Torpedo
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The torpedo, historically called a locomotive torpedo, is a self-propelled explosive projectile weapon, launched above or below the water surface, propelled underwater toward a target, and designed to detonate on contact or in proximity to a target.
Torpedoes may be launched from submarines, surface ships, helicopters and fixed-wing aircraft, unmanned naval mines and naval fortresses. They are also used in conjunction with 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.
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[edit] Etymology
The word torpedo comes from a genus of electric rays in the order Torpediniformes, which in turn comes from the Latin "torpere" (to stun). There is no physical resemblance between the ray and the mechanical torpedo. In naval usage, the term "torpedo" was used by Robert Fulton denoting a towed gunpowder charge used by his submarine Nautilus in 1800–1805 to demonstrate that it could sink warships.
[edit] History
Prior to the invention of the self-propelled naval torpedo, the term "torpedo" was applied to any number of different types of explosive devices, generally having the property of being secret or hidden, including devices we would today call booby traps, land mines and naval mines, among others.
[edit] Early naval "torpedoes"
Although the term "torpedo" was not coined until 1800, the early submarine Turtle attacked using an explosive very similar in intent and operation to Fulton's "torpedoes." Turtle dove under a British vessel and attach a bomb by means of an auger. The bomb was detonated by a timed fuse, probably a type of clockwork mechanism. In its only recorded attack, Turtle failed to penetrate the hull of HMS Eagle, which had been copper-plated to resist the action of marine worms.
The first usage of the term "torpedo" to refer to a naval explosive was by Fulton. This type of towed torpedo, fitted with one of several types of contact fuses, remained in use through the American Civil War. The Confederate submarine H. L. Hunley was originally designed to use this type.
During the American Civil War the term "torpedo" was used for what is today called a contact mine, floating on or below the water surface using an air-filled demijohn or similar flotation device. (As self-propelled torpedoes were developed the tethered variety became known as stationary torpedoes and later mines.) Several types of naval "torpedo" were developed and deployed, most often by the Confederates, who faced a severe disadvantage in more traditional warfare methods.
Civil War "torpedoes" floated freely on the surface or were tethered to the bottom using a line and a weight holding the mine just below the surface. They were detonated when struck by a ship, or after a set time, but were unreliable. These could be as much a danger to Confederate as to Union shipping, and were sometimes marked with flags that could be removed if Union attack was deemed imminent. Rivers mined with Confederate torpedoes were often cleared by Unionists placing captured Confederate soldiers with knowledge of the torpedoes' location in small boats ahead of the main fleet.
"Torpedoes" (mines) could also be detonated electrically by an operator on shore, so friendly vessels or low-value enemy vessels could be ignored while waiting for the capital ships to sail over them. However, the Confederacy was plagued by a chronic shortage of materials including platinum and copper wire and acid for batteries, and the wires had a tendency to break.
Former USN Commander Matthew Fontaine Maury, who served as a Commander in the Confederacy, was probably the first to use torpedoes in the USA. Maury developed an underwater electrical "torpedo".
David Farragut encountered tethered and floating contact mines in 1864 at the American Civil War Battle of Mobile Bay. After his leading ironclad, USS Tecumseh, was sunk by a tethered contact mine (torpedo), his vessels halted, afraid of hitting additional torpedoes. Inspiring his men to push forward, Farragut famously yelled, "Damn the torpedoes, full speed ahead!"
The first torpedoes driven at specific targets were spar torpedoes; the explosive device was on the end of a spar up to 40 feet (12m) long projecting forward underwater from the bow of the attacking vessel. When driven up against the enemy and detonated, a hole would be caused below the water line. Spar torpedoes were employed by the Confederate submarine Hunley and David-class torpedo boats, among others.
[edit] Bombs and booby traps
During the Civil War, the term "torpedo" was also used to refer to various types of bombs and booby traps. Confederate General Gabriel Rains deployed "sub-terra shells" or "land torpedoes", artillery shells with pressure fuses buried in the road by retreating Confederate forces to delay their pursuers. These were the forerunners of modern land mines. Union generals publicly deplored this conduct.
