Patent Publication Number: US-8986131-B2

Title: Golf club head and golf club with aerodynamic features

Description:
FIELD 
     Aspects of this invention relate generally to golf clubs and golf club heads, and, in particular, to a golf club and golf club head with aerodynamic features. 
     BACKGROUND 
     The distance a golf ball travels when struck by a golf club is determined in large part by club head speed at the point of impact with the golf ball. Club head speed in turn can be affected by the wind resistance or drag associated with the club head, especially given the large club head sizes of typical modern drivers. The club head of a driver, fairway wood, or metal wood in particular experiences significant aerodynamic drag during its swing path. The drag experienced by the club head leads to reduced club head speed and, therefore, reduced distance of travel of the golf ball after it has been struck. 
     Air flows in a direction opposite to the golf club head&#39;s trajectory over those surfaces of the golf club head that are roughly parallel to the direction of airflow. An important factor affecting drag is the behavior of the air flow&#39;s boundary layer. The “boundary layer” is a thin layer of air that lies very close to the surface of the club head during its motion. As the airflow moves over the surfaces, it encounters an increasing pressure. This increase in pressure is called an “adverse pressure gradient” because it causes the airflow to slow down and lose momentum. As the pressure continues to increase, the airflow continues to slow down until it reaches a speed of zero, at which point it separates from the surface. The air stream will hug the club head&#39;s surfaces until the loss of momentum in the airflow&#39;s boundary layer causes it to separate from the surface. The separation of the air streams from the surfaces results in a low pressure separation region behind the club head (i.e., at the trailing edge as defined relative to the direction of air flowing over the club head). This low pressure separation region creates pressure drag. The larger the separation region, the greater the pressure drag. 
     One way to reduce or minimize the size of the low pressure separation region is by providing a streamlined form that allows laminar flow to be maintained for as long as possible, thereby delaying or eliminating the separation of the laminar air stream from the club surface. 
     Reducing the drag of the club head not only at the point of impact, but also during the course of the entire downswing prior to the point of impact, would result in improved club head speed and increased distance of travel of the golf ball. When analyzing the swing of golfers, it has been noted that the heel/hosel region of the club head leads the swing during a significant portion of the downswing and that the ball striking face only leads the swing at (or immediately before) the point of impact with the golf ball. The phrase “leading the swing” is meant to describe that portion of the club head that faces the direction of swing trajectory. For purposes of discussion, the golf club and golf club head are considered to be at 0° orientation when the ball striking face is leading the swing, i.e. at the point of impact. It has been noted that during a downswing, the golf club may be rotated by about 90° or more around the longitudinal axis of its shaft during the 90° of downswing prior to the point of impact with the golf ball. 
     During this final 90° portion of the downswing, the club head may be accelerated to approximately 65 miles per hour (mph) to over 100 mph, and in the case of some professional golfers, to as high as 140 mph. Further, as the speed of the club head increases, typically so does the drag acting on the club head. Thus, during this final 90° portion of the downswing, as the club head travels at speeds upwards of 100 mph, the drag force acting on the club head could significantly retard any further acceleration of the club head. 
     Club heads that have been designed to reduce the drag of the head at the point of impact, or from the point of view of the club face leading the swing, may not function well to reduce the drag during other phases of the swing cycle, such as when the heel region of the club head is leading the downswing. 
     It would be desirable to provide a golf club head that reduces or overcomes some or all of the difficulties inherent in prior known devices. Particular advantages will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of certain embodiments. 
     SUMMARY 
     The principles of the invention may be used to provide a golf club head with improved aerodynamic performance. In accordance with certain aspects, a golf club head includes one or more drag reducing structures on the body member. The drag-reduction structures are expected to reduce drag for the body member during a golf swing from an end of a backswing through a downswing. 
     In accordance with certain aspects, a golf club includes a shaft and a club head secured to a distal end of the shaft. The club head includes a body member having a ball striking face, a heel, a toe, a rear and a crown. The crown includes a forward crown region, a rearward crown region, and a crown transition region. The forward crown region may extend rearwardly from the ball striking face. The rearward crown region may extend forwardly from the rear. The rearward crown region has a smaller height dimension than the forward crown region. The crown transition region may extend generally in a heel-to-toe direction between the forward crown region and the rearward crown region. 
     According to some aspects, the forward crown region may be substantially horizontally-oriented. The rearward crown region may also be substantially horizontally-oriented. The crown transition region may be substantially vertically-oriented crown. 
     According to other aspects, the slope of the crown transition region may decrease monotonically as the crown transition region extends from the heel toward the toe. 
     In accordance with other aspects, the crown transition region may lie at an angle that ranges from approximately 5 degrees to 40 degrees from a front plane of the club head. 
     The rearward crown region may have a substantially planar surface or a substantially convexly-curved surface, as viewed from a side perpendicular to a centerline of the club head. Further, the rearward crown region may have a substantially planar surface or a substantially convexly-curved surface, as viewed from the back of the club head along the centerline. Optionally, a majority of the surface of the rearward crown region may be either a substantially planar surface or a substantially convexly-curved surface. 
     The forward crown region may extend rearwardly from the ball striking face to a forward crown transition feature. The forward crown transition feature may be formed by the intersection of the forward crown region and the crown transition region. Further, the forward crown transition feature may be defined as having a tangent, drawn in a vertical plane that is parallel to the centerline of the club head when the club head is in the 60 degree lie angle position, at 45 degrees to the horizontal. A tangent to the forward crown transition region measured at a centerline of the club head may range from approximately 0 degrees to approximately 25 degrees from a front plane of the club head. 
     Similarly, the rearward crown region may extend forwardly from the rear to a rearward crown transition feature. The rearward crown transition feature may be formed by the intersection of the rearward crown region and the crown transition region. Further, the rearward crown transition feature may be defined as having a tangent, drawn in a vertical plane that is parallel to the centerline of the club head when the club head is in the 60 degree lie angle position, at 45 degrees to the horizontal. An angle of the rearward crown transition region measured at a centerline of the club head may range from approximately 10 degrees to approximately 35 degrees from a front plane of the club head. 
     Further, according to certain aspects, the height of the center of gravity of the club head may be less than or equal to 1.75 cm. The body member may have a volume of greater than equal to 420 cc. Alternatively, the body member may have a volume of greater than equal to 445 cc. The length and/or the breadth of the club head may be greater than 12.0 cm. 
     A channel may extend, at least partially, along and adjacent to the trailing edge of the aft body member. The channel, or portions thereof, may function as a Kammback structure over at least a portion of the downswing of the golf club. 
     In accordance with even further aspects, a club head includes a body member having a ball striking face, a heel, a toe, a rear and a sole. The sole includes a forward sole region, a rearward sole region, and a sole transition region. The forward sole region may extend rearwardly from the ball striking face. The rearward sole region may extend forwardly from the rear. The rearward sole region has a smaller height dimension than the forward sole region. The sole transition region may extend generally in a heel-to-toe direction between the forward sole region and the rearward sole region. 
     By providing a golf club head with one or more of the drag-reduction structures disclosed herein, it is expected that the total drag of the golf club head during a player&#39;s downswing can be reduced. This is highly advantageous since the reduced drag will lead to increased club head speed and, therefore, increased distance of travel of the golf ball after being struck by the club head. 
     These and additional features and advantages disclosed here will be further understood from the following detailed disclosure of certain embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top plan view of a golf club according to illustrative aspects. 
         FIG. 2  is a perspective view of the golf club of  FIG. 1 , showing a schematic expected airflow over and under the club head when the heel leads the swing. 
         FIG. 3  is schematic top plan view of a golf club according to certain aspects. 
         FIG. 4  is a schematic front view of the club head of  FIG. 3 , generally viewed from the toe side. 
         FIG. 5  is a schematic perspective view of the club head of  FIG. 3 , generally viewed from the top heel side. 
         FIG. 6  is a schematic perspective view of the club head of  FIG. 3 , generally viewed from the toe side. 
         FIG. 7  is a schematic rear elevation view of the club head of  FIG. 3 . 
         FIG. 8  is a schematic perspective view of the club head of  FIG. 3 , generally viewed from the heel side. 
         FIG. 9  is a schematic top view of a club head illustrating certain club head parameters in accordance with the disclosure. 
         FIGS. 10A and 10B  are a schematic top plan view and a schematic front elevation view, respectively, of the club head of  FIG. 9  illustrating certain club head parameters. 
         FIG. 11A  is a schematic of a surface profile taken along section XI-XI of the club head of  FIG. 9  illustrating certain club head parameters. Section XI-XI of  FIG. 9  is coincident with the centerline of the club head.  FIG. 11B  is a schematic of an enlarged portion of the surface profile of  FIG. 11A , particularly showing details of the crown transition region. 
         FIG. 12  is a schematic of a surface profile taken along section XII-XII of the club head of  FIG. 9  illustrating certain club head parameters. Section XII-XII is parallel to the front plane of the club head. 
         FIGS. 13A through 13E  are schematic top plan views of club heads according to other example aspects. 
         FIGS. 14A through 14D  are schematics of various surface profiles of the crown transition feature taken along the centerlines of club heads according to certain aspects. 
         FIG. 15  is a schematic perspective view of a club head, generally viewed from the top heel side, according to another aspect. 
         FIG. 16  is a schematic perspective view of a club head, generally viewed from the bottom heel side, according to even another aspect. 
         FIG. 17  is a schematic of an enlarged portion of a sole surface profile taken along a centerline of the embodiment of  FIG. 16 , particularly showing details of the sole transition region. 
