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Long-rod Penetrator
A kinetic energy penetrator (KEP), also known as long-rod penetrator (LRP), is a type of ammunition designed to penetrate vehicle armour using a flechette-like, high-sectional density projectile. Like a bullet or kinetic energy weapon, this type of ammunition does not contain explosive payloads and uses purely kinetic energy to penetrate the target. Modern KEP munitions are typically of the armour-piercing fin-stabilized discarding sabot (APFSDS) type. History Early cannons fired kinetic energy ammunition, initially consisting of heavy balls of worked stone and later of dense metals. From the beginning, combining high muzzle energy with projectile weight and hardness have been the foremost factors in the design of such weapons. Similarly, the foremost purpose of such weapons has generally been to defeat protective shells of armored vehicles or other defensive structures, whether it is stone walls, sailship timbers, or modern tank armour. Kinetic energy ammunition, in its vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hardness
In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard metals such as titanium and beryllium are harder than soft metals such as sodium and metallic tin, or wood and common plastics. Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, hardness can be measured in different ways, such as scratch hardness, indentation hardness, and rebound hardness. Hardness is dependent on ductility, elastic stiffness, plasticity, strain, strength, toughness, viscoelasticity, and viscosity. Common examples of hard matter are ceramics, concrete, certain metals, and superhard materials, which can be contrasted with soft matter. Measuring hardness There are three main types of hardness measurements: ''scratch' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant typically need an additional 11% chromium. Because of its high tensile strength and low cost, steel is used in buildings, infrastructure, tools, ships, trains, cars, machines, electrical appliances, weapons, and rockets. Iron is the base metal of steel. Depending on the temperature, it can take two crystalline forms (allotropic forms): body-centred cubic and face-centred cubic. The interaction of the allotropes of iron with the alloying elements, primarily carbon, gives steel and cast iron their range of unique properties. In pure iron, the crystal structure has relatively little resistance to the iron atoms slipping past one another, and so pure iron is quite ductile, or soft and easily formed. In steel, small amounts of carbon, other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clog (shoe)
Clogs are a type of footwear made in part or completely from wood. Used in many parts of the world, their forms can vary by culture, but often remained unchanged for centuries within a culture. Traditional clogs remain in use as protective footwear in agriculture and in some factories and mines. Although they are sometimes negatively associated with cheap and folkloric footwear of farmers and the working class, some types are considered fashion wear today, such as Swedish träskor or Japanese geta. Clogs are also used in several different styles of dance, where an important feature is the sound they produce against the floor. Clog dancing is one of the fundamental roots of tap dancing, but with tap shoes the taps are free to click against each other and produce a different sound from clogs. Types The Oxford English Dictionary defines a clog as a "thick piece of wood", and later as a "wooden soled overshoe" and a "shoe with a thick wooden sole". Welsh traditional clog mak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing military alliances: the Allies and the Axis powers. World War II was a total war that directly involved more than 100 million personnel from more than 30 countries. The major participants in the war threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. Aircraft played a major role in the conflict, enabling the strategic bombing of population centres and deploying the only two nuclear weapons ever used in war. World War II was by far the deadliest conflict in human history; it resulted in 70 to 85 million fatalities, mostly among civilians. Tens of millions died due to genocides (including the Holocaust), starvation, ma ... [...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] |
External Ballistics
External ballistics or exterior ballistics is the part of ballistics that deals with the behavior of a projectile in flight. The projectile may be powered or un-powered, guided or unguided, spin or fin stabilized, flying through an atmosphere or in the vacuum of space, but most certainly flying under the influence of a gravitational field. Gun-launched projectiles may be unpowered, deriving all their velocity from the propellant's ignition until the projectile exits the gun barrel. However, exterior ballistics analysis also deals with the trajectories of rocket-assisted gun-launched projectiles and gun-launched rockets; and rockets that acquire all their trajectory velocity from the interior ballistics of their on-board propulsion system, either a rocket motor or air-breathing engine, both during their boost phase and after motor burnout. External ballistics is also concerned with the free-flight of other projectiles, such as balls, arrows etc. Forces acting on the projectile W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sabot (firearms)
