Kinetic Racquet Tests

Kinetic Racquet Tests By Rudratpatna V. Ramnath, Ph.D. Professor of Aeronautics and Astronautics, M.I.T. Kinetic Racquet Tests By Rudrapatna V. Ramnath, PhD Professor of Aeronautics and Astronautics Massachusetts Institute of Technology SYNOPSIS The Kinetic racquet developed by ProKennex was put through a series of rigorous and exhaustive 1. Tests in the Sports Dynamics and Technology tests in the laboratory and through play-tests. These Laboratory at M.I.T. tests were conducted in the Sports Dynamics and 2. Play Tests Technology Laboratory at the Massachusetts Institute of 3. Tests with a Robot Arm Technology under the direction of Dr. Rudrapatna V. Ramnath, Professor of Aeronautics and Astronautics. The racquets used for this test consisted of the Dr. Ramnath was Technical Advisor to the ATP Tour following: and formerly Technical Editor of World Tennis and Tennis magazines. The complement of tests followed Two sets of identical weight and designs, except the guidelines and procedures developed and set up at that one set with the Kinetic system, and the the Sports Dynamics and Technology Laboratory at other set was conventional (i.e. without the M.I.T. These have been carried out for the annual Kinetic System), were tested. Each set was made racquet reviews of World Tennis and Tennis magazines up of two copies. The racquets were strung with and also for the ATP Tour. Based on these, a data base Tecnifibre strings, one at 52 lbs. and the other at of over a thousand racquets has been maintained over 57 (and 60) lbs. tension. Thus, identical the years comprising many designs, different shapes, racquets, with and without the Kinetic System, at sizes and materials. the same string tensions were available for testing. The tests consist of static and dynamic tests to measure the various parameters for the racquet affecting Apart from the single tests for length, weight, its performance during play. Appropriate head area, etc., the tests included important parameters instrumentation and procedures have been developed such as stiffness, shock and vibration dampening and and refined over the years in order to achieve high frequency, and most importantly, the power zone. measurement accuracy and to track subtle effects. The Consistent with established procedures, all these Kinetic racquet was tested with the standard tests parameters were measured with the racquet held developed at M.I.T, and on the tennis court. However, stationary and also with the racquet in motion. The in this particular case, a three-pronged test was initiated power zone was mapped on the racquet head and its for the Kinetic racquet and consisted of the following: centroid was calculated. This procedure was repeated for the Coefficient of CONCLUSIONS Restitution and the Center of Percussion. The rigorous and exhaustive tests on the Kinetic Both the Kinetic and non-Kinetic racquets at racquet (a) in the laboratory at M.I.T., (b) using the robot different string tensions were play-tested on the court. arm test set up in Taiwan and (c) by play-test indicate The test format consisted of a minimum of two hours that the results corroborate each other. The following play with a prescribed set of drills involving different conclusions can be drawn on the appropriate processing strokes followed by actual competitive play. and interpretation of the data: ¾ The Kinetic system provides a new design degree RESULTS of freedom for performance improvement not found in the conventional design approaches. The data obtained from the test conducted in Usually any improvement in one performance the Sports Dynamics and Technology Laboratory at measure can only be achieved at the expense of Massachusetts Institute of Technology and in Taiwan another. For example, attempts to enhance (using both stationary and moving racquets), was stability typically result in a degradation of verified and processed in accordance with the maneuverability. Therefore, stability and established practice and procedures. The test results maneuverability requirements force a showed a number of advantages of the Kinetic system. compromise in design. However, the Comparing similar Kinetic and non-Kinetic racquets, independent design degree of freedom inherent performance improvement due to the Kinetic system in the Kinetic system enables the designer to can be summarized as follows: improve one performance parameter without detriment to the other desirable properties. For ¾ Shock reduction is better than 20% example, the Kinetic masses raise the power ¾ Vibration Dampening Ratio(s) Enhancement is zone without permanently increasing the 43% moment of inertia. This feature is beneficial to a ¾ Power Zone Enlargement is about 12-15% player of high skill who can generate great ¾ Power Zone is raised by about 0.75 power through higher swing velocities and the ¾ Center of Percussion is raised by about 0.9 raised power zone. inches ¾ The Differential Dynamic Compensation exists ¾ Shock reduction and vibration dampening effects and is demonstrable as evidenced by are significant. The Kinetic system results in accelerometer readings on the head periphery impressive improvement in shock reduction and due to hit points at mirror image locations dampening characteristics. about the racquet longitudinal axis. ¾ Further, the area of the power zone is enlarged reducing angular effort on off-center hits. A true by the Kinetic system, showing a larger area of ball trajectory is the result. minimum acceptable power, making the ¾ Measurements of Center of Percussion (CP) and racquet more forgiving. This is very useful to the maximum Coefficient of Restitution (COR) the average recreation player. locations all indicate the benefits of raised power and comfort zones. ¾ The Differential Dynamic Compensation adds greater stability and control to the racquet by // end .

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