Golf ball
A golf ball is a
ball designed for use in the game of
golf.
An appendix to the "Rules of Golf" defines that a golf ball must not weigh more than 45.93
grams , that its diameter must not be less than 42.67 mm , and that its shape may not differ significantly from a symmetric
sphere. Like golf clubs, golf balls are subject to testing and approval by the
Royal and Ancient Golf Club of St Andrews and the
United States Golf Association, and those that do not conform with the regulations may not be used in competitions .
History
Encyclopedia
A
golf ball is a
ball designed for use in the game of
golf.
An appendix to the "Rules of Golf" defines that a golf ball must not weigh more than 45.93
grams , that its diameter must not be less than 42.67 mm , and that its shape may not differ significantly from a symmetric
sphere. Like golf clubs, golf balls are subject to testing and approval by the
Royal and Ancient Golf Club of St Andrews and the
United States Golf Association, and those that do not conform with the regulations may not be used in competitions .
History
Wooden balls were used until the early 17th century, when the
featherie ball was invented. A featherie is a handsewn cowhide bag stuffed with
goose feathers and coated with paint. Due to its superior flight characteristics, the featherie remained the standard ball for more than two centuries.
In 1848, the Rev. Dr. Robert Adams invented the
gutta percha ball . Because gutties were cheaper to produce and could be manufactured with textured surfaces to improve their aerodynamic qualities, they replaced feather balls completely within a few years.
In the twentieth century, multi-layer balls were developed, first as wound balls consisting of a solid or liquid-filled core wound with a layer of rubber thread and a thin outer shell. This design allowed manufacturers to fine-tune the length, spin and "feel" characteristics of balls. Wound balls were especially valued for their soft feel.
Today's golf balls have progressed into having cores of
titanium compounds, hybrid materials, softer shells and a more pressurized core. They usually consist of a two-, three-, or four-layer design, consisting of various synthetic materials like surlyn or urethane blends. They are available in a great variety of playing characteristics to suit the needs of golfers of different proficiency.
Aerodynamics
When a golf ball is hit, the impact, which lasts less than a millisecond, determines the ball’s velocity, launch angle and spin rate, all of which influence its trajectory .
A ball moving through air experiences two major aerodynamic forces: lift and drag. Drag slows the forward motion, whereas lift acts in a direction perpendicular to it. The magnitude of these forces depends on the behavior of the boundary layer of air moving with the ball surface.
Every modern golf ball has dimples; their purpose is to increase and shape the lift and drag forces by modifying the behavior of the boundary layer. It should be noted that drag and lift forces exist also on smooth balls: they are only modified, not created, by dimples.
Dimpled balls fly farther than non dimpled balls due to the combination of two effects:
Firstly, the dimples delay separation of the boundary layer from the ball. Early separation, as seen on a smooth sphere, causes significant wake turbulence, the principal cause of drag. The separation delay caused by the dimples therefore reduces this wake turbulence, and hence the drag.
Secondly, backspin generates lift by deforming the airflow around the ball, in a similar manner to an airplane wing. Backspin is imparted in almost every shot due to the golf club's loft . A backspinning ball experiences an upward lift force which makes it fly higher and longer than a ball without spin would. Sidespin occurs when the clubface is not aligned perpendicularly to the direction of swing, leading to a lift force that makes the ball curve to one side or the other. Unfortunately the dimples magnify this effect as well as the more desirable upward lift derived from pure backspin.
In order to keep the aerodynamics optimal, the ball needs to be clean. Golfers can wash their balls manually, but there are also mechanical
ball washers available.
Design
Most golf balls on sale today have about 300 - 450 dimples. There were a few balls having over 500 dimples before. The record holder was a ball with 1,070 dimples -- 414 larger ones and 656 pinhead-sized ones. All brands of balls, except one, have even-numbered dimples. The only odd-numbered ball on market is a ball with 333 dimples.
Officially sanctioned balls are designed to be as
symmetrical as possible. This symmetry is the result of a dispute that stemmed from the Polara, a ball sold in the late 1970s that had six rows of normal dimples on its equator but very shallow dimples elsewhere. This asymmetrical design helped the ball self-adjust its spin-axis during the flight. The USGA refused to sanction it for tournament play and, in 1981, changed the rules to ban aerodynamic asymmetrical balls. Polara's producer sued the USGA and the association paid US$1.375 million in a 1985 out-of-court settlement.
The
United States Patent and Trademark Office's
patent database is a good source of past dimple designs. Most designs are based on
Platonic solids such as
icosahedron.
Examples
These two balls are disclosed in . As shown in the illustration, these two balls are easily made with a two-piece mold. And since there is no dimple located on any of these dotted great circles , the mold can be two
hemispheres.
Golf balls also come in different colorss, which helps with finding the ball when lost or in distinguishing your ball from other players' balls. White is the most common color.
See also
External links
History
Footnotes