Confederate secret agent John Maxwell used a clockwork mechanism to detonate a large "horological torpedo" (time bomb) on August 9, 1864. The bomb was hidden in a box marked "candles" and placed aboard a barge containing Union ammunition—20,000-30,000 artillery shells and 75,000 rounds of small arms ammunition—that was moored at City Point, Virginia, on the James River. The explosion caused more than $2 million in damage and killed at least 43 people.
The coal torpedo was a bomb shaped like a lump of coal, to be hidden in coal piles used for fueling Union Naval Vessels. The bomb would be shoveled into the firebox along with the real coal, causing an explosion. Although the North referred to the device as the coal torpedo in newspaper articles, the Confederates referred to it as a "coal shell."
[edit] Self-propelled torpedoes
From World War I, the word torpedoes was used only for self-propelled projectiles that travelled under or on water.
Arabs are known to have what could be described as torpedoes as early as the 15th century. Records tell of a self-propelled pear shaped bomb with a spear at the front which impaled itself in the enemy ships and then blew up.[1]
The first prototypes of a self-propelled torpedo were created by I.F. Alexandrovskii, Russian naval specialist and designer of submarine, and Giovanni Luppis an Austrian naval officer (though ethnically Italian) from Fiume (today Rijeka, Croatia), a port city of the Austrian Empire. In 1865 Alexandrovskii offered his project of "self-propelled torpedo" to Russian Naval Ministry. In 1860, Giovanni Luppis presented the salvacoste (coastsaver), a floating weapon, driven by ropes from the land. The project was not taken up by the Navy. Luppis knew Robert Whitehead, an English engineer who was the manager of a Fiume factory and in 1864 Luppis made a contract with him in order to perfect the invention. The result was a submarine weapon, the Minenschiff, the first real self-propelled 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 Fiume. In 1870, they improved the devices to travel up to approximately 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).
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 18 inches (457 mm) in diameter and 19 feet (5.8 m) long, made of polished steel or phosphor-bronze, with a 200 lb (90 kg) gun-cotton warhead. It was propelled by two propellers driven by a three-cylinder Brotherhood compressed-air engine, using air compressed to around 1,300 lb/in² (approx 90 atmospheres). The torpedo was designed to self-regulate its course and depth as far as possible.
Whitehead faced competition from the American Lieutenant Commander John A. Howell, whose own design, driven by flywheel, was simpler and cheaper. Whitehead purchased rights to the gyroscope in 1890 (ironically from Howell) to improve control of his designs, which came to be called the "Devil's device".
On 16 January 1877, the Turkish steamer Intibah became the first vessel to be sunk by torpedoes, launched from torpedo boats operating from the tender Velikiy Knyaz Konstantin under the command of Stepan Osipovich Makarov during the Russo-Turkish War of 1877-78.
In another early use of the torpedo, Blanco Encalada was sunk by a torpedo from the gunboat Almirante Lynch, during the Chilean Civil War on April 23, 1891.
By this time the torpedo boat had gained recognition for its effectiveness, and the first torpedo boat destroyers (usually called simply destroyers) were built to counter it. Torpedoes were also used to equip gunboats making them torpedo gunboats, of around 1,000 tons displacement.
Around 1897, Nikola Tesla patented a remote controlled boat and later demonstrated the feasibility of radio-guided torpedoes to the United States military, but they were not adopted until the 1960s.
Later, torpedoes were given (homing) guidance systems.
In the inter-war years tight budgets caused nearly all navies to skimp on testing their torpedoes. As a result, only the Japanese had fully-tested torpedoes at the start of the Second World War. All classes of ship, including submarines, and aircraft were armed with torpedoes.
Naval strategy at the time was to use torpedoes, launched from submarines or warships, to attack enemy warships in a fleet action on the high seas. Targeting enemy merchant shipping was prohibited by rules of war. There was concern torpedoes would be ineffective against warships' heavy armor; an answer to this was to detonate torpedoes underneath a ship, breaking its back. This had been demonstrated by magnetic influence mines in World War I: the shock wave of an explosion under a ship is well propagated by the water and is very destructive. The torpedo is set to run beneath the ship, and the magnetic exploder to activate at the correct time. Germany, Britain, and the U.S. had independently devised ways to do this; German and American torpedoes, however, suffered problems with their depth-keeping mechanisms, coupled with faults in magnetic pistols shared by all designs.
