GB2237513A

GB2237513A - Tennis racket

Info

Publication number: GB2237513A
Application number: GB9019585A
Authority: GB
Inventors: Richard Janes
Original assignee: Spalding and Evenflo Companies Inc
Current assignee: Spalding and Evenflo Companies Inc
Priority date: 1989-10-30
Filing date: 1990-09-07
Publication date: 1991-05-08
Also published as: AU6487190A; IT9048388A1; FR2654352A1; JPH03170174A; DE9017690U1; IT9048388A0; SE9003442L; CA2023934A1; ES2026056A6; DE4028401A1; IT1246320B; SE9003442D0; GB9019585D0

Abstract

A tennis racket has a frame fabricated of graphite fibers in an epoxy resin matrix formed in a tubular configuration, the frame including a handle 16 at one end; a head 14 at the other end; beams 18 therebetween coupling the head and handle; and a yoke 20 cohered to the lower end of the head to thereby generally form an ellipse, the head having a major axis Y coextensive with the axis 30 of the frame and being of a first dimension when measured at the widest point of the interior edge and having a minor axis X transverse with respect thereto measured at the widest point of the interior edge of the frame, the minor axis to major axis aspect ratio being about 0.9:1, the beams being formed linearly and diverging from the central axis equally and oppositely at about 30 degrees for supporting the head, at their upper ends, at regions widely spaced from the axis, the area within the head being between about 95 and 105 square inches. Also disclosed is a frame for such tennis racket. Also disclosed is a method of stringing such frame with the horizontal strings at a higher pull tension than the vertical strings. <IMAGE>

Description

1 1 HIGH ASPECT RATIO TENNIS RACKET HEAD AND METHOD OF STRINGING This

invention relates to a high aspect ratio tennis racket head and method of stringing and, more particularly, to a tennis racket having an elliptical head with about an 0.9 to 1 aspect ratio with linear beam portions coupling the head and handle and to a method of stringing such racket to insure proper tensioning without deformation of the racket frame.

In tennis, players use rackets to strike a resilient ball across a net. The racket is constructed of a frame having a handle end gripped by the player, and having a looped head portion with crossed strings, and having an intermediate portion or beams coupling the handle and head.

Rackets are normally symmetric about a central axis 15along the length of the handle and through the head. Most rackets have heads which are oval or elliptical in shape with its longer dimension in the direction of the axis and with Its smaller dimension transverse thereto. The strings are strung through the head at a predetermined tension adjusted 20to the style of play of the user. Generally, the strings define a sweet spot located at or slightly below the geometric center of the head. The sweet spot is that point where, when striking a ball, minimum vibrations are imparted to the player and near maximum power is generated for propelling the ball away from the strings. A particular distance from the sweet spot in all directions is the power zone where significant power is still imparted to a struck ball even though not at the sweet spot itself. Ihe power zone may also be defined as any point on the strings with a 0.35 or greater coefficient of restitution.

Heads are elliptically designed with their transverse dimension, measured at their widest point, being. about 75 percent of their longitudinal or axial dimension, measured at their widest point. This is a 0.75 to 1.0 (0.75:1) aspect ratio. By having higher aspect ratios approaching 1:1 or even higher, there will be a movement of the sweet spot higher on the racket head away from the handle. Due to the shorter overall head length, the sweet spot is moved a greater distance from the handle. This increases the mechanical advantage of the racket since the sweet spot is further from the handle and area of holding by the player.

Increases of the aspect ratio have the positive effect of abating twisting of the racket about its axis in the hand of the player when a ball is struck laterally offset from the sweet spot and axis. However, most beam portions coupling the head and handle are curved in a reverse direction. concave. with respect to the curvature of the head, convex. Such a curved beam configuration generates 5 contact points on the head undesirably close to the axis, weakening head support and reducing racket stability while Increasing the tendency of racket twisting during offaxis hits. In addition. any curvature of the beams structurally weakens them from a mechanical standpoint when compared to straight beams. Curved beams, whether concave or convex, deform more than straight beams. Further straight beams couple with and support the head at widely spaced tangent points for greater head stability.

