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Submarine Division 71
A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Submarines are referred to as ''boats'' rather than ''ships'' irrespective of their size. Although experimental submarines had been built earlier, submarine design took off during the 19th century, and they were adopted by several navies. They were first widely used during World War I (1914–1918), and are now used in many navies, large and small. Military uses include attacking enemy surface ships (merchant and military) or other submarines, and for aircraft carrier protection, blockade running, nuclear deterrence, reconnaissance, conventional land attack (for example, using a cruise missile), and covert insertion of spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
US Navy 040730-N-1234E-002 PCU Virginia (SSN 774) Returns To The General Dynamics Electric Boat Shipyard
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five major unincorporated territories, nine United States Minor Outlying Islands, Minor Outlying Islands, and 326 Indian reservations. The United States is also in Compact of Free Association, free association with three Oceania, Pacific Island Sovereign state, sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Palau, Republic of Palau. It is the world's List of countries and dependencies by area, third-largest country by both land and total area. It shares land borders Canada–United States border, with Canada to its north and Mexico–United States border, with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Special Forces
Special forces and special operations forces (SOF) are military units trained to conduct special operations. NATO has defined special operations as "military activities conducted by specially designated, organized, selected, trained and equipped forces using unconventional techniques and modes of employment". Special forces emerged in the early 20th century, with a significant growth in the field during the Second World War, when "every major army involved in the fighting" created formations devoted to special operations behind enemy lines. Depending on the country, special forces may perform functions including airborne operations, counter-insurgency, counter-terrorism, foreign internal defense, covert ops, direct action, hostage rescue, high-value targets/manhunt, intelligence operations, mobility operations, and unconventional warfare. In Russian-speaking countries, special forces of any country are typically called , an acronym for "special purpose". In the United State ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buoyancy
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the displaced fluid. For this reason, an object whose average density is greater than that of the fluid in which it is submerged tends to sink. If the object is less dense than the liquid, the force can keep the object afloat. This can occur only in a no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ballast Tank
A ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide hydrostatic stability for a vessel, to reduce or control buoyancy, as in a submarine, to correct trim or list, to provide a more even load distribution along the hull to reduce structural hogging or sagging stresses, or to increase draft, as in a semi-submersible vessel or platform, or a SWATH, to improve seakeeping. Using water in a tank provides easier weight adjustment than the stone or iron ballast used in older vessels, and makes it easy for the crew to reduce a vessel's draft when it enters shallower water, by temporarily pumping out ballast. Airships use ballast tanks mainly to control buoyancy and correct trim. History The basic concept behind the ballast tank can be seen in many forms of aquatic life, such as the blowfish or argonaut octopus. The concept has been invented and reinvented many times by humans to serve a variety of purpo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diving Plane Diving planes, also known as hydroplanes, are control surfaces found on a submarine which allow the vessel to pitch its bow and stern up or down to assist in the process of submerging or surfacing the boat, as well as controlling depth when submerged. Bow and stern planes Diving planes are usually fitted in two pairs, the '' bow planes'' at the front of the submarine and the ''stern planes'' at the rear. The stern planes function in much the same way as an aircraft's elevator. As the planes are a long distance fore-and-aft from the hull's centre of buoyancy, they introduce a pitching moment. Ballast tanks within the submarine adjust buoyancy to be neutral, making the boat controllable. The position of the planes controls the pitch of the boat and, with the forward motion of the boat, this controls depth. If not carefully controlled, this could lead to a 'porpoising' motion whereby the planesman continually hunts for a stable combination of depth and pitch. For easier berth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