Inadequate testing had failed to reveal the effect of the earth's magnetic field on ships and exploder mechanisms, which resulted in premature detonation. The Kriegsmarine and the Royal Navy promptly identified and eliminated the problems. In the United States Navy (USN) there was an extended wrangle over the issue. The magnetic pistol problems had concealed a deeper design flaw: the mechanical firing pin moved perpendicular to the torpedo's path, and its weight caused it to drag in its cylinder upon impact.[1]. Cursory trials had allowed bad designs to enter service. Both the Navy and Congress were too busy protecting their own interests to correct the errors; fully-functioning torpedoes only became available to the USN twenty-one months into the Pacific War.[2]
[edit] Propulsion
[edit] Compressed air
This first, successful, 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 180m (200yd) at an average speed of 6.5 knots (12kph). The speed and range of later models was enhanced by increasing the pressure of the stored air. In 1906 Whitehead built torpedoes which were able to travel nearly 1000m (1100yd) at an average speed of 35kt (64kph).
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.
[edit] Heated torpedoes
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 torpedoes started around 1904.
[edit] Wet-heater
A further enhancement was the use of water to cool the combustion chamber. This not only solved heating problems so that more fuel could be burnt, but also allowed additional power to be generated by feeding the resulting steam into the engine together with the combustion products. Torpedoes with such a propulsion system became known as wet heaters while heated torpedoes without steam generation were, retrospectively, called dry heaters. Most torpedoes used in World War I and World War II were wet-heaters.
[edit] Compressed oxygen
The amount of fuel that can be burnt by a 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 (nicknamed long lance postwar by historian Samuel E. Morison) for destroyers in the 1930s, which used pure oxygen instead of compressed air and had an unmatched performance in World War II.
[edit] Steam
A derivative of the compressed-air torpedo was the steam torpedo. Developed by Vickers Ltd, it mixed alcohol (first ethanol, later methanol) with compressed air in the combustion chamber, producing "steam". This increased speed, but produced a visible wake.[3]
[edit] 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 25 knots for over 2,400 m.
[edit] Flywheel
The Howell torpedo used by the US Navy in the late 1800s featured a heavy flywheel which had to be spun up before launch. It was able to travel about 750m at an average speed of 30knts. The Howell torpedo had the advantage of not leaving a trail of bubbles behind it, unlike compressed air torpedoes. This gave the target vessel less chance to detect and evade the torpedo, and avoided giving away the attacker's position.
[edit] Electric propulsion
Electric propulsion systems also avoided tell-tale bubbles. John Ericsson invented an electrically propelled torpedo in 1873; it was powered via a cable from an external power source, as batteries of the time had insufficient capacity.
Germany introduced the first battery-powered torpedo shortly before World War II, the G7e. It was slower and had shorter range than the conventional G7a, but was wakeless and much cheaper. Its lead-acid rechargeable battery was sensitive to shock, required frequent maintenance before use, and required preheating for best performance. The experimental G7ep, an enhancement of the G7e, used primary cells.
Modern electric torpedoes such as the Mark 24 Tigerfish or DM2 series commonly use silver oxide batteries which need no maintenance, allowing torpedoes to be stored for years without losing performance.
[edit] Modern propulsion systems
Modern torpedoes utilize a variety of drive mechanisms that include gas turbines (the British Spearfish torpedo), monopropellants and sulphur hexafluoride gas sprayed over a block of solid lithium. Some torpedoes, such as the Russian VA-111 Shkval or the German Barracuda, use supercavitation to increase their speed to over 200 knots (370 km/h); compare the speed of the Mark 46 torpedo, which does not use supercavitation, of about 28 knots (32 mi/h, 52 km/h).
[edit] Torpedo classes and diameters
Torpedoes are launched several ways:
- Many torpedo boats such as the U.S. WW2 PT boats launch from a deck-mounted "drop collar".
