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1. (WO1980002510) RAQUETTE DE TENNIS
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS

It is understood that minor changes may be made in the devices of the invention without departing from the spirit of the invention and the scope of the claims.

I claim:

Claim 1. A complete tennis racket comprising at least a frame having a head portion supporting a string netting in a plane and a handle portion having a grip portion suitably adapted for the hand to grip; said netting having a length along the longitudinal axis of said frame greater than 22.86 centimeters and a width along an axis perpendicular to said longitudinal axis greater than 19.05 centimeters; said racket having a weight W in grams; a center of percussion located at a distance Cp in centimeters from the end of the grip portion, when tested in accordance with test 4 of Fig. 40 herein before defined, said center of percussion taken about a pivot located at the end of the grip portion, said pivot having an axis perpendicular to the longitudinal axis of said frame and parallel to the plane of said string netting; said racket having a length L in centimeters from the end of the grip portion to the end of the head portion; said racket having a center of gravity located at a distance Cg in centimeters from the end of the grip portion; said racket having a first moment of inertia Is in gram centimeters squared about said pivot and Is is directly proportional to the product of Cp , Cg, W, given by the formula


and said racket characterized in that the magnitude of Cp divided by the magnitude of L given by the formula Cp /L is greater than 0.71; and the magnitude of the weight W is less than 303.345 grams.

Claim 2. A racket as in Claim 1 wherein the said length L is greater than 64.77 centimeters.

Claim 3. A racket as in claim 2; and the said magnitude of the moment of inertia Is is greater than 457,256 gram-centimeters squared and less than 631,015 gram-centimeters squared.

Claim 4. A tennis racket as in claim 2; and said racket having a weight and stiffness distribution providing for the nodal pivot closest to the grip portion end to be located at a distance N centimeters from the said end of the said end of the grip portion, when tested in accordance with test 15 of Fig. 40 herein before defined; said racket characterized in that the magnitude .of said distance N divided by the magnitude of the distance L. given by the formula N | L, is greater than 0.28.

Claim 5. A racket as in claim 2; and said racket having a weight and stiffness distribution providing for a frequency of vibration greater than 140 cycles per second when tested in accordance with test 13 of Fig. 40 herein before defined.

Claim 6. A tennis racket as in claim 2; and said racket having a weight and stiffness distribution providing for a frequency of vibration greater than 175 cycles per second when tested in accordance with test 16 of Fig. 40 herein before defined.

Claim 7. A tennis racket as in claim 2; and said racket having a weight and stiffness distribution providing a frequency of vibration greater than 34 cycles per second when tested in accordance with test 18 of Fig. 40 herein before defined.

Claim 8. A tennis racket as in claim 2; and said racket having a weight and stiffness distribution providing a frequency of vibration greater than 40 cycles per second when tested in accordance with test 20 of Fig. 40 herein before defined.

Claim 9. A tennis racket as in claim 2; and said racket having a weight and stiffness distribution providing a frequency of vibration greater than 90 cycles per second when tested in accordance with test 22 of Fig. 40 herein before defined.

Claim 10. A tennis racket as in claim 2; and said racket having a center of the said string netting, located at a distance Cp in centimeters from the end of the grip portion; said racket providing for the
difference in the magnitude of the said distance Cf and the said distance C p divided by the distance Cp given by the formula (C f- Cp) /Cp to be less than 0.12.

Claim 11. A tennis racket as in claim 2; and said racket having a weight distribution providing a second moment of inertia Iα, in gram centimeters squared about a longitudinal axis running from the center of the head portion end to the center of the grip portion end; said racket further characterized in that the magnitude of the moment of inertia Iα divided by the magnitude of the said moment of inertia Is given by the formula Iα /Is is greater than 0.020.

Claim 12. A complete tennis racket comprising at least a frame having a head portion supporting a string netting in a plane, and a handle portion having a grip portion suitably adapted for the hand to grip, said netting having a length along the longitudinal axis of said frame greater than 22.86 centimeters and a width along an axis perpendicular to said axis greater than 19.05 centimeters; said racket having a weight W in grams; a center of percussion located at a distance Cp in centimeters from the end of the grip portion, when tested in accordance with test 4 of Fig. 40 herein before defined, said center of percussion taken about a pivot located at the end of the grip portion, said pivot having an axis perpendicular to the longitudinal axis of said racket and parallel to the plane of said string netting; said racket having a length L in centimeters from the end of the grip portion to the end of the head portion; said racket having a center of gravity located at a distance Cg in centimeters from the end of the grip portion; said racket
having a first moment of inertia Is in gram centimeters squared about said pivot, and Is is directly proportional to the product of Cp , Cg, W given by the formula
ls - (Cp)(Cg)(w) ; said racket characterized in that the magnitude of Cp is greater than 47.625 centimeters, and the weight is less than 303.345 grams.