     
    
    
     The figures referred to above are not drawn necessarily to scale, should be understood to provide a representation of particular embodiments of the invention, and are merely conceptual in nature and illustrative of the principles involved. Some features of the golf club head depicted in the drawings may have been enlarged or distorted relative to others to facilitate explanation and understanding. The same reference numbers are used in the drawings for similar or identical components and features shown in various alternative embodiments. Golf club heads as disclosed herein would have configurations and components determined, in part, by the intended application and environment in which they are used. 
     DETAILED DESCRIPTION 
     An illustrative embodiment of a golf club according to aspects of the invention is shown in  FIGS. 1 and 2 . As can generally be seen in  FIG. 1 , the top or crown of the club head may be provided with an elongated feature, generally extending from the heel toward the toe, which separates a front or forward crown region from a rear or rearward crown region. This elongated feature provides a transition region, wherein the height of the forward crown region is stepped down or transitioned to the height of the rearward crown region. By transitioning the height of the crown from the front or forward crown region to the rear or rearward crown region, it is expected that air flowing over and/or under the club head from the heel toward the toe (see  FIG. 2 ) will encounter less resistance. Thus, it is expected that the transition region will result in reduced drag over the course of the golfer&#39;s downswing, higher club head speed at the moment of impact with the golf ball, and increased travel distance of the golf ball. 
     An embodiment of a golf club head  14  is shown schematically in  FIGS. 3-8  in order to illustrate certain aspects of the invention. The golf club head  14  may be attached to a shaft  12  (see  FIG. 5 ), to form a golf club  10 . The golf club head  14  may be a driver, as shown. The shaft  12  of the golf club  10  may be made of various materials, such as steel, aluminum, titanium, graphite, or composite materials, as well as alloys and/or combinations thereof, including materials that are conventionally known and used in the art. Additionally, the shaft  12  may be attached to the club head  14  in any desired manner, including in conventional manners known and used in the art (e.g., via adhesives or cements at a hosel element, via fusing techniques (e.g., welding, brazing, soldering, etc.), via threads or other mechanical connectors (including releasable and adjustable mechanisms), via friction fits, via retaining element structures, etc.). 
     In the example structure of  FIGS. 3-8 , the club head  14  includes a body member  15  to which the shaft  12  is attached at a hosel or socket  16  configured for receiving the shaft  12  in known fashion. The body member  15  includes a plurality of portions, regions or surfaces. For example, the body member  15  includes a ball striking face  17 , a crown  18 , a toe  20 , a rear  22 , a heel  24 , a hosel region  26  and a sole  28 . For certain club heads, the body member  15  may be hollow. 
     Referring to  FIG. 4 , the ball striking face  17  may be essentially flat or it may have a slight curvature or bow (for example, a “bulge” and/or a “roll”). Although the golf ball may contact the ball striking face  17  at any spot on the face, the desired-point-of-contact  17   a  of the ball striking face  17  with the golf ball is typically approximately centered within the ball striking face  17 . 
     Still referring to  FIGS. 3-8 , the crown  18 , which is located on the upper or top side of the club head  14 , extends from the ball striking face  17  back toward the rear  22  of the golf club head  14 . When the club head  14  is viewed from below, the crown  18  cannot be seen. 
     The sole  28 , which is located on the lower or ground side of the club head  14  opposite to the crown  18 , extends from the ball striking face  17  back toward the rear  22 . As with the crown  18 , the sole  28  extends across the width of the club head  14 , from the heel  24  to the toe  20 . When the club head  14  is viewed from above, the sole  28  cannot be seen. 
     The rear  22  is positioned opposite the ball striking face  17 , is located between the crown  18  and the sole  28 , and extends from the heel  24  to the toe  20 . When the club head  14  is viewed from the front, the rear  22  cannot be seen. 
     The heel  24  extends from the ball striking face  17  to the rear  22 . When the club head  14  is viewed from the toe-side, the heel  24  cannot be seen. 
     The toe  20  is shown as extending from the ball striking face  17  to the rear  22  on the side of the club head  14  opposite to the heel  24 . When the club head  14  is viewed from the heel-side, the toe  20  cannot be seen. 
     The socket  16  for attaching the shaft  12  to the club head  14  is located within the hosel region  26 . The hosel region  26  is shown as being located at the intersection of the ball striking face  17 , the heel  24  and the crown  18  and may encompass those portions of the face  17 , the heel  24  and the crown  18  that lie adjacent to the socket  16 . Generally, the hosel region  26  includes surfaces that provide a transition from the socket  16  to the ball striking face  17 , the heel  24 , the crown  18  and/or the sole  28 . 
       FIG. 9  is a schematic top view of a club head illustrating certain club head parameters in accordance with the disclosure. For example, referring to  FIG. 9 , the body member  15  may be described as having a front body portion  15   a  and an aft body portion  15   b . The front body portion  15   a  and the aft body portion  15   b  are not necessarily distinct components, but rather are general regions of the club head  14 . Front body portion  15   a  may generally include the ball striking face  17  and those portions of the crown  18 , toe  20 , sole  28  and hosel region  26  that lie forward of the longitudinal axis  12   a  of the shaft  12  (when the club head is in the 60 degree lie angle position). The aft body portion  15   b  includes the remaining regions of the club head  14 . 
     The body member  15  may be provided with an aft body member  15   b  having a generally or substantially squared profile of a trailing edge  15   c  when viewed from above and/or below. For purposes of this disclosure, the trailing edge  15   c  is defined as the perimeter edge of the aft body member  15   b  that would be contacted by a vertical when the club head is in the 60 degree lie angle position. Further, for purposes of this disclosure, the trailing edge is that portion of the vertically-contacted perimeter edge that extends around the back half of the club head. The club head  14  having such a generally squared profile could be described as a “square head.” Although not a true square in geometric terms, the aft body member  15   b  would be considered substantially square as compared to a more traditional, rounded, club head. It is further to be appreciated by persons of ordinary skill in the art that the body member  15  may be provided with a more traditional round head shape. The phrase “round head” does not refer to a body member  15  having a back half that is completely round but, rather, to a body member  15  with an aft body member  15   b  having a generally or substantially rounded profile of a trailing edge  15   c  when viewed from above and/or below. 
     A longitudinal axis or shaft axis  12   a  extending longitudinally down the center of the shaft  12  is shown in  FIG. 9 . A grip or other handle element (not shown) may be positioned on the shaft  12  to provide a golfer with a slip resistant surface with which to grasp the golf club shaft  12 . 
     For purposes of this disclosure, and referring to  FIGS. 10A and 10B , with a club head positioned at 60-degree lie angle as defined by the USGA (see USGA, “Procedure for Measuring the Club Head Size of Wood Clubs”), the “centerline” of the club head  14  may be considered to coincide with the indicator on the face squaring gauge when the face squaring gauge reads zero for clubs having a neutral face angle. The length (L) of the club head extends from the outermost point of the toe to the outermost point of the heel, as defined by the above-referenced USGA procedure. The breadth (B) of the club head extends from the outermost point of the face to the outermost point of the rear. Similar to the procedure for determining the outermost point of the toe (but now turned 90 degrees), the outermost points of the face and rear may be defined as the points of contact between the club head in the USGA 60-degree lie angle position with a vertical plate running parallel to the longitudinal axis  12   a  of the shaft  12 . The vertical plane associated with this measurement of the outermost point of the face may be referred to as the “front plane” of the club head. The height (H) of the club head extends from the uppermost point of the crown to the lowermost point of the sole, as defined by the above-referenced USGA procedure. The terms “above,” “upper,” “top,” “below,” “lower,” “bottom,” “front,” “back,” “heel-side,” “toe-side,” etc. all may refer to views associated with the club head  14  when it is positioned at this USGA 60-degree lie angle. 
       FIG. 11A  is a schematic of a surface profile taken along section XI-XI, i.e., along the centerline, of the club head of  FIG. 9  for the purpose of illustrating certain club head parameters.  FIG. 11B  is a schematic of an enlarged portion of the surface profile of the crown transition region of  FIG. 11A . For purposes of this disclosure, “breadth” (B) measurements or dimensions are taken parallel to the centerline of the club head and parallel to the ground. A “centerline breadth” (B C ) measurement or dimension refers to the breadth as measured along the centerline of the club head. Generally, a breadth (B) measurement is measured from the front plane; a breadth dimension may be the difference (ΔB) between two breadth (B) measurements. “Height” (H) measurements or dimensions are taken parallel to a vertical plane when the club head is in its 60-degree lie angle position. A “centerline height” (H C ) measurement or dimension refers to a vertical measurement taken at the centerline of the club head. Generally, a height (H) measurement is measured from the lowermost horizontal plane; a height dimension may be the difference (ΔH) between two height (H) measurements. 
     According to certain aspects, the various embodiments of various club heads  14  may include one or more drag-reducing structures in order to reduce the overall drag on the club head  14  during a user&#39;s golf swing from the end of a user&#39;s backswing through the downswing. The drag-reducing structures may be configured to provide reduced drag during the entire downswing of a user&#39;s golf swing or during a significant portion of the user&#39;s downswing, not just at the point of impact. 