- From a torpedo tube mounted either in a trainable deck mount (common in destroyers), or fixed above or below the waterline of a surface vessel (as in cruisers, battleships, and armed merchant cruisers), or aboard a submarine.
- From shackles aboard low-flying aircraft or helicopters.
- 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 caliber 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.
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.
- 450 mm (17.7 inch) 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:
- Allied torpedoes of the Second World War.
- Some torpedoes of the Imperial Japanese Navy.
- Torpedoes of the Kriegsmarine
- NATO torpedoes.
- Some Soviet and Russian torpedoes, including the current ASW models.
- 24 inch (610 mm) torpedoes were used by the Imperial Japanese Navy, most famously the deck launched Type 93 torpedo ('Long Lance'), also some Kaiten kamikaze torpedoes.
- 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 (762 mm) 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.
[edit] Torpedoes used by various navies
[edit] German Navy
Modern German Navy:
- DM2A4 heavyweight torpedo
- DM2A3 heavyweight torpedo
- MU 90 lightweight impact torpedo
- Mark 46 torpedo
- Barracuda supercavitating torpedo (under development)
The torpedoes used by the WWII Kriegsmarine included:
[edit] Imperial Japanese Navy
The torpedoes used by the Imperial Japanese Navy (WWII) included:
[edit] Royal Navy
The torpedoes used by the Royal Navy include:
[edit] Russian Navy
Torpedoes used by the Russian Navy include:
[edit] US Navy
The four major torpedoes in the United States Navy inventory are:
- the Mark 48 heavyweight torpedo,
- the Mark 46 lightweight and
- the Mark 50 advanced lightweight.
- the Mark 54 torpedo.
[edit] See also
- List of torpedoes
- Acoustic torpedo
- Torpedo boat
- Torpedo bomber
- Submarine
- Missile guidance
- Human torpedo
- Bangalore Torpedo
- Autonomous Underwater Vehicle
[edit] External links
- Modern Torpedoes And Countermeasures [2]
- US Navy torpedo data cut and pasted from a Navy Fact File
- A slightly more recent writeup on the Mk-48 is available at a SSBN 624 web site by Clwyd
- Early History of the Torpedo Torpedo History
- US Naval Undersea Museum Torpedo Display
- US Naval Undersea Museum Torpedo Collection
- Super Cavitation Torpedo 'Barracuda' [3]
- http://www.hansonclan.co.uk
- http://www.globalsecurity.org
- http://www.btinternet.com/~philipr/torps
- http://www.geocities.com/gwmccue
- http://www.geocities.com/Pentagon/1592/ustorp1
- http://navytorpedo.com
- Civil War Torpedoes
- http://naval.undersea.museum
- http://www.weymouthdiving.co.uk/torpedoes.htm
- Self-propelled torpedo of Alexandrovskii-in Russian
- Alexandrovskii Ivan Feodorovich-in Russian
[edit] Sources
- Blair, Clay. Silent Victory. Philadelphia: Lippincott, 1975.
- Milford, Frederick J. "U.S. Navy Torpedoes: Part One--Torpedoes through the Thirties". The Submarine Review, April 1996. {quarterly publication of the Naval Submarine League, P.O. Box 1146, Annandale, VA, 22003)
- _______. "U.S. Navy Torpedoes: Part Two--The Great Torpedo Scandal, 1941-43". The Submarine Review, October 1996.
- _______. "U.S. Navy Torpedoes: Part Three--WW II development of conventional torpedoes 1940-1946". The Submarine Review, January 1997.
- The Columbia Encyclopedia, Sixth Edition, online.
- O'Kane, Richard H. (1987). "Seventh Patrol", Wahoo: The Patrols of America's Most Famous World War II Submarine. Novato, California: Presidio Press.
- Perry, Milton F. "Infernal Machines: The story of Confederate submarine and mine warfare." Louisiana State University Press, 1985.
- Crowley, R.O. "Confederate Torpedo Service" in The Century / Volume 56, Issue 2, The Century Company, New York, June 1898.
