Patent Publication Number: US-2022226702-A1

Title: Golf club head with improved inertia performance

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 17/700,439, filed on Mar. 21, 2022, which is a continuation-in-part of co-pending U.S. patent application Ser. No. 16/912,276, filed on Jun. 25, 2020, which is a continuation-in-part of U.S. patent application Ser. No. 16/219,651, filed on Dec. 13, 2018, both of which are hereby incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a new and improved golf club having improved Moment of Inertia (MOI) characteristics, combined with an improved Center of Gravity (CG) location. More specifically, the golf club head in accordance with the present invention achieves a relative low Moment of Inertia (MOI) about the Z-axis (MOI-Z), a low MOI about the Shaft Axis (MOI-SA), all combined with a high MOI about the X and Y-axis (MOI-X and MOI-Y) and maintaining a consistently and relatively low CG location measured along a direction tangent to the hosel axis along the X-Y plane (CG-B). 
     BACKGROUND OF THE INVENTION 
     With the development of the modern day oversized metalwoods, the performance capabilities of these types of golf clubs have increased dramatically over their predecessor, “the persimmon wood”. One of the ways these metalwood type golf clubs have been performing better than their predecessors is in the increase in overall distance, generally attributed to the inherent elastic deformation of thin metallic metal materials used by these metalwoods. Another way the metalwood type golf clubs have been outperforming their predecessors is in the increase in overall forgiveness of the golf club head, generally attributed to the increase in the MOI of the golf club head itself. 
     The MOI of a golf club head generally is a term used to describe the ability of an object to resist rotational movement upon impact with a secondary object. In the case of a golf club head, MOI refers to the ability of the golf club head to resist undesirable twisting upon impact with a golf ball, as such a twisting movement will generally change the face angle of the golf club head away from the intended target line, sending the golf ball away from the intended target. 
     U.S. Pat. No. 5,354,055 to MacKeil shows one of the earliest attempts to increase the MOI of a golf club head by placing the Center of Gravity (CG) location rearward. U.S. Pat. No. 6,364,788 to Helmstetter et al. shows the utilization of weighting members to help control the MOI of the golf club head. Both of these patents refer to the MOI-y of the golf club head, as it relates to the ability of the golf club head to stay stable when encountering an off-center impact in the heel and toe direction. 
     U.S. Pat. No. 7,850,542 to Cackett et al. illustrates a further development in the MOI research wherein a recognition of the different axis of rotation of the different MOI&#39;s. (Alternatively known as Ixx, Iyy, and Izz instead of MOI-X, MOI-Y, and MOI-Z) Despite the recognition and identification of the difference in MOI values, U.S. Pat. No. 7,850,542 only focuses its attention on Ixx and Iyy (adapted and changes to the current reference nomenclature), without any recognition of the importance of the last MOI number, Izz, nor MOI-SA and how they can affect the performance of the golf club. 
     Despite the above, none of the references recognizes the importance of the MOI of the golf club head horizontally forward and aft of the face (MOI-Z), and ways to design a golf club that takes advantage of the performance characteristics of golf club with more optimal MOI-Z values along with the minimized MOI-SA values. Moreover, a closer investigation of the MOI-Z values will yield CG locations that will work in conjunction with the above MOI-Z values to create more performance. Hence, it can be seen from the above there is a need for more research and a design of a golf club capable of achieving better performance by investigating the importance of MOI-Z and MOI-SA as well as the CG location and designing a golf club head. 
     BRIEF SUMMARY OF THE INVENTION 
     One aspect of the present invention is a golf club head comprising of a frontal portion further comprising a striking face that defines a face center, located at a forward portion of the golf club head; a rear portion located aft of the striking face; and at least one weighting member located near a central portion of the golf club head in a heel to toe orientation, substantially in line with and behind the face center; wherein an x-axis is defined as a horizontal axis tangent to a geometric center of said striking face with the positive direction towards a heel of said golf club head, a y-axis is a horizontal axis orthogonal to said x-axis with a positive direction towards a crown of said golf club head, and a z-axis being orthogonal to both said x-axis and said y-axis with a positive direction towards a frontal portion of said golf club head, and wherein said golf club head has a MOI-Y to MOI-Z ratio of greater than about 1.50. 