     As described in detail in co-pending U.S. patent application Ser. No. 12/779,669, filed May 13, 2010, entitled “Golf Club Assembly and Golf Club With Aerodynamic Features,” and naming Gary Tavares, et al. as inventors, which is incorporated herein in its entirety, it is noted that the ball striking face  17  does not lead the swing over the entire course of a player&#39;s downswing. Only at the point of impact with a golf ball is the ball striking face  17  ideally leading the swing, i.e., the ball striking face  17  is ideally substantially perpendicular to the direction of travel of club head  14  (and the flight of the golf ball) at the point of impact. However, it is known that during the player&#39;s backswing and during the player&#39;s downswing, the player&#39;s hands, wrists, arms, shoulders, torso, and/or hips twist the golf club  10  such that yaw is introduced, thereby pivoting the ball striking face  17  away from its position at impact. With the orientation of the ball striking face  17  at the point of impact considered to be 0°, during the backswing the ball striking face twists away from the user toward the toe  20  and the rear  22  to a maximum of 90° (or more) of yaw, at which point the heel  24  is the leading edge of the club head  14 . 
     Second it may be noted, that aerodynamic boundary layer phenomena acting over the course of the player&#39;s downswing may cause a reduction in club speed due to drag. During a player&#39;s downswing, the air pressure and the energy in the boundary layer flowing over the surface of the club head tend to increase as the air travels over the length of the club head. The greater the air pressure and energy in the boundary layer, the more likely the boundary layer will separate from the club head  14 , thereby creating a low pressure separation zone behind the club head. The larger the separation zone, the greater the drag. Thus, according to certain aspects, drag-reducing structures may be designed to reduce the air pressure and the energy in the boundary layer, thereby allowing the boundary layer to maintain contact with the surface of the club head over a longer distance and thereby reducing the size of the separation zone. Further, according to certain aspects, the drag-reducing structures may be designed to maintain laminar flow over the surface of the club head over the greatest distance possible. A laminar flow results in less drag due to friction over the surface of the club head, and thus, maintaining a laminar air flow over the entire surface of the club head may be the most desirable. Further, by delaying the separation of the boundary layer flow, from the surface of the club head, the size of the separation zone in the trailing region is reduce and correspondingly drag due to the low-pressure separation zone is reduced. 
     In general, it is expected that minimizing the size of the separation zone behind the club head  14 , i.e., maintaining a boundary layer airflow for as long as possible, should result in the least drag. Further, it is expected that maintaining a boundary layer over the club head  14  as the club head changes orientation during the player&#39;s downswing should also result in increase club head speed. Thus, some of the example drag-reducing structures described in more detail below may be provided to maintain a boundary layer airflow over one or more of the surfaces of the club head  14  when the ball striking face  17  is generally leading the swing, i.e., when air flows over the club head  14  from the ball striking face  17  toward the rear  22 . Additionally, it is expected that some of the example drag-reducing structures described in more detail below may provide various means to maintain a boundary layer airflow over one or more surfaces of the club head  14  when the heel  24  is generally leading the swing, i.e., when air flows over the club head  14  from the heel  24  toward the toe  20 . Moreover, it is expected that some of the example drag-reducing structures described in more detail below may provide various means to maintain a boundary layer airflow over one or more surfaces of the club head  14  when the hosel region  26  is generally leading the swing, i.e., when air flows over the club head  14  from the hosel region  26  toward the toe  20  and/or the rear  22 . The example drag-reducing structures disclosed herein may be incorporated singly or in combination in club head  14  and are applicable to any and all embodiments of the club head  14 . 
     Referring then to  FIGS. 3-8 , the crown  18  extends from the ball striking face  17  to the rear  22  and from the heel  24  to the toe  20 . According to certain aspects, a drag-reducing structure may be provided as a stepped-down or rearward crown region  110  formed in the crown  18 . The crown  18  includes a forward crown region  120  that is located adjacent the ball striking face  17 . The rearward crown region  110  is located adjacent the rear  22 . The rearward crown region  110  is stepped down or has a reduced height relative to the forward crown region  120 . By way of non-limiting example, the maximum height of the rearward crown region may be less than the minimum height of the forward crown region. Thus, referring to  FIG. 2 , which schematically illustrates air flowing from the heel  24  toward the toe  20  over and under the club head, it is expected that the club head  14  with the rearward crown region  110  will more readily maintain a laminar boundary layer airflow for a longer distance over the surface of the crown  18  (relative to club heads without the stepped down crown region) when the heel  24  is generally leading the swing. 
     As shown in  FIGS. 3-8  and also in  FIG. 11A , the forward crown region  120  extends rearwardly from the ball striking face  17 . Further, the forward crown region  120  extends from the hosel region  26  to the toe  20 . Generally, the forward crown region  120  has a relatively horizontally-oriented surface. The surface may have a shallow or gentle convex curvature. The transition from the forward crown region  120  to the ball striking face  17  may be provided as a generally convex, smooth merging of the surface of the forward crown region  120  to the surface of the ball striking face  17 . Similarly, the transition from the forward crown region  120  to the toe  20  may be a generally convex, smooth merging of the surface of the forward crown region  120  to the surface of the toe  20 . Additionally, the transition of the forward crown region  120  to the hosel region  26  is also a smooth merging of the surface of the hosel region  26  to the surface of the forward crown region  120 , but this transition generally includes a concavely curved surface. 
     The rearward crown region  110  extends forward from the rear  22 . Further, the rearward crown region  110  extends from the heel  24  to the toe  20 . According to some aspects, and referring for example to  FIG. 8 , this rearward crown region  110  provides a reduced club head profile when viewed from the heel-side of the club head  14 , i.e., the height of the rearward crown region  110  is less than the height of the forward crown region  120 . Generally, referring for example to  FIG. 11A , the rearward crown region  110  may have a relatively horizontally-oriented surface with a relatively planar or a slightly convex curvature. At the transition from the rearward crown region  110  to the heel  24 , a generally convex, smooth merging of the surface of the rearward crown region  110  to the surface of the heel  24  may be provided. Similarly, the transition from the rearward crown region  110  to the toe  20  involves a generally convex, smooth merging of the surface of the rearward crown region  110  to the surface of the toe  20 . Even further, the transition from the rearward crown region  110  to the rear  22  may include a generally convex, smooth merging of the surface of the rearward crown region  110  to the surface of the rear  22 . 
     According to certain aspects, and as best shown in  FIGS. 1 ,  2 ,  3 ,  5  and  7 , another drag-reducing structure may be provided as a generally elongated crown transition region  130  located between the forward crown region  120  and the rearward crown region  110 . The crown transition region  130  may be formed as an aerodynamically smooth, continuous surface, particularly as the crown transition region  130  extends in the heel-to-toe direction. The relatively smooth extent of the crown transition region  130  in the heel-to-toe direction is expected to assist in the maintenance of a laminar boundary layer over the crown  18  (particularly when the heel  24  leads the swing). In combination with the reduced profile presented by the club head  14  due to the lowered crown region  110 , the aerodynamically-shaped crown transition region  130  is expected to provide a more aerodynamically efficient club head  14 . 
     The crown transition region  130  generally extends from the heel  24  toward the toe  20 . In other words, the crown transition region  130  may be generally oriented in a heel-to-toe direction. Further, the crown transition region  130  extends across the centerline of the club head  14 . By way of non-limiting examples, the crown transition region  130  may extend from the heel  24  to the toe  20 , from the heel-to-crown transition feature  18   a  toward the toe  20 , or even from the heel-to-crown transition feature  18   a  to the toe-to-crown transition feature  18   b.    
     Thus, as shown in  FIGS. 1 ,  2 ,  3 ,  5  and  7  and also in  FIGS. 13A-13E , the crown transition region  130  may be a generally elongated feature that extends from a heel-side end  130   a  to a toe-side end  130   b . The crown transition region  130  is bounded along its forward crown edge by a forward crown transition feature  132  and along its rearward crown edge by a rearward crown transition feature  134 . Thus, the heel-side end  130   a  and the toe-side end  130   b  of the crown transition region  130  are also bounded by the forward and rearward crown transition features  132 ,  134 . 
     As shown in  FIGS. 1 and 2  and also in profile in  FIGS. 11A ,  11 B and  14 A- 14 D, the crown transition region  130  may provide a relatively vertically-oriented crown surface extending between the relatively horizontally-oriented surface of the forward crown region  120  and the relatively horizontally-oriented surface of the rearward crown region  110 . When viewed from a perpendicular to the centerline, as in FIGS.  11 A,  11 B and  14 A, the transition from the forward crown region  120  to the rearward crown region  110  may be provided as a gradual transition between the forward crown transition feature  132  and the rearward crown transition feature  134 . Alternatively, the transition region  130  may provide a more abrupt transition from the forward crown region  120  to the rearward crown region  110 , as for example shown in  FIGS. 14C and 14D . The abruptness of the transition may be represented by the slope of the crown transition region  130 , i.e., the ratio (ΔH C /ΔB C ) of the change in height (ΔH C ) of the crown transition region  130  to the change in breadth (ΔB C ) of the crown transition region  130 . Another way of representing the abruptness of the crown transition region  130  is with the angle (θ C ) of the slope, i.e., the tangent of the angle (θ C ) is the slope. Generally, the crown transition region  130  would be provided as a smooth transition, i.e., the transition surface would not include sharp corners or jagged features, although ripples or undulations are considered within the scope of the invention. 
     The height dimension (ΔH C ) of the crown transition region  130  is measured as the difference between the height of the forward crown transition feature  132  (H CF ) and the height of the rearward crown transition feature  134  (H CR ). Referring to  FIGS. 11A and 11B , the change in height ΔH C  is H CF  minus H CR . The breadth dimension (ΔB C ) of the crown transition region  130  is measured as the difference between the breadth of the rearward crown transition feature  134  (B CR ) and the breadth of the forward crown transition feature  132  (B CF ). Thus, still referring to  FIGS. 11A and 11B , the breadth dimension ΔB C  of the crown transition region  130  is B CR  minus B CF . This breadth dimension ΔB C  may vary, i.e., increasing and/or decreasing, as the crown transition region  130  extends from the heel  24  towards the toe  20 . A centerline slope (ΔH C /ΔB C ) of the crown transition region  130  is defined as the slope of the crown transition region  130  measured along the centerline of the club head  14 . 
