|
HMS Zebra (R81)
HMS ''Zebra'' was a W and Z-class destroyer, Z-class destroyer. She was to have been named but was renamed in January 1943 before launching. The destroyer was launched on 18 March 1944 at William Denny & Brothers shipyard in Dumbarton, Scotland and ship commissioning, commissioned on 13 October 1944. She was 'adopted' by the civil community of Urmston, then in the county of Lancashire. Design and construction The Z-class were War Emergency Programme destroyers, intended for general duties, including use as Anti-submarine warfare, anti-submarine escort, and were to be suitable for mass-production. They were based on the hull and machinery of the pre-war J-, K- and N-class destroyer, J-class destroyers, but with a lighter armament (effectively whatever armament was available) in order to speed production. The Z-class of eight ships formed the 10th Emergency Flotilla, one of five flotillas of War Emergency destroyers ordered under the 1941 War Construction Programme (the U, V, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zebra
Zebras (, ) (subgenus ''Hippotigris'') are African equines with distinctive black-and-white striped coats. There are three living species: the Grévy's zebra (''Equus grevyi''), plains zebra (''E. quagga''), and the mountain zebra (''E. zebra''). Zebras share the genus ''Equus'' with horses and asses, the three groups being the only living members of the family Equidae. Zebra stripes come in different patterns, unique to each individual. Several theories have been proposed for the function of these stripes, with most evidence supporting them as a deterrent for biting flies. Zebras inhabit eastern and southern Africa and can be found in a variety of habitats such as savannahs, grasslands, woodlands, shrublands, and mountainous areas. Zebras are primarily grazers and can subsist on lower-quality vegetation. They are preyed on mainly by lions, and typically flee when threatened but also bite and kick. Zebra species differ in social behaviour, with plains and mountain zebra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waterline Length
A vessel's length at the waterline (abbreviated to L.W.L)Note: originally Load Waterline Length is the length of a ship or boat at the level where it sits in the water (the ''waterline''). The LWL will be shorter than the length of the boat overall (''length overall'' or LOA) as most boats have bows and stern protrusions that make the LOA greater than the LWL. As a ship becomes more loaded, it will sit lower in the water and its ambient waterline length may change; but the registered L.W.L it is measured from a default load condition. This measure is significant in determining several of a vessel's properties, such as how much water it displaces, where the bow and stern waves occur, hull speed, amount of bottom-paint needed, etc. Traditionally, a stripe called the "boot top" is painted around the hull just above the waterline. In sailing boats, longer waterline length will usually enable a greater maximum speed, because it allows greater sail area, without increasing beam or d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keel Laying
Laying the keel or laying down is the formal recognition of the start of a ship's construction. It is often marked with a ceremony attended by dignitaries from the shipbuilding company and the ultimate owners of the ship. Keel laying is one of the four specially celebrated events in the life of a ship; the others are launching, commissioning and decommissioning. In earlier times, the event recognized as the keel laying was the initial placement of the central timber making up the backbone of a vessel, called the keel. As steel ships replaced wooden ones, the central timber gave way to a central steel beam. Modern ships are most commonly built in a series of pre-fabricated, complete hull sections rather than around a single keel. The event recognized as the keel laying is the first joining of modular components, or the lowering of the first module into place in the building dock. It is now often called "keel authentication", and is the ceremonial beginning of the ship's life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depth Charge
A depth charge is an anti-submarine warfare (ASW) weapon. It is intended to destroy a submarine by being dropped into the water nearby and detonating, subjecting the target to a powerful and destructive Shock factor, hydraulic shock. Most depth charges use explosive, high explosive charges and a fuze set to detonate the charge, typically at a specific depth. Depth charges can be dropped by ships, patrol aircraft, and helicopters. Depth charges were developed during World War I, and were one of the first viable methods of attacking a submarine underwater. They were widely used in World War I and World War II, and remained part of the anti-submarine arsenals of many navies during the Cold War, during which they were supplemented, and later largely replaced, by anti-submarine homing torpedoes. A depth charge fitted with a nuclear warhead is also known as a "nuclear depth bomb". These were designed to be dropped from a patrol plane or deployed by an anti-submarine missile from a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QF 2-pounder Naval Gun
The 2-pounder gun, officially the QF 2-pounder ( QF denoting "quick firing") and universally known as the pom-pom, was a British autocannon, used as an anti-aircraft gun by the Royal Navy.British military of the period traditionally denoted smaller guns in terms of the approximate weight of the standard projectile, rather than by its bore diameter, which in this case was 40 mm. References to 40-mm anti-aircraft guns invariably mean the Bofors gun, while references to 2-pounder anti-aircraft guns mean this gun. The name came from the sound that the original models make when firing. This QF 2-pounder was not the same gun as the Ordnance QF 2-pounder, used by the British Army as an anti-tank gun and a tank gun, although they both fired , projectiles. Predecessors - Boer War and the Great War QF 1 pounder The first gun to be called a pom-pom was the 37 mm Nordenfelt-Maxim or "QF 1-pounder" introduced during the Second Boer War, the smallest artillery piece of that war. It fir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oerlikon 20 Mm Cannon