A collateral problem encountered with attempts to 15increase the aspect ratio of tennis racket heads is in the stringing. Tennis rackets are normally held In a vice and strung by a machine preset to apply a particular nominal tension to the strings while interweaving them through holes in the frame. The major or vertical strings, parallel with the axis, are normally strung from a first common string. The minor or horizontal or cross strings, transverse to the axis. are then strung from a second common string at the same tension. Because of their shape approaching a circle, high aspect ratio rackets do not provide adequate frame strength and/or predetermined string tension when strung in the conventional manner. As a result, it is not uncommon to see high aspect ratio heads which are deformed and/or play with string tensions at variance from their intended tensions due 5 to unpredictable tensions and/or deformations of the frame during stringing. The present invention provides a more even response on the ball by the strings in both axes.

The patent literature discloses various approaches to high aspect ratio tennis racket frames. Note, for 10example, U.S. Patent No. 4,732,384 to Seymour wherein a 1:1 aspect ratio is utilized thus resulting in a totally circular frame. Such tennis racket features a high sweet spot with reipect to the handle but, unfortunately suffers from the defect of difficulty to string accurately. Further, the beam 15portions of the.frame coupling the head and handle are in a reverse curve thereby weakening the frame at this area. The weakening is sufficient that it could deform during hitting to create errant shots. Further, such reverse curve makes the beam contact with the adjacent portions of the head 20excessively close to the axis thereby increasing the tendency of the racket to twist about its axis or the player's hand when striking the ball on the strings laterally offset from the sweet spot and axis. Lastly, such reverse curve makes contact lower on the head further weakening the coupling.

United Kingdom Patent No. 427,206 to Nash discloses another circular racket having a 1:1 aspect ratio. Its beam portions of the frame coupling the head and handle are essentially linear. Such tennis racket was designed in 1933 or earlier and was obviously constructed of wood and not of the more advanced materials in a cylindrical configuration as utilized today.

Another patent, U.S. Patent No. 3,801,099 to Lair, illustrates an aspect ratio in a tennis racket head in excess of 1:1. In other words, its head width is greater than its length measured along the axis. Such a design increases the mechanical advantage of the racket by raising the sweet spot with respect to the handle. Such racket, however, even further increases the problem of stringing and frame stability and, from a playing standpoint, is generally considered unwieldy.

A last patent is U.S. Patent Number 31999,75 to Head. One of the major disadvantages of the oversized rackets as disclosed in this patent is the fact 20that in order to realize control, the strings must be strung at extremely high tensions. This adds vibrations and detracts from gripping of the ball by the strings during hitting. This high string tension also adds to the danger of racket breakage due to the increased amount of force being applied to the racket during stringing. The present invention creates a unique combination of characteristics not all present in the current over- sized racket. The present racket has equal or greater stability due to the width of the head and throat which is the distance of the beam from the twist axis which is an imaginary line extending longitudinally along the center of the racket and handle. Additionally, the present ra6ket differs from the typical oversize racket in that the head is very short instead of very long to thereby combine the stability advantage of wide heads with the mechanical advantage of a short head. This is because the average player always tries to hit the ball in the center of the head. Therefore, the center of the head of the present invention is a significant distance greater from 15the player'B hand than in the prior art. Another distinct advantage is that due to the shorter string lengths, the present rackets are strung at a relatively lower string tension providing final tensions which are even In the cross and main strings.

The final prior art are those small headed rackets which have been commercially sold for several years. Such rackets have aspect ratios approaching 0.89:1 but the area of the strings in the head is less than 70 square inches. Such rackets used curved beams and have short strings. They do 1 c-7- not have the stability of rackets with wider heads and their target area are unacceptably small. Simply stated, they were not very playable.

As illustrated by these patents and a great number of other patents as well as commercial rackets, efforts are continuously being made in an attempt improve tennis rackets. Such efforts are made to render tennis rackets of ever increasing capabilities during play. None of these previous efforts, however, provides the benefits attendant with the present invention. Additionally, the prior patents and commercial devices do not suggest the present inventive combination of method steps and component elements arranged and configured as disclosed and claimed herein. The present invention achieves its intended purposes, objects and advantages through a new, useful and unobvious combination of method steps and component elements, with the use of a mini-mum number of functioning parts, at a reasonable cost to manufacture and by employing only readily available materials.