Claim 13. A racket as in claim 12; and the said magnitude of Is is greater than 457,256 gram
centimeters squared and less than 731,611 gram centimeters squared.

Claim 14. A racket as in claim 12; and said racket having a weight and stiffness distribution providing for the nodal pivot closest to the grip portion end to be located at a distance N centimeters from the end of the grip portion, when tested in accordance with test 15 of Fig. 40 herein before defined; said racket characterized in that the magnitude of the said distance N is greater than 19.05 centimeters.

Claim 15. A tennis racket as in claim 12;
and said racket having a weight and stiffness distribution providing a frequency of vibration greater than 140 cycles per second when tested in accordance with test 13 of Fig. 40 herein before defined.

Claim 16. A tennis racket as in claim 12; and said racket having a weight and stiffness distribution providing a frequency of vibration greater than 175 cycles per second when tested in accordance with test 16 of Fig. 40 herein before defined.

Claim 17. A tennis racket as in claim 12; and said racket having a weight and stiffness distribution providing a frequency of vibration greater than 34 cycles per second when tested in accordance with test 18 of Fig. 40 herein before defined.

Claim 18. A tennis racket as in claim 12; and said racket having a weight and stiffness distribution providing a frequency of vibration greater than 40 cycles per second when tested in accordance with test 20 of Fig. 40 herein before defined.

Claim 19. A tennis racket as in claim 12; and said racket having a weight and stiffness distribution providing a -frequency of vibration greater than 90 cycles per second when tested in accordance with test 22 of Fig. 40 herein before defined.

Claim 20. A tennis racket as in claim 12; and said racket having a center of said string netting located at a distance Cp in centimeters from the end of the grip portion; said racket characterized in that the difference in the magnitude of the distance Cf and the said distance Cp divided by the said distance Cp given by the formula (Cf -Cp)/Cp is less than 0.12.

Claim 21. A tennis racket as in claim 12; and said racket having a weight distribution providing a second moment of inertia Iα in gram centimeters squared about a longitudinal axis running from the center of the grip portion end to the center of the head portion end; said racket further characterized in that the magnitude of the moment of inertia Iα divided by the magnitude of the said moment of inertia Is given by the formula Iα /Is is greater than 0.020.

Claim 22. A complete tennis racket comprising at least a frame having a head portion supporting a string netting in a plane, and a grip portion suitably adapted for the hand to grip; said racket having a weight and stiffness distribution providing for the nodal pivot closest to the grip portion end being located at a distance N centimeters from the said end of the grip
portion, when tested in accordance with test 15 of Fig. 40 herein before defined; said racket characterized in that the magnitude of the said distance hi is greater than 19.05 centimeters.

Claim 23. A complete tennis racket comprising at least a frame having a head portion supporting a string netting in a plane, and a grip portion suitably adapted for the hand to grip; said racket having a weight and stiffness distribution providing for the nodal pivot closest to the grip portion end being located at a distance N from the said end of the grip portion, when tested in accordance with test 15 of Fig. 40 herein before defined; said racket having a length L from the end of the grip portion to the end of the head portion; said racket characterized in that the magnitude of the said distance N divided by the said distance L given by the formula N/L. is greater than 0.28.

Claim 24. A complete tennis racket comprising at least a frame including a head portion supporting a string netting, and a grip portion suitably adapted for the hand to grip; said racket having a weight and stiffness distribution providing a frequency of vibration f in cycles per second when tested in accordance with test 13 of Fig. 40 herein before defined; and said racket having a length L in centimeters from the end of the grip portion to the end of the head portion; said racket characterized in that the magnitude of f is greater than 150 cycles per second and the magnitude of L is greater than 64.77 centimeters.

Claim 25. A complete tennis racket comprising at least a metal frame having a head portion supporting a string netting, and a grip portion suitably adapted for the hand to grip; said racket having a weight and stiffness distribution providing a frequency of vibration f in cycles per second when tested in accordance with test 16 of Fig. 40 herein before defined; and said racket having a length L in centimeters from the end of the grip portion to the end of the head portion; said racket characterized in that the magnitude of f is greater than 175 cycles per second, and the magnitude of L is greater than 64.77 centimeters.

Claim 26. A complete tennis racket comprising at least a frame having a head portion supporting a
string netting, and a grip portion suitably adapted for the hand to grip; said racket having a weight W in grams and a center of gravity located at a distance Cg in centimeters from the end of the grip portion, said racket having a length L in centimeters from the end of the grip portion to the end of the head portion; said racket characterized in that the magnitude of the said distance Cg divided by the said length L given by the formula Cg/ L is greater than 0.56; and said racket has a weight W less than 303.345 grams; and the ratio of W/L is less than 0.4.

Claim 27. A tennis racket as in claim 22; and said racket having a center of gravity located at a distance Cg from the end of the grip portion; and said racket having a length L from the end of the grip portion to the end of the head portion; said racket further character ized in that the magnitude of the said distance Cg divided by the magnitude of the said distance L given by the formula Cg /L is greater than 0.56.

