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Hop-up (airsoft)
Hop-up {{cite book, author=Kovacs Bloomfield, title=Airsoft! How to Win an Airsoft War: Secret Tactics for Success Revealed!, url=https://books.google.com/books?id=Y8tuufbh_NAC&pg=PA20, date=1 March 2012, publisher=Ebook.GD Publishing, isbn=978-1-61323-030-5, pages=17–20 is the backspin put on airsoft pellets and BBs to increase their range via the Magnus effect. Hop-up devices apply backspin to the projectile reducing the air pressure on its top side. This causes the plastic pellet to fall less over a given distance than it would without the spin applied, extending the effective range of the weapon without increasing velocity. In airsoft guns, this is usually implemented as a projection (called a bucking) into the path of the projectile, on the top of the barrel. The bucking momentarily hinders the top side of the projectile, imparting a backspin that can exceed 1,000 rpm (17 rotations per second). This is usually adjustable so that the effect can be tuned to suit the weight o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hop-up Animation
Hop-Up may refer to: *Hop-up (airsoft) Hop-up {{cite book, author=Kovacs Bloomfield, title=Airsoft! How to Win an Airsoft War: Secret Tactics for Success Revealed!, url=https://books.google.com/books?id=Y8tuufbh_NAC&pg=PA20, date=1 March 2012, publisher=Ebook.GD Publishing, isbn=978-1- ..., a piece of rubber increasing range of airsoft gun with Magnus effect. * Hop-up (TT-01), aftermarket gears for R/C chassis made by Tamiya {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Backspin
In racquet sports and golf, backspin or underspin refers to the reverse rotation of a ball, in relation to the ball's trajectory, that is imparted on the ball by a slice or chop shot. Backspin generates an upward force that lifts the ball (see Magnus effect). While a normal hit bounces well forward as well as up, backspin shots bounce higher and less forward. Backspin is the opposite of topspin. In racket sports, the higher bounce imparted by backspin may make a receiver who has prepared for a different shot miss or mis-hit the ball when swinging. A backspin shot is also useful for defensive shots because a backspin shot takes longer to travel to the opponent, giving the defender more time to get back into position. Also, because backspin shots tend to bounce less far forward once they reach the opposite court, they may be more difficult to attack. This is especially important in table tennis because one must wait for the ball to bounce before hitting it, whereas in tennis the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airsoft
Airsoft is a team game in which participants eliminate opposing players by tagging them out of play with spherical plastic projectiles shot with mock air weapons(usually powered by an electronic motor) called airsoft guns. Although similar to paintball in concept and gameplay, airsoft pellets do not leave visible markings on their target and hits are not always apparent. Though the pellets leave bruises or welts on exposed skin (and so protective gear is recommended), the game relies heavily on an honor system in which players who have been hit are expected to call themselves out. The airsoft guns used are mostly magazine-fed, with some having manual/battery-powered spring- piston pump power plants similar to Nerf Blasters, or pneumatically powered by replaceable compressed gas (e.g. propane ("green gas"), 1,1,1,2-tetrafluoroethane or ) canisters. Many airsoft guns also have mounting platforms compatible with genuine firearm accessories, and most cosmetically res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BB Gun
A BB gun is a type of air gun designed to shoot metallic spherical projectiles called BBs (not to be confused with similar-looking bearing balls), which are approximately the same size as BB-size lead birdshot used on shotguns ( in diameter). Modern BB guns usually have a smoothbore barrel with a caliber, and use steel balls that measure in diameter and in weight, usually zinc- or copper-plated for corrosion resistance. Some manufacturers still make the slightly larger traditional lead balls that weigh around , which are generally intended for use in rifled barrels (due to lead having better malleability and exerting less wear on riflings). The term "BB gun" is frequently used incorrectly to describe airsoft guns, which shoot plastic pellets (also often referred to as "BBs") that are larger (usually in diameter) but much less dense than metal BBs, and have significantly lower ballistic performance. The term is also sometimes used to describe a pellet gun, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnus Effect
The Magnus effect is an observable phenomenon commonly associated with a spinning object moving through a fluid. The path of the spinning object is deflected in a manner not present when the object is not spinning. The deflection can be explained by the difference in pressure of the fluid on opposite sides of the spinning object. The Magnus effect is dependent on the speed of rotation. The most readily observable case of the Magnus effect is when a spinning sphere (or cylinder) curves away from the arc it would follow if it were not spinning. It is often used by association football and volleyball players, baseball pitchers, and cricket bowlers. Consequently, the phenomenon is important in the study of the physics of many ball sports. It is also an important factor in the study of the effects of spinning on guided missiles—and has some engineering uses, for instance in the design of rotor ships and Flettner aeroplanes. Topspin in ball games is defined as spin about a ho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boundary Layer
