US 1539019 A
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May 26, 1925. 1,539,019
J. P. NIKONOW TENNIS RACKET Filed Feb. '7, 1924 2 9 E2, 3 F123? Eg 5 Patented May 2 6, 1925.
um'rao STATYE'S PATENT omen.
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Application filed February 7, 1984. SerialNo. 691,174.
To all whom it may concern.
Be it known that I, JoHN P. Nmonow, citizen of the United States, and resident of New York, in the county of New York i and State of New York, have invented certain new and useful Improvements in Tennis Rackets, of which the following is a speci fication.
My invention relates to tennis rackets and has for its object to provide a racket with greater efficiency for striking the ball.
In ordinary tennis rackets the weights are so distributed that the center of gravity is located approximately in the mi dle of the racket length, consequently its center of percussion, or center of application of the force of the blow for a circular swing around its handle, is located near the racket end of the gut, and not in its center. But since in most cases the ball is struck with the center of the'racket face (or gut), it follows, that with ordinary rackets a more or less large part of the force of the blow is wasted in reaction'on the players hand. In my racket I provide a construction in which the weights are so distributed that the center of percussion for a wrist swing, or a swing around the handle, is' located at the center of the racket face.
My invention is more fully described in the accompanying specification and drawing in which- Fig. 1 is a plan view of my racket, Fig. 2 is a side view, Fig. 3 is a section of the handle on a line A-A, Fig. 4 is a section B-B, and Fig. 5 is a section C-C.
My racket is provided with a handle 1 of a standard size of a sufiicient length only for a hand grip, made of some light material, such as a light sort of wood. The intermediate portion 2 of the racket is made of a light section reinforced only in a transverse direction (section AA) to render this racket sufliciently stiff and, at the same time, to reduce the air resistance to the rapid movement of the racket. The racket oval 3 is also made light and of a streamline sec tion (B-B) to reduce the air resistance. The end of the racket oval is made substan- 0 tially heavier by increasing its width (section C-C), this increased width also help ing to reduce the air resistance by improving its streamline effect. An additional weight 4 may be also added in the form of a metal strip, or of some other heavy material. An ordmary racket gut 5 is strung in the oval 3.
It should be noted that the oval 3 may be of any ordinary shape, even approaching an octagonal, s uare or round shapes and will be called an oval in this general meaning.
The ob ect of such weight distribution is to dlsplace the center of gravity G towards the oval end of the-racket to. such distance X from the handle end, that the center of percusslon P for an axis passing through its handle end (axis 2z Fig. 1) becomes located in the middle of the oval, or at its geometrical center.
We have a formula for determining this distance Y from the center of percusslon to the handle end:
Y I/wX Where I is a moment of inertia of racket in relation to the axis 2z, w-weight of the racket, and X--distanc-e ofits center of gravity. Expressing'in terms of a moment of inertia in relation to the center of gravity (which we denote I0), we have:
I Io X 'w From this equation we can determine the distance X for a given distance Y, as the weight of the racket w and the moment of inertia Io are known.
It can be seen from this equation that in order to move the center of gravity inside of the oval it is necessary to increase or Io.
The distance X can be lengthened by reducing the weight of the handle and increasing the weight of the oval. The moment of inertia forthe same weight can be increased by concentrating a large part of this weight near the racket end.
This may be accomplished best by increasing the racket section C-O near its end and by adding an extra heavy metal strip 4. The section should be increased in a streamline fashion in a direction perpendicular to the face of the oval so as to reduce the air resistance.
An ordinary racket is about 26 inches long with center of gravity at about 13 in. from the end, and wlth the center of the oval at about 19 inches from the handle end, the center of percussion being at about 16 in. from the handle end.
In order to have the center of percussion the middle of the oval, the'distance X should be made about 16 inches, or from 15 to 17, depending on the distribution of the weights it will 'be shorter for greater additional weight 4.
With he center of percussion at the middle of the oval it is possible to use lighter racket for the same effect in strikin the ball, for instance, a 12 oz. racket may eve op just as much power in driving the ball at the same. spee as a 14% oz. ordinary racket. The muscular effort will be reduced by having a lighter racket to swing, and the accuracy of driving may be improved on account of more uniform force of striking the ball, as in my racket the force is about the same on both sides of the center of the oval, while in an ordinary racket the force is much lower at one end of the oval, and greater nearer the handle.
Im ortant advantages of my racket are that it can be made lighter for the same striking force, or may give greater force for the same weight, also that it relieves the layers hand from the reaction when the Ball is struck too far from the center of percussion. Consequently the racket may beheld loosely relieving the hand muscles, and the driving may be more accurate on account of more uniform striking force.
I claim as my invention:
1. In a tennis racket, the combination with an oval, a gut strung in said oval, a handle an intermediate member connecting said oval with said handle, said intermediate member and said oval being shaped in a streamline him in a direction perpendicular to the face of said racket.
2. In a tennis racket, the combination with an oval, a gut strung in said oval, a handle, an intermediate member connecting said handle with said oval, said intermediate member and said oval being flattened and sharpened in a direction perpendicular to the face of saidracket. '3. In a tennis racket, the combination with an oval, a gut strung in said oval, a handle, an intermediate member connecting said handle with said oval, said oval with said intermediate member being of a flattened section with sharp edges extending in a direction perpendicular to the face of said racket, the cross-sectional area of said oval being greater at the end opposite to said handle.
4. In a tennis racket, the combination with an oval, a gut strung in said oval, a handle, an intermediate member connecting said oval with said handle, the weight of said oval being greater than the weight of said handle with said intermediate member, said oval being of a heavier section at the end opposite to said handle.
5. In a tennis racket, the combination with an oval frame, a gut strung in said frame, and a handle extending from said frame, the cross-sectional area of said frame being greater at the end opposite to said handle.
Signed at New York in the county of New York and State of New York this 5th day of February A. D. 1924.
JOHN P. NIKONOW.