Claim 28. A tennis racket as in claim 23;
and said racket having a center of gravity located at a distance Cg from the end of the grip portion; and said racket having a length L from the end of the grip portion to the end of the head portion; said racket further characterized in that the magnitude of the said distance Cg divided by the magnitude of the distance L given by the formula Cg / L is greater than 0.56.

Claim 29. A tennis racket as in claim 24; and said racket having a center of gravity located at a distance Cg from the end of the grip portion; said racket further characterized in that the magnitude of the said distance Cg divided by the magnitude of the said distance L given by the formula Cg/L is greater than 0.56.

Claim 30. A complete tennis racket comprising at least a frame having a head portion supporting a string netting and a grip portion suitably adapted for the hand to grip; said racket having a weight distribution providing a first moment of inertia Is in gram centimeters squared about a pivot located at the end of the grip portion, said pivot having an axis perpendicular to the longitudinal axis of said racket running from the center of the head portion end to the center of the grip portion end, and parallel to the plane of said string netting, and a second moment of inertia I α in gram centimeters squared about said longitudinal axis; and said racket having a center of gravity located at a distance Cg from the end of the grip portion; and said racket having a length L from the end of the grip portion to the end of the head portion; said racket characterized in that the magnitude of said distance Cg divided by the magnitude of the said distance L given by the formula Cg/L is greater than 0.56; and the magnitude of the moment of inertia Iα divided by the magnitude of the said moment of inertia Is given by the formula I α/Is is greater than 0.020.

Claim 31. A complete tennis racket comprising at least a frame having a head portion supporting a string netting, and a grip portion suitably adapted for the hand to grip; said racket having a weight W in grams, a center of percussion located a distance Cp in centimeters from the end of the grip portion, when tested in accordance with test 4 of Fig. 40 herein before defined, said center of percussion taken about a pivot located at the end of the grip portion, said pivot having an axis perpendicular to the longitudinal axis of said
frame and parallel to a plane containing the surface of the frame; said racket having a center of gravity located at a distance Cg in centimeters from the end of the grip portion; said racket characterized in that the
magnitude of the said distance Cg divided by the magnitude of the said distance Cp given by the formula Cg / Cp is greater than 0.80 and the magnitude of the weight is less than 303.345 grams.

Claim 32. A tennis racket as in claim 23; and said racket having a center of percussion located at a distance Cp in centimeters from the end of the grip
portion when tested in accordance with test 4 of Fig.
40 herein before defined; said center of percussion
taken about a pivot located at the end of the grip portion, said pivot having an axis perpendicular to the longitudinal axis of said frame and parallel to a plane containing the surface of the frame; said racket having a center of gravity located at a distance Cg in centimeters from the end of the grip portion; said racket further characterized in that the magnitude of the said distance Cg divided by the magnitude of the said distance Cp given by the formula Cg/Cpis greater than 0.80.

Claim 33. A tennis racket as in claim 24; and said racket having a center of percussion located at a distance Cp in centimeters from the end of the grip
portion, when tested in accordance with test 4 of Fig.
40 herein before defined; said center of percussion
taken about a pivot located at the end of the grip portion, said pivot having an axis perpendicular to the longitudinal axis of the racket and parallel to a plane containing the surface of the frame; said racket having a
center of gravity located at a distance Cg in centimeters from the end of the grip portion; said racket further characterized in that the magnitude of the said distance Cg divided by the magnitude of the said distance Cp given by the formula Cg /Cp is greater than 0.80.

Claim 34. A tennis racket as in claim 2;
wherein the said frame is made of metal having a modulus of elasticity in tension ε in Kilograms per square
centimeter, and a density α in Kilograms per cubic
centimeter, and the ratio ε/α is less than 279.4 X 106.

Claim 35. A tennis racket as in claim 2;
wherein the said frame utilizes a composite of fibers and resin, and further the magnitude of the said weight W is less than 283.5 grams.

Claim 36. A tennis racket as in claim 12;
wherein the said frame is made of metal having a modulus of elasticity in tension ε in Kilograms per square
centimeter and a density α in Kilograms per cubic
centimeter, and the ratio of ε/α is less than 279.4 X
106.

Claim 37. A tennis racket as in claim 12;
wherein the said frame utilizes a composite of fibers, and resin; and further the magnitude of the weight W is less than 283.5 grams.

Claim 38. A tennis racket as in claim 12;
and said head portion being an elongated strip having a center portion and two adjacent end portions curved to inclose said string netting; said handle portion being a thin wall tube having located at a first end said grip portion suitably formed for the hand grip, and said tube gradually formed along the length toward a second end portion into a crossectional shape having an upper wall and a lower wall located at a substantial distance from a plane bisecting said tube lengthwise and said plane being parallel to the plane of said string netting; said second end portion of said tube being fastened to said head portion.

