SLC (manned torpedo)
 Manned torpedo SLC-200
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The SLC (siluro a lenta corsa = slowly moving torpedo), later renamed Maiale (pig), was a manned torpedo of the Italian Navy , which was based on its torpedo predecessor Mignatta ( leech ). This was designed in 1918 by Corvette Captain Ing. Raffaele Rosetti. The SLC (correct designation SLC-200 ) should, however, in contrast to its predecessor, be submersible.
Development history
The use of manned torpedoes had in the Italian Navy as early as World War I began. According to the provisions of the Naval Conference of 1922, Italy and other states were subject to restrictions on surface and underwater forces , so that all development work and redesign were subsequently suspended. In the run-up to the Italo-Ethiopian War , the manned torpedo experienced a renaissance. The SLC was conceived in 1935 under the two first lieutenants Teseo Tesei and Elias Toschi .
After the plans were examined and approved by the naval command , two prototypes of the SLC were commissioned. The San Bartolomeo underwater weapons factory in La Spezia was commissioned to build it in the strictest of secrecy , and the two prototypes were delivered in 1935. The extensive tests that followed, which took place both in the dry dock in La Spezia and at sea, were satisfactory and required only minor modifications to future equipment. At the same time as the start of series production of the SLC , a training center was set up which was primarily intended to deal with the training of future "torpedo riders". These soon found a new name for the SLCs , which they called Maiale in the future .
With the end of the Abyssinian War and a subsequent military relaxation in the Mediterranean area, the construction of the SLC and its team training was discontinued in 1936, but reactivated again in 1938. An organizational change in the "SLC combat group" took place on July 10, 1939, when all Italian small combat units were combined in the " Decima Mas ", the 10th Schnellboot Flotilla.
Manning
The crew of an SLC consisted of two people who were placed one behind the other on the torpedo in appropriate seats and footrests. The front torpedo rider, usually an officer, acted as the commander and helmsman; the one behind was the "surgeon". Both wore a light wet suit that left their heads and hands free. Their breathing was ensured by an oxygen diving device, which was supplied by means of compressed oxygen in a bottle via a pressure reducing valve to a breathing bag that the torpedo riders wore around their mouths. The exhalation also took place in the breathing bag, which then went through a calcium-soda cartridge together with the fresh oxygen in order to remove the carbon dioxide from the air mixture. The breathing apparatus could be used up to a water depth of 15 meters, its breathing gas supply was used up after six hours of operation. However, accidents due to carbon dioxide poisoning and various breathing problems due to high water pressure increased, especially because the maximum depth of 15 meters was often exceeded during operations and the breathing bag was pressed in by the higher water pressure, which could lead to suffocation of the person. The marine management then introduced a compressed air diving device that could be used up to a water depth of 40 meters and guaranteed compressed air between 150 and 200 atmospheres from a bottle regardless of water pressure. The exhaled carbon dioxide escaped through filters into the surrounding water.
construction
The SLC-200 was the standard torpedo of the Italian Navy and was about 5.33 meters long. The 1.8 meter long head section housed the 250 kg explosive charge and a trim tank. The circuit worked by means of a 4-speed resistance circuit. The battery and engine compartment were located in the middle. The stern was provided with a stern compensation tank and ended in the propeller shaft tunnel, propeller protection as well as rudder and rudder. The flooding was done by means of a lever and the emptying by compressed air. After about 6 to 7 seconds the SLC was submerged. The seats for the two torpedo riders were attached to the top of the torpedo. The front one was provided with a protective screen that served as a breakwater. In this cockpit all important instruments such as magnetic compass , voltmeter , ammeter , depth gauge and manometer were housed, which were provided with luminous numbers. The control was carried out by means of steering wheels. The backrest of the rear seat was hollow and equipped with a compressed air net lifter and net scissors in order to be able to overcome any barriers. A wooden board and a coiled rope were also housed there so that explosive charges could be attached.
Intended use
Due to the short range of the SLC , which was only 10 nm , and the low speed of only 2.5 kn , operations had to be carried out at night. In addition, the torpedo first had to be brought close to the target, which was mostly a port, by tugs. This usually took place on the deck of the carrier ship used. The naval management even designed specially designed pressure vessels in which the SLC could be brought to the target area on deck by conventional submarines. This was necessary because enemy aircraft crews could see submerged boats up to 50 meters deep in the Mediterranean Sea. The submarines Scire (3 SLC ), U-Murena and U-Grongo (4 SLC each ) and U-Iride were used for this. Plans for a drop from the air had to be abandoned due to the lack of readiness of the Italian Air Force.
