Magnus effect
The Magnus effect is a phenomenon that occurs when a spinning object is moving through a fluid or gas (air).
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 airplanes.
[5] The overall behaviour is similar to that around an aerofoil (see lift force), but with a circulation generated by mechanical rotation rather than shape of the foil.
The wake and trailing air-flow have been deflected downwards; according to Newton's third law of motion there must be a reaction force in the opposite direction.
In wind tunnel studies, (rough surfaced) baseballs show the Magnus effect, but smooth spheres do not.
[16][17][7]: 18 In 1672, Isaac Newton had speculated on the effect after observing tennis players in his Cambridge college.
[18][19] In 1742, Benjamin Robins, a British mathematician, ballistics researcher, and military engineer, explained deviations in the trajectories of musket balls due to their rotation.
[20][21][22][23] Pioneering wind tunnel research on the Magnus effect was carried out with smooth rotating spheres in 1928.
[24] Lyman Briggs later studied baseballs in a wind tunnel,[10] and others have produced images of the effect.
The Magnus effect explains commonly observed deviations from the typical trajectories or paths of spinning balls in sport, notably association football, table tennis,[27] tennis,[28] volleyball, golf, baseball, and cricket.
The curved path of a golf ball known as slice or hook is largely due to the ball's spin axis being tilted away from the horizontal due to the combined effects of club face angle and swing path, causing the Magnus effect to act at an angle, moving the ball away from a straight line in its trajectory.
[citation needed] In table tennis, the Magnus effect is easily observed, because of the small mass and low density of the ball.
4.19 in which the pressure gradient is not caused by the ball's spin, but rather by its raised seam, and the asymmetric roughness or smoothness of its two halves; however, the Magnus effect may be responsible for so-called "Malinga Swing",[31][32] as observed in the bowling of the swing bowler Lasith Malinga.
In airsoft, a system known as hop-up is used to create a backspin on a fired BB, which greatly increases its range, using the Magnus effect in a similar manner as in golf.
In baseball, pitchers often impart different spins on the ball, causing it to curve in the desired direction due to the Magnus effect.
The PITCHf/x system measures the change in trajectory caused by Magnus in all pitches thrown in Major League Baseball.
In addition to this, even in completely calm air a bullet experiences a small sideways wind component due to its yawing motion.
In a very simple case where we ignore various complicating factors, the Magnus force from the crosswind would cause an upward or downward force to act on the spinning bullet (depending on the left or right wind and rotation), causing deflection of the bullet's flight path up or down, thus influencing the point of impact.
[37] Some aircraft have been built to use the Magnus effect to create lift with a rotating cylinder instead of a wing, allowing flight at lower horizontal speeds.
[2] The earliest attempt to use the Magnus effect for a heavier-than-air aircraft was in 1910 by a US member of Congress, Butler Ames of Massachusetts.
The effect is also used in a special type of ship stabilizer consisting of a rotating cylinder mounted beneath the waterline and emerging laterally.
Air is carried around the object; this adds to the velocity of the airstream above the object and subtracts below resulting in increased airspeed above and lowered airspeed below.
