Diameter profiled golf club shaft to reduce drag

Abstract

A golf club includes a golf club head, a shaft adapter secured within a hosel of the golf club head, and a shaft secured within the shaft adapter. The golf club shaft is formed from a fiber reinforced polymer and extends along a longitudinal axis between a tip end and a grip end. The golf club shaft includes a tip end section, a grip end section, and a tapered section between the tip end section and the grip end section. The tapered section of the shaft includes a reference portion within the upper half that has a frustoconical shape with a near-constant taper rate, and a narrowed portion within the lower half. The narrowed portion is recessed relative to a reference surface extrapolated from the frustoconical shape.

1 . A golf club comprising:
 a golf club head comprising a strike face and a hosel defining a hosel internal bore;   a shaft adapter secured within the hosel internal bore;   a shaft formed from a fiber reinforced polymer and extending along a longitudinal axis between a tip end and a grip end, the shaft including:
 a tip end section abutting the tip end, wherein the tip end section is at least partially secured within the shaft adapter; 
 a grip end section abutting the grip end; and 
 a tapered section interconnecting the tip end section and the grip end section, wherein the tapered section includes an upper portion comprising an upper 60% of the tapered section and a lower portion comprising a lower 60% of the tapered section as measured along the longitudinal axis, the upper portion abutting the grip end section, and the lower portion abutting the tip end section, the tapered section further including:
 a reference portion at least partially located within the upper portion, wherein the outer surface of the reference portion has a frustoconical shape with a near-constant taper rate; 
 a narrowed portion at least partially located within the lower portion and between the tip end and the reference portion, wherein an outer surface of the narrowed portion is recessed relative to a reference surface extrapolated from the frustoconical shape toward the tip end; 
 a first region with a first taper rate (R1); 
 a second region with a second taper rate (R2); 
 a third region with a third taper rate (R3);
 wherein the first region is closest to the tip end, the third region is located closest to the grip end, and the second region is positioned between the first region and the third region. 
 
 
   
     
     
         2 . The golf club of  claim 1 , wherein the shaft adapter further comprises a generally tubular body having a shaft adapter inner bore adapted to receive the tip end of the shaft, and an outer surface adapted to be secured within the hosel internal bore. 
     
     
         3 . The golf club of  claim 2 , wherein the shaft adapter further comprises a strain relief portion that extends beyond a terminal end of the hosel. 
     
     
         4 . The golf club of  claim 3 , wherein the strain relief portion is a separate component that nests within a portion of the tubular body while also extending beyond a terminal edge of the tubular body. 
     
     
         5 . The golf club of  claim 4 , wherein the strain relief portion comprises a softer or more elastic material than a material forming the shaft adapter body. 
     
     
         6 . The golf club of  claim 1 , wherein the fiber reinforced polymer in the narrowed portion comprises a plurality of fibers oriented parallel to the longitudinal axis (0-degree fibers). 
     
     
         7 . The golf club of  claim 1 , wherein R1 in less than R3. 
     
     
         8 . The golf club of  claim 1 , wherein R2 is greater than each of R1 and R3. 
     
     
         9 . The golf club of  claim 1 , wherein R2 is greater than R3, R3 is greater than R1, and R1 is greater than 0. 
     
     
         10 . The club of  claim 1 , wherein R3 I less than each of R1 and R2. 
     
     
         11 . The club of  claim 10 , wherein R1 is equal to R2. 
     
     
         12 . The club of  claim 1 , wherein the first region and the second region are located entirely within the lower portion of the tapered region. 
     
     
         13 . The golf club of  claim 1 , wherein the tapered section has a length of greater than about 30 inches, and wherein the first region is located entirely within about the first 15 inches of the tapered section closest to the tip end section. 
     
     
         14 . The golf club of  claim 1 , wherein the first region and second region are located entirely within about 20 inches of the tapered section located closest to the tip end section. 
     
     
         15 . The golf club of  claim 1 , wherein the tip end section is cylindrical and has an outer diameter of from about 0.300 in. to about and 0.315 in. 
     
     
         16 . The golf club of  claim 1 , wherein the grip end section has an outer diameter of from about 0.550″ to 0.650″; and
 wherein the outer diameter of the tapered section transitions from the outer diameter of the tip end section to the outer diameter of the grip end section. 
 
     
     
         17 . The golf club of  claim 1 , wherein at least 40% of the narrowed portion, by length along the longitudinal axis, has an outer diameter that is more than about 6% smaller than the reference surface. 
     
     
         18 . The golf club of  claim 1 , wherein at least 50% of the narrowed portion, by length along the longitudinal axis, has an outer diameter that is more than about 7% smaller than the reference surface. 
     
     
         19 . The golf club of  claim 1 , wherein approximately 14 inches of the tapered section located closest to the tip end is narrowed relative to the reference surface; and wherein 11 inches of the tapered section located closest to the tip end is narrowed by greater than about 7% relative to the reference surface. 
     
     
         20 . The golf club of  claim 19 , wherein 9 inches of the tapered section located closest to the tip end is narrowed by greater than 9% relative to the reference surface.