Therefore, it is an object of this invention to provide a tennis racket with a frame fabricated of graphite fibers in an epoxy resin matrix formed in a tubular configuration, the frame including a handle at one end; a head at the other end; beams therebetween coupling the head and handle; and a yoke cohered to the lower ends of the head to thereby generally form an ellipse, the head having a major axis coextensive with the axis of the frame and being of a first dimension when measured at the widest point of the 5 Interior edge of the frame and having a minor axis transverse with respect thereto when measured at the widest point of the Interior edge of the frame, the minor axis to major axis aspect ratio being about 0.9:1, the beams being formed linearly and diverging from the central axis equally and 10oppositely at about 30 degrees for supporting the head, at their upper ends, at regions widely spaced from the axis, the area within the head being between about 95 and 105 square inches and to provide a frame for such tennis racket and to provide a method of stringing such frame with the horizontal 15strings at a higher pull tension than the vertical strings.

It is a further object of this Invention to increase the aspect ratio of tennis rackets and thereby create a higher sweet spot and power zone with respect to the handle It is a further object of this Invention to Increase the mechanical advantage and stability of tennis rackets.

It Is a further object of this Invention to couple the head and handle of high aspect ratio tennis rackets by essentially linear beam portions coupling with the head tangentially at widely spaced points high on the head.

Also, it is an object of this invention to string 5 high aspect ratio tennis rackets at different pull tensions 5 horizontally and vertically in order to attain resultant similarity of final tensions in the cross and main strings and without deformation of the frame.

The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure.

Accordingly, other objects and a fuller understanding of the invention may be had by referring to e.g. the detailed description of the preferred embodiment in addition to the claims taken in conjunction with the accompanying drawings.

Reference should be made to the claims with the specific embodiment shown in the attached drawings (given as one example). The present invention may be incorporated into an improved tennis racket comprising a tubular frame configured into a handle, a head, intermediate beams therebetween and a yoke cohered to the lower portion of the head to thereby generally form an ellipse, the head having a major axis coextensive with the axis of the racket of a first dimension and having a minor axis transverse with respect thereto, the minor axis to major axis aspect ratio being about 0. 9:1, the beams of the frame being linear and diverging from the central axis equally and oppositely for supporting the head at locations widely spaced from the axis, the racket also including strings strung horizontally and vertically through the head to constitute the striking surface of the racket.

The beams extend at angles of e.g. 30 degrees from the axis. The frame is fabricated of graphite fibers in an epoxy resin. The strings form an area of between e.g. 95 and 105 square inches. The head is e.g. an ellipse with its two focal point lying on the axis of the frame and racket. The racket 60g. includes a grommet strip 20extending around the external periphery of the head through which the strings pass in a serpentine path to constitute the striking surface of the racket. The racket e.g. includes a bumper guard on the upper external periphery of the head.

The invention may also be incorporated into a frame fabricated of graphite fibers in an epoxy resin matrix formed in a tubular configuration, the frame including a handle at one end; a head at the other end; beam 5therebetween coupling the head and handle; and a yoke cohered to the lower ends of the head to thereby form an ellipse with the two focal points of the ellipse lying on the longitudinal axis of the frame, the head having a major axis coextensive with the axis of the frame and being of a first dimension 10when measured at the widest point of the interior edge of the frame and having a minor axis transverse with respect thereto when measured at the widest point of the interior edge of the frame, the minor axis to major axis aspect ratio being about 0.9:1, the beams being formed linearly and diverging from the 15central axis equally and oppositely at about 30 degrees for supporting the frame, at their upper ends, at regions widely spaced from the axis, the area within the head being about 95 and 105 square inches.

The present invention may be incorporated 20into a method of stringing a racket having a high aspect ratio, the method including the steps of stringing a first common string in a serpentine path through vertically displaced holes in the frame at a first pull tension; and, thereafter stringing a second common string in a serpentine path through the horizontally displaced holes in the frame and interleafed through the strings of the first common string at a pull tension greater than the first tension to thereby constitute primary and secondary string In a grid pattern at an essentially common final tension without distorting the frame. The tension of the second string is about 10 lbs. greater than the first tension. The first string is strung vertically nd the second string is strung horizontally. The vertical strings are longer than the horizontal strings.

The foregoing has outlined some pertinent and important features of the present invention in order that the detailed description of the invention that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the Invention. It should be appreciated by those skilled in the art that the conception and the disclosed specific embodiment 20may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not 1 depart from the spirit and scope of the invention as set forth in the appended claims.

For a fuller understanding of the nature and objects of the invention. reference should be had to the following detailed description taken in conjunction with the accompanying drawings in which (by way of an example):

Figure 1 Is a perspective illustration of a tennis racket constructed in accordance with the principles of the present invention.

Figure 2 is a plan view of the frame of the tennis racket shown in Figure 1.

Similar reference characters refer to similar parts throughout the several figures.

