol of liquid water droplets. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization. Saturated or superheated steam is inv ...

. The steam propels the torpedo in a closed

Rankine cycle The Rankine cycle is an idealized thermodynamic cycle describing the process by which certain heat engines, such as steam turbines or reciprocating steam engines, allow mechanical work to be extracted from a fluid as it moves between a heat sour ...

, supplying power to a

pump-jet A pump-jet, hydrojet, or water jet is a marine system that produces a jet of water for propulsion. The mechanical arrangement may be a ducted propeller (axial-flow pump), a centrifugal pump, or a mixed flow pump which is a combination of bot ...

. This propulsion system offers the very important deep-water performance advantage in that the combustion products—

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

and

lithium fluoride Lithium fluoride is an inorganic compound with the chemical formula LiF. It is a colorless solid that transitions to white with decreasing crystal size. Its structure is analogous to that of sodium chloride, but it is much less soluble in water. ...

—occupy less volume than the reactants, so the torpedo does not have to force these out against increasing water pressure as it approaches a deep-diving submarine.

General characteristics, Mk 50

*Primary function: air and ship-launched lightweight torpedo *Contractor:

Alliant Techsystems Alliant Techsystems Inc. (ATK) was an American Aerospace manufacturer, aerospace and arms industry, arms manufacturer headquartered in Arlington County, Virginia. The company operated across 22 states, Puerto Rico, and internationally. ATK reven ...

, Westinghouse *Length: *Weight: approx. *Diameter: *Speed: > *Power Plant: Stored Chemical Energy Propulsion System *Propulsion: Pump Jet *Guidance system: Active/passive acoustic homing *Warhead: high explosive

Comparable weapons

* Stingray torpedo *

MU90 Impact The MU90 Impact is a Franco-Italian advanced lightweight anti-submarine torpedo of the third generation developed for the French Navy, French and Marina Militare, Italian navies, as well as for export. It is designed to outperform the United States ...

* Yu-11 torpedo

Notes

References

MK-50 Advanced Lightweight Torpedo
via FAS
Issues Related to the Navy's Mark-50 Torpedo Propulsion System, General Accounting Office, January 1989 - has diagrams showing internal general arrangement, retrieved December 18, 2012
{{Mark-series torpedoes Aerial torpedoes Torpedoes of the United States Military equipment introduced in the 1990s