Torpedo

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Please see electric ray for the genus of electric ray

A modern torpedo, historically called a self-propelled torpedo, is a self-propelled guided projectile that (after being launched above or below the water surface) operates underwater and is designed to detonate on contact or in proximity to a target. Torpedoes are weapons that may be launched from submarines, surface ships, helicopters and fixed-wing aircraft, unmanned naval mines and naval fortresses

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They are also used as parts of other weapons; the Mark 46 torpedo used by the United States becomes the warhead section of the ASROC (Anti-Submarine ROCket) and the Captor mine uses a submerged sensor platform that releases a torpedo when a hostile contact is detected.

Contents

Etymology

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The word torpedo comes from the Torpedo genus of electric rays in the order Torpediniformes, which in turn comes from the Latin "torpere", to be stiffened or paralyzed. There is no physical resemblance between the ray and the mechanical torpedo.

In naval usage, the term "torpedo" was first used by Robert Fulton who used the word for the towed gunpowder charge used by his submarine Nautilus in 1800–1805 to demonstrate that it could sink warships.

The term became generally used to refer to tethered naval mines, developed in the American Civil War in the 1860s by Matthew F. Maury, a Confederate Admiral (these are what David Farragut was referring to when he ordered his men to "damn the torpedoes, full speed ahead"). This use of the word to refer to what are now called "mines" lasted until World War I. As self-propelled torpedoes were developed the tethered variety was referred to as "stationary torpedo" and later "mine".

The Bangalore Torpedo, invented in 1912, is a cylindrical explosive device` on the end of a pipe used to clear minefields and barbed wire. As such it can be considered a land form of the spar torpedo.

History

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The first torpedoes driven at the target were spar torpedoes – the explosive device was on the end of a spar up to 40 feet long projecting forward under the water from the attacking vessel. When driven up against the enemy and detonated a hole would be caused below the water line. These devices were used in the American Civil War.

Attempts had been made to develop unpowered but directable towed torpedoes, such as the torpedo created by John and Frederick Harvey. Matthew F. Maury worked on an electric torpedo design during the American Civil War, but the result wasn't an effective weapon.

The first prototypes of a self-propelled torpedo were created by Ivan Lupis-Vukić, a retired Croatian naval engineer who served in the Austro-Hungarian Navy. The design was presented to the Emperor Franz Joseph in the port city of Rijeka in 1860. Robert Whitehead, an English engineer/entrepreneur, was working in the Trieste port on navy projects, so in 1864 Lupis made a contract with him in order to perfect the invention. This resulted in Minenschiff, the first self-propelling torpedo, officially presented to the Imperial Naval commission on December 21, 1866.

After the government decided to invest in the invention, Whitehead started the first torpedo factory in Rijeka. In 1870, they improved the devices to travel up to 1,000 yards (914 m) at a speed of up to six knots, and by 1881 the factory was exporting its torpedoes to ten other countries. The torpedo was powered by compressed air and had an explosive charge of gloxyline or gun-cotton. Whitehead went on to develop more efficient devices, demonstrating torpedoes capable of 18 knots (1876), 24 knots (1886) and finally 30 knots (1890).

Whitehead purchased rights to the gyroscope in 1890 to improve self-regulation of his designs. Whitehead's torpedoes came to be called the Devil's device.

In 1877 the British Admiralty paid him £15,000 for certain of his developments and he opened a new factory near Portland harbour in 1891. The largest Whitehead torpedo was 19 feet (5.8 m) long, 18 inches (457 mm) in diameter made of polished steel or phosphor-bronze, the explosive charge was up to 200 lb (90 kg) of gun-cotton. The air was compressed to around 1,300 lb/in² (approx 90 times atmospheric pressure) and drove two propellers through a three cylinder Brotherhood engine. Considerable effort was taken in trying to ensure that the torpedo self-regulated its course and depth.

Blanco Encalada was the first ship sunk in a military action by a self-propelled torpedo from the torpedo gunboat Lynch, during the Chilean civil war on April 23 1891. During this time, the torpedo boat invented by John Ericsson gained recognition for its efficiency, and the first torpedo boat destroyers were built to counter it.

Around 1897, Nikola Tesla patented a remote controlled boat and later demonstrated the feasibility of radio-guided torpedoes to the United States military. Radio remote controlled torpedoes remained uninvestigated until the 1960s.

During World War I, torpedoes came to mean self-propelled projectiles fired from a ship or submarine. Later, torpedoes were given (homing) guidance systems.

In the inter-war years, tight budgets in nearly all navies caused them to skimp on testing their torpedoes. As a result, only the Japanese had fully-tested torpedoes at the start of the Second World War. The instrument used in German torpedoes to gauge running depth changed over time, so torpedoes of this design ran ever deeper than that dialed-in at firing as the U-Boat continued its voyage. The contact fuzes of US Navy torpedoes would not detonate with straight-on, but only at an angle, while those of the German navy had directly the opposite problem. The Royal Navy had problems as well.

All classes of ship from destroyers to battleships were armed with torpedoes.

Propulsion

Compressed air

This first, successfull, self-propelled torpedo of 1866 used compressed air as its energy source. The air was stored at pressures of up to 2.55 MPa and fed to a piston engine which turned a single propeller at about 100 rpm. It was able to travel about 180 m at an average speed of 6.5 knots. The speed and range of later models was enhanced by increasing the pressure of the stored air. In 1906 Whitehead built torpedos which were able to travel nearly 1000m at an average speed of 35 kts.