Claim 39. A tennis racket having great rigidity and strength with a minimum of weight comprising a head member and a handle member; said head member being an elongated hollow tubular metal strip having a center portion and two adjacent end portions shaped to partially inclose a space, said head member adapted to support a string netting in a plane; said handle member being a thin wall aluminum alloy tube having a yield strength greater than 3866.94 kilograms per square centimeter and said wall having a thickness less than 0.0635 centimeters and said tube having a grip portion, and a shaft portion, said grip portion suitably formed for the hand to grip and said shaft portion gradually formed along the length toward the head member into a crossectional shape having an upper wall and a lower wall and two side walls, said walls being substantially planar and said side walls being substantially perpendicular to said upper and lower walls; said end portions of the head member having a crossectional shape to provide an upper surface and a lower surface located at a distance from a plane bisecting the head member lengthwise and said plane being parallel to the plane of said string netting; and said upper and lower walls of said shaft portion being located at substantially the same said distance from said plane, and said upper and lower walls of the shaft portion being fastened to the said upper and lower surfaces of the end portions of said head member; and wherein the portion of said handle member having an axial length of 35.56 centimeters from the handle end of the racket, has a weight less than 85.05 grams, and the weight of the racket extending beyond the said length of 35.56 centimeters is greater than 170.1 grams.

Claim 40. A tennis racket as in claim 39, wherein said side walls are selectively perforated to provide apertures in portions there of to reduce the weight with a minimum reduction in strength and rigidity.

Claim 41. A tennis racket comprising a head member and a handle member; said head member being an elongated metal strip having a center portion and two adjacent end portions shaped to partially inclose a space, said head member adapted to support a string netting in a plane; said handle member being a thin wall tube having located at a first end a grip portion, said grip portion suitably formed for the hand to grip and said tube gradually formed along the length toward the second end portion into a crossectional shape having an upper wall and a lower wall located at a substantial distance from a plane bisecting said handle lengthwise and said plane being parallel to the plane of said string netting, said second end portion being fastened to the said end portions of the head member; said head member having the center portion substantially straight and lying perpendicular to a first axis, said axis running longitudinally from the center of the head end of the racket to the center of the handle end, and the said two adjacent end portions each substantially straight and forming corners with the center portion, and having the said end portions directed to converge toward a location in the second end portion of said handle member; a second axis perpendicular to the said first axis, said second axis being at a distance of 7.62 centimeters from the head end of the racket, said second axis intersecting said head member at locations, said locations being at the surface of said head member laterally outermost from said first axis, and the distance between said locations being greater than 22.86 centimeters; a third axis starting at one of the said locations on said head member, and running toward a point on the said first axis, said point being at a distance of 48.26 centimeters from the head end of the racket; a first plane being perpendicular to the said first axis and containing the said second axis, and a second plane being perpendicular to the said first axis and being located at a distance of 41.91 centimeters from the head end of the racket, and the portion of the racket lying between said first and second planes having a surface laterally outermost from said third axis, said surface being laterally on the same side of the first axis as the third axis, and said surface having a maximum distance from said third axis less than 1.905 centimeters.

Claim 42. A tennis racket having great rigidity and light weight comprising a head member, a throat member, and a handle member; said head member being an elongated hollow tubular metal strip having a center portion and two adjacent end portions shaped to partially inclose a space, said head member adapted to support a string
netting in a plane; said handle member being a thin wall aluminum alloy tube having a yield strength greater than 3866.94 kilograms per square centimeter and said wall having a thickness less than 0.0635 centimeters and said tube having a grip portion and a shaft portion, said grip portion suitably formed for the hand to grip and said shaft portion gradually formed along the length toward the head member into a crossectional shape having an upper wall and a lower wall and two side walls, said upper and lower walls lying parallel to the plane of said string netting and said sidewalls lying perpendicular to said plane and said walls being substantially planar;
said end portions of said head member having a crosssectional shape having an upper surface and a lower surface located at a distance from a plane bisecting said head member lengthwise and said plane being parallel to the plane of said string netting; and said upper and lower walls of said shaft portion being located at substantially the same said distance from said plane bisecting said head member lengthwise; and said throat member comprising a separate first planar sheet of thin wall metal havinga portion fastened to the exterior of said upper wall of the shaft portion of said handle member and another portion of said first sheet fastened to the said upper surface of said head member, and a second separate sheet of thin wall metal having a portion fastened to the exterior of the said lower wall of the shaft portion of the handle member, and another portion of said second sheet fastened to the lower surface of said head member; and wherein the portion of said handle member having an axial length of 35.56 centimeters from the handle end of the racket has a weight less than 85.05 grams, and the weight of the racket extending beyond the said length of 35.56 centimeters is greater than 170.1 grams.

Claim 43. A tennis racket as in claim 42;
and a string netting supported by said head member, and wherein the said first and second sheets of thin wall metal of the throat member having portions of said sheets adjacent to said string netting suitably adapted to support said string netting; and said string netting supported by said throat member.

