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SSM - Midget Submarines

Midget submarines are able to perform various underwater missions. Like a mackerel, such a mini submarine is characterized by its speed and maneuverability. An equipment with its own sonar can allow the autonomous detection of enemy vessels. A system is conceivable wherein several of these underwater vehicles work together.

In terms of maritime transport equipment, developed countries attach great importance to the special forces specially developed for their special forces and equipped with highly usable and concealed transport tools, especially small, low-noise, high-speed ships suitable for secret activities in shallow coastal waters. The US Navy special forces are equipped with more than 150 maritime transport vessels and special submarines.

Near the end of the Great War, the Italians began to experiment with midget submarines and manned torpedoes for use in attacking enemy ships in sheltered anchorages. One of these two-man submersibles, a mignatta (leech), was used to attack the Austrian battleship Viribus Unitis in the port of Pola in November 1918, just as the war was ending. In the 1930s, the Italians again started working on small submersibles, and two naval engineers, Elios Toschi and Teseo Tesei, designed a manned torpedo. The official Italian name for their craft was Siluro a Lenta Corsa (SLC, or slowrunning torpedo), but the Italian operators nicknamed it a �maiale� (pig). During the early part of World War II, the Italian SLCs conducted a number of bold raids against the British at Alexandria, Algiers, and Gibraltar, during which they sank or seriously damaged 50,000 tons of merchant shipping and over 60,000 tons of warships.

The British had captured some Italian SLC vehicles during an unsuccessful Italian attack on Gibraltar, and they immediately initiated a crash program to produce very similar vehicles, which they called chariots. They also initiated a second program to build midget submarines; these were identified as X-craft. In the spring of 1943, as the new X-craft became available, the British started training for an attack on the Tirpitz, which was still anchored in northern Norway. In September 1943, four X-craft penetrated Kaafiord, where the 40,000 ton Tirpitz was moored behind an extensive barrier of mines and antisubmarine nets, and successfully attacked the ship.The X-craft also conducted two raids on Bergen, Norway, in April and September of 1944, during which they sank a 7,800-ton ship and a floating drydock. The X-craft were moved to the Pacific theater of operations when the war in Europe ended. In July 1945, the X-craft were used to attack a Japanese heavy cruiser anchored in Johore Strait just above the city of Singapore.

The Germans also developed a number of midget submarines, including the Biber (beaver), Molch (salamander), and Seehund (seal) classes, for use against the invasion fleet, but the first of these, the Biber, was not available until January 1945.

In 1936, the Japanese started a secret project at the Kure Naval base to build two-man midget submarines. To maintain security, these small, 46-ton, Type A Ko-hyoteki-class submarines, assembled from prefabricated subsections, were kept on an isolated island at the Kure Arsenal. Japan launched five midget submarines near Pearl Harbor the night before the attack on December 7th. One of those subs was first seen by the USCG Condor at 3:50 a.m., about two miles from the harbor�s entrance. The Condor notified the USS Ward, which spotted the sub tailing the USS Antares into the harbor, opened fire and sank it. About an hour later, the air attack began. Americans sank two other Japanese subs during the battle. A fourth Japanese sub called the Ha-19 never made it into the harbor. A fifth Japanese sub that was launched that day was never found.

USS X-1 Experimental Midget Submarine was America's only midget submarine. The United States currently uses SEAL Delivery Vehicles (SDV) MK 11 Shallow Water Combat Submersibles (SWCS) to deliver Sea, Air, Land (SEAL) team naval special warfare commandoes. SEALs conduct clandestine missions infiltrating their objective areas by fixed- and rotary-wing aircraft, Navy surface ships, combatant craft, submarines and ground mobility vehicles. In the United States, the Advanced SEAL Delivery System (ASDS) was a proposed combatant submersible developed for clandestine insertion and extraction of Special Operations Forces (SOF). It would transport SEALs in a dry environment and deliver them ready for action. Its advanced sonar systems and unique electro-optical systems will provide a new level of undersea situational awareness. Submarines are converted with latching pylons and a hatch in order to host the ASDS for transport to mission areas.

The US Navy has a variety of special operations underwater insertion tactics. A Lock-Out Trunk allows Special Operations Forces to launch up to 60 feet below the water�s surface. Using LOT for insertion allows a ship to deploy four Combat Rubber Raiding Crafts with five divers in a 20-30 minute cycle with a proficient crew. A Lock-Out Chamber, which takes approximately 45-60 minutes to execute, is capable of up launching 12 CRRC�s and 12 swimmers per cycle by flooding the lock-out chamber and sending them through a converted missile tube. The final method is a slant deck insertion, Though it is used least often due to its tactical inferiority over the other methods, it is the simplest. During slant deck operations, the submarine will surface half way out of the water, with the front raised higher than the rear, and SOF teams can launch their CRRC�s off the top deck. The clandestine nature of most SEAL missions meant that the mission challenge was to infiltrate, execute the mission, and leave without indigenous personnel knowing that the operators ever were there.

