The science of spin : Going ballistic – golf swing – Brief Article
According to Alastair Cochran and John Stobbs’ book Search for the Perfect Swing, there are two types of spin that aid the flight of projectiles. An artillery shell, or bullet (far left), is designed to spin around an axis lying along its line of flight. An accurately struck golf ball spins around a horizontal axis that lies across the line of flight.
“A golf ball always has backspin, due to the loft of the club,” says Maxfli’s John Calabria. “The ball has a principal axis of rotation parallel to the clubface and perpendicular to the line of flight. When this axis is tilted in either direction you get sidespin [which causes hooks and slices].
“A bullet is controlled by what is called rifling spin, which is produced by the grooves in the gun barrel,” Calabria says. “A bullet’s flight is much more controlled, due to the effect of the barrel. However, it is affected by outside influences such as wind, gravity and air resistance, the same as a golf ball would be.”
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