Claim 44. A tennis racket having rigidity and light weight comprising a head member, a throat member, and a handle member; said head member being an elongated hollow tubular metal strip having a center portion and two adjacent end portions shaped to partially inclose a space, said head member adapted to support a string netting in a plane; said handle member being a thin wall aluminum alloy tube having a yield strength greater than 3866.94 kilograms per square centimeter and said wall thickness less than 0.0635 centimeters and said tube having a grip portion suitably formed for the hand to grip and a shaft portion gradually formed along the length toward the head member into a crosssectional shape having a planar upper wall and a planar lower wall and two planar side walls, said upper and lower walls lying parallel to the plane of said string netting and said side walls lying perpendicular to said upper and lower walls; said end portions of said head member having a crossectional shape having an upper surface and a lower surface located at a distance from a plane bisecting said head member lengthwise and said plane being parallel to the plane of said string netting; and said upper and lower walls of said shaft portion being located at substantially the same said distance from said plane bisecting said head member lengthwise; and said throat member comprising a sheet of thin wall material formed into a substantially u-shaped crosssection having a first planar side opposing a second planar side and a third substantially planar side therebetween, said third side being straight in a direction perpendicular to a plane passing through the longitudinal axis of the racket, said plane being perpendicular to the plane of said string netting; said first and second sides being fastened to the said upper and lower surfaces of the said end portions of said head member and said first and second sides lying exterior to and being fastened to the said upper wall and lower wall of said shaft portion of said handle member, and the third side of said throat member adapted to support said string netting.

Claim 45. A tennis racket frame having strength and rigidity with a minimum of weight; said frame having a head portion, supporting a string netting in a plane, a throat portion, and a handle portion; a throat member comprising a sheet of thin wall material formed into a substantially u-shaped crossection having a first planar side opposing a second planar side and a third side between said first and second sides, and said
first and second sides each lying in a plane and said third side being straight in a direction perpendicular to a plane passing through the longitudinal axis of said racket frame, said plane being perpendicular to the plane of said string netting; said first and second sides being fastened to the outer surfaces of the throat portion of said frame.

Claim 46. A tennis racket as in claim 45 wherein the said first and second sides are selectively perforated to provide multiple apertures, in portions thereof to reduce the weight, the number of said apertures occurring in 2.54 centimeters of length of said sides being greater than 3.

Claim 47. A tennis racket as in claim 39;
and a string netting supported by said head member; and a planar strip of material having a first surface lying in a plane, placed at a location on a surface of said string netting, said strip having sufficient length and breadth to extend over the spaces between multiple strings and said surface of said strip having adhesive means to fasten to said strings, and said location on said string netting positioned to reduce the probability of impact of said strip with a ball during play; and said strip comprised of material capable of damping the vibratory motion of said strings subsequent to the impact of the ball upon said strings; said strip having a second surface parallel to said first surface and said second surface being substantially durable, non-abrasive, and non-adhesive.

Claim 48. A tennis racket comprising at. least a head portion and a string netting supported by said head portion; a planar strip of material having a first surface lying in a plane placed at a location on a surface of said string netting, said strip having sufficient length and breadth to extend over the spaces between multiple strings and said surface of said strip having adhesive means to fasten to said strings, and said location on said string netting positioned to reduce the probability of impact of said strip with a ball during play; and said strip comprised of material capable of damping the vibratory motion of said strings subsequent to the impact of a ball upon said strings.

Claim 49. A tennis racket as in claim 48;
and said strip having a second surface parallel to said first surface, said second surface being non-adhesive and durable.

Claim 50. A complete tennis racket having rigidity and strength with a minimum of weight, said racket comprising at least a head portion supporting a string netting in a plane, and a handle portion; said handle portion comprising a thin wall material formed into a tube having a first end grip portion suitably formed for the hand to grip, and said tube gradually formed along the length toward the head portion into a crossectional shape suitable for joining with said head portion; and wherein a portion of said racket having an axial length of 35.56 centimeters from the handle end has a weight less than 85.05 grams, and the said grip portion of the handle has a circumference greater than 10.795 centimeters and less than 13.335 centimeters, and the weight of the portion of the racket extending beyond the said distance of 35.56 centimeters from the handle end is greater than 170.1 grams.

Claim 51. A tennis racket as in claim 50 wherein said handle portion being selectively perforated to provide apertures in portions thereof to reduce the weight with a minimum reduction in strength and rigidity.

Claim 52. A racket as in claim 50 wherein the material of said handle portion is an aluminum alloy having a yield strength greater than 3866.94 kilograms per square centimeter and having a wall thickness less than 0.0635 centimeters.