     The slope (ΔH C /ΔB C ) of the crown transition region  130  may vary as the transition region extends from the heel towards the toe. By way of non-limiting example, the crown transition region  130  may be steepest at its heel-side end  130   a , i.e., closest to the heel-to-crown transition feature  18   a , and progressively less steep as it extends toward the toe  20 . Thus, the crown transition region  130  may have a slope (ΔH C /ΔB C ) that decreases monotonically as it extends from the heel  24  toward the toe  20 . As another non-limiting example, the crown transition region  130  may be steepest in its central region and progressively less steep as it extends toward the heel  24  and towards the toe  20 . By way of a non-limiting example, the slope (ΔH C /ΔB C ) of the crown transition region  130  at the centerline may be less than or equal to approximately 80% of the slope (ΔH C /ΔB C ) of the crown transition region  130  at the heel-side end  130   a . Alternatively, the slope (ΔH C /ΔB C ) of the crown transition region  130  at the centerline may be less than or equal to approximately 70%, less than or equal to approximately 60%, less than or equal to approximately 50%, or even less than or equal to approximately 40% of the slope (ΔH C /ΔB C ) of the crown transition region  130  at the heel-side end  130   a.    
     Alternatively, the maximum slope of the crown transition region  130  need not be at the heel-side end  130   a . Thus, by way of even other non-limiting examples, the slope (ΔH C /ΔB C ) of the crown transition region  130  at the centerline may be less than or equal to approximately 80%, less than or equal to approximately 70%, less than or equal to approximately 60%, less than or equal to approximately 50%, or even less than or equal to approximately 40% of the maximum slope of the crown transition region  130 . Further, the slope (ΔH C /ΔB C ) of the crown transition region  130  at the centerline may range from approximately 30% to approximately 80%, from approximately 30% to approximately 70%, from approximately 30% to approximately 60%, or even from approximately 50% to approximately 80% of the maximum slope of the crown transition region  130 . 
     According to some aspects, the slope (ΔH C /ΔB C ) of the crown transition region  130  may be equal to approximately 1.0. This corresponds to an angle (θ C ) of the slope (ΔH C /ΔB C ) of approximately 45 degrees. According to other aspects, the angle (θ C ) of the slope (ΔH C /ΔB C ) may be approximately 45 degrees, approximately 50 degrees, or even approximately 55 degrees. These slopes (ΔH C /ΔB C ) would generally be considered to be relatively gradual transitions. According to even other aspects, the angle (θ C ) of the slope (ΔH C /ΔB C ) may be approximately 60 degrees, approximately 65 degrees, approximately 70 degrees or even approximately 75 degrees. These slopes (ΔH C /ΔB C ) would generally be considered to be moderate transitions. According to even other aspects, the angle (θ C ) of the slope (ΔH C /ΔB C ) may be approximately 80 degrees, approximately 85 degrees, approximately 90 degrees, or even greater than approximately 90 degrees (i.e., when the crown transition region  130  folds back under the forward crown region  120 ). These slopes (ΔH C /ΔB C ) would generally be considered to be abrupt transitions. 
       FIGS. 14A-14D  schematically illustrate various surface profiles of exemplary crown transition regions  130 , as viewed from a perpendicular to the centerline.  FIG. 14A  illustrates a crown transition region having an angle θ C  of the slope ΔH C /ΔB C  of between approximately 40 to approximately 50 degrees.  FIG. 14B  illustrates a crown transition region having an angle θ C  of the slope ΔH C /ΔB C  of between approximately 60 to approximately 70 degrees.  FIG. 14C  illustrates a crown transition region having an almost vertical slope, i.e., the angle θ C  of the slope ΔH C /ΔB C  lies between approximately 80 to approximately 90 degrees. Finally,  FIG. 14D  illustrates a crown transition region having an angle θ C  of the slope ΔH C /ΔB C  of between approximately 90 to approximately 100 degrees. 
     At the centerline of the club head  14  and referring to  FIGS. 11A and 11B  and also to the schematic illustrations of  FIGS. 14A-14D , the height dimension of the crown transition region  130  (i.e., the difference in height (ΔH C =H CF −H CR ) from the forward crown transition feature  132  to the rearward crown transition feature  134  at the centerline) may range from approximately 5 mm to approximately 30 mm. More preferably, the centerline height dimension ΔH of the crown transition region  130  may range from approximately 5 mm to approximately 25, from approximately 5 mm to approximately 20, or even from approximately 5 mm to approximately 15. For relatively shallow crown transition regions  130  the centerline height dimension ΔH C  may be less than or equal to 10 mm; for relatively deep crown transition regions  130  the centerline height dimension ΔH C  may be greater than or equal to 15 mm. 
     Further, at the centerline of the club head  14 , the breadth dimension (i.e., ΔB C =B CR −B CF ) of the crown transition region  130  may range from approximately 5 mm to approximately 30 mm. More preferably, the breadth dimension ΔB C  of the crown transition region  130  at the centerline may range from approximately 5 mm to approximately 25, from approximately 5 mm to approximately 20, or even from approximately 5 mm to approximately 15. For relatively narrow crown transition regions  130  the breadth dimension ΔB C  at the centerline may be less than or equal to 10 mm; for relatively broad crown transition regions  130  the breadth dimension ΔB C  at the centerline may be greater than or equal to 15 mm. According to other aspects, the breadth dimension ΔB C  of the crown transition region  130  at the centerline (ΔB C =B CR −B CF ) may be less than or equal to approximately 25%, approximately 20%, approximately 15%, approximately 10%, or even approximately 5% of the maximum breath B of the club head  14 . 
     According to even other aspects, the crown transition region  130  may be limited to the middle 50% of the total breadth (B) of the club head  14 . In other words, according to this aspect, if the breadth (B) of the club head  14  is divided into four quadrants, the crown transition region  130  does not lie in the quadrant closest to the ball striking face  17  nor does the crown transition region  130  lie in the quadrant closest to the rear  22 . 
     Further, the height of the crown transition region  130  may vary as the crown transition region  130  extends away from the heel  24 . The height dimension (ΔH C ) of the crown transition region  130 , i.e., the difference in height from the forward crown transition feature  132  (H CF ) to the rearward crown transition feature  134  (H CR ), may be measured in any vertical plane that is parallel to the centerline of the club head  14 . In the illustrative embodiment shown best in  FIG. 7 , the height of the crown transition region  130  initially increases as the region  130  extends away from the heel-side end  130   a , then stays relatively constant until it crosses the centerline of the club head  14 , and finally decreases as the region approaches the toe-side end  130   b . Thus, by way of non-limiting example, the height dimension (ΔH C ) of the crown transition region  130  at the heel-side end  130   a  may be less than the height dimension (ΔH C ) of the crown transition region at the centerline. This increase in the height dimension of the crown transition region  130  may arise because the height (H CF ) of the forward crown transition feature  132  may be greater at the centerline than at the heel  24 , while the height (H CR ) of the rearward crown transition feature  134  may remain relatively constant across the length of the club head  14 . Further, the height dimension (ΔH C ) of the crown transition region  130  at the centerline may be greater than the height dimension (ΔH C ) of the crown transition region at the toe-side end  130   b . By way of non-limiting example, the maximum height dimension of the crown transition region  130  may range from approximately 5 to approximately 30 mm. Alternatively, the maximum height dimension of the crown transition region  130  may be less than or equal to 15 mm. 
     Further, according to another aspect, the crown transition region  130  may be provided with a fairly constant height dimension (ΔH C ). Thus, by way of non-limiting examples, the difference between the maximum height dimension (ΔH CMAX ) and the minimum height dimension (ΔH CMIN ) of the crown transition region  130 , i.e., between the heel-side end  130   a  and the toe-side end  130   b , may be less than or equal to approximately 10 mm, less than or equal to approximately 8 mm, less than or equal to 6 mm, less than or equal to 4 mm, or even less than or equal to less than 2 mm. 
     Similarly, the crown transition region  130  may change in breadth as the crown transition region  130  extends away from the heel  24 .  FIG. 3  and  FIGS. 13A-13E  schematically illustrate various shapes for exemplary crown transition regions  130 , as viewed from above. Referring to  FIGS. 11A and 11B , the breadth dimension (ΔB C ) of the crown transition region  130 , i.e., the difference in breadth from the rearward crown transition feature  134  (B CR ) to the forward crown transition feature  132  (B CF ), may be measured in any vertical plane that is parallel to the centerline of the club head  14 . In the embodiment shown in  FIG. 3 , the breadth dimension (ΔB C ) of the crown transition region  130  initially increases as the region  130  extends away from the heel-side end  130   a  until it crosses the centerline of the club head  14  and then decreases as the transition region  130  approaches the toe-side end  130   b . Thus, by way of non-limiting example, the breadth dimension (ΔB C ) of the crown transition region  130  at the heel-side end  130   a  may be less than the breadth dimension (ΔB) of the crown transition region  130  at the centerline. Even further, the breadth dimension (ΔB C ) of the crown transition region  130  at the heel-side end  130   a  may be less than at the centerline and the breadth dimension (ΔB C ) at the centerline may be less than the breadth dimension (ΔB C ) of the crown transition region at the toe-side end  130   b  (see also  FIGS. 13A and 13B ). In other words, according to some embodiments, the breadth dimension (ΔB C ) of the crown transition region  130  may increase along its length from the heel-side end  130   a  to the toe-side end  130   b . According to some aspects, the breadth dimension (ΔB C ) of the crown transition region  130  at the heel-side end  130   a  may be less than or equal to approximately 50%, approximately 30% or even approximately 20% of the maximum breadth (B) of the club head  14 . 