The often long approach routes were, if possible, covered over water and without breathing apparatus. Once the SLC reached the target area, it was half flooded and detached. This was called the depth of glasses . The SLC then ran towards its target at minimum speed in order not to create a telltale wake. About 30 to 50 meters from the target he finally dived. When it arrived below the ship's target, the SLC was carefully made to surface until it almost touched the bottom of the ship. The surgeon removed the explosive charge from the bow of the SLC and attached it to the enemy ship using magnets. A rope about 1.5 meters long, to which the actual explosive charge was attached, hung from this magnet. The timer could be set up to a duration of 150 minutes. After this was done, the crew and the torpedo were able to withdraw or set the SLC to self-destruct and go into captivity.
Missions (selection)
- August 22, 1940: U-Iride sunk in preparation for an SLC attack by British aircraft in Bomba Bay (near Tobruk ).
- September 29, 1940: U-Gondar with SLC sunk by British anti-submarine units about 100 nm off Alexandria .
- September 29, 1940: U-Scire with three SLC , whose mission was aborted due to the departure of the British Gibraltar fleet.
- October 30, 1940: U-Scire disembarked three SLC off Gibraltar. However, all three had to be given up due to technical defects. Although the self-destruct function had been activated for all of them, an SLC came into Spanish hands, probably due to a technical defect in the ignition system. Through corresponding Spanish press releases and the use of agents, the English naval command became aware of the existence and specifications of these devices.
- May 26, 1941: U-Scire rebooted three SLC off Gibraltar. As a result of further technical problems and no worthwhile goals, all three SLCs were blown up by their crews.
- July 26, 1941: Operazione Malta Due : A combined blow with speedboats and explosives as well as two SLC led to the demolition of the bridge at St Elmo ( Malta ). The actual target, the port, is not reached. SLC co-developer Tesei dies in this attack.
- September 21, 1941: U-Scire disembarked three SLC off Gibraltar. Here the tanker Fiona Shell (2,444 GRT) was sunk, the tanker Denbydale (8145 GRT) and the motor ship Durham (10,893 GRT) were damaged.
- December 18, 1941: U-Scire disembarked three SLC off the port of Alexandria. These were able to set the battleships HMS Queen Elizabeth and HMS Valiant aground. The Norwegian tanker Sagona (7554 GRT) and the destroyer Jervis were also badly damaged. This mission marked the climax of the SLC missions.
- December 12, 1942: U-Ambra disembarked three SLC and 10 combat swimmers. These severely damaged the freighters Ocean Vanguisher (7174 BRT), Berto (1493 BRT), Empire Centaur (7041 BRT) and Harmattan (4558 BRT) in the port of Algiers .
- May 7, 1943: sinking of the freighter Camerata (4875 GRT) as well as damage to the freighters Pat Harrison (7000 GRT) and Mahsud (7500 GRT) by three SLC .
- 4th August 1943: sinking of the tanker Thorshövdi (9,944 GRT) and damage to the freighters Harrison Gray Otis and Standridge (together 13,151 GRT) by three SLC .
Some copies of the SLC were taken over by the fascist RSI after the Cassibile armistice and came under German control there. They were used in the small combat units of the navy. However, there are no reports of such operations.
As early as 1942, the Royal Navy had salvaged some sunken SLC off Gibraltar. These served, in addition to a completely intact alluvial torpedo, as a template for the British Chariot .
Notes and individual references
- ↑ Later versions could carry up to 300 kg of explosives.
- ^ Joseph Caruana, The Battle of Grand Harbor. July 26, 1941, St. Julians 2004, pp. 33-34.
literature
- Harald Fock: Naval small weapons. Manned torpedoes, small submarines, small speedboats, explosives yesterday - today - tomorrow. Nikol, Hamburg 1996, ISBN 3-930656-34-5 , pp. 20-24.
- Maurizio Brescia: Mussolini's Navy: A Reference Guide to the Regia Marina 1930-1945 , Seaforth Publishing, 2012, ISBN 9781848321151 , p. 194 [1]
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