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Sonar Decoy
A sonar decoy is a device for decoying sonar. Most are released from submarines to act as a false target. Submarine decoys The first submarine decoys were the German Bold fitted to U-boats of World War II. These were a pellet of calcium hydride in a simple metal container. On contact with sea water, the calcium hydride decomposed to produce a trail of hydrogen gas bubbles that acted as a bubble curtain and reflected ASDIC impulses to produce a false target. The container trapped hydrogen and floated, with a crude spring valve to maintain buoyancy to keep it at a constant depth. Later decoys, such as Sieglinde, were motorised and could deploy their false target away from the host submarine, increasing safety. Torpedo decoys Decoys were also used by surface ships to decoy the developing acoustic torpedoes. These were usually towed behind the host. Example decoys Bubble decoys Reflective bubble targets * Bold * Sieglinde Hammer and explosive decoys These were intended ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pillenwerfer
Bold (a term derived from kobold) was a German sonar decoy, used by U-boats during the Second World War from 1942 onwards. It consisted of a metal canister about in diameter filled with calcium hydride. It was launched by an ejector system colloquially referred to as ''Pillenwerfer'' (English: "pill thrower"). When mixed with seawater, the calcium hydride produced large quantities of hydrogen which bubbled out of the container, creating a false sonar target. A valve opened and closed, holding the device at a depth of about . The device lasted 20 to 25 minutes. The Royal Navy called it SBT (Submarine Bubble Target). See also * Sieglinde (decoy) Sieglinde was a sonar decoy used during the Second World War by German U-boats. ''Sieglinde'' was installed in chambers on the sides of the U-boat. It could be ejected to a considerable distance from the boat when attempting to hide from a seeker' ... External links Sonar decoys at uboataces.com Sonar decoys Weapons countermeasures S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASDIC
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to 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) to extrem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fanfare (decoy)
The T-Mk 6 Fanfare is a towed sonar decoy developed after the Second World War by the United States Navy. It replaced the Foxer Foxer was the code name for a British built acoustic decoy used to confuse German acoustic homing torpedoes like the G7 torpedo during the Second World War. A US version codenamed FXR was deployed at the end of September 1943 on all transatlanti ... noisemaker. It was more effective than the Foxer, producing a sound similar to a ship's propeller, rather than wideband noise. File:USS Cassin Young-IMG 5402.jpg, Winches and decoys on board USS ''Cassin Young'' File:USS Cassin Young-IMG 5403.jpg, A towed decoy on board USS ''Cassin Young'' External links * https://web.archive.org/web/20060222070937/http://www.de220.com/Armament/Decoys/Decoys.htm * https://web.archive.org/web/20060213013431/http://www.de220.com/Mysteries/Mysteries.htm Sonar decoys Weapons countermeasures {{weapon-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foxer
Foxer was the code name for a British built acoustic decoy used to confuse German acoustic homing torpedoes like the G7 torpedo during the Second World War. A US version codenamed FXR was deployed at the end of September 1943 on all transatlantic escort vessels. A Canadian version was also built called the CAAT (Canadian Anti-Acoustic Torpedo) device. It was replaced in US service by the Fanfare noisemaker. The device consisted of one or two noise-making devices towed several hundred metres astern of the ship. The noise makers mechanically generated a far louder cavitation noise than the ship's propellers. This noise distracted the acoustic torpedoes away from the rear of the ship into a circling pattern around the noise maker until the torpedo ran out of fuel. The downside of the ''Foxer'' was that it also rendered the ship's own ASDIC ineffective and concealed any other U-boat nearby that could approach the convoy. Nevertheless, the FXR countermeasure proved to be highly effec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mobile Submarine Simulator
The mobile submarine simulator (MOSS) MK70 is a sonar decoy used by submarines of the United States Navy. It was a 10-inch vehicle, without an explosive warhead, but able to generate both an active sonar echo and a passive sound signature recorded to be extremely similar to that of the launching submarine. The purpose of MOSS was to create multiple targets all with the same acoustic signature. MOSS was originally developed by Gould until Westinghouse acquired that division. Some current underwater training targets are modeled after MOSS's design. The MOSS first entered service in 1976 and was deployed on all American SLBM, ballistic missile submarines from the 1980s until it was withdrawn in the mid 1990s. Unmanned underwater vehicles Sonar decoys See also * ADM-160 MALD {{Submarine-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AN/SLQ-25 Nixie
The AN/SLQ-25 Nixie and its variants are towed torpedo decoys used on US and allied warships. It consists of a towed decoy device (TB-14A) and a shipboard signal generator. The decoy emits signals to draw a torpedo away from its intended target. The Nixie attempts to defeat a torpedo's passive sonar by emitting simulated ship noise, such as propeller and engine noise, which is more attractive than the ship to the torpedo's sensors. The AN/SLQ-25A Nixie is a clean-sheet design when compared to the AN/SLQ-25 Nixie. Apart from a few minor mechanical components, they share no common parts. The AN/SLQ-25A utilises a fiber optic tow cable (FOTC) and a 10-horsepower RL-272C double drum winch. Several engineering changes resulted in COTS equipment being utilised extensively in the system. A diagnostic program can be initiated locally or from the remote control station, and tests all electronic functions. The AN/SLQ-25B includes equipment of the AN/SLQ-25A and incorporates a towed ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acoustic Torpedo