With particular reference to the Figures, there is shown in Figures 1, a perspective illustration of a tennis racket 10 constructed in accordance with the principles of the present invention. The frame 12, by itself, is shown in Figure 2, a plan view.

The major component of the tennis racket is the f raLme 12. The frame is constructed of conventional materials preferably graphite fiber impregnated with an epoxy resin as is commonly used in tennis rackets today. Other acceptable material a are e. g. epoxy re a in with ceramic f iber, kevlar fiber or fiberglass fiber or aluminum. It is of a hollow tubular construction shaped in an oval configuration at the head or head end 14 and with the tube in parallel, side-by-side relationship at the handle end or handle 16.

Therebetween, the frame has an intermediate portion or beams 18 coupling the head and the handle. A yoke 20 closes the oval at its lower end. The yoke is initially formed separately but coupled to the remainder of the frame during the fabrication process to thereby become an essentially integral component of the frame and racket. The beams and yoke form an open throat. The joining of the yoke with the head and the beams with the head is by cohesion, an intermingling of common components including fibers of the cohered materials. Adhered materials such as wood components joined by glue are simply inadequate for the requirements of the present invention.

The other principle component of the racket is the strings 24 and 26 which are essentially interwoven through holes in the frame along parallel lines. Main or vertical strings 24 extend parallel with the central axis 30 of the frame and racket. Minor or cross horizontal strings are strung in the head perpendicular to the central axis in an X axis 32 and are interwoven through the vertical strings.

Together the strings lie in a plane and constitute the striking surface for hitting the ball during play. The strings extend through small holes or apertures 36 and 38 around the entire periphery of the head including the yoke 5 which can be considered as an integral extension of the lower portion of the head. The main strings are formed from a common first string extending through vertically aligned holes 36 while the minor strings are formed from a common second string extending through horizontally aligned holes 38.

Another principle component of the racket is the handle 16. The handle is fabricated of a pallet or underlisting on the frame which is then covered by spirally wrapping leather or synthetic grip thereover. Weights, as of 15lead, may be added to the handle portion of the frame beneath the pallet for balancing purposes.

The head end of the frame may be provided with a grommet strip 42 and/or bumper strip 44. The grommet strip 42 is a moldable, hard, synthetic material such as nylon on 20the radial exterior of the head with barrels extending through the head holes through which the strings pass. The bumper strip 44 is also of a similar material and extends radially exterior of the head at its upper extent. It extends axially a greater distance than the grommet strip to preclude scraping the frame. Such components are conventional in the tennis art.

As can be seen in the Figures, the Inner periphery, of the head is of an elliptical shape. The two focal points 5 48 and 50 of the ellipse are located on the main axis 30 of the frame within the head. The major dimension of the racket along the axis 30 is greater than the minor dimension axis 32 which is perpendicular with respect to the major dimension and axis. Note the X and Y arrows of Figures 2. When measured at their widest points, the ratio of the minor axis to the major axis Is 0.9:1 plus or minus 5 percent. This relationship constitutes the aspect ratio of the head and racket. An aspect ratio is defined as the ratio of one dimension to another. In the instant application the aspect ratio of the head as referred to herein Is the ratio of the width of the head measured at its widest point to the length of the head measured at its widest point. In one preferred embodiment, the minor axis is 10.44 Inches and the major axis Is 11.60 inches measured at the interior edges of the frame.

20The overall length of the racket Is 27 Inches. This represents a 0.9:1 aspect ratio with a 95 square Inch face within the head. In another preferred embodiment, the minor axis is 10.98 inches and the major axis is 12.20 Inches measured at the Interior edges of the frame. The overall W1 length of the racket is 27 inches. This represents a 0.9:1 aspect ratio with 105.1 square inch face within the head. A string area of between about 90 square inches plus or minus 5 percent is preferred, i.e., 95 to 105 square inches.

The majority of tennis rackets in use today have an aspect ratio of about 0.75:1. By keeping the overall length of the tennis racket of the present invention essentially the same as that of the conventional racket, the sweet spot of the racket, as well as the peripherally adjacent power zone 10around the sweet spot, is located upwardly with respect to the handle.

The sweet spot 54 is that particular point on the strings of a racket where, when striking the ball, the vibration imparted to the racket and hand of the player are 15at a minimum. The sweet spot is at or slightly below the geometric center of the head. At the sweet spot the power transferred by the strings to struck ball approach the greatest. This is the preferred place for the player to strike the ball with the racket. Peripherally therearound is 20the power zone where vibrations are also minimal and power approaches the power of the sweet spot. The more remote from the sweet spot, the more vibrations are generated and the less power is transferred from the strings to the ball.