A sabot (, ) is a supportive device used in firearm/artillery ammunitions to fit/patch around a projectile, such as a bullet/shotgun slug, slug or a flechette-like projectile (such as a kinetic energy penetrator), and keep it aligned in the center of the barrel (firearms), barrel when fired. It allows a narrower projectile with high sectional density to be fired through a gun barrel, barrel of much larger caliber, bore diameter with maximal acceleration, accelerative transfer of kinetic energy. After leaving the muzzle (firearms), muzzle, the sabot typically separates from the projectile in flight, diverting only a very small portion of the overall kinetic energy. The sabot component in projectile design is the relatively thin, tough and deformable seal known as a driving band or obturation ring needed to trap propellant gases behind a projectile, and also keep the projectile centered in the barrel, when the outer shell of the projectile is only slightly smaller in diameter than t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Muzzle Velocity
Muzzle velocity is the speed of a projectile (bullet, pellet, slug, ball/shots or shell) with respect to the muzzle at the moment it leaves the end of a gun's barrel (i.e. the muzzle). Firearm muzzle velocities range from approximately to in black powder muskets, to more than in modern rifles with high-velocity cartridges such as the .220 Swift and .204 Ruger, all the way to for tank guns firing kinetic energy penetrator ammunition. To simulate orbital debris impacts on spacecraft, NASA launches projectiles through light-gas guns at speeds up to . Projectile velocity For projectiles in unpowered flight, its velocity is highest at leaving the muzzle and drops off steadily because of air resistance. Projectiles traveling less than the speed of sound (about in dry air at sea level) are ''subsonic'', while those traveling faster are ''supersonic'' and thus can travel a substantial distance and even hit a target before a nearby observer hears the "bang" of the shot. Projec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terminal Ballistics
Terminal ballistics (also known as wound ballistics) is a sub-field of ballistics concerned with the behavior and effects of a projectile when it hits and transfers its energy to a target. Bullet design (as well as the velocity of impact) largely determine the effectiveness of penetration. General The concept of terminal ballistics can be applied to any projectile striking a target. Much of the topic specifically regards the effects of small arms fire striking live targets, and a projectile's ability to incapacitate or eliminate a target. Common factors include bullet weight, composition, velocity, and shape. Firearm projectiles Classes of bullets There are three basic classes of bullets: * Those designed to maximize accuracy at varying ranges, * Those designed to maximize damage to a target (by penetrating as deeply as possible), * Those designed to avoid over-penetration of a target. This is done by deformation (to control the depth to which the bullet penetrates) which, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sailship
A sailing ship is a sea-going vessel that uses sails mounted on masts to harness the power of wind and propel the vessel. There is a variety of sail plans that propel sailing ships, employing square-rigged or fore-and-aft sails. Some ships carry square sails on each mast—the brig and full-rigged ship, said to be "ship-rigged" when there are three or more masts. Others carry only fore-and-aft sails on each mast, for instance some schooners. Still others employ a combination of square and fore-and-aft sails, including the barque, barquentine, and brigantine. Early sailing ships were used for river and coastal waters in Ancient Egypt and the Mediterranean. The Austronesian peoples developed maritime technologies that included the fore-and-aft crab-claw sail and with catamaran and outrigger hull configurations, which enabled the Austronesian expansion into the islands of the Indo-Pacific. This expansion originated in Taiwan BC and propagated through Island Southeast A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Defensive Wall
A defensive wall is a fortification usually used to protect a city, town or other settlement from potential aggressors. The walls can range from simple palisades or earthworks to extensive military fortifications with towers, bastions and gates for access to the city. From ancient to modern times, they were used to enclose settlements. Generally, these are referred to as city walls or town walls, although there were also walls, such as the Great Wall of China, Walls of Benin, Hadrian's Wall, Anastasian Wall, and the Atlantic Wall, which extended far beyond the borders of a city and were used to enclose regions or mark territorial boundaries. In mountainous terrain, defensive walls such as ''letzis'' were used in combination with castles to seal valleys from potential attack. Beyond their defensive utility, many walls also had important symbolic functions representing the status and independence of the communities they embraced. Existing ancient walls are almost always masonry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
