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British U-class Submarine
The British U-class submarines (officially "''War Emergency 1940 and 1941 programmes, short hull''") were a class of 49 small submarines built just before and during the Second World War. The class is sometimes known as the ''Undine'' class, after the first submarine built. A further development was the British V-class submarine of 1942. Background The Royal Navy was limited to no more than of submarines by the London Naval Treaty of 1930. The tonnage limit led to proposals for smaller submarines which was also prompted by trials with larger submarines demonstrating that they were easier to find and lacked manoeuvrability. By coincidence the First World War-vintage H-class submarines used for training in anti-submarine warfare were reaching the end of their useful service. The Rear-Admiral Submarines, Noel Laurence, wanted a class of small, inexpensive boats for training, armed with torpedoes for short-range patrols. In March 1934 wrote a specification for a "Small, Simple, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holy Loch
The Holy Loch ( gd, An Loch Sianta/Seunta) is a sea loch, a part of the Cowal peninsula coast of the Firth of Clyde, in Argyll and Bute, Scotland. The "Holy Loch" name is believed to date from the 6th century, when Saint Munn landed there after leaving Ireland. Kilmun Parish Church and Argyll Mausoleum is said to stand where Saint Munn's church was once located. Robertson's Yard at Sandbank, a village on the loch, was a major wooden boat building company in the late 19th and early 20th centuries. During World War II, the loch was used as a British Royal Navy submarine base. From 1961 to 1992, it was used as a United States Navy ballistic missile submarine base. In 1992, the Holy Loch base was deemed unnecessary following the demise of the Soviet Union and subsequently closed. Geography Open on the Firth of Clyde at its eastern end, the Sea Loch is approximately wide and between long, varying with the tide. The town of Dunoon on the Cowal peninsula lies on the shores of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: ''passive'' sonar means listening for the sound made by vessels; ''active'' sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and SODAR (an upward-looking in-air sonar) is used for atmospheric investigations. The term ''sonar'' is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heligoland
Heligoland (; german: Helgoland, ; Heligolandic Frisian: , , Mooring Frisian: , da, Helgoland) is a small archipelago in the North Sea. A part of the German state of Schleswig-Holstein since 1890, the islands were historically possessions of Denmark, then became the possessions of the United Kingdom from 1807 to 1890, and briefly managed as a war prize from 1945 to 1952. The islands are located in the Heligoland Bight (part of the German Bight) in the southeastern corner of the North Sea and had a population of 1,127 at the end of 2016. They are the only German islands not in the vicinity of the mainland. They lie approximately by sea from Cuxhaven at the mouth of the River Elbe. During a visit to the islands, August Heinrich Hoffmann von Fallersleben wrote the lyrics to "", which became the national anthem of Germany. In addition to German, the local population, who are ethnic Frisians, speak the Heligolandic dialect of the North Frisian language called . Name Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Admiralty (United Kingdom)
The Admiralty was a department of the Government of the United Kingdom responsible for the command of the Royal Navy until 1964, historically under its titular head, the Lord High Admiral – one of the Great Officers of State. For much of its history, from the early 18th century until its abolition, the role of the Lord High Admiral was almost invariably put "in commission" and exercised by the Lords Commissioner of the Admiralty, who sat on the governing Board of Admiralty, rather than by a single person. The Admiralty was replaced by the Admiralty Board in 1964, as part of the reforms that created the Ministry of Defence and its Navy Department (later Navy Command). Before the Acts of Union 1707, the Office of the Admiralty and Marine Affairs administered the Royal Navy of the Kingdom of England, which merged with the Royal Scots Navy and the absorbed the responsibilities of the Lord High Admiral of the Kingdom of Scotland with the unification of the Kingdom of Great B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shadowgraph U British Class Groupe I Submarine
Shadowgraph is an optical method that reveals non-uniformities in transparent media like air, water, or glass. It is related to, but simpler than, the schlieren and schlieren photography methods that perform a similar function. Shadowgraph is a type of flow visualisation. In principle, a difference in temperature, a different gas, or a shock wave in the transparent air cannot be seen by the human eye or cameras. However, all these disturbances refract light rays, so they can cast shadows. The plume of hot air rising from a fire, for example, can be seen by way of its shadow cast upon a nearby surface by the uniform sunlight. Sunlight shadowgraph Some aquatic predators detect their transparent prey by way of their shadows cast upon the ocean floor. It was Robert Hooke who first scientifically demonstrated the sunlight shadowgraph and Jean-Paul Marat who first used it to study fire. A modern account of shadowgraphy is given by Gary S. Settles. Applications Applications of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salvo
