Golf club head having trip step feature

Abstract

An aerodynamic golf club head incorporating a trip step feature located on the crown section. The benefits associated with the reduction in aerodynamic drag force associated with the trip step may be applied to drivers, fairway woods, and hybrid type golf club heads. The trip step is located between a crown apex and the back of the club head and may be continuous or discontinuous. The trip step enables a significant reduction in the aerodynamic drag force exerted on the golf club head by forcing the air passing over the club head from laminar flow to turbulent flow just before the natural separation point of the airstream from the crown. This selectively engineered transition from laminar to turbulent flow over the crown section slightly increases the skin friction but results in less aerodynamic drag than if the air were to detach from the crown section at the natural separation point.

1 . An aerodynamic golf club head ( 100 ) comprising:
 A) a hollow body ( 110 ) having a face ( 200 ), a sole section ( 300 ), a crown section ( 400 ), a front ( 112 ), a back ( 114 ), a heel ( 116 ), and a toe ( 118 );   B) the face ( 200 ) having a top edge ( 210 ) and a lower edge ( 220 ), wherein a top edge height (TEH) is the elevation of the top edge ( 210 ) above a ground plane (GP), and a lower edge height (LEH) is the elevation of the lower edge ( 220 ) above the ground plane (GP);   C) the crown section ( 400 ) having a crown apex ( 410 ) located an apex height (AH) above the ground plane (GP), wherein the crown section ( 400 ) has a trip step ( 500 ) located between the crown apex ( 410 ) and the back ( 114 ), and the trip step ( 500 ) has;
 i) a trip step heel end ( 550 ), a trip step toe end ( 560 ), and a trip step thickness ( 540 ); 
 ii) a trip step leading edge ( 510 ) having a leading edge profile ( 512 ), and wherein:
 a) the trip step leading edge ( 510 ) is located a trip step offset ( 514 ) behind the face top edge ( 210 ); 
 b) the trip step leading edge ( 510 ) is located behind the crown apex ( 410 ) an apex-to-leading edge offset ( 516 ); 
 c) the trip step leading edge ( 510 ) at the trip step heel end ( 550 ) is located behind the crown apex ( 410 ) an apex-to-heel LE offset ( 517 ); and 
 d) the trip step leading edge ( 510 ) at the trip step toe end ( 560 ) is located behind the crown apex ( 410 ) an apex-to-toe LE offset ( 518 ). 
 
   
   
   
       2 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein the aerodynamic golf club head ( 100 ) has a face-on normalized aerodynamic drag force of less than 1.0 lbf when exposed to a 90 mph wind parallel to the ground plane (GP) when the aerodynamic golf club head ( 100 ) is positioned in a design orientation and the wind is oriented at the front ( 112 ) of the aerodynamic golf club head ( 100 ). 
   
   
       3 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein the club head ( 100 ) has a crown toe projection distance ( 420 ) measured in a direction parallel to a shaft axis (SA) in a plane parallel to the ground plane (GP) from a center of the face ( 200 ) to the most distant toe portion ( 118 ) of the club head ( 100 ), and the trip step ( 500 ) extends across at least fifty percent of the crown toe projection distance ( 420 ). 
   
   
       4 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein the trip step ( 500 ) includes at least one curve and has a trip step radius of curvature (Rts), a portion of the crown section ( 400 ) between the crown apex ( 410 ) and the face ( 200 ) has an apex-to-front radius of curvature (Ra-f), and the trip step radius of curvature (Rts) is less than twice the apex-to-front radius of curvature (Ra-f). 
   
   
       5 . The aerodynamic golf club head ( 100 ) of  claim 4 , wherein the trip step radius of curvature (Rts) is at least fifty percent of the apex-to-front radius of curvature (Ra-f), and no greater than one hundred and fifty percent of the apex-to-front radius of curvature (Ra-f). 
   
   
       6 . The aerodynamic golf club head ( 100 ) of  claim 4 , wherein the trip step ( 500 ) has at least a toe radius of curvature (Rtst) and a heel radius of curvature (Rtsh), and the heel radius of curvature (Rtsh) is greater than the toe radius of curvature (Rtst). 
   
   
       7 . The aerodynamic golf club head ( 100 ) of  claim 6 , wherein the heel radius of curvature (Rtsh) is at least ten percent greater than the toe radius of curvature (Rtst). 
   
   
       8 . The aerodynamic golf club head ( 100 ) of  claim 7 , wherein the heel radius of curvature (Rtsh) is at least twenty-five percent greater than the toe radius of curvature (Rtst). 
   
