The game of tennis dates back officially to 1873, when the first book of rules was published by Major Walter Clopton Wingfield of north Wales. But tennis has antecedents in ball games played with the hand that evolved in Europe before the Renaissance. These games were played first with the bare hand, later with gloved hands, then with hands wrapped in rope. Later, a wooden bat was introduced, and the first rackets seem to have showed up during the fifteenth century. These early rackets were smaller than modern tennis rackets, and were strung in various patterns. When rules of tennis were standardized by Wingfield and others following him, the shape and size of the court was specified, and the kind of ball that could be used. There were, however, no rules governing the racket size, shape, or material makeup.
Until 1965, all professional tennis rackets were made of wood. A steel tennis racket was patented in 1965 by the French player Rene Lacoste, and in 1968 the Spalding company marketed the first aluminum rackets. These metal rackets caught on gradually. What the metal rackets made possible was a change in design to allow a broader head. Wooden rackets could not be made wider or longer in the head without causing problems with the stringing: if the head was too broad, string tension became too great, and the racket did not play well. But the greater strength of metal frames could accommodate greater string tension. An oversized aluminum racket developed by Howard Head in the mid 1970s was at first scoffed at by professionals, but amateurs quickly discovered that they could hit better with it. The prime hitting area, or so called "sweet spot," was doubled in size in the the new, larger rackets, and so for most people, it was easier to use. The larger rackets became the standard at all levels of play by the early 1980s.
The International Tennis Federation finally adopted rules defining acceptable tennis rackets in 1981. The Federation had banned a racket introduced in 1977 that used an innovative stringing technique. Players using "spaghetti string" rackets scored huge upsets over high-ranked opponents, and after only five months, these rackets were not allowed in professional play. The first racket rules allowed the racket and strings to be made of any materials, and did not limit the size, weight, or shape. Strings were required to interlace or be bonded at cross points at least a quarter inch (0.64 cm) and not more than a half inch (1.3 cm) apart. No attachments were allowed that might alter the flight of the ball, and the weight distribution along the longitudinal axis of the racket must not change in play. Later the maximum length of rackets was limited to 32 in (81 cm). This was modified again in January 1997, bringing the length back down to 29 in (74 cm).
The average racket is now about 28 in (71 cm) long, and weighs from 10-14 oz (284-397 g). There have been many recent innovations in racket technology, not all of which have caught on with players. One maker markets a hexagonal racket, while others are making rackets with extra wide bodies. A racket made of a new material—graphite fiber-reinforced thermoplastic viscoelastic polymer—was designed to have variable flexibility, depending on how hard the ball is struck. A design to alleviate tennis elbow employs small lead bearings enclosed in plastic chambers inside the head frame. The movement of the bearings as the racket connects with the ball is supposed to cushion the vibrations that might cause pain to the player's arm. But the most common rackets are now made of aluminum or of a composite of graphite, fiberglass, and other materials.
Aluminum rackets are usually made of one of several alloys. One popular alloy contains 2% silicon, as well as traces of magnesium, copper, and chromium. Another widely used alloy contains 10% zinc, with magnesium, copper, and chromium. The zinc alloy is harder, though more brittle, and the silicon alloy is easier to work. Composite rackets may contain many different materials. They usually consist of a sandwich of different layers around a hollow core or a polyurethane foam core. The typical layers of a composite racket are fiberglass, graphite, and boron or kevlar. Other materials may be used as well, such as ceramic fibers for added strength.
Other materials found in tennis rackets are nylon, gut, or synthetic gut for the strings, and leather or synthetic material for the handle grip. Nylon is probably the most common string material, and only a few professionals still use gut, which is made from twisted cow or sheep intestine. Synthetic gut is made from nylon which has been twisted to achieve the same effect as natural gut. Old wooden rackets usually used a leather handle grip, but modern rackets generally use a leather-like replacement such as vinyl. Rackets may have plastic parts too, such as the yoke at the base of the head and the cap at the bottom of the handle.
Most rackets sold in the United States are mass produced at one of several large factories in Japan or elsewhere in Asia. So regardless of the brand, chances are the racket was made by one of the methods described below. Rackets with unusual features might be exceptions. Also, top of the line rackets are often sold unstrung, and the buyer has it strung to his or her specifications at a pro shop. So in this case, the stringing step at the factory would be skipped.
Inspectors check the rackets at many points in the manufacturing process. When the frames are first taken from the molds, they are inspected visually. Defective rackets are set apart, and passing rackets may be roughly graded for quality. Aluminum rackets are subjected to stress tests to determine
The science of tennis rackets is surprisingly complex—not the manufacturing process but the physics of string and frame vibration as the ball connects with the racket. Rackets are now being designed by laboratory scientists who use mathematics to calculate the effects of weight, size, and material changes. Since the rules governing acceptable rackets are very broad, innovators have a lot of leeway. New rackets are also being made with computer-aided design (CAD) and computer-aided manufacturing (CAM), which allows precise calculation of material rigidity and center of gravity. As such advanced science is being lavished on the tennis racket, doubtless new models with eccentric features will continue to be developed. The trend today is toward lighter, bigger rackets, and these are viable because of advanced materials engineering.
Brody, Howard. "How Would a Physicist Design a Tennis Racket?" Physics Today, March 1995, pp. 26-31.
Fisher, Marshall Jon. "Racket Science." The Sciences, November/December 1996, pp. 10-11.
Gelberg, Nadine J. "The Big Technological Tennis Upset." Invention & Technology, Spring 1997, pp. 56-61.
Sparrow, David. "More Length, More Strength." Sports Illustrated, May 27, 1996, p. 16.
— Angela Woodward