Golf Ball Construction and Flight Dynamics

After a long history in which the golf ball has changed drastically in materials and style, its current construction is directly related to the dynamics of its flight path (trajectory). The lift and drag properties of the golf ball and its speed and spin rate have been—and continue to be—critical components in how golf balls are constructed.

Golf balls were originally made from wood. They traveled no more than about 100 yd (91 m). Later, Scottish golf enthusiasts made balls with boiled goose and chicken feathers, which were tightly wrapped inside a leather cover. Around 1850, the ball's construction was changed to gutta-percha—at that time, a elementary type of rubber. These golf balls were able to travel about 200 yd (182 m). Later, sap from Malaysian trees was used to make balls. At the beginning of the twentieth century, a two-piece ball was developed that had a rubber core encased in gutta-percha, now pliable natural latex. Eventually, the dimpled surface of the modern golf ball was adopted to stabilize the flight of golf balls.

According to the United States Golf Association (USGA), all golf balls must possess a diameter not less than 1.7 ins (4.3 cm) and weigh no more than 1.6 oz (45.9 g). Besides this requirement, modern golf balls vary somewhat in construction. Most modern golf balls are a two-piece construction, having a thin cover of a plastic resin called Surlyn and a large rubber core. Three-piece golf balls are characterized by a middle layer of material that is squeezed between the core and the cover (those parts found in the two-piece ball). The middle layer is rubber thread (windings) stretched many times its original length in a process called compression, or the degree to which the inside of the golf ball is wound tight. These golf balls are designed to produce increased spin. In both ball types, the more compressed the core, the farther, on average, the ball travels when hit because there is less deformation of the ball at impact. Therefore at impact, the energy transfer from club to ball is maximized. A harder ball also allows the ball to roll farther.

The dimpled pattern on the golf ball creates aerodynamic lift, which allows the ball to remain in the air longer. Dimpled design has changed significantly over the years, from random patterns, to ordered rows, to more complicated interstitial designs, along with different depths, shapes, sizes, distribution pattern, and numbers of dimples. For instance, the number of dimples varies from 300 to

Dimples on the surface of the golf ball play a key role in the speed once hit.
500 dimples, with most golf balls ranging between 350 and 450 dimples. By scientifically experimenting with dimple characteristics and the construction of particular golf balls, manufacturers can optimize the resulting trajectory for both distance and control.

In addition, as the air travels around the ball, the dimpling of the golf ball creates a smaller wake (disturbed air behind ball) and, thus, much less aerodynamic drag than a golf ball with a smooth surface. In fact, a dimpled golf ball has about one-half the drag of a smooth one. Thus, a golf ball with well-designed dimples will travel over twice as far as a smooth-surfaced golf ball.

The Magnus effect, named after German physicist Heinrich Gustav Magnus (1802–1870) who described it in 1853, is a lifting force that is experienced by rotating bodies such as golf balls as they travel through a fluid medium such as air. With respect to a golf ball, the Magnus force is an upward push due to drag differences at the top and bottom parts of the dimpled golf ball. The top part moves slower relative to the air around it, so there is less drag flowing over the ball. In addition, the boundary layer around the ball allows turbulent air to slow down its spin (or rotation). Spin rate is associated with the flight speed a golf ball attains while rotating on its axis. It is measured in revolutions per minute (rpm). The spin rate of a ball hit by a driver generally ranges between 2,000 and 4,000 rpm. Excessive amounts of spin cause the ball to carry vertically too high (thus losing horizontal distance) and too little spin prevents the ball from gaining enough vertical distance (also reducing horizontal distance). The proper spin rate is critical in order to accomplish the ideal parabolic path for a golf ball.

Although many factors have made a direct impact on increased driving distances in golf (such as improvements in drivers), one of the most important factors has been the improved construction of the golf ball. In fact, in great part due to improved golf ball construction, touring members of the Professional Golf Association (PGA) have increased their average driving distance from about 257 yd (235 m) in 1980 to about 280 yd (256 m) in 2001.

SEE ALSO Golf; Golf swing dynamics.