     In another aspect of the present invention is a golf club head comprising of a golf club head comprising of a frontal portion further comprising a striking face that defines a face center, located at a forward portion of the golf club head, a rear portion located aft of the striking face, and at least one weighting member located near a central portion of the golf club head in a heel to toe orientation, substantially in line with and behind the face center; wherein an x-axis is defined as a horizontal axis tangent to a geometric center of said striking face with the positive direction towards a heel of said golf club head, a y-axis is a horizontal axis orthogonal to said x-axis with a positive direction towards a crown of said golf club head, and a z-axis being orthogonal to both said x-axis and said y-axis with a positive direction towards a frontal portion of said golf club head, and wherein said golf club head has a MOI-X, MOI-Z, and CG-Z numbers that satisfies the equation 
     
       
         
           
             
               
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     In another aspect of the present invention, the golf club head has a volume of 250 cc to 400 cc. More particularly, the golf club head comprises a frontal portion further comprising a striking face that defines a face center, located at a forward portion of the golf club head, a rear portion located aft of the striking face, and at least one weighting member located near a central portion of the golf club head in a heel to toe orientation, substantially in line with and behind the face center; wherein an x-axis is defined as a horizontal axis tangent to a geometric center of said striking face with the positive direction towards a heel of said golf club head, a y-axis is a vertical axis orthogonal to said x-axis with a positive direction towards a crown of said golf club head, and a z-axis being orthogonal to both said x-axis and said y-axis with a positive direction towards a frontal portion of said golf club head. The golf club head in accordance with the present invention achieves a relative low Moment of Inertia (MOI) about the z-axis (MOI-Z), a low MOI about the shaft axis (MOI-SA), all combined with a high MOI about the x-axis and low MOI about the y-axis (MOI-X and MOI-Y) and maintaining a consistently and relatively low CG. Moreover, the preferred embodiment golf club head has a MOI-X, MOI-Y, MOI-Z, CG-Z and CG-Y numbers that satisfies a number of equations. In one embodiment, the golf club head can have a MOI-X/MOI-Y of greater than or equal to 0.65. In another embodiment, the golfclub head can have a CG-Z to club head depth ratio of greater than or equal to about 0.33. Moreover, the golf club head can have a CG-Y to crown height ration of less than or equal to about 0.35. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. 
         FIG. 1  of the accompanying drawings shows a perspective view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG. 2  of the accompanying drawings shows a top view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG. 3  of the accompanying drawings shows a frontal view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG. 4  of the accompanying drawings shows a plot of MOI-Z vs MOI-Y numbers for the current invention, compared to prior art golf club heads; 
         FIG. 5  of the accompanying drawings shows a plot of MOI-Z vs MOI-Shaft Axis numbers for the current invention, compared to prior art golf club heads; 
         FIG. 6  of the accompanying drawings shows a plot of MOI-Y vs MOI-Shaft Axis numbers for the current invention, compared to prior art golf club heads; 
         FIG. 7  of the accompanying drawings shows a plot of MOI-X vs MOI-Shaft Axis numbers for the current invention, compared to prior art golf club heads; 
         FIG. 8  of the accompanying drawings shows a plot of MOI-Z vs CG-B/Face Width numbers for the current invention, compared to prior art golf club heads; 
         FIG. 9  of the accompanying drawings shows a plot of MOI-Z vs CG-B/Head Width numbers for the current invention, compared to prior art golf club heads; 
         FIG. 10  of the accompanying drawings shows a plot of MOI-X/MOI-Z vs CG-Z numbers for the current invention, compared to prior art golf club heads; 
         FIG. 11  of the accompanying drawings shows a plot of MOI-Y/MOI-Z vs CG-Z numbers for the current invention, compared to prior art golf club heads; 
         FIG. 12  of the accompanying drawings shows a plot of (MOI-X+MOI-Y)/MOI-Z vs CG-Z numbers for the current invention, compared to prior art golf club heads; 
         FIG. 13  of the accompanying drawings shows an exploded sole perspective view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG. 14  of the accompanying drawings shows a horizontal cross-sectional view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG. 15  of the accompanying drawings shows a vertical cross-sectional view of a golf club head in accordance with an exemplary embodiment of the present invention; 
         FIG. 16  of the accompany drawings shows a perspective view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 17  of the accompanying drawings shows a top view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 18  of the accompanying drawings shows a frontal view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 19  of the accompanying drawings shows a horizontal cross-sectional view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 20  of the accompanying drawings shows a vertical cross-sectional view of a golf club head in accordance with an alternative embodiment of the present invention; 
         FIG. 21  of the accompanying drawings shows a top view of a golf club head in accordance with an alternative embodiment of the present invention; and 
         FIG. 22  of the accompanying drawings shows a frontal view of the golf club head in accordance with  FIG. 21  with the face insert removed; and 
         FIG. 23  is an exploded view of the golf club head in  FIGS. 21-22  from a heel perspective. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description describes the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
     Various inventive features are described below and each can be used independently of one another or in combination with other features. However, any single inventive feature may not address any or all of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below. 
