Tennis Rackets Readings: Ch 7, Websites: Welcome to RacquetTECH.com, http://www.racquetresearch.com Materials Wood -not used much anymore. Why? Metal - Aluminum is stiffer, more control, lighter . Steel - heavier, less control. Composite - combine fiberglass with aluminum, Graphite, Kevlar, ceramic. (I-Beam Construction - Fig 7.3) Construction Sizes - maximum size is 32 inches long, head 15.5X11.5 in (178 sq in) (Fig 7.4) Traditional - up to 80 sq in Midsize - 81-90 sq in Super midsize - 91-100 sq in Oversize - 101-110 sq in Super oversize - 111 sq in and above Wide-Body rackets and shapes Frame has aerodynamic design (Fig 7.5) Head frame is wider when viewed from the side Increased stiffness Vibration-free innovations

I-beam construction: Sizes:

Throat Shapes

Frame Designs

Playing and String Characteristics Playing characteristics Stiffness and flexibility (ground strokers want flexibility) Weight and balance - handle-loaded for lower MOI about the hands and greater MOI about the COM (less impact recoil effect) New trends and gimmicks Curved handle – did not catch on String dampeners Mass on frame edges “Shock absorbing” handles String characteristics (Fig 7.9, 7.10) Gut vs synthetic Gut is expensive and is not durable Elasticity of synthetics degrades at high tensions Thickness - thicker strings increase control Tension - higher tension for more control, lower for more power Suggested appropriate tensions on next slide

Strings: Types, Shapes, Tension

Swing Weights (From Racquet Tech Sept, 1999)

Summary of “The modern tennis racquet” by Howard Brody (1996) Introduction Wood no longer used because of limited strength/wt ratio Modern racquets are lighter, stiffer, longer, thicker, wider, and have a bigger head Rules limit length of racket and size of head New rules are made when some innovations come along Strings String deformation is more relevant than string tension For a given racquet, strings are more efficient in returning energy than the ball, so looser strings give more post-impact ball velocity Most players now use synthetic strings Website for racquet stringers: Welcome to RacquetTECH.com

Brody article, cont’d Sweet spots of the racket – place where impact feels good Center of percussion – no reaction force at hand Reaction force of a non-central hit can be minized by increasing MOI about COP Node of fundamental mode of vibration (125-200 Hz) Vibration dampening helps minimize vibrations when impact is not on the node Node and COP are usually close together Power spot – point of maximum COR Location depends on both swing mechanics and racquet design Design objective is to make power spot coincide with COP, & node – at the racquet face center.

Brody article, cont’d Racket width and stability Impacts off the longitudinal axis of racquet produce twist Twist effect can be minimized by maximizing MOI about longitudinal axis Make racquet face larger, or load around perimeter of racquet Why does using a larger grip size help with twist effect? Racket length Traditional standard length is 27 inches Maximum is 32 inches, but ATP uses 29 in max Which length is best? Conclusion – modern racquet is better due to More power, less effort, more forgiving, more durable

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