Claim 53. A tennis racket as in claim 1 comprising a frame member being an elongated strip of material shaped to form a head portion a throat portion and a pair of spaced sides into a shaft portion; said head portion curved to inclose a space suitable for supporting a string netting, said strip adapted to support said string netting; and a tubular grip member of thin wall material shaped for the hand to grip fastened to the ends of the spaced sides of the shaft portion of said frame member; and throat members being two sheets of thin wall material, each sheet having a top edge portion, a bottom edge portion connected with side edge portions; said sheets having the side edge portions fastened to the said strip of material at the throat portion of said frame member.

Claim 54. A tennis racket as in claim 24 comprising a frame member made of an elongated strip of material shaped to form a head portion a throat portion and a pair of spaced sides into a shaft portion; said head portion curved to inclose a space suitable for supporting a string netting, said strip adapted to support said string netting; a tubular grip member of thin wall material shaped for the hand to grip fastened to the ends of the spaced sides of the shaft portion of said frame member; throat members being two sheets of thin wall material, each sheet having a top edge portion, a bottom edge portion connected with side edge portions; said sheets having the side edge portions fastened to the strip of material at the throat portion of said frame member.

Claim 55. A tennis racket as in claim 1
comprising a frame formed of a resin reinforced fiber material having a head portion, a throat portion, and a shaft portion; said head portion inclosing a space
suitable to support a string netting in a plane, said head portion having two arms of thin wall crossection approaching the throat portion, said two arms of said head portion merging with the throat portion; said throat portion merging with the shaft portion, said shaft portion merging with the grip portion, said grip portion having a crossection having a thin wall. Said grip portion formed suitably for the hand to grip.

Claim 56. A tennis racket as in claim 1 having a hollow metal frame of two part shell construction
comprising substantially outer and inner shells each having an open side and two opposing sides connected by a central wall, the outer shell receiving the inner shell in an inverted position therein, said opposing sides of the outer shell adjacent to the opposing sides of the inner shell; means for fastening said sides of the outer shell to the adjacent side of the inner shell; said frame having a head portion capable of supporting a string netting in a plane, a throat portion a shaft portion.

Claim 57. A tennis racket as in claim 53;
and a removable thin sleeve tightly secured without
pleats over said grip member, said sleeve being made of thin cloth, said cloth having all fibers woven and lying substantially in a surface, said cloth having an upper side and a lower side, and said cloth having at least one side free of adhesive material, and said cloth being durable, and light in weight.

Claim 58. A tennis racket comprising at least a head portion, a throat portion, and a grip portion;
said head portion being an elongated strip of material shaped to partially inclose a space for a string netting, said head portion adapted to support said string netting; said head portion comprising a center portion and two adjacent side portions, said center portion being substantially straight and placed perpendicular to a first axis running longitudinally from the center of the head portion to the center of the grip portion end, and the two adjacent side portions being substantially straight and forming corners with the center portion and said side portions directed to converge toward the throat portion of said racket; a second axis perpendicular to the said first axis, said second axis being at a distance of 7.62 centimeters from the head end of the racket, said second axis intersecting said head portion at locations, said locations being at the surface of said head portion laterally outermost from said first axis and the distance between said locations being greater than 22.86 centimeters, a third axis starting at one of the said locations on the said head portion and running toward a point on the said first axis said point being at a distance of 48.26 centimeters from the head end of the racket; a first plane being perpendicular to said first axis and containing said second axis, and a second plane being perpendicular to the said first axis and being located at a distance of 41.91 centimeters from the head end of the racket, and the portion of the racket lying between said first and second planes having a surface laterally outermost from said third axis, said surface being laterally on the same side of the first axis as the third axis and said surface having a maximum distance from said third axis less than 1.905 centimeters; and said material of said head portion having a modulus of elasticity in tension greater than 175.77 X 10 kilograms per square centimeter and said material having a yield strength in tension greater than 1054.62 kilograms per square centimeter.

Claim 59. A tennis racket as in claim 2
wherein the magnitude of W is less than 283.5 grams.

Claim 60. A tennis racket as in claim 12 wherein the magnitude of W is less than 283.5 grams.

Claim 61. A tennis racket as in claim 5 wherein the said frequency of vibration is greater than 150 cycles per second.

Claim 62. A tennis racket as in claim 15 wherein the said frequency of vibration is greater than 150 cycles per second.

Claim 63. A tennis racket as in claim 24 wherein the said frequency of vibration is greater than 155 cycles per second.

Claim 64. A tennis racket as in claim 22 wherein the said distance N is greater than 20.32 centimeters.

Claim 65. A tennis racket as in claim 23 wherein the said ratio N /L is greater than 0.31.

Claim 66. A tennis racket as in claim 12 wherein the distance C p is greater than 49.53 centimeters.

Claim 67. A tennis racket as in claim 12 and having a displacement less than 0.02032 centimeters for D, when tested in accordance with test 14 of Fig. 40 herein before defined.

Claim 68. A tennis racket as in claim 41 wherein said head member has a greater weight per centimeter of length at the locations of said corners than at other locations on said head member.