At higher pressures the cooling experienced by the air as it expanded in the engine caused icing problems (see adiabatic cooling). This was remedied by heating the air with seawater before it was fed to the engine. Unexpectedly, this increased engine performance further, because the air expanded even more after heating.

Heated torpedos

This led to the idea of injecting a liquid fuel, like kerosene, into the air and igniting it. In this manner the air is heated up more and expands even further, and the burned propellant adds more gas to drive the engine. Construction of such heated torpedos started around 1904.

Wet-heater

A further enhancement to this design was the use of water to cool the combustion chamber. This not only solved heating problems so that more fuel could be burnt, but it also allowed additional power to be generated by feeding the resulting steam into the engine together with the combustion products. Torpedos with such a propulsion system became known as wet heaters while torpedos without steam generation were, retrospectivly, called dry heaters. Most torpedos used in World War I and World War II were wet-heaters.

Compressed oxygen

The amount of fuel that can be burnt by an torpedo engine is limited by the amount of oxygen it can carry. Since compressed air contains only about 21% of oxygen, engineers in Japan developed the Type 93 torpedo (better known as the long lance) in the 1930s, which used pure oxygen instead of compressed air and had an unmatched performance in World War II.

Wire driven

The Brennan torpedo had two wires wound around drums inside the torpedo. A shore based steam powered winch pulled the wires which spun the drums and drove the propeller. Such systems had been in use for coastal defence of the British homeland and colonies from 1887 to 1903. Speed was about 25knts for over 2400m.

Flywheel

Another source of mechanical energy is a flywheel. The Howell torpedo in use with the US Navy of the late 1800s featured a heavy flywheel which has to be spun up before launch. It was able to travel about 750m with an average speed of 30knts. The advantage of the Howell torpedo was, that it didn't leave a trail of bubbles behind it like compressed air torpedos, giving the target less chance to detect and evade the torpedo.

Modern propulsion systems

Modern torpedos utilize a variety of energy sources that include electric batteries, monopropellant and sulphur hexafluoride gas sprayed over a block of solid lithium.

Torpedo classes and diameters

Torpedoes are most commonly launched in one of four ways:

  • From the deck-mounted torpedo launcher of a vessel on the surface.
  • From a torpedo tube mounted either below the waterline of a vessel on the surface, or on a submarine.
  • From a low-flying aircraft or helicopter.
  • As the final stage of a compound rocket or ramjet powered munition (sometimes called an assisted torpedo).

Many navies have two weights of torpedoes:

  • A light torpedo used primarily as a close attack weapon, particularly by aircraft.
  • A heavy torpedo used primarily as a standoff weapon, particularly by submerged submarines.

In the case of deck or tube launched torpedoes, the diameter of the torpedo is obviously a key factor in determining the suitability of a particular torpedo to a tube or launcher, similar to the calibre of the gun. The size is not quite as critical as for a gun barrel, but diameter has become the most common way of classifying torpedoes.

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Length, weight, and other factors also contribute to compatibility. In the case of aircraft launched torpedoes, the key factors are weight, provision of suitable attachment points, and launch speed. Assisted torpedoes are the most recent development in torpedo design, and are normally engineered as an integrated package. Versions for aircraft and assisted launching have sometimes been based on deck or tube launched versions, and there has been at least one case of a submarine torpedo tube being designed to fire an aircraft torpedo.

As in all munition design, there is a compromise between standardisation, which simplifies manufacture and logistics, and specialisation, which may make the weapon significantly more effective. Small improvements in either logistics or effectiveness can translate into enormous operational advantages.

Some common torpedo diameters (using the most common designation, metric or inch, and listed in increasing order of size):

  • 12.75 inch (approximately 324 mm) is the most common size for light torpedoes.
  • 16 inch (406 mm) was the size of the earliest specialised Soviet ASW torpedoes. 16 inch torpedo tubes were fitted to Soviet Hotel, Echo and early Delta class submarines, often in addition to 21 inch tubes.
  • 17.7 inch (450 mm) was the standard size for light torpedoes of the Imperial Japanese Navy. This size is sometimes referred to as 18 inches.
  • 21 inch (533 mm) is the most common size for heavy torpedoes, including:
  • 24 inch (610 mm) torpedoes were used by the Imperial Japanese Navy, most famously the deck launched Type 93 torpedo, also some Kaitens.
  • 650 mm (approximately 25.6 inches) is the largest torpedo diameter used by the Russian navy, see Type 65 torpedo. Adaptors are used to fire 533 mm (21 inch) munitions from 650 mm tubes.

Even larger sizes of torpedo tube, including 660 mm (26 inches), 30 inch (about 762mm) and 36 inch (about 914 mm), have been installed on some nuclear submarines. These tubes are designed to be capable of firing large diameter munitions such as cruise missiles, as well as the standard 21 inch heavy torpedo. See torpedo tube.

Torpedoes used by various navies

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US Navy

The four major torpedoes in the United States Navy inventory are:

Royal Navy

The torpedoes used by the Royal Navy include:

Imperial Japanese Navy

The torpedoes used by the Imperial Japanese Navy (WWII) included:

German Navy

The torpedoes used by the Kriegsmarine include

Russian Navy

Torpedoes used by the Russian Navy include:

See also

External links

Retrieved from "http://en.freepedia.org/Torpedo.html"


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