   
       9 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein the apex-to-leading edge offset ( 516 ) is less than fifty percent of the crown apex setback dimension ( 412 ). 
   
   
       10 . The aerodynamic golf club head ( 100 ) of  claim 9 , wherein the apex-to-leading edge offset ( 516 ) is at least ten percent of the crown apex setback dimension ( 412 ). 
   
   
       11 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein the lineal length of the trip step ( 500 ) is greater than seventy-five percent of the heel-to-toe dimension (HT). 
   
   
       12 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein the lineal length of the trip step ( 500 ) is greater than the heel-to-toe dimension (HT). 
   
   
       13 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein the apex-to-toe LE offset ( 518 ) is greater than the apex-to-leading edge offset ( 516 ). 
   
   
       14 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein trip step leading edge ( 510 ) is separated from a trip step trailing edge ( 520 ) by a trip step width ( 530 ), wherein the trip step width ( 530 ) is less than the apex-to-leading edge offset ( 516 ). 
   
   
       15 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein the hollow body ( 110 ) has a front-to-back dimension (FB) of at least 4.4 inches, a club head volume of at least 400 cc, a maximum top edge height (TEH) of at least 2 inches, an apex ratio of the apex height (AH) to the maximum top edge height (TEH) of at least 1.13, and a frontal cross sectional area of less than 11 square inches. 
   
   
       16 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein at least a portion of the trip step ( 500 ) projects outward from the club head ( 100 ) and a point of maximum projection has a trip step thickness ( 540 ), wherein the point of maximum projection does not extend above the crown apex ( 410 ). 
   
   
       17 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein at least a portion of the trip step ( 500 ) projects inward toward an interior of the club head ( 100 ) and a point of maximum projection has a trip step depth ( 545 ), wherein the trip step depth ( 545 ) is at least five percent of the difference between the apex height (AH) and the top edge height (TEH). 
   
   
       18 . The aerodynamic golf club head ( 100 ) of  claim 17 , wherein the trip step leading edge ( 510 ) is separated from a trip step trailing edge ( 520 ) by a trip step width ( 530 ), and the trip step width ( 530 ) is at least equal to the trip step depth ( 545 ). 
   
   
       19 . The aerodynamic golf club head ( 100 ) of  claim 1 , wherein
 i) a portion of the crown section ( 400 ) between the crown apex ( 410 ) and the face ( 200 ) has an apex-to-front radius of curvature (Ra-f) that is less than 3 inches; and   ii) a portion of the crown section ( 400 ) has a heel-to-toe radius of curvature (Rh-t) at the crown apex ( 410 ) that is less than 4 inches;   iii) wherein the aerodynamic golf club head ( 100 ) has;
 a) a first moment of inertia (MOIy) about a vertical axis through a center of gravity (CG) of the aerodynamic golf club head ( 100 ) that is at least 4000 g*cm 2 ; and 
 b) a second moment of inertia (MOIx) about a horizontal axis through the center of gravity (CG) that is at least 2000 g*cm 2 . 
   
   
   
       20 . The aerodynamic golf club head ( 100 ) of  claim 19 , wherein a club head volume is at least 440 cc. 
   
   
       21 . The aerodynamic golf club head ( 100 ) of  claim 19 , wherein an apex ratio of the apex height (AH) to the maximum top edge height (TEH) is at least 1.2. 
   
   
       22 . The aerodynamic golf club head ( 100 ) of  claim 19 , wherein the apex-to-front radius of curvature (Ra-f) is less than an apex-to-rear radius of curvature (Ra-r), and the apex-to-rear radius of curvature (Ra-r) is less than the heel-to-toe radius of curvature (Rh-t). 
   
   
       23 . The aerodynamic golf club head ( 100 ) of  claim 15 , wherein 5% to 10% of the club head volume is above the elevation of the maximum top edge height (TEH). 
   
   
       24 . The aerodynamic golf club head ( 100 ) of  claim 19 , wherein the crown apex ( 410 ) is behind the forward most point on the face ( 200 ) a distance that is a crown apex setback dimension ( 412 ), and the crown apex setback dimension ( 412 ) is less than 1.75 inches. 
   
   
       25 . The aerodynamic golf club head ( 100 ) of  claim 19 , wherein the crown apex setback dimension ( 412 ) is less than a distance between a vertical projection of the center of gravity (CG) on the ground plane (GP) and a second vertical projection of the forward most point on the face ( 200 ).