A salvo is the simultaneous discharge of artillery or firearms including the firing of guns either to hit a target or to perform a salute. As a tactic in warfare, the intent is to cripple an enemy in one blow and prevent them from fighting back. Overview Troops armed with muzzleloaders required time to refill their arms with gunpowder and shot. Gun drills were designed to enable an almost continuous rain of fire on the enemy by lining troops into ranks, allowing one rank to fire a salvo, or volley, while the other ranks prepared their guns for firing. The term is commonly used to describe the firing of broadsides by warships, especially battleships. During fleet engagements in the days of sail, from 17th century until the 19th century, ships of the line were maneuvered with the objective of bringing the greatest possible number of cannon to bear on the enemy and to discharge them in a salvo, causing enough damage and confusion as to allow time for the cannon to be swabbed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Periscope Depth
A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position. In its simplest form, it consists of an outer case with mirrors at each end set parallel to each other at a 45° angle. This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I. Military personnel also use periscopes in some gun turrets and in armoured vehicles. More complex periscopes using prisms or advanced fiber optics instead of mirrors and providing magnification operate on submarines and in various fields of science. The overall design of the classical submarine periscope is very simple: two telescopes pointed into each other. If the two telescopes have different individual magnification, the difference between them causes an overall magnification or reduction. Early examples Johannes Hevelius described an early ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bow Wave
A bow wave is the wave that forms at the bow of a ship when it moves through the water. As the bow wave spreads out, it defines the outer limits of a ship's wake. A large bow wave slows the ship down, is a risk to smaller boats, and in a harbor can damage shore facilities and moored ships. Therefore, ship hulls are generally designed to produce as small a bow wave as possible. Description The size of the bow wave is a function of the speed of the ship, its draft, surface waves, water depth, and the shape of the bow. A ship with a large draft and a blunt bow will produce a large wave, and ships that plane over the water surface will create smaller bow waves. Bow wave patterns are studied in the field of computational fluid dynamics. The bow wave carries energy away from the ship at the expense of its kinetic energy—it slows the ship. A major goal of naval architecture is therefore to reduce the size of the bow wave and improve the ship's fuel economy. Modern ships are commonl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torpedo Tubes
A torpedo tube is a cylindrical device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers) installed aboard surface vessels. Deck-mounted torpedo launchers are usually designed for a specific type of torpedo, while submarine torpedo tubes are general-purpose launchers, and are often also capable of deploying mines and cruise missiles. Most modern launchers are standardized on a diameter for light torpedoes (deck mounted aboard ship) or a diameter for heavy torpedoes (underwater tubes), although other sizes of torpedo tube have been used: see Torpedo classes and diameters. Submarine torpedo tube A submarine torpedo tube is a more complex mechanism than a torpedo tube on a surface ship, because the tube has to accomplish the function of moving the torpedo from the normal atmospheric pressure within the submarine into the sea at the ambient ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cavitation
Cavitation is a phenomenon in which the static pressure of a liquid reduces to below the liquid's vapour pressure, leading to the formation of small vapor-filled cavities in the liquid. When subjected to higher pressure, these cavities, called "bubbles" or "voids", collapse and can generate shock waves that may damage machinery. These shock waves are strong when they are very close to the imploded bubble, but rapidly weaken as they propagate away from the implosion. Cavitation is a significant cause of wear in some engineering contexts. Collapsing voids that implode near to a metal surface cause cyclic stress through repeated implosion. This results in surface fatigue of the metal causing a type of wear also called "cavitation". The most common examples of this kind of wear are to pump impellers, and bends where a sudden change in the direction of liquid occurs. Cavitation is usually divided into two classes of behavior: inertial (or transient) cavitation and non-inertial c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Motors
An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. An electric generator is mechanically identical to an electric motor, but operates with a reversed flow of power, converting mechanical energy into electrical energy. Electric motors can be powered by direct current (DC) sources, such as from batteries, or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. Electric motors may be classified by considerations such as power source type, construction, application and type of motion output. They can be powered by AC or DC, be brushed or brushless, single-phase, two-phase, or three-phase, axial or radial flux, and may be air-cooled or liquid-cooled. Standardized motors provide c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