If one would consider the sweet spot as the striking surface of a hammer, it can be readily understood that the present racket, in effect. increases the length between the handle and the striking surface. This increases the mechanical advantage of the racket of the present Invention over prior art rackets given the same head size. And, since the power zone is also rendered higher on the axis, the racket provides a 4reater mechanical advantage for stronger shot making by the player.

Another feature of the present invention is in the intermediate portion or beams of the frame coupling the head and the handle. The beams are linear in construction over the majority of their lengths and are each angled at about 30 degrees from the central axis. All known rackets of modern tubular design, such as those fabricated of graphite as in the preferred embodiment, have beams coupling the head to the handle which are curved concave, oppositely from the convex beam curvature. The present Invention, however, has straight or linear segments of frame along their entire extent of the beams 18 except at the points of merging the handle.

The straight line design of this portion of the frame adds stability to the frame and racket when a ball is struck on the strings offset from the axis. The further the ball strikes the strings from the axis the greater will be 1 beams as opposed to the prior art curved design.

The straight line design of the beams 18, at the angles utilized in the present invention, adds a further benefit. Specifically, the beam portions of the frame make contact tangentially with the head for coupling at a distance further removed from the axis than in prior art designs. This design feature adds further stability against torquing forces since the stabilizing forces of the frame coupling the head are further separated. This is akin to attempting to stop rotation of a body by holding it at two points close to the point of rotation. By holding the rotating body further from the axis of rotation, the rotation inhibiting moment forces are increased tending to more efficiently abate rotation. The beam to head contact is also higher on the head further Increasing stability and the strength of the coupling.

The last significant feature of the present Invention Is in the stringing of the racket. In the conventional racket, which is more elongated along the axis 30 as compared to the present racket, the main or vertical strings 24 are strung first and unrestricted. The cross or horizontal strings 26, however, being strung second are restricted by the friction of the main strings.

Consequently. when the racket is fully strung, the vertical strings are usually about 10 lbs. greater in tension than the horizontal strings. The reason for this Is the friction of the vertical strings inhibits the horizontal strings to decrease their tension and also act to deform the vertical strings to increase their tension. Secondly, the vertical strings are displaced slightly by the interweaving horizontal strings so the vertical strings will pick up a slight amount of additional tension. The displacement of the strings Is perpendicular to the plane of the strings. For exampler when a racket Is completely strung, with the stringing machine set at about 60 lbs. nominally it will have a finished string tension of strings about 50 lbs. in the vertical strings. The horizontal strings will have a tension of about 40 lbs.

1 1 Conventional rackets have greater frame strength at their upper and lower ends where they are formed with smaller radii of curvature than the sides at 3 o'clock and 9 o'clock. The string tensions are matched to accommodate this feature 5 of structural difference with greater string tension vertically than horizontally. It can thus be seen that variations from the standard in either frame design should be compensated for by a correlated variation in string tension. Such was not understood by the prior art designers of tennis racket frames.

This example is exaggerated when one deviates from the standard type elliptical head in favor of the present 0.9:1 aspect ratio or greater. Elliptical rackets of the past were designed to overcome the inherent problems of 15variation of string rate because they were designed to have an aspect ratio of 0.75:1. When aspect ratio is increased to about 0.9 or greater, the vertical strings and the cross strings must be very close to equal in final string tensions. The reason for this is because the arcs at 3 and 9 o'clock on 20the frame are almost identical to the arcs at 12 and 6 o'clock. Therefore, the load bearing capability of all strings have to be equal. In order to make the load bearing capabilities equal, one must string the vertical strings at 10 lbs. lower in pull tension than the horizontal strings.

Then the final finished string tension will be essentially equal in all directions. Such string tensioning provides the benefit of equal forces being applied to the ball. Because of strings of equal length, the main strings are reduced in length which results in reduced trampolining during a shot, a further benefit. Trampolining is too much elastic reaction during a shot due to long strings. The present invention provides superior results with less trampolining Strings of equal length and tension horizontally and vertically abate trampolining due to the two above described factors. Such equal strings provide greater control of the depth of the shot when compared with larger area racket heads or high aspect ratio heads strung conventionally.