In physics and fluid mechanics, a boundary layer is the thin layer of fluid in the immediate vicinity of a bounding surface formed by the fluid flowing along the surface. The fluid's interaction with the wall induces a no-slip boundary condition (zero velocity at the wall). The flow velocity then monotonically increases above the surface until it returns to the bulk flow velocity. The thin layer consisting of fluid whose velocity has not yet returned to the bulk flow velocity is called the velocity boundary layer. The air next to a human is heated resulting in gravity-induced convective airflow, airflow which results in both a velocity and thermal boundary layer. A breeze disrupts the boundary layer, and hair and clothing protect it, making the human feel cooler or warmer. On an aircraft wing, the velocity boundary layer is the part of the flow close to the wing, where viscous forces distort the surrounding non-viscous flow. In the Earth's atmosphere, the atmospheric bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isaac Newton
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, theologian, and author (described in his time as a " natural philosopher"), widely recognised as one of the greatest mathematicians and physicists and among the most influential scientists of all time. He was a key figure in the philosophical revolution known as the Enlightenment. His book (''Mathematical Principles of Natural Philosophy''), first published in 1687, established classical mechanics. Newton also made seminal contributions to optics, and shares credit with German mathematician Gottfried Wilhelm Leibniz for developing infinitesimal calculus. In the , Newton formulated the laws of motion and universal gravitation that formed the dominant scientific viewpoint for centuries until it was superseded by the theory of relativity. Newton used his mathematical description of gravity to derive Kepler's laws of planetary motion, account for ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Tunnels
Wind tunnels are large tubes with air blowing through them which are used to replicate the interaction between air and an object flying through the air or moving along the ground. Researchers use wind tunnels to learn more about how an aircraft will fly. NASA uses wind tunnels to test scale models of aircraft and spacecraft. Some wind tunnels are large enough to contain full-size versions of vehicles. The wind tunnel moves air around an object, making it seem as if the object is flying. Most of the time, large powerful fans suck air through the tube. The object being tested is held securely inside the tunnel so that it remains stationary. The object can be an aerodynamic test object such as a cylinder or an airfoil, an individual component, a small model of the vehicle, or a full-sized vehicle. The air moving around the stationary object shows what would happen if the object was moving through the air. The motion of the air can be studied in different ways; smoke or dye can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Dynamics
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation. Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fluid dynamics problem typically involves the calculation of various properties of the fluid, such as flow velocity, pressure, density, and temperature, as functions of space and ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Textbooks
A textbook is a book containing a comprehensive compilation of content in a branch of study with the intention of explaining it. Textbooks are produced to meet the needs of educators, usually at educational institutions. Schoolbooks are textbooks and other books used in schools. Today, many textbooks are published in both print and digital formats. History The history of textbooks dates back to ancient civilizations. For example, Ancient Greeks wrote educational texts. The modern textbook has its roots in the mass production made possible by the printing press. Johannes Gutenberg himself may have printed editions of ''Ars Minor'', a schoolbook on Latin grammar by Aelius Donatus. Early textbooks were used by tutors and teachers (e.g. alphabet books), as well as by individuals who taught themselves. The Greek philosopher Socrates lamented the loss of knowledge because the media of transmission were changing. Before the invention of the Greek alphabet 2,500 years ago, knowledge an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airsoft
Airsoft is a team game in which participants eliminate opposing players by tagging them out of play with spherical plastic projectiles shot with mock air weapons(usually powered by an electronic motor) called airsoft guns. Although similar to paintball in concept and gameplay, airsoft pellets do not leave visible markings on their target and hits are not always apparent. Though the pellets leave bruises or welts on exposed skin (and so protective gear is recommended), the game relies heavily on an honor system in which players who have been hit are expected to call themselves out. The airsoft guns used are mostly magazine-fed, with some having manual/battery-powered spring- piston pump power plants similar to Nerf Blasters, or pneumatically powered by replaceable compressed gas (e.g. propane ("green gas"), 1,1,1,2-tetrafluoroethane or ) canisters. Many airsoft guns also have mounting platforms compatible with genuine firearm accessories, and most cosmetically res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