     According to other aspects and as generally shown in  FIG. 13C , the breadth dimension (ΔB C ) of the crown transition region  130  may decrease along its length from the heel-side end  130   a  to the toe-side end  130   b . According to some embodiments, the breadth dimension (ΔB C ) of the crown transition region  130  at the toe-side end  130   b  may be less than or equal to approximately 50%, approximately 30% or even approximately 20% of the maximum breadth (B) of the club head  14 . According to even other embodiments and as generally shown in  FIG. 13D , the breadth dimension (ΔB C ) of the crown transition region  130  may be generally constant along its length from the heel-side end  130   a  to the toe-side end  130   b . The maximum breadth dimension (ΔB CMAX ) of the crown transition region  130  may range from approximately 5 to approximately 40 mm. Alternatively, the maximum breadth dimension (ΔB CMAX ) of the crown transition region  130  may be less than or equal to 25 mm. 
     As noted above, in certain embodiments (see e.g.,  FIGS. 13A and 13B ), the crown transition region  130  need not extend completely across the crown  18  from the heel-side to the toe-side. Thus, for example, at its toe-side end  130   b  the crown transition region  130  may smoothly merge into the substantially horizontally-oriented surface of the crown  18 . As shown in  FIG. 13A , beyond the toe-side end  130   b , the crown  18  adjacent to the toe may be configured without any transition region formed between the forward crown region  120  and the rearward crown region  110 . According to this aspect, beyond the toe-side end  130   b  of the crown transition region  130 , the surface of the crown  18  forms a smooth convex surface devoid of any transition features and having a slope less than 1.0. In particular, the surface of the crown  18  beyond the toe-side end  130   b  of the crown transition region  130  may be free of any inflection points (as discussed below) and may be free of any forward and/or rearward crown transition features. Similarly, as schematically illustrated in  FIG. 13B , to the heel side of the heel-side end  130   a , the surface of the crown  18  may be configured without any transition region formed between the forward crown region  120  and the rearward crown region  110 . In contrast, according to other embodiments, the crown transition region  130  may extend all the way across the crown  18  as schematically shown in  FIGS. 13C and 13D . In the particular embodiments of  FIGS. 13C and 13D  the crown transition region  130  extends from the heel-to-crown transition feature  18   a  to the toe-to-crown transition feature  18   b.    
     The crown transition region  130 , as viewed from above, may be angled toward the rear  22  and away from the front plane as it extends away from the heel  24 . Referring to  FIG. 9  and as described in more detail below, a top-view orientation angle of the crown transition region  130  is referred to by the symbol β C . In the embodiment of  FIGS. 3-8 , as best shown in  FIG. 3 , the transition region  130  may be generally oriented at a relatively shallow angle β C  from the front plane. Indeed, referring to  FIG. 13D , it can be seen that the crown transition region  130  may be generally oriented at an angle substantially parallel to the front plane. Referring to  FIG. 13E , it can be seen that the crown transition region  130  may be generally oriented at a considerably larger angle from the front plane, i.e., at an angle greater than 10°, at an angle greater than 20°, or even at an angle greater than 30° from the front plane. According to certain aspects, the crown transition region  130  may be angled from approximately 0° to approximately 45° from the front plane. Other preferred orientations of the transition region  130  may be at an angle from approximately 0° to approximately 30°, at an angle from approximately 5° to approximately 20°, or even at an angle from approximately 5° to approximately 15° from the front plane. 
     As best shown in  FIG. 11B  and  FIG. 14B , when viewed from a perpendicular to the centerline of the club head  14  (i.e., when viewed from the side of the club head  14 ), the surface profile of the crown transition region  130  may be described as being generally “S-shaped.” This S-shape surface profile is due to the presence of an inflection point  130   c . For purposes of the present disclosure, the term “inflection point” refers to a point on a surface profile of the crown transition region  130  at which the change in curvature changes sign, i.e., where the second derivative changes sign. In other words, the inflection point  130   c  is the point on the curve at which the surface profile changes from being concave downward to concave upward, or vice versa. Even more simply, the inflection point  130   c  is where the tangent to the surface profile crosses the curve. 
     By way of a non-limiting example, a majority of the surface of the crown transition region  130  may have a convex surface profile. On the other side of the inflection point  130   c , the crown transition region  130  may have a concave surface profile. In some embodiments, a majority of the surface of the crown transition region  130  may have a concave surface profile. As another option, a majority of the surface of the transition region  130  may have a relatively planar surface profile (see e.g.,  FIGS. 14A and 14C ). 
     Further, for purposes of this disclosure and referring back to  FIGS. 9-12 , features of the club head  14  may be defined by the transitions of the surfaces from a substantially vertically-oriented surface to a substantially horizontally-oriented surface. Thus, a heel-to-crown transition feature  18   a  may be defined within a heel-to-crown transition region, i.e., where the heel surface and the crown surface merge. With the club head in the 60-degree lie angle position, and referring to  FIG. 12 , the heel-to-crown transition feature  18   a  may be defined as that portion of the merged heel-to-crown surface wherein a tangent (Tangent A), drawn in a vertical plane that is parallel to the front plane, is at an angle of 45 degrees to the horizontal. Thus, the heel-to-crown transition feature  18   a  may demarcate where a vertically-oriented heel geometry merges with a horizontally-oriented crown geometry. (A substantially horizontally-oriented surface is defined as having a normal to the surface that has an angle to the horizontal of greater than 45 degrees. A substantially vertically-oriented surface is defined as having a normal to the surface that has an angle to the horizontal of less than 45 degrees.) The heel-to-crown transition feature  18   a  may be considered to be part of the crown  18 , part of the heel  24 , or part of both the crown  18  and the heel  24 . The heel-to-crown transition feature  18   a  may be seen when the club head is viewed from above (see  FIG. 9 ). 
     Similarly, still referring to  FIGS. 9-12 , a toe-to-crown transition feature  18   b  may be defined within the toe-to-crown transition region, i.e., where the toe surface and the crown surface merge. Referring in particular to  FIG. 12 , the toe-to-crown transition feature  18   b  may be defined as that portion of the merged toe-to-crown surface wherein a tangent (Tangent B), drawn in a vertical plane that is parallel to the front plane, is at an angle of 45 degrees to the horizontal. Thus, the toe-to-crown transition feature  18   b  may demarcate where the vertically-oriented toe geometry merges with the horizontally-oriented crown geometry. The toe-to-crown transition feature  18   b  may be considered to be part of the crown  18 , part of the toe  20 , or part of both the crown  18  and the toe  20 . The toe-to-crown transition feature  18   b  may be seen when the club head is viewed from above (see  FIG. 9 ). 
     Now referring to  FIG. 9  and  FIGS. 11A-11B , a front-to-crown transition feature  18   c  may be defined within the front-to-crown transition region, i.e., where the front surface and the crown surface merge. The front-to-crown transition feature may be defined as that portion of the merged front-to-crown surface wherein a tangent (Tangent C), drawn in a vertical plane that is perpendicular to the front plane, is at an angle of 45 degrees to the horizontal. Thus, the front-to-crown transition feature  18   c  may demarcate where the vertically-oriented front geometry merges with the horizontally-oriented crown geometry. The front-to-crown transition feature  18   c  may be considered to be part of the crown  18 , part of the front  17 , or part of both the crown  18  and the front  17 . The front-to-crown transition feature  18   c  may be seen when the club head is viewed from above (see  FIG. 9 ). 
     Even further and again referring to  FIGS. 9 and 11 , a rear-to-crown transition feature  18   d  may be defined within the rear-to-crown transition region, i.e., where the rear surface and the crown surface merge. The rear-to-crown transition feature  18   d  may be defined as that portion of the merged rear-to-crown surface wherein a tangent (Tangent D), drawn in a vertical plane that is perpendicular to the front plane, is at an angle of 45 degrees to the horizontal. Thus, the rear-to-crown transition feature  18   d  may demarcate where the vertically-oriented rear geometry merges with the horizontally-oriented crown geometry. The rear-to-crown transition feature  18   d  may be considered to be part of the crown  18 , part of the rear  22 , or part of both the crown  18  and the rear  22 . The rear-to-crown transition feature  18   d  may be seen when the club head is viewed from above (see  FIG. 9 ). 
     Thus, generally, the crown  18  may be considered to extend front-to-rear between the front-to-crown transition feature  18   c  and the rear-to-crown transition feature  18   d , and further to extend side-to-side between the heel-to-crown transition feature  18   a  and the toe-to-crown transition feature  18   b.    
     Referring to  FIG. 9  and  FIGS. 11A and 11B , the crown transition region  130  may be defined by its forward and lower transition features  132 ,  134 , i.e., where the crown surfaces adjacent to the transition region  130  transition from the substantially vertically-oriented surface of the transition region  130  to the substantially horizontally-oriented surfaces of the forward crown region  120  and the rearward crown region  110 . Thus, at its forward, forward edge the crown transition region  130  may be delimited by a forward crown transition feature  132 . The forward crown transition feature  132  is located where the surface of the forward crown region  120  and the surface of the crown transition region  130  merge. The surface of this merging area typically would have a generally convex curvature, when viewed from a perpendicular to the centerline of the club head  14 , as shown for example in  FIGS. 11A and 11B . More specifically, the forward crown transition feature  132  may be defined as that portion of the merged surface wherein a tangent to the merged surface (Tangent E), drawn in a vertical plane that is parallel to the centerline, is at an angle of 45 degrees to the horizontal (see  FIGS. 11A and 11B ). Thus, the forward crown transition feature  132  may demarcate where the more vertically-oriented geometry of the crown transition region  130  transitions to the more horizontally-oriented geometry of the forward crown region  120 . The forward crown transition feature  132  may be considered to be part of the forward crown region  120 , part of the crown transition region  130 , and/or part of both the forward crown region  120  and the crown transition region  130 . The forward crown transition feature  132  may be seen when the club head is viewed from above (see e.g.,  FIG. 3 ). Further, the forward crown transition  132  feature may be visible when the club head is viewed from the heel-side of the club head  14  and/or from the back of the club head  14 . 