The Oerlikon 20 mm cannon is a series of autocannons, based on an original German Becker Type M2 20 mm cannon design that appeared very early in World War I. It was widely produced by Oerlikon Contraves and others, with various models employed by both Allied and Axis forces during World War II. Many versions of the cannon are still used today. Blowback-operated models History Origins During World War I, the German industrialist Reinhold Becker developed a 20 mm caliber cannon, known now as the 20 mm Becker using the advanced primer ignition blowback (API blowback) method of operation. This used a 20×70mmRB cartridge and had a cyclic rate of fire of 300 rpm. It was used on a limited scale as an aircraft gun on ''Luftstreitkräfte'' warplanes, and an anti-aircraft gun towards the end of that war. Because the Treaty of Versailles banned further production of such weapons in Germany, the patents and design works were transferred in 1919 to the Swiss firm SEMAG (''Seeba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bofors 40 Mm Automatic Gun L/60
The Bofors 40 mm Automatic Gun L/60 (often referred to simply as the "Bofors 40 mm gun", the "Bofors gun" and the like, see name) is an anti-aircraft autocannon, designed in the 1930s by the Swedish arms manufacturer AB Bofors. The gun was designed as an intermediate anti-aircraft gun, filling the gap between fast firing close-range small calibre anti-aircraft guns and slower firing long-range high calibre anti-aircraft guns, a role which previously was filled by older outdated guns. The Bofors 40 mm L/60 was for its time perfectly suited for this role and outperformed competing designs in the years leading up to World War II in both effectiveness and reliability. It entered the export market around 1932 and was in service with 18 countries by 1939. Throughout World War II it became one of the most popular and widespread medium-weight anti-aircraft guns. It was used by the majority of the western Allies and some Axis powers such as Nazi Germany and Hungary. In the pos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-aircraft Warfare
Anti-aircraft warfare, counter-air or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It includes Surface-to-air missile, surface based, subsurface (Submarine#Armament, submarine launched), and air-based weapon systems, associated sensor systems, command and control arrangements, and passive measures (e.g. barrage balloons). It may be used to protect naval, ground, and air forces in any location. However, for most countries, the main effort has tended to be homeland defence. NATO refers to airborne air defence as counter-air and naval air defence as anti-aircraft warfare. Missile defense, Missile defence is an extension of air defence, as are initiatives to adapt air defence to the task of intercepting any projectile in flight. In some countries, such as Britain and Germany during the World War II, Second World War, the Soviet Union, and modern NATO a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steam Turbine
A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbine involves advanced metalwork to form high-grade steel alloys into precision parts using technologies that first became available in the 20th century; continued advances in durability and efficiency of steam turbines remains central to the energy economics of the 21st century. The steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency from the use of multiple stages in the expansion of the steam, which results in a closer approach to the ideal reversible expansion process. Because the turbine generates rotary motion, it can be coupled to a generator to harness its motion into electricity. Such turbogenerators are the core of thermal power stations which can be fueled by fossil-fuels, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parsons Marine Steam Turbine Company
Parsons Marine Steam Turbine Company was a British engineering company based on the River Tyne at Wallsend, North East England. History Charles Algernon Parsons founded the company in 1897 with £500,000 of capital. It specialised in building the steam turbine engines that he had invented for marine use. The first vessel powered by a Parsons turbine was ''Turbinia'', launched in 1894. The successful demonstration of this vessel led to the creation of the company and the building of engines for the first two turbine-powered destroyers for the Royal Navy, and , launched in 1899. Although both these vessels came to grief, the new engines were not to blame, and the Admiralty was convinced. Parsons' son became a director in the company and was replaced during the First World War by his daughter Rachel Parsons. Parsons turbines powered the Royal Navy's first turbine powered battleship, , and the world's first turbine ocean liners, and '' Virginian''. Parsons turbines powered the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Three-drum Boiler
Three-drum boilers are a class of water-tube boiler used to generate steam, typically to power ships. They are compact and of high evaporative power, factors that encourage this use. Other boiler designs may be more efficient, although bulkier, and so the three-drum pattern was rare as a land-based stationary boiler. The fundamental characteristic of the "three-drum" design is the arrangement of a steam drum above two water drums, in a triangular layout. Water tubes fill in the two sides of this triangle between the drums, and the furnace is in the centre. The whole assembly is then enclosed in a casing, leading to the exhaust flue. Firing can be by either coal or oil. Many coal-fired boilers used multiple firedoors and teams of stokers, often from both ends. Development Development of the three-drum boiler began in the late 19th century, with the demand from naval ships that required high power and a compact boiler. The move to water-tube boilers had already begun, with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Displacement (ship)
The displacement or displacement tonnage of a ship is its weight. As the term indicates, it is measured indirectly, using Archimedes' principle, by first calculating the volume of water displaced by the ship, then converting that value into weight. Traditionally, various measurement rules have been in use, giving various measures in long tons. Today, tonnes are more commonly used. Ship displacement varies by a vessel's degree of load, from its empty weight as designed (known as "lightweight tonnage") to its maximum load. Numerous specific terms are used to describe varying levels of load and trim, detailed below. Ship displacement should not be confused with measurements of volume or capacity typically used for commercial vessels and measured by tonnage: net tonnage and gross tonnage. Calculation The process of determining a vessel's displacement begins with measuring its draft.George, 2005. p.5. This is accomplished by means of its "draft marks" (or "load lines"). A mer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Displacement (ship)")