When the Chednan sinking incidient occurred in March 2010, the ROK-led international investigation concluded that the South Korean warship had been sunk by a North Korean torpedo fired by a midget submarine. North Korea denied that it was responsible for the sinking, and China dismissed the ROK conclusions as not credible and argued that "China will not be partial to either side" but hoped South Korea and other relevant parties remain calm, and handle the incident properly. Thus, the UN Security Council issued a presidential statement condemning the attack but without identifying the attacker.

In the early 20th Century, the the military value of submarine war vessels depends to a very great extent on their cruising ability and the range and distance which they can cover without returning to a home port for supplies, fuel and the like. Therefore, in order to produce a submarine vessel of the greatest military value it must be of great size and capacity, and was, accordingly, expensive to build. The military effectiveness of such vessel was no greater than that of a smaller one, provided the smaller vessel can be transported to the point of operation with the same feasibility as in the case of the larger vessel. Furthermore, submarine attack on fleets or convoys was far more effective if made by a number of submarines. If a large number of small submarines could be placed in position for such an attack the results vould be far greater than if a smaller number of larger submarines were employed for the same purpose.

A mother submarine vessel can have means for transporting a secondary submarine vessel safely and quickly, in which the secondary submarine vessel can be securely carried against accidental displacement. The secondary small submarine vessel can be quickly and safely released or launched when necessary, and the secondary small submarine can be easily and expeditiously returned to a normal position with respect to the mother vessel.

In recent years, there has been an increased demand for submarine missions that take place in littoral or shallow waters where the risk of detection is greater. A submerged submarine can leave a wake that is detectable from the air. The size of this wake increases with greater displacement and speed and less depth. The probability of detection by active sonars and magnetic anomaly detection equipment also increases with greater displacement and less depth. In addition, a submerged submarines' ultimate limitation in navigating shallow waters is its total submerged draught. Among the possible solutions to this dilemma, there should be a requirement for submarines to be smaller and stealthier while not losing any of their "blue-water" capabilities.

The earliest submarine appeared during American Revolution. After 200 years' development, from an early manpower submarine to a diesel-electric submarine and a nuclear power submarine, the submarine has become an important part of a modern navy. However a diving principle of the submarine has not changed. The diving principle is that a specific gravity of the submarine is changed via inhaling or blowing out seawater, in such a manner that the submarine is able to dive or surface. Therefore all of the modern submarines have double-skin structures, wherein a pressure hull inside is a cylinder having high roundness, and personnel, equipments, etc. are all in the pressure hull. A nonpressure hull outside is in a shape having low water resistance, e.g. water-drop shapes, a water box between the two hulls controls the submarine to dive or surface, and the non-pressure hull is able to resist attacks of underwater ordnances, e.g. depth bombs, to some extent.

As a tactics or strategic weapon, the modern submarine has developed well, but the submarine still has some disadvantages such as a low deadweight, a low tank capacity and a complicated structure. When the submarine is sailing under water, a submerged displacement is larger than a water-borne displacement, so the water resistance is increased. With a large tank of water added, an underwater mobility of the submarine is not good. Therefore, applications of the modern submarines are limited, and usually limited to an assault weapon.

Boat submersible in water, unlike the water of a ship, only the relationship between the center of gravity and center of buoyancy in determines the stability, the weakness of a lack of stability because it can not increase the distance between the structure on the center of gravity and center of buoyancy the case, conventionally, because they were ensure stability by increasing the distance between the center of gravity and center of buoyancy gained ballast to the bottom of the submersible, the entire submarine becomes heavy.

An important issue in the field of submersible boats is buoyancy, and the design of means for taking the boat to a desired level in or on the water and keeping it there until another decision regarding the level is made. Such means may comprise two buoyancy chambers which are arranged at opposite sides of the submersible boat. Conventional submersibles suffer from many deficiencies. One such deficiency is the sole use of variable buoyancy. In the case of catastrophic failure of a variable buoyancy system, the corresponding submersible will generally sink.

Another deficiency is that conventional submersibles maneuver using a static system of ballast adjustment and vectored thrust. The use of such systems result in submersibles that are slow and bulky, and that are without advanced maneuvering capabilities such as, for example, aircraft. As a result, undesirable emergency situations such as, for example, entanglements, can occur with some frequency, and the ability to avoid such situations is diminished.

Hiding illicit cargo on the outside of the hull of medium to large vessels e.g. on the sea-chests or the rudder trunks of large vessels or even on underwater appendices (assuming low enough transit speed at sea) is a commonly quoted and long-known method for smuggling, which can only be countered by diver inspections prior to departure or soon after arrival of the vessel. Hull inspections by divers are manpower intensive, expensive and dangerous for the divers. Consequently, such hull inspections are carried out relatively infrequently, except maybe for high value naval units when lying at anchor far from their home bases.

More recently, since it has been recognized that harbors represent potential targets for terrorist attacks, harbour security has become an important matter of concern. One of the threats that have to be dealt with is the use of hostile equipment (e.g. a mine or a torpedo) attached as a keel appendice or in a cavity on the outside of the hull of a ship. Sinking a large vessel at the entrance of a large port or exploding a dirty bomb in the centre of a large coastal metropolis could result, with a high probability, in major human, social and economic damages.