     Referring back to  FIG. 9  and  FIGS. 11A-11B , the forward crown transition feature  132  may extend from the heel  24  toward the toe  20 . Further, as with the crown transition region  130 , the forward crown transition feature  132  extends across the centerline of the club head  14 . Thus, by way of non-limiting examples, the forward crown transition feature  132  may extend from proximate the heel  24  to the toe  20 , from the heel-to-crown transition feature  18   a  toward the toe  20 , or even from the heel-to-crown transition feature  18   a  to the toe-to-crown transition feature  18   b . Referring to  FIGS. 13A-13E , and particularly to  FIGS. 13D and 13E , according to certain embodiments, at least a portion of the forward crown transition feature  132  may extend from the heel  24  toward the toe  20  in an approximately straight line, when viewed from above. Alternatively, the forward crown transition feature  132  may have a slight curvature, when viewed from above. For example, the forward crown transition feature  132  may have a slightly concave curvature (see e.g.,  FIG. 13A ). 
     Referring to  FIG. 9 , the forward crown transition feature  132  may extend toward the toe  20  at an angle α from a front plane of the club head, when viewed from above. As the forward crown transition feature  132  extends from the heel toward the toe, the angle α may change, i.e., the forward crown transition feature  132  may be curved. For purposes of this disclosure, when the forward crown transition feature  132  is curved when viewed from above, a centerline angle α c  may be defined as the angle of the tangent to the transition feature  132  taken where the transition feature  132  crosses the centerline of the club head  14 . According to certain embodiments, the forward crown transition feature  132  may extend toward the toe  20  at a centerline angle α c  of from −5 degrees to 25 degrees, from 0 degrees to 25 degrees, from 0 degrees to 15 degrees, from 0 degrees to 10 degrees, or even at an angle of less than or equal to 5 degrees, from a front plane of the club head, when viewed from above. 
     Referring to  FIG. 9  and  FIGS. 11A-11B , at its lower edge the crown transition region  130  may be delimited by a rearward crown transition feature  134 . The rearward crown transition feature  134  is located where the surface of the rearward crown region  110  and the surface of the crown transition region  130  merge. The surface of this merging area has a generally concave curvature, when viewed from a perpendicular to the centerline of the club head  14 , as shown for example in  FIGS. 11A and 11B . The rearward crown transition feature  134  may be defined as that portion of the merged surface wherein a tangent to the surface (Tangent F), drawn in a vertical plane that is perpendicular to the front plane, is at an angle of 45 degrees to the horizontal (see  FIGS. 11A and 11B ). Thus, similar to the forward crown transition feature  132 , the rearward crown transition feature  134  may demarcate where the more vertically-oriented geometry of the crown transition region  130  transitions to the more horizontally-oriented geometry of the rearward crown region  110 . The rearward crown transition feature  134  may be considered to be part of the rearward crown region  110 , part of the crown transition region  130 , or part of both the rearward crown region  110  and the crown transition region  130 . In general, the rearward crown transition feature  134  may be visible when the club head  14  is viewed from above (see  FIGS. 3 and 9 ). Further, the rearward crown transition feature  134 , or some portion thereof, may be visible when the club head is viewed from the back (see  FIG. 7 ). 
     Referring back to  FIGS. 3 and 9 , the rearward crown transition feature  134  may extend from the heel  24  toward the toe  20 . Further, as with the crown transition region  130 , the rearward crown transition feature  134  extends across the centerline of the club head  14 . Thus, by way of non-limiting examples, the rearward crown transition feature  134  may extend from proximate the heel  24  to the toe  20 , from the heel-to-crown transition feature  18   a  toward the toe  20 , or even from the heel-to-crown transition feature  18   a  to the toe-to-crown transition feature  18   b . Referring to  FIGS. 13A-13E , and particularly to  FIGS. 13D and 13E , according to certain embodiments, at least a portion of the rearward crown transition feature  134  may extend from the heel  24  toward the toe  20  in an approximately straight line, when viewed from above. Alternatively, the rearward crown transition feature  134  may have a slight curvature, when viewed from above. For example, the rearward crown transition feature  134  may have a slightly convex curvature (see e.g.,  FIG. 13E ). 
     Referring back to  FIG. 9 , the rearward crown transition feature  134  may extend toward the toe  20  at an angle γ from the front plane of the club head  14 , when viewed from above. As the rearward crown transition feature  134  extends from the heel toward the toe, the angle γ may change, i.e., the rearward crown transition feature  134  may be curved. For purposes of this disclosure, when the rearward crown transition feature  134  is curved when viewed from above, a centerline angle γ c  may be defined as the angle of the tangent to the transition feature  134  taken where the transition feature  134  crosses the centerline of the club head  14 . According to certain embodiments, the rearward crown transition feature  134  may extend toward the toe  20  at an angle γ c  of from 0 degrees to 45 degrees, from 0 degrees to 30 degrees, from 0 degrees to 20 degrees, from 0 degrees to 15 degrees, or even at an angle of less than or equal to 10 degrees, from the front plane of the club head  14 , when viewed from above. 
     The crown transition region  130 , itself, when viewed from above, may be angled toward the rear  22  and away from the front plane (or from the ball striking face  17 ) as it extends away from the heel  24 . The degree of angling (i.e., the top-view orientation) of the crown transition region  130  may be characterized by taking the average of the centerline angle α C  of the forward crown transition feature  132  and the centerline angle γ C  of the rearward crown transition feature  134 . Referring to  FIG. 9 , this orientation angle of the crown transition region  130  is referred to by the symbol β C , wherein β C =½(α C +γ C ). In the embodiment of  FIGS. 3-8 , as best shown in  FIG. 3 , the crown transition region  130  may be generally oriented at an angle β C  of from between 5 and 15 degrees. According to certain aspects, the crown transition region  130  may have a top-view orientation angle β C  of approximately 0° (see e.g.,  FIG. 13D ), approximately 5°, approximately 10°, approximately 15°, approximately 20°, approximately 25° (see e.g.,  FIG. 13E ), or even up to approximately 30° from the front plane. Thus, for example, preferred orientations of the characteristic angle β c  of the crown transition region  130  may range from approximately 0° to approximately 20°, from approximately 5° to approximately 20°, or even from approximately 5° to approximately 15° from the front plane. Thus, by way of non-limiting examples,  FIGS. 13A-13E  schematically illustrate various orientations for exemplary crown transition regions  130 , as viewed from above. 
     According to certain aspects, the forward crown region  120  may have a centerline breadth dimension (measured from the face-to-crown transition feature  18   c  to the forward crown transition feature  132  in the vertical plane of the centerline) that is greater than or equal to approximately 30%, greater than or equal to approximately 40%, greater than or equal to approximately 45%, or even greater than or equal to approximately 50% of the maximum breadth (B) of the club head  14 . According to other aspects, the rearward crown region  110  may have a centerline breadth dimension (measured from rear-to-crown transition feature  18   d  to the rearward crown transition feature  134  in the vertical plane of the centerline) that is greater than or equal to approximately 30%, greater than or equal to approximately 40%, greater than or equal to approximately 45%, or even greater than or equal to approximately 50% of the maximum breadth (B) of the club head  14 . 
     According to even other aspects, the rearward crown region  110  may have a centerline height (measured in the vertical plane of the centerline when the club is in the 60 degree lie angle position) that less than or equal to approximately 70%, less than or equal to approximately 60%, less than or equal to approximately 50%, or even less than or equal to approximately 40% of the maximum height (H) of the club head  14 . It may be preferable to have the centerline height of the rearward crown region  110 , measured along the centerline of the club head from the rearward crown transition feature  134  to the rear-to-crown transition feature  18   d , range from approximately 40% to approximately 60%, or even from approximately 45% to approximately 55%, of the maximum height (H) of the club head  14 . Optionally, it may be preferable to have the centerline height of the rearward crown region  110 , measured along the centerline of the club head from the rearward crown transition feature  134  to the rear-to-crown transition feature  18   d , vary by no more than approximately ±10% or even by no more than approximately ±5%. 
     The forward crown region  120  provides a smooth surface for air encountering the ball striking face  17  to flow up and over, particularly when the ball striking face  17  is leading the swing. The rearward crown region  110  provides a smooth surface on the crown  18  for air encountering the heel  24  to flow up and over, particularly when the heel  24  is leading the swing. The crown transition region  130  allows the forward crown region  120  to be at a different, greater height than the rearward crown region  110 . Thus, advantageously, the height of the front body portion  15   a  of the club head  14  may be designed quasi-independently from the height of the aft body portion  15   b  of the club head  14 . This may allow for a greater height of the ball striking face  17 , while allowing a cross-sectional area of the heel  24  to be reduced to provide greater aerodynamic streamlining for air flowing over the heel  24 . 
