Human torpedoes or manned torpedoes are a type of diver propulsion vehicle on which the diver rides, generally in a seated position behind a fairing. They were used as secret naval weapons in World War II. The basic concept is still in use.
The name was commonly used to refer to the weapons that Italy, and later (with a larger version) Britain, deployed in the Mediterranean and used to attack ships in enemy harbors. The human torpedo concept has occasionally been used by recreational divers, although this use is closer to midget submarines.
The concept of a small, manned submarine carrying a bomb was developed and patented by a British naval officer in 1909, but was never used during the First World War. The Italian Navy experimented with a primitive tiny sub (Mignatta) carrying two men and a limpet mine: this craft successfully sank Austro-Hungarian battleship SMS Viribus Unitis on 1 November 1918.
The first truly practical human torpedo was the Italian Maiale (nicknamed the "pig" because it was difficult to steer) used in the Second World War.
The Maiale was electrically propelled by a 1.6 horsepower (1.2 kW) motor in most of the units manufactured, with a top speed of 3 knots (5.6 km/h) and often required a travel time of up to two hours to its target. Two crewmen in diving suits rode astride, each equipped with an oxygen rebreather apparatus. They steered the craft to the enemy ship. The "pig" could be submerged to 15 metres (49 ft), and hypothetically to 30 metres (98 ft), when necessary. On arrival at the target, the detachable warhead was released for use as a limpet mine. If they were not detected, the operators then rode the mini sub away to safety.
Development began in 1935 but the first 11 were not completed until 1939 by San Bartolomeo Torpedo Workshops in La Spezia, Italy and a larger number followed. The official Italian name for the majority of the craft that were manufactured was Siluro a Lenta Corsa (SLC or "Slow-running torpedo"). Two distinct models were made, Series 100 and then (in 1942) Series 200 with some improvements. At least 50 SLCs were built by September 1943.
In operation, the Maiale torpedo was carried by another vessel (usually a conventional submarine), and launched near the target. Most manned torpedo operations were at night and during the new moon to cut down the risk of being seen. Attacks in 1940 were unsuccessful but in 1941, the Italian navy successfully entered the harbor of Alexandria and damaged the two British battleships HMS Queen Elizabeth and HMS Valiant, as well as the tanker Sagona. This feat encouraged the British to develop their own torpedo "chariots".
The last Italian model, the SSB (for Siluro San Bartolomeo, "San Bartolomeo Torpedo") was built with a partly enclosed cockpit, a more powerful motor and larger 300 kg (660 lb) warhead (up from the earlier SLC's 220 and 250 kg (490 and 550 lb) warheads). Three units were made but not operationally used because Italy surrendered in 1943.
The first British version of the concept was named the Chariot manned torpedo. Two models were made; Mark I was 20 feet (6.1 m) long while Mark II was 30 feet (9.1 m) long, both suitable for carrying two men. Later versions were larger, starting with the original X-class submarine, a midget submarine, 51 feet (16 m) long, no longer truly a human torpedo but similar in concept. The X-Class were capable of 6.5 knots (12.0 km/h) on the surface or 5.5 knots (10.2 km/h) submerged. They were designed to be towed to their intended area of operations by a full-size 'mother' submarine.
The German navy also developed a manned torpedo by 1943, the Neger, intended for one man, with a top speed of 4 knots (7.4 km/h) and carrying one torpedo; the frequent technical problems often resulted in the deaths of operators. Roughly 200 of these were made and they did manage to sink a few ships. The later Marder (pine marten in English) was about 27 feet (8.2 m) long and more sophisticated and could dive to depths of 27 metres (89 ft) but with very limited endurance. About 500 were built.
A typical manned torpedo has a propeller, hydroplanes, a vertical rudder and a control panel with controls for its front rider. It usually allows for two riders who sit facing forwards. It has navigation aids such as a compass, and nowadays modern aids such as sonar and GPS positioning and modulated ultrasound communications gear. It may have an air (or other breathing gas) supply so its riders do not have to drain their own apparatus while they are riding it. In some the riders' seats are enclosed; in others the seats are open at the sides as in sitting astride a horse. The seat design includes room for the riders' swimfins (if used). There are flotation tanks (typically four: left fore, right fore, left aft, right aft), which can be flooded or blown empty to adjust buoyancy and attitude.
For other events, see Operations of X Flottiglia MAS and British commando frogmen.
Some nations including Italy have continued to build and deploy manned torpedoes since 1945.
For information on Italian manned torpedo operations, see Decima Flottiglia MAS.
Main article: Chariot manned torpedo
See also: British commando frogmen
See also: German commando frogmen
This extreme form of a genuine human torpedo carried a second torpedo underneath, which was launched at the target. Speed: 4 knots (7.4 km/h), and about 10 hours at 3 knots. One seat. This manned torpedo was named after its inventor Richard Mohr.
These very small submarines carried two torpedoes and one or two men. There were other types that never ran into production. In July 1944 Nazi Germany's Kriegsmarine introduced their human torpedoes to harass allied positions at Normandy anchorages. Although they could not submerge, they were difficult to observe at night and inflicted several losses on allied vessels. They were also used to harass allied vessels in the invasion of southern France but were largely ineffective.
There are pictures and descriptions of modern US Chariot-like underwater frogman-carriers used by SEALs and a fast surface boat that can submerge, here:
Argentina developed manned torpedoes and special mini-submarines in the 1950s, the latter with a torpedo attached under the two-men crew. Their crews were trained by Eugenio Wolk, a former member of the Italian Decima MAS.
In Poland, in the months before the outbreak of the Second World War, a number of volunteers came forward to pilot torpedoes against German warships. A Bureau of Living torpedoes was set up to organize and train these volunteers, and prepare suitable equipment, but nothing had come to fruition before the German invasion and occupation.
The Yugoslav Navy did not have manned torpedoes, but frogmen used the underwater device called R-1 Diver for a variety of missions, including: mine clearance, infiltration, clandestine surveillance and security, and assault missions on enemy shipping and naval objects. These small apparatuses were relegated to the navies of Croatia (HRM) (1991) and Montenegro (2007).
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