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A golf ball is a ball designed for use in the game of golf.
An appendix to the Rules of Golf defines, by the rules of the game, that a golf ball must not weigh more than 45.93 grams (1.620 oz), that its diameter must not be less than 42.67 mm (1.680 in), 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 (Rule 5-1).
History
Wooden balls were used until the early 17th century, when the featherie ball was invented.This was a new and exicting feature to the game of golf. A featherie is a handsewn cowhide bag stuffed with goose feathers and coated with paint. The feathers in the ball were enough to fill a tophat. They were boiled and put in the cowhide bag. As it cooled, the feathers would expand and the hide would shrink, making a compact ball. Due to its superior flight characteristics, the featherie remained the standard ball for more than two centuries. However, an experienced ball maker could only make about two in one day, so they were expensive. Also, it was hard to make a perfectly spherical ball, and because of that, the ball often flew irregularly. When playing in wet weather, the stiches in the ball would rot, and the ball would split open after hitting a soft surface.
In 1848, the Rev. Dr. Robert Adams (or Robert Adam Paterson) invented the gutta percha ball (or guttie). 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, (named either ; a two-piece, three-piece or a four-piece ball) 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 (and its behavior when it hits the ground).
A ball moving through air experiences two major aerodynamic forces, lift and drag. 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. This is called the Magnus effect. Backspin is imparted in almost every shot due to the golf club's loft (i.e. angle between the clubface and a vertical plane). 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. (Some dimple designs are claimed to reduce sidespin effects.)
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 (in four different sizes) 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 U.S. patent 4,560,168. 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 (one of them is red), the mold can be two hemispheres.
Golf balls also come in different colors, which helps with finding the ball when lost or in distinguishing your ball from other players' balls. White is the most common color.
Hexagonal Dimples
Some of the new technological advances in a golf ball have hexagonal dimples. This new technology enables the ball to have less drag than the normal dimpled golf balls. The balls have variations on the size of the dimples and also some have deeper dimples than others, Callaway is the main supplier of the hexagonal design golf balls, such as the Callaway HX.
Selection
There are many types of golf balls on the market, and customers often face a difficult decision. Golf balls are divided into two categories: recreational and advanced balls. Recreational balls are oriented toward the ordinary golfer, who generally have low swing speeds (80 miles per hour or lower) and lose golf balls on the course easily. These balls are made of two layers, with the cover firmer than the core. Their low compression and side spin reduction characteristics suit the lower swing speeds of average golfers quite well. Furthermore, they generally have lower prices than the advanced balls.
Advanced balls are made of multiple layers (three or more), with a soft cover and firm core. They induce a greater amount of spin from lofted shots (wedges especially), as well as a sensation of softness in the hands in short-range shots. However, these balls require a much greater swing speed that only the physically strong players could carry out to compress at impact. If the compression of a golf ball does not match a golfer's swing speed, either the lack of compression or over-compression will occur, resulting in loss of distance. There are also many brands and colors to choose from, with colored balls and better brands generally being more expensive), making an individual's choice more difficult.
See also
External links
- Golf Ball Dimples - How Many? (written for kids)
- Golf ball aerodynamics
- Flight Dynamics of Golf Balls
- Aerospace Grad Making His Mark on the Game of Golf
- Sci. Am.: How do dimples in golf balls affect their flight?
- Making a Dent: Dimple technology continues to aid advancements in golf balls
- Let's See How It'll Fly
- On Golf Ball Design (DOC format)
- A St. Mary's Project: The Aerodynamics of Golf Ball Flight (PDF format)
History
- The evolution of the golf ball
- A history of the golf ball
- Evolution of the Dimpled Golf Ball
- History of the golf ball at The Golf Course
Footnotes
- Sources conflict as to the exact name.