The present disclosure includes that contained in the appended claims as well as that of the foregoing description. Although this invention has been described in its preferred form 9 it is understood that the present disclosure of the preferred form has been made only by way of example and numerous changes in the details of construction and combination and arrangement of parts may be resorted to without departing from the scope of the appended claims. In the present application, any numerical value includes the precise value and any value "about" or "substantially" the same as the precise value, e.g. "about 0.9:111 includes substantially 0.9:1. "Essentially" may be "subs tantially".

I A

Claims

1. A tennis racket comprising a tubular frame configured into a handle, a head, intermediate beams therebetween and a yoke cohered to the lower portion of the head to thereby generally form an ellipse, the head having a major axis coextensive with the axis of the racket of a first dimension and having a minor axis transverse with respect thereto, the minor axis to major axis aspect ratio being about 0.9:1, the beams of the frame being linear and diverging from the central axis equally and oppositely for supporting the head at locations widely spaced from the axis, the racket also including strings strung horizontally and vertically through the head to constitute the striking surface of the racket.

2. The racket as set forth in claim I wherein the beams extend at angles of about 30 degrees from the axis.

3. The racket as set forth in claim 1 wherein the frame is fabricated of graphite fibers in an epoxy resin.

4. The racket as set forth in claim I wherein the 20strings form an area of between about 95 and 105 square inches.

5. The racket as set forth in claim 1 wherein the head is formed as an ellipse with its two focal points lying on the axis of the frame and racket 9 or substantially 25thereon.

6. The racket as set forth in claim 1 and further including a grommet strip extending around the external periphery of the head through which the strings pass in a serpentine path to constitute the striking surface of the 5 racket.

7. The racket set forth in claim 6 and further including a bumper guard on the upper external periphery of the head. ?

8. For use in a tennis racket, an improved frame fabricated of graphite fibers in an epoxy resin matrix formed in a tubular configuration, the frame including: a handle at one end; a head at the other end; beams therebetween coupling the head and handle; and a yoke cohered to the lower ends of the head to thereby form an ellipse with the two focal points of the ellipse lying on the longitudinal axis of the frame, the head having a major axis coextensive with the axis of the frame and being of a first dimension when measured at the widest point of the interior edge and having a minor axis transverse with respect thereto measured at the widest point of the interior edge of the frame, the minor axis to major axis aspect ratio being about 0.9:1, the beams being formed linearly and diverging from the central axis equally and oppositely at about 30 degrees for supporting the frame, at their upper ends, at regions widely spaced from the axis, the area within the head being between about 95 and 105 square inches.

9. A method of stringing a racket having a high aspect ratio, the method including stringing a first common string in a serpentine path through vertically displaced holes in the frame at a first pull tension; and thereafter, stringing a second common string In a serpentine path through the horizontally displaced holes In the frame and interleafed through the strings of the first common string at a tension pull greater than the first tension to thereby constitute primary and secondary string in a grid pattern at an essentially common final tension without distorting the frame.

10. The method as set forth in claim 9 wherein the tension of the second string is about 10 lbs. greater than the first tension.

11. The method as set forth in claim 9 wherein the first string is strung vertically and the second string is strung horizontally.

12. The method as set forth in claim 11 wherein the vertical strings are longer than the horizontal strings.

13. A tennis racket with a frame fabricated of graphite fibers In an epoxy resin matrix formed In a tubular configuration, the frame Including a handle at one end; a head at the other end; beams therebetween coupling the head and handle; and a yoke cohered to the lower ends of the head to thereby generally form an ellipse, the head having a major axis coextensive with the axis of the frame and being of a first dimension when measured at the widest point of the Interior edge and having a minor axis transverse with respect thereto measured at the widest point of the interior edge of the frame, the minor axis to major axis aspect ratio being about 0.9:1, the beams being formed linearly and diverging from the central axis equally and oppositely at about 30 degrees for supporting the head, at their upper ends, at regions widely spaced from the axis, the area within the head being between about 95 and 105 square Inches.

14. A tennis racket frame, substantially as hereinbefore described with reference to and as shown in the accompranying drawings.

15. A tennis racket, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

16. A method of stringing a tennis racket, or other racket, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

Published 1991 at The Patent Office. State House. 66/71 High Holborn. London WC I R4M. Further copies maybe obtained from Sales Branch. Unit 6, Nine Mile Point. Cwinfelinfach. Cross Keys. Nc%%T)ort. NPI 7HZ. Printed by Multiplex techniques lid. St Mary Cray. Rent.