     Because the crown transition region  130  steps down to the rearward crown region  110  from the forward crown region  120 , the body member  15  may be generally “flattened” as compared to other, more conventional, club heads. Thus, the flattened body member  15  of the present club head  14  may have a greater length (L) and/or breadth (B) than club heads having similar volumes. By way of non-limiting example, the club head breadth (B) may be greater than or equal to approximately 11.5 cm, or even greater than or equal to approximately 12.0 cm. Similarly, by way of non-limiting example, the club head length (L) may be greater than or equal to approximately 11.5 cm, or even greater than or equal to approximately 12.0 cm. Additionally, it is expected that the “flattening” of the club head relative to club heads having the same volume may result in the height of the center of gravity (CG) of the club head  14  being less than or equal to approximately 2.0 cm, less than or equal to approximately 1.75 cm, or even less than or equal to approximately 1.5 cm. Because of the increase breadth, the distance of the center of gravity (CG) from the front plane of the club head  14  may be greater than or equal to approximately 3.0 cm, greater than or equal to approximately 3.5 cm, or even greater than or equal to approximately 4.0 cm. 
     Further, it is expected that the “flattening” of the club head relative to club heads having the same volume will allow for a more streamlined club head with improved moment-of-inertia (MOI) characteristics. For example, it is expected that the moment-of-inertia (Izz) around a vertical axis associated with the club head&#39;s center-of-gravity may be greater than 3100 g-cm 2 , greater than 3200 g-cm 2 , or even greater than 3300 g-cm 2  for square-head type club heads. Further, it is expected that the moment-of-inertia (Ixx) around a horizontal axis associated with the club head&#39;s center-of-gravity may be greater than 5250 g-cm 2 , greater than 5350 g-cm 2 , or even greater than 5450 g-cm 2  for square-head type club heads. The vertical (z) axis and the horizontal (x) axis are defined with the club head in the 60° lie angle position (see  FIGS. 10A and 10B ). 
     According to even further aspects and as shown, according to one embodiment, in  FIG. 15 , the club head  14  may include a “Kammback” feature  23 . The Kammback feature  23  may extend across at least a portion of the rear  22  from the heel  24  to the toe  20  and/or that extends across at least a portion of the toe  20  from the rear  22  to the ball striking face  17 . Further, as shown in  FIG. 15 , the Kammback feature  23  may extend into the heel  24 . 
     Generally, Kammback features are designed to take into account that a laminar flow, which could be maintained with a very long, gradually tapering, downstream (or trailing) end of an aerodynamically-shaped body, cannot be maintained with a shorter, tapered, downstream end. When a downstream tapered end would be too short to maintain a laminar flow, drag due to turbulence may start to become significant after the downstream end of a club head&#39;s cross-sectional area is reduced to approximately fifty percent of the club head&#39;s maximum cross section. This drag may be mitigated by shearing off or removing the too-short tapered downstream end of the club head, rather than maintaining the too-short tapered end. It is this relatively abrupt cut off of the tapered end that is referred to as the Kammback feature  23 . 
     It is known that during a significant portion of the golfer&#39;s downswing the heel  24  and/or the hosel region  26  lead the swing. During these portions of the downswing, either the toe  20 , portion of the toe  20 , the intersection of the toe  20  with the rear  22 , and/or portions of the rear  22  form the downstream or trailing end of the club head  14 . Thus, the Kammback feature  23 , when positioned along at least a portion of the toe, at the intersection of the toe  20  with the rear  22 , and/or along at least a portion of the rear  22  of the club head  14 , may be expected to reduce turbulent flow, and therefore reduce drag due to turbulence, during these portions of the downswing. 
     According to certain aspects, the Kammback feature  23  may include a continuous channel or groove  29  formed about a portion of a periphery of club head  14 . As illustrated in  FIG. 15 , groove  29  extends along a portion of the toe  20 , along the entirety of the rear  22 , and then along a portion of the heel  24 . As can be seen in  FIG. 15 , groove  29  may have a tapered end. 
     Another illustrative embodiment of a golf club according to aspects of the invention is shown in  FIGS. 16 and 17 . As can generally be seen in  FIG. 16 , the bottom or sole of the club head may be provided with an elongated feature, generally extending from the heel toward the toe, which separates a front or forward sole region from a rear or rearward sole region. This elongated feature on the sole, similar to the elongated feature on the crown described above, provides a transition region, wherein the height of the forward sole region is stepped down or transitioned to the height of the rearward sole region. By transitioning the height of the sole from the front or forward sole region to the rear or rearward sole region, it is expected that air flowing over and/or under the club head from the heel toward the toe will encounter less resistance. Thus, it is expected that the transition region will result in reduced drag over the course of the golfer&#39;s downswing, higher club head speed at the moment of impact with the golf ball, and increased travel distance of the golf ball. 
     Thus, according to this aspect of the invention, and referring to  FIG. 16 , another drag-reducing structure, similar to crown transition region  130 , may be provided on the sole  28 . A generally elongated sole transition region  230  is located between the forward sole region  220  and the rearward sole region  210 . The sole transition region  230  may be formed as an aerodynamically smooth, continuous surface that extends in the heel-to-toe direction. The relatively smooth extent of the sole transition region  230  in the heel-to-toe direction is expected to assist in the maintenance of a laminar boundary layer over the sole  18  (particularly when the heel  24  leads the swing). The sole transition region  230 , particularly in combination with a reduced profile presented by the club head  14  due to the reduced sole region  210 , is expected to provide a more aerodynamically efficient club head  14 . 
     The sole transition feature  230  is provided with many of the characteristics of the crown transition region  130 . Thus, for purposes of this disclosure, the above explanation of the characteristics of the crown transition region  130  may be applied to the sole transition region  230 . Characteristics of the crown transition feature  130  generally are associated with items number 1xx, while similar characteristics of the sole transition region  230  are generally associated with item numbers 2xx. 
     Thus, for example, the sole transition region  230  generally extends from the heel  24  toward the toe  20  such that the sole transition region  230  may be generally oriented in a heel-to-toe direction. Further, the sole transition region  230  extends across the centerline of the club head  14 . 
     Thus, as shown in  FIG. 16 , the sole transition region  230  may be a generally elongated feature that extends from a heel-side end  230   a  to a toe-side end  230   b . The sole transition region  230  is bounded along its forward sole edge by an forward sole transition feature  232  and along its rearward sole edge by a rearward sole transition feature  234 . Thus, the heel-side end  230   a  and the toe-side end  230   b  are also bounded by the forward and rearward sole transition features  232 ,  234 . 
     As shown in  FIG. 17 , the sole transition region  230  may provide a relatively vertically-oriented sole surface extending between the relatively horizontally-oriented surface of the forward sole region  220  and the relatively horizontally-oriented surface of the rearward sole region  210 . The transition from the forward sole region  220  to the rearward sole region  210  may be provided as a gradual transition between the forward sole transition feature  232  and the rearward sole transition feature  234 . Alternatively, the sole transition region  230  may provide a more abrupt transition from the forward sole region  220  to the rearward sole region  210 . The abruptness of the transition may be represented by the slope of the sole transition region  230 , i.e., the ratio of the change in height (ΔH S ) of the sole transition region  230  to the change in breadth (ΔB S ) of the sole transition region  230 . Generally, the sole transition region  230  would be provided as a smooth transition, i.e., the transition surface would not include sharp corners or jagged features. 
     The slope (ΔH S /ΔB S ) of the sole transition region  230  may vary as the transition region in the sole  28  extends from the heel towards the toe. By way of non-limiting example, the sole transition region  230  may be steepest at its heel-side end  230   a , and progressively less steep as it extends toward the toe  20 . Thus, the sole transition region  230  may have a slope (ΔH S /ΔB S ) that decreases monotonically as it extends from the heel  24  toward the toe  20 . As another non-limiting example, the sole transition region  230  may be steepest in its central region and progressively less steep as it extends toward the heel  24  and towards the toe  20 . Thus, for example, the slope (ΔH S /ΔB S ) of the sole transition region  230  at the centerline may be less than or equal to approximately 80% of the slope (ΔH S /ΔB S ) of the sole transition region  230  at the heel-side end  230   a . Alternatively, the slope (ΔH S /ΔB S ) of the sole transition region  230  at the centerline may be less than or equal to approximately 70%, less than or equal to approximately 60%, less than or equal to approximately 50%, or even less than or equal to approximately 40% of the slope (ΔH S /ΔB S ) of the sole transition region  230  at the heel-side end  230   a.    
     Alternatively, the maximum slope of the sole transition region  230  need not be at the heel-side end  230   a . Thus, by way of even other non-limiting examples, the slope (ΔH S /ΔB S ) of the sole transition region  230  at the centerline may be less than or equal to approximately 80%, less than or equal to approximately 70%, less than or equal to approximately 60%, less than or equal to approximately 50%, or even less than or equal to approximately 40% of the maximum slope of the sole transition region  230 . Further, the slope (ΔH S /ΔB S ) of the sole transition region  230  at the centerline may range from approximately 30% to approximately 80%, from approximately 30% to approximately 70%, from approximately 30% to approximately 60%, or even from approximately 50% to approximately 80% of the maximum slope of the sole transition region  230 . 
     Similar to the various embodiments of the crown transition features  130  schematically illustrated in  FIGS. 14A-14D , the sole transition feature  230  may also be provided with various surface profiles. Thus, according to some aspects, the slope (ΔH S /ΔB S ) of the sole transition region  230  may be equal to approximately 1.0. According to other aspects, the slope (ΔH S /ΔB S ) may be greater than approximately 1.0, greater than approximately 1.3, or greater than approximately 1.6. These slopes (ΔH S /ΔB S ) would generally be considered to be relatively moderate transitions. According to even other aspects, the slope (ΔH S /ΔB S ) may be greater than approximately 2, greater than approximately 4, approximately vertical, or may even become negative (i.e., when the sole transition region  230  folds back under the forward sole region  220 ). These slopes (ΔH S /ΔB S ) would generally be considered to be abrupt transitions. 
