TORPEDO

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.

Contents

Etymology

History

Early naval "torpedoes"

Bombs and booby traps

Self-propelled torpedoes

Propulsion

Compressed air

Heated torpedoes

Wet-heater

Compressed oxygen

Steam

Wire driven

Flywheel

Electric propulsion

Modern propulsion systems

Torpedo classes and diameters

Guidance and tactics

Torpedoes used by various navies

German Navy

Imperial Japanese Navy

Indian Navy

Royal Navy

Russian Navy

U.S. Navy

See also

References

Sources

External links

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 torpedo was so named by Robert Fulton, who used it to refer to a towed gunpowder charge that was used by his submarine ''Nautilus'' to demonstrate that it could sink warships. Fulton's experiments were conducted 1800 to 1805.

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.
Much like the invention of the helicopter, the earliest torpedoes are thought to have existed as concepts many centuries before being developed as working devices. The earliest known description of what might be called a torpedo is found in the work of Syrian scholar Hassan Al-Rammah in 1275. His works show illustrations of a rocket-propelled device that appears to have been designed to move on the surface of water.^[1]
Torpedoes were also later developed in what is now Rijeka, Croatia.

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 shipworm.
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. Electricity was a new technology, and the limitations of direct current for effective distance was poorly understood, so failures were also possible because of the decrease in voltage when the torpedoes were placed too far from the batteries. Former United States Navy Commander Matthew Fontaine Maury, who served as a commander in the Confederate Navy, did work on the development an underwater electrical mine.
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 (12 m) 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. However these torpedoes would be able to cause as much harm to their handlers as to their targets.

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".

Self-propelled torpedoes

From World War I onwards, the word ''torpedo'' was used only for self-propelled projectiles that travelled under or on water.
The first working prototype of the self-propelled torpedo we know today was created by a chance commission placed by Giovanni Luppis, an Austrian naval officer from Fiume (today Rijeka, Croatia), a port city of the Austrian Empire, on Robert Whitehead, an English engineer who was the manager of a Fiume factory. In 1864, Luppis presented Whitehead with the plans of the ''salvacoste'' (coastsaver), a floating weapon, driven by ropes from the land, and made a contract with him in order to perfect the invention.
Whitehead was unable to improve the machine substantially, since the clockwork motor, the attached ropes and the surface attack mode all contributed to a slow and cumbersome weapon. However, he kept considering the problem after the contract had finished, and eventually developed a tubular device, designed to run underwater on its own, and powered by compresed air.
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.
Maintaining proper depth was a major problem in the early days but Whitehead introduced his "secret" in 1868 which overcame this. It was a mechanism consisting of a hydrostatic valve and pendulum which caused the torpedo's hydroplanes to be adjusted so as to maintain a preset depth.
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 1000 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 (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 engine, using compressed air of around 1300 lb/in² (91kg/cm², or approximately 88 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 self-propelled 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 (later simply destroyers) were built to counter it. Torpedoes were also used to equip gunboats of around 1,000 tons displacement, thus becoming torpedo gunboats.
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 there was an extended wrangle over the issue, exemplified in the three-fold problems plaguing the Mark 14 torpedo. The magnetic pistol problems had concealed two deeper design flaws: The depth regulator caused it to run some ten feet too deep and the mechanical firing pin moved perpendicular to the torpedo's path where its weight caused it to drag in its cylinder upon sharp impact.^[2]. Cursory trials had allowed bad designs to enter service. Both the Navy Bureau of Ordnance and the United States 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.^[3]

Propulsion

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 180 m (200yd) at an average speed of 6.5 knots (12 km/h). 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 1000 m (1100yd) at an average speed of 35kt (64 km/h).
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. This increased engine performance further, because the air expanded even more after heating.

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.

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.

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.

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.^[4]

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.

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 750 m 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.

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.

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).

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.