     Before beginning the discussion on the current inventive golf club head and its performance criteria, it is worthwhile to note here that the discussion below will be based on a coordinate system  101  and axis of measurement that is critical to the proper valuation of the performance numbers. Hence, it is important to recognize here that although the specific names given for the measurements below are important to the understanding of the current invention, the naming nomenclature should not be viewed in vacuum. Rather, the importance is the numbers presented below needs to be taken in context with how the coordinate system relates to the golf club head itself. In order to provide sufficient information to avoid any ambiguity, each of the figures provided below referencing a golf club head will all be accompanied by a coordinate system that is all consistent with one another. 
     Pursuant to the above, and to establish the reference coordinate system for the subsequent discussion,  FIG. 1  of the accompanying drawings shows the coordinate system  101  that will be used to define the various measurement and performance figures for the current invention. The x-axis used by the current discussion refers to the axis that is horizontal to the striking face from a heel to toe direction. The y-axis used by the current discussion refers to the vertical axis through the club in a crown to sole direction. The z-axis used by the current discussion refers to the horizontal axis that is horizontal front to back in a forward and rear direction. Alternatively speaking, it can be the x-axis is defined as a horizontal axis tangent to a geometric center of the striking face with the positive direction towards a heel of the golf club head, a y-axis is a horizontal axis orthogonal to the x-axis with a positive direction towards a top of the golf club head, and a z-axis being orthogonal to both the x-axis and the y-axis with a positive direction towards a front of the golf club head. The x-y-z coordinate system described above shall be the same for all subsequent discussions. 
       FIG. 1  of the accompanying drawings shows a perspective view of a golf club head  100  in accordance with an embodiment of the present invention. In this perspective view shown in  FIG. 1 , the golf club head  100  may not look very different than other golf club heads, but the subsequent figures and discussion will show that the internal components and the material properties of this golf club head  100  allows it to achieve unique performance properties consistent with the present invention. What  FIG. 1  does show is a location of a face center  102  of the frontal portion  104  of the golf club head  100  that contains a striking face insert. The face center, as shown here and referred to by the current invention, relates to the geometric center of the striking face portion of said golf club head  100  measured by the USGA provided face center template as it would be commonly known to a person of ordinary skill in the golf club art. Attached to the rear of the frontal portion  104  is a rear portion  106 , which makes up the back end of the golf club head  100 . 
     In this embodiment of the present invention, the frontal portion  104  may generally be made out of a steel type material having a density of between about 7.75 g/cc and about 8.00 g/cc, allowing a significant portion of the mass of the golf club head  100  to be concentrated at a frontal bottom region of the golf club head  100 . The rear portion  106  of the golf club head  100  in this embodiment of the present invention may generally be made out of the standard titanium material having a density of between about 4.00 g/cc and about 5.00 g/cc, allowing the rear portion  106  of the golf club head  100  to be relatively lightweight. However, it should be noted that in alternative embodiments of the present invention, the frontal portion  104  may also be made out of a standard titanium material such as TI-6-4, Ti-8-1-1, SP-700, or any other type of titanium material without departing from the scope and content of the present invention. 
     In order to illustrate more specific features of the golf club head  100 ,  FIGS. 2 and 3  of the accompanying drawings is provided to give more insight into some of the specific inherent characteristics of the golf club head  200  that will be important to determine its improved performance. First off,  FIG. 2  of the accompanying drawings, in addition to illustrating a golf club head  200  with a frontal portion  204  and a rear portion  206 , also shows a Center of Gravity (CG)  210  location along the x-z plane on the coordinate system  201 . Although the details of the CG location will be discussed in more detail with respect to the inertia properties of the golf club head  200 , the general direction of the current inventive golf club head  200  is to have a CG location that is strategically located at a distance back from the frontal portion of the golf club head  200  to yield the most advantageous results. 