Claim 69. A tennis racket as in claim 58, wherein said head portion has a greater weight per centimeter of length at the locations of said corners than at other locations on said head portion.

Claim 70. A tennis racket as in claim 24
wherein the said frame is made of material having a modulus of elasticity in tension ε in kilograms per
square centimeter and a density α in kilograms per cubic centimeter, and the ratio of ε/α is less than
279,4 x 106.

Claim 71. A racket as in claim 1; and said racket having a weight and stiffness distribution providing for a frequency of vibration greater than 90
cycles per second when tested in accordance with test
13 of Fig. 40 herein before defined.

Claim 72. A racket as in claim 1 and said racket having a weight and stiffness distribution providing for a frequency of vibration f in cycles per second when tested in accordance with test 13 of Fig. 40 herein before defined; and said racket further characterized in that the product of said length L squared and said
frequency f given by the expression L2f is greater than 419,354.

Claim 73. A racket as in claim 31 and said racket having a weight and stiffness distribution providing a frequency of vibration f in cycles per second when tested in accordance with test 13 of Fig. 40 herein
before defined, and said racket having a length L in centimeters from the end of the grip portion to the end of the head portion; said racket further characterized in that the product of the said length L squared and the said frequency f given by the expression L2f is greater than 419,354.

Claim 74. A racket as in claim 72 wherein the said length L is greater than 58.42 centimeters.

Claim 75. A racket as in claim 12 and said racket having a weight and stiffness distribution providing for a frequency of vibration greater than 90
cycles per second when tested in accordance with test 13 of Fig. 40 herein before defined.

Claim 76. A racket as in claim 15; and said racket having said distance Cp greater than 49.022 centimeters.

Claim 77. A tennis racket as in claim 24;
and said racket having a center of percussion located at a distance Cp in centimeters from the end of the grip portion, when tested in accordance with test 4 of Fig.
40 herein before defined, said center of percussion taken about a pivot located at the end of the grip portion, said pivot having an axis perpendicular to the longitudinal axis of said frame and parallel to the plane of the said string netting; said racket characterized in that the magnitude of Cp divided by the magnitude of the said length L , given by the formula Cp /L is greater than 0.71.

Claim 78. A tennis racket as in claim 24;
and said racket having a weight and stiffness distribution providing for the nodal pivot closest to the grip portion end being located at a distance N from the said end of the grip portion when tested in accordance with test 15 of Fig. 40 herein before defined, said racket characterized in that the magnitude of the said distance N divided by the said length L given by the formula N/L is greater than 0.28.

Claim 79. A tennis racket as in claim 23; and said racket having a center of percussion located at a distance Cp in centimeters from the end of the grip
portion when tested in accordance with test 4 of Fig. 40 herein before defined, said center of percussion taken about a pivot located at the end of the grip portion, said pivot having an axis perpendicular to the longitudinal axis of said frame and parallel to the plane of said string netting; said racket characterized in that the magnitude of Cp divided by the magnitude of the said distance L , given by the formula Cp/L is greater than 0.71.

Claim 80. A tennis racket as in claim 24, and said racket having a frame member formed of a resin reinforced fiber material; and said racket having a center of percussion located at a distance Cp in centimeters from the end of the grip portion, when tested in accordance with test 4 of Fig. 40. herein before defined, said center of percussion taken about a pivot located at the end of the grip portion, said pivot having an axis perpendicular to the longitudinal axis of said frame and parallel to the plane of said string netting; said racket characterized in that the magnitude of Cp divided by the said length L , given by the formula Cp /L is greater than 0.71.

Claim 81. A tennis racket as in claim 23;
and said racket having a frame member formed of a resin reinforced fiber material; and said racket having a center of percussion located at a distance Cp in centimeters from the end of the grip portion, when tested in accordance with test 4 of Fig. 40 herein before defined, said center of percussion taken about a pivot located at the end of the grip portion, said pivot having an axis perpendicular to the longitudinal axis of said frame and parallel to the plane of said string netting; said racket characterized in that the magnitude of Cp divided by the magnitude of the said distance L given by the formula Cp/L is greater than 0.71.

Claim 82. A tennis racket as in claim 63; and said racket having a frame member formed of a resin reinforced fiber material.

Claim 83. A racket comprising a frame having at least a head portion, a handle portion and a grip portion; said frame being an elongated strip of material having a crossection providing tubular edge portions joined by a central web portion; material located within said tubular edge portions, said material suitable for moving freely within said tubular edge portions by the force of gravity and by the centrifugual force generated by the swing of said racket, the swing weight of said frame being changed by the movement of said material.

Claim 84. A racket as in claim 83; and means for entrapping at will said material in selected sections of the tubular edge portions of said strip, and means for releasing at will said entrapped material, thereby changing the swing weight of said frame member.

Claim 85. A racket as in claim 83, wherein the said material within the tubular edge portions is pellets.