An acoustic torpedo is a torpedo that aims itself by listening for characteristic sounds of its target or by searching for it using sonar (acoustic homing). Acoustic torpedoes are usually designed for medium-range use, and often fired from a submarine. The first passive acoustic torpedoes were developed nearly simultaneously by the United States Navy and the Germans during World War II. The Germans developed the G7e/T4 Falke, which was first deployed by the submarines , and in March 1943. Few of these torpedoes were actually used and quickly phased out of service in favor of the T4's successor, the G7es T5 ''Zaunkönig'' torpedo in August 1943. The T5 first saw widespread use in September 1943 against North Atlantic escort vessels and merchant ships in convoys. On the Allied side, the US Navy developed the Mark 24 mine, which was actually an aircraft launched, anti-submarine passive acoustic homing torpedo. The first production Mk. 24s were delivered to the U.S. Navy in Mar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sieglinde (decoy)
Sieglinde was a sonar decoy used during the Second World War by German U-boats. ''Sieglinde'' was installed in chambers on the sides of the U-boat. It could be ejected to a considerable distance from the boat when attempting to hide from a seeker's 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 navigate, measure distances (ranging), communicate with or detect objects on o ... equipment. The Sieglinde was powered by electric motors, allowing it to move at , and to periodically ascend or dive, thus imitating the sonar return of an actual submarine. This allowed the real U-boat to slip away quietly from pursuing ships. It was typically used in combination with ''Pillenwerfer'' (or ''Bold'') decoys. References External links Sonar decoys at uboataces.com Sonar decoys Weapons countermeasures U-boats {{military-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bubble Curtain
A bubble curtain is a system that produces bubbles in a deliberate arrangement in water. It is also called pneumatic barrier. The technique is based on bubbles of air (gas) being let out under the water surface, commonly on the bottom. When the bubbles rise they act as a barrier, a curtain, breaking the propagation of waves or the spreading of particles and other contaminants. Uses It can be used for the following purposes: * to reduce propagation of shock waves (e.g. acoustic waves from engines or pile driving, explosions etcetera), * to reduce liquid or debris floating on the surface from spreading * to prevent salt intrusion * to control the movements of fish * for decoration and airing in aquariums In June 2010, Okaloosa County, Florida used air bubble curtains to help protect their Destin Pass coastline from oil produced in the Gulf of Mexico by the Deepwater Horizon oil spill. They hoped to push oil up to the surface for booms and skimming boats to collect the oil. Bri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decoy
A decoy (derived from the Dutch ''de'' ''kooi'', literally "the cage" or possibly ''ende kooi'', " duck cage") is usually a person, device, or event which resembles what an individual or a group might be looking for, but it is only meant to lure them. Decoys have been used for centuries most notably in game hunting, but also in wartime and in the committing or resolving of crimes. Hunting In hunting wildfowl, the term decoy may refer to two distinct devices. One, the duck decoy (structure), is a long cone-shaped wickerwork tunnel installed on a small pond to catch wild ducks. After the ducks settled on the pond, a small, trained dog would herd the birds into the tunnel. The catch was formerly sent to market for food, but now these are used only by ornithologists to catch ducks to be ringed and released. The word ''decoy'', also originally found in English as "coy", derives from the Dutch ''de Kooi'' (the cage) and dates back to the early 17th century, when this type of duck ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcium Hydride
Calcium hydride is the chemical compound with the formula , and is therefore an alkaline earth hydride. This grey powder (white if pure, which is rare) reacts vigorously with water liberating hydrogen gas. is thus used as a drying agent, i.e. a desiccant. is a saline hydride, meaning that its structure is salt-like. The alkali metals and the alkaline earth metals heavier than beryllium all form saline hydrides. A well-known example is sodium hydride, which crystallizes in the NaCl motif. These species are insoluble in all solvents with which they do not react. crystallizes in the (cotunnite) structure. Preparation Calcium hydride is prepared from its elements by direct combination of calcium and hydrogen at 300 to 400 °C. Uses Reduction of metal oxides is a reducing agent for the production of metal from the metal oxides of Ti, V, Nb, Ta, and U. It is proposed to operate via its decomposition to Ca metal: : Hydrogen source has been used for hydrogen production. In t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
U-boat
U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic warfare role (commerce raiding) and enforcing a naval blockade against enemy shipping. The primary targets of the U-boat campaigns in both wars were the merchant convoys bringing supplies from Canada and other parts of the British Empire, and from the United States, to the United Kingdom and (during the Second World War) to the Soviet Union and the Allied territories in the Mediterranean. German submarines also destroyed Brazilian merchant ships during World War II, causing Brazil to declare war on both Germany and Italy on 22 August 1942. The term is an anglicised version of the German word ''U-Boot'' , a shortening of ''Unterseeboot'' ('under-sea-boat'), though the German term refers to any submarine. Austro-Hungarian Navy submarines were also kno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