Guidance and tactics

The first guided torpedo was the Victorian era Brennan Torpedo which could be steered onto its target by varying the relative speeds of its contra-rotating propellers. However the Brennan Torpedo required a substantial infrastructure and was not suitable for ship-board use. Therefore for the first part of its history the torpedo was guided only in the sense that its course could be regulated so as to maintain a fixed depth and, through gyroscopes, a straight course. With such torpedoes the method of attack in small torpedo boats, Torpedo bombers and small submarines, was to set on a collision course abeam to the target and to release the torpedo at the last minute, before peeling away; all the time running a gauntlet of defensive fire.
In larger ships and submarines fire control calculators gave a wider engagement envelope. Originally plotting tables with specialised slide rules these could reconcile the speed, distance and course of a target with the firers own speed and course, together with the performance of its torpedoes to give a firing solution. By the time of the Second World War all sides had developed automatic calculators as exemplified by the US Torpedo Data Computer; although submarine commanders were still expected to be able to calculate a firing solution by hand as a back up against mechanical failure.
Against high value targets and multiple targets individual submarines would launch a spread of torpedoes across the course of the target or targets, to increase the probability of success. Similarly squadrons of torpedo boats and torpedo bombers would attack together creating a "comb" of torpedoes across the target's course. Faced with such an attack the prudent thing for a target to do was to turn 90 degrees to its original course and steam away from the torpedoes and the firer, allowing the relatively short range torpedoes to use up their fuel. However an alternative was to "run the comb" turning 90 degrees but to steam towards the torpedoes and their firer. The intention of such a tactic was still to minimise the size of target offered to the torpedoes, but at the same time be able to aggressively engage the firer. This was the tactic that Jellicoe's Battle of Jutland critics advocated, Jellicoe's caution at running from the torpedoes being seen as the reason why the German fleet managed to escape.
The use of multiple torpedoes to engage single targets greatly reduces a submarines combat endurance and its ability to stay on patrol. This can be improved by insuring that a target can be effectively engaged by a single torpedo, this gave rise to the guided torpedo. Guided torpedoes can use passive and active guidance or a mix of the two to give semi-active guidance. Passive torpedoes home in on emissions from a target, usually noise from the target creating a passive acoustic torpedo. Active acoustic torpedoes home in on the reflection of a signal, a "ping", from the torpedo or its parent vehicle, however this has the disadvantage of giving away the presence of the firer. In semi-active mode a torpedo can be fired to the last known position or calculated position of a target, the target is than acoustically illuminated once the torpedo is in attack range.
Torpedoes can operate on a fire and forget principle or be controlled by its firing vessel. During the Second World War the US experimented with frequency hopping radio controlled torpedoes using matching pairs of punched card rolls based on that of Player pianoes. Modern torpedoes use an umbilical wire; the advantage of the umbilical being that the processing power that can be fitted into the hull of a submarine or ship is vastly greater than that which can be fitted into even the largest torpedo. Torpedoes such as the Mark 48 torpedo can operate in a variety of modes increasing tactical flexibilty.
A ship's acoustic signature is not the only emission that a torpedo can home in on. To engage the US super carriers the Soviet Union developed the 53-65 wake homing torpedoes.

Torpedoes used by various navies

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:

★ G7a (T1)

★ G7e (T2)

★ T3

★ T4 (Falke)

★ G7es (Zaunkönig)

★ T11

Imperial Japanese Navy

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

★ Type 91 torpedo

★ Type 92 torpedo

★ Type 93 torpedo

★ Type 95 torpedo

★ Type 97 torpedo

★ Kaiten

Indian Navy

★ Advanced Experimental Torpedo (Light weight torpedo)

★ Varunastra (Heavy weight torpedo)

★ Takshak (Thermal torpedo) ^[5]

Royal Navy

The torpedoes used by the Royal Navy include:

★ Spearfish torpedo

★ Stingray torpedo

★ Tigerfish torpedo

Russian Navy

Torpedoes used by the Russian Navy include:

★ Type 53 torpedo

★ Type 65 torpedo

★ APR-3E torpedo

★ VA-111 Shkval torpedo

U.S. Navy

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

★ the Mark 46 lightweight;

★ the Mark 48 heavyweight torpedo;

★ the Mark 50 advanced lightweight; and

★ the Mark 54 Lightweight Hybrid Torpedo.

See also

★ List of torpedoes

★ Acoustic torpedo

★ Torpedo boat

★ Torpedo bomber

★ Submarine

★ Missile guidance

★ Human torpedo

★ Bangalore Torpedo

★ Autonomous Underwater Vehicle

References

1. Muslim Rocket Technology Prof. Dr. Mohamed Mansour
2. O'Kane, 1987
3. Blair, p.20
4. Blair, p.30-1.
5. NSTL achievements

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.

External links

★ Swedish Bofors 'Torpedo 2000' promo video

★ Modern Torpedoes And Countermeasures [1]

★ 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' [2]