Claim 86. A racket as in claim 83, wherein the said material within the tubular edge portions is a liquid.

Claim 87. A racket comprising at least a tubular frame having a head portion supporting a string netting in a plane, and a grip portion, a first axis running from the center of the head portion end to the center of the grip portion end, and a second axis through the end of the grip portion being perpendicular to said first axis and parallel to a plane containing the surface of the head portion of said frame; material suitable for moving freely within the said tubular frame; means for entrapping said material in portions of the said tubular frame at selected locations; and means for releasing said entrapped material at will, thereby changing the swing weight of said racket at will.

Claim 88. A racket as in claim 87, wherein the said selected locations of said frame are first locations in the head portion and second locations are in the grip portion.

Claim 89. A racket as in claim 88, wherein the said selected locations in the head portion lie on a line through the center of said string netting, said line being parallel to the said second axis through the end of the grip portion.

Claim 90. A racket as in claim 88, wherein the said selected locations in the head portion lie on a line through the center of percussion of the racket, said center of percussion taken about said second axis through the grip portion end and said line being parallel to said second axis.

Claim 91. A method of rating a racket, said racket having at least a head portion and a grip portion; said method comprising the steps of measuring the numerical value of the weight; measuring the numerical value of the distance from a pivot located near the end of the said grip portion to the center of gravity of the said racket; measuring the numerical value of the distance from said pivot to the center of percussion of said racket about said pivot, the axis of said pivot being perpendicular to the longitudinal axis of the racket; obtaining a
numerical product by multiplying the said numerical value of the weight, the said numerical value of the distance of the center of gravity from said pivot, and the said numerical value of the distance of the center of percussion of the said racket from said pivot, said product having a numerical value Is being related to the swing weight of said racket about said pivot; and rating the racket by said numerical value Is .

Claim 92. A method of rating a racket as in claim 91, wherein the said numerical value of the distance from the said pivot to the center of percussion is measured by the step of measuring the time period for one complete oscillation, when the racket is supported as a pendulum at the said pivot; and obtaining the said distance by the formula
where T is the said time period, g is the gravitational constant, and Cp is the said distance from the said pivot to the center of percussion.

Claim 93. A method of rating a racket as in claim 91; and labeling the racket frame with said numerical value Is .

Claim 94. A method of rating a racket as in claim 91; and labeling the racket frame with symbols related to said numerical value Is.

Claim 95. A method of rating a racket as in claim 91; and labeling the racket frame with a first numerical value of the weight, with a second numerical value of the distance of the center of gravity from said pivot, with a third numerical value of the distance
from the said pivot to the center of percussion, and with a fourth numerical value of the product obtained by
multiplying the said first, second, and third numerical values.

Claim 96. A method of obtaining a desired change in the swing weight of a racket, said racket
having at least a head portion and a grip portion, said change having a numerical value Δ Is ; said method comprising the step of changing the weight of the racket an amount having a numerical value Δ W at a portion of the racket located at a distance having a numerical' value ℓ from a pivot axis located in the grip portion, said change Δ Is and said distance ℓ being selected to obtain the desired change in the swing weight ΔIs said numerical value Δ I s being related to said numerical value Δ W and said numerical value ℓ by the formula ΔIs= ΔW ℓ2.

Claim 97. A method for rating the width of the sweet spot of a racket, said racket having at least a head portion and a grip portion; said method comprising measuring a first numerical value of the moment of inertia about a first axis running along the longitudinal axis of said racket; measuring a second moment of inertia about a second axis transverse to said first axis, said second axis being located in the said grip portion;
obtaining a third numerical value of the ratio of the second numerical value to the first numerical value, said third numerical value being related to the said width of the sweet spot; and labeling the racket with symbols related to said third numerical value.

Claim 98. A method for rating a racket, said racket having at least a head portion- and a grip portion; said method comprising measuring the numerical value of the frequency of vibration, said vibration occurring when the racket is given a blow, and the racket is
supported at a nodal pivot, thereby allowing the racket to vibrate substantially freely, said numerical value being related to the vibratory characteristics of the racket when impacted by a blow.

Claim 99. A method for rating a racket as in claim 98, wherein the blow is applied at the head portion, and the nodal pivot is located near the said grip portion.

Claim 100. A method for rating a racket as in claim 98; and labeling the racket with symbols related to the said numerical value of the frequency of vibration.

Claim 101. A method for rating a racket; said racket having at least a head portion and a grip portion; said method comprising measuring the numerical value of the distance from the end of the racket adjacent to the grip portion, to the location of a nodal pivot near the said end of the racket, said numerical value being related to the weight and stiffness distribution of the racket and the vibratory characteristics of the racket when impacted by a blow.

Claim 102. A method of rating a racket as in claim 101; and labeling the racket with symbols related to the said numerical value of the said distance of the nodal pivot from the end of the racket adjacent to the grip portion.