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Hop-up (airsoft)
Hop-up {{Dead link, date=August 2024 , bot=InternetArchiveBot , fix-attempted=yes 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. It allows the mechanism to shoot BBs in a curved trajectory. In airsoft guns, this is usually implemented as a small rubber protrusion, 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 through means of a dial or set screw so that the effect can be tuned to suit the weight and speed of the projectile and each player's preference. The primary cause of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hop-up Animation
Hop-Up may refer to: * Hop-up (airsoft), 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 sports, 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. The technique was invented in 1986 by a Robert Esperat during the Calgary Olympics. 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 wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airsoft
Airsoft, also known as survival game () in Japan where it was popular, is a team sport, team-based shooting sport, shooting game in which participants eliminate opposing players out of play by shooting them with airsoft pellets, spherical plastic projectiles shot from 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 pellet impacts can leave small bruises or welt (bruise), welts on exposed skin (and so protective gear is still recommended), the game relies heavily on an honor system in which players who have been hit are expected to call themselves out of play in keeping with honesty, fairness and sportsmanship. The airsoft guns used are mostly magazine (firearms), magazine-fed, with some having manual/battery (electricity), battery electric motor, motor-powered spring (device), spring-piston pump powerplant, power plants similar to Nerf Blasters, or pne ... [...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 in 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 (because lead is more malleable and exerts less wear on riflings). The term "BB gun" is frequently used colloquially 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, which shoots d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnus Effect
The Magnus effect is a phenomenon that occurs when a spin (geometry), spinning Object (physics), object is moving through a fluid. A lift (force), lift force acts on the spinning object and its path may be deflected in a manner not present when it is not spinning. The strength and direction of the Magnus force is dependent on the speed and direction of the rotation of the object. The Magnus effect is named after Heinrich Gustav Magnus, the German physicist who investigated it. The force on a rotating cylinder is an example of Kutta–Joukowski theorem, Kutta–Joukowski lift, named after Martin Kutta and Nikolay Zhukovsky (scientist), Nikolay Zhukovsky (or Joukowski), mathematicians who contributed to the knowledge of how lift is generated in a fluid flow. Description 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 football (soccer) and volleybal ... [...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 Boundary (thermodynamic), bounding surface formed by the fluid flowing along the surface. The fluid's interaction with the wall induces a No-slip condition, 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, 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 viscosity, viscous forces distort the surrounding non-viscous flow. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isaac Newton
Sir Isaac Newton () was an English polymath active as a mathematician, physicist, astronomer, alchemist, theologian, and author. Newton was a key figure in the Scientific Revolution and the Age of Enlightenment, Enlightenment that followed. His book (''Mathematical Principles of Natural Philosophy''), first published in 1687, achieved the Unification of theories in physics#Unification of gravity and astronomy, first great unification in physics and established classical mechanics. Newton also made seminal contributions to optics, and Leibniz–Newton calculus controversy, shares credit with German mathematician Gottfried Wilhelm Leibniz for formulating calculus, infinitesimal calculus, though he developed calculus years before Leibniz. Newton contributed to and refined the scientific method, and his work is considered the most influential in bringing forth modern science. In the , Newton formulated the Newton's laws of motion, laws of motion and Newton's law of universal g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Tunnels
A wind tunnel is "an apparatus for producing a controlled stream of air for conducting aerodynamic experiments". The experiment is conducted in the test section of the wind tunnel and a complete tunnel configuration includes air ducting to and from the test section and a device for keeping the air in motion, such as a fan. Wind tunnel uses include assessing the effects of air on an aircraft in flight or a ground vehicle moving on land, and measuring the effect of wind on buildings and bridges. Wind tunnel test sections range in size from less than a foot across, to over , and with air speeds from a light breeze to hypersonic. The earliest wind tunnels were invented towards the end of the 19th century, in the early days of aeronautical research, as part of the effort to develop heavier-than-air flying machines. The wind tunnel reversed the usual situation. Instead of the air standing still and an aircraft moving, an object would be held still and the air moved around it. In this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Dynamics
In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in motion) and (the study of water and other liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moment (physics), moments on aircraft, determining the mass flow rate of petroleum through pipeline transport, pipelines, weather forecasting, predicting weather patterns, understanding nebulae in interstellar space, understanding large scale Geophysical fluid dynamics, geophysical flows involving oceans/atmosphere and Nuclear weapon design, 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 fl ... [...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, but also of learners (who could be independent learners outside of formal education). 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 transmissi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airsoft
Airsoft, also known as survival game () in Japan where it was popular, is a team sport, team-based shooting sport, shooting game in which participants eliminate opposing players out of play by shooting them with airsoft pellets, spherical plastic projectiles shot from 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 pellet impacts can leave small bruises or welt (bruise), welts on exposed skin (and so protective gear is still recommended), the game relies heavily on an honor system in which players who have been hit are expected to call themselves out of play in keeping with honesty, fairness and sportsmanship. The airsoft guns used are mostly magazine (firearms), magazine-fed, with some having manual/battery (electricity), battery electric motor, motor-powered spring (device), spring-piston pump powerplant, power plants similar to Nerf Blasters, or pne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