     At the centerline of the club head  14  and referring to  FIG. 17 , the height dimension ΔH S  of the sole transition region  230  may range from approximately 2 mm to approximately 20 mm. More preferably, the centerline height dimension ΔH S  of the sole transition region  230  may range from approximately 2 mm to approximately 15, from approximately 2 mm to approximately 10, or even from approximately 2 mm to approximately 5. For relatively shallow sole transition regions  230  the centerline height dimension ΔH S  may be less than or equal to 5 mm; for relatively deep sole transition regions  230  the centerline height dimension ΔH S  may be greater than or equal to 15 mm. 
     Further, at the centerline of the club head  14 , the breadth dimension ΔB S  of the sole transition region  230  may range from approximately 5 mm to approximately 30 mm. More preferably, the breadth dimension ΔB S  of the sole transition region  230  at the centerline may range from approximately 5 mm to approximately 25, from approximately 5 mm to approximately 20, or even from approximately 5 mm to approximately 15. For relatively narrow sole transition regions  230 , the breadth dimension ΔB S  at the centerline may be less than or equal to 10 mm; for relatively broad sole transition regions  230 , the breadth dimension ΔB S  at the centerline may be greater than or equal to 15 mm. According to other aspects, the breadth dimension ΔB S  of the sole transition region  230  at the centerline may be less than or equal to approximately 25%, approximately 20%, approximately 15%, approximately 10%, or even approximately 5% of the maximum breath B of the club head  14 . Similar to the corresponding feature of the crown transition region  130 , the sole transition region  230  may be limited to the middle 50% of the total breadth (B) of the club head  14 . 
     Further, similar to the corresponding feature of the crown transition region  130 , the height ΔH S  of the sole transition region  230  may vary as the sole transition region  230  extends away from the heel  24 . The height dimension ΔH S  of the sole transition region  230  may be measured in any vertical plane that is parallel to the centerline of the club head  14 . In the illustrative embodiment shown best in  FIG. 16 , the height of the sole transition region  230  initially increases as the region  230  extends away from the heel-side end  230   a , then stays relatively constant until it crosses the centerline of the club head  14 , and finally decreases as the region approaches the toe-side end  230   b . Thus, by way of non-limiting examples, the height dimension ΔH S  of the sole transition region  230  at the heel-side end  230   a  and/or at the toe-side end  230   b  may be less than the height dimension of the sole transition region at the centerline. By way of non-limiting example, the maximum height dimension ΔH S  of the sole transition region  230  may range from approximately 2 to approximately 20 mm. Alternatively, the maximum height dimension ΔH S  of the sole transition region  230  may be less than or equal to 10 mm. 
     Further, according to another aspect, the sole transition region  230  may be provided with a fairly constant height dimension ΔH S . Thus, by way of non-limiting examples, the difference between the maximum height dimension and the minimum height dimension of the sole transition region  230  may be less than or equal to approximately 6 mm, less than or equal to approximately 4 mm, or even less than or equal to less than approximately 2 mm. 
     Similar to the corresponding feature of the crown transition region  130 , the sole transition region  230  may change in breadth as the sole transition region  230  extends away from the heel  24 . The breadth dimension ΔB S  of the sole transition region  230  may be measured in any vertical plane that is parallel to the centerline of the club head  14 . The breadth dimension ΔB S  of the sole transition region  230  initially increases as the region  230  extends away from the heel-side end  230   a  until it crosses the centerline of the club head  14  and then decreases as the transition region  230  approaches the toe-side end  230   b . Thus, by way of non-limiting example, the breadth dimension ΔB S  of the sole transition region  230  at the heel-side end  230   a  may be less than the breadth dimension ΔB S  of the sole transition region  230  at the centerline. Even further, the breadth dimension ΔB S  of the sole transition region  230  at the heel-side end  230   a  may be less than at the centerline and the breadth dimension ΔB S  at the centerline may be less than the breadth dimension ΔB S  of the sole transition region at the toe-side end  130   b . In other words, according to some embodiments, the breadth dimension ΔB S  of the sole transition region  230  may increase along its length from the heel-side end  230   a  to the toe-side end  230   b . According to some aspects, the breadth dimension ΔB S  of the sole transition region  230  at the heel-side end  230   a  may be less than or equal to approximately 50%, approximately 30% or even approximately 20% of the maximum breadth (B) of the club head  14 . 
     According to other aspects, the breadth dimension ΔB S  of the sole transition region  230  may decrease along its length from the heel-side end  130   a  to the toe-side end  230   b . According to some embodiments, the breadth dimension ΔB S  of the sole transition region  230  at the toe-side end  130   b  may be less than or equal to approximately 50%, approximately 30% or even approximately 20% of the maximum breadth (B) of the club head  14 . According to even other embodiments, the breadth dimension ΔB S  of the sole transition region  230  may be generally constant along its length from the heel-side end  230   a  to the toe-side end  230   b . The maximum breadth dimension of the sole transition region  230  may range from approximately 5 to approximately 30 mm. Alternatively, the maximum breadth dimension of the sole transition region  230  may be less than or equal to 20 mm. 
     In certain embodiments, the sole transition region  230  need not extend completely across the sole  28  from the heel-side  24  to the toe-side  20 . Thus, for example, at its toe-side end  230   b  the sole transition region  230  may smoothly merge into the substantially horizontally-oriented surface of the sole  28 . Beyond the toe-side end  230   b , the sole  28  adjacent to the toe  20  may be configured without any transition region formed between the forward sole region  220  and the rearward sole region  210 . According to this aspect, beyond the toe-side end  230   b  of the sole transition region  230 , the surface of the sole  28  forms a smooth convex surface devoid of any transition features and having a slope less than 1.0. In particular, the surface of the sole  28  beyond the toe-side end  230   b  of the sole transition region  230  may be free of any inflection points and may be free of any forward and/or rearward sole transition features. Similarly, to the heel side of the heel-side end  230   a , the surface of the sole  28  may be configured without any transition region formed between the forward sole region  220  and the rearward sole region  210 . According to even other embodiments, the sole transition region  230  may extend all the way across the sole  28 . In these particular embodiments, the sole transition region  230  extends from a heel-to-sole transition feature to a toe-to-sole transition feature, i.e., where the surfaces of the substantially vertically-oriented surfaces transition at an angle of 45 degrees to the substantially horizontally-oriented sole surface. 
     Similar to the corresponding features of the crown transition region  130 , the sole transition region  230  may be angled toward the rear  22  and away from the front plane as it extends away from the heel  24 . For example, the transition region  230  may be generally oriented substantially parallel to the front plane or at a relatively shallow angle from the front plane. Optionally, the sole transition region  230  may be generally oriented at an angle greater than 10° from the front plane or even at an angle greater than 20° from the front plane. Thus, according to certain aspects, the sole transition region  230  may be angled from approximately 0° to approximately 30° from the front plane. Other preferred orientations of the transition region  230  may be at an angle from approximately 0° to approximately 20°, at an angle from approximately 5° to approximately 20°, or even at an angle from approximately 5° to approximately 15° from the front plane. 
     As best shown in  FIG. 17 , when viewed from a perpendicular to the centerline of the club head  14  (i.e., when viewed from the side of the club head  14 ), the surface profile of the sole transition region  230  may be described as being generally “S-shaped.” This S-shape surface profile is due to the presence of an inflection point  230   c . By way of a non-limiting example, a majority of the surface of the sole transition region  230  may have a convex surface profile. On the other side of the inflection point  230   c , the sole transition region  230  may have a concave surface profile. In some embodiments, a majority of the surface of the sole transition region  230  may have a concave surface profile. As another option, a majority of the surface of the transition region  230  may have a relatively planar surface profile. 
     Thus it can be seen, given the benefit of this disclosure, that the crown transition region  130  essentially separates or decouples the curvature of the surface of the forward crown region  120  from the curvature of the surface of the rearward crown region  110  and that the sole transition region  230  essentially separates or decouples the curvature of the surface of the forward sole region  220  from the curvature of the surface of the rearward sole region  210 . In other words, to a certain extent, the curvature characteristics of the surface of the forward crown region  120  (and/or the forward sole region  220 ) may be developed without consideration of the curvature characteristics being developed for the surface of the rearward crown region  110  (and/or the rearward sole region  210 ). This offers the club head designer greater flexibility when shaping the surfaces of the crown  18  and/or the sole  28  and incorporating or developing aerodynamic features. 
     When the club head  14  is viewed from the heel-side, it can be seen that the forward region of the club head, by virtue of its larger cross-sectional area, will displace more air than a rear region of the club head. Thus, it is expected that the pressure build-up of the air flowing over the club head  14  in the forward region will be greater than the pressure build-up of the air flowing over the club head  14  in the rear region. By stepping down or lowering the crown (and/or the sole) in the rearward region of the club head  14 , the aerodynamic profile of the club head, especially when the heel  24  and/or hosel region  26  of the club head  14  are leading the swing, will be reduced. 
     Thus, while there have been shown, described, and pointed out fundamental novel features of various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, it is expressly intended that all combinations of those elements and/or steps which perform substantially the same function, in substantially the same way, to achieve the same results are within the scope of the invention. Substitutions of elements from one described embodiment to another are also fully intended and contemplated. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.