     More specifically, in the current invention, the CG location rearward from the striking face, identified here as CG-Z is generally between about 25 mm to about 40 mm, more preferably between about 26 mm and about 38 mm, and most preferably between about 27 mm and about 36 mm, all measured rearward from the face center  202  along the Z axis shown by the coordinate system  201 . In addition to illustrating the CG-Z  212  numbers, an alternative measurement method is provided to measure how far back the CG  210  is located within the club head  200 . In this alternative method, the CG  210  is measured from the shaft axis  215 , and this measurement is illustrated as CG-C  214  is generally measured to be between about 10 mm to about 25 mm, more preferably between about 12 mm to about 23 mm, and most preferably between about 14 mm to about 21 mm, all measured rearward from the shaft axis  215  along the Z axis shown by the coordinate system  201 . 
     It should be noted that the strategic location of the CG  210  location rearward along the Z axis, irrespective of whether it is measured from the face center  202  or the shaft axis  215 , is critical to the proper functionality of the current inventive golf club head  200 . If the CG  210  location is too far forward, the golf club head  200  can result in a low MOI-X and MOI-Y as well as too low of a backspin when contacting a golf ball to yield desirable results. However, in the alternative, if the CG  210  location is too far rearward, the golf club head  200  can produce too much spin to yield desirable results. Hence, it can be seen that the criticality of the CG location rearward of along the Z axis is a fine balance of a very specific range of numbers that can severely hinder the performance of the golf club head  200  if it deviates from the ranges articulated above. 
       FIG. 3  of the accompanying drawings shows another important CG  210  measurement that is important to the proper functionality of the current invention. More specifically,  FIG. 3 , in addition to illustrating all of the basic components of the golf club head  200  as previously shown, now introduces another measurement of the CG  210  location from the shaft axis  215  along an x-y plane shown by coordinate system  301 . More specifically,  FIG. 3  shows a CG  210  measurement that is perpendicular to the shaft axis  215  along this x-y plane away from the actual shaft axis  215  itself, called CG-B for the purpose of this application. The CG-B of the golf club head  210  may generally be between about 32 mm and about 39 mm, more preferably between about 33 mm and about 38 mm, and most preferably about 35 mm. 
     In addition to illustrating the very important CG-B measurement of the golf club head,  FIG. 3  of the accompanying drawings also shows measurements W 1  and W 2 , indicative of the width of the golf club head  200  itself and the width of the face of the golf club head  200  respectively. In this embodiment of the present invention, the width of the golf club head W 1  may generally be between about 130 mm to and about 140 mm, more preferably between about 132 mm to about 138 mm, and most preferably about 136 mm. The width of the face W 2  may generally be between about 95 mm and about 105 mm, more preferably between about 97 mm and about 103 mm, and most preferably about 100 mm. 
     Now that the CG location of the golf club head  200  has been defined, the other important features associated with the present invention relates to the Moment of Inertia (MOI) of the golf club head  200 . The MOI of a golf club head generally depicts the ability of the golf club head to resist twisting when it impacts an object at a location that is not aligned with the CG location previously discussed. More specifically, the MOI of a golf club head relates to the ability of the golf club head to resist twisting relative to the CG location. As is well known in the art, the MOI of the golf club head  200  may generally be broken down to three unique components, relating to the ability of the golf club head  200  to resist rotation along three different axes, with the origin of the three axes being coincident with the CG location of the golf club head. The three axes of rotation for which the MOI is generally referred coincides with the coordinate system  101 ,  201 , and  301  (shown in  FIG. 1 ,  FIG. 2 , and  FIG. 3  respectively), where MOI-X is measured about the X axis passing through the CG location, MOI-Y is measured about the Y axis passing through the CG location, and MOI-Z is measured about the Z axis passing through the CG location. 
     As the previously discussion already hinted, the current inventive golf club head  200  may generally have a high value for the MOI about the X and Y axis, while maintaining a low MOI about the Z axis. More specifically, the current inventive golf club head  200  may generally have a MOI about the X axis (MOI-X) that is greater than about 300 kg-mm 2 , more preferably greater than about 310 kg-mm 2 , and most preferably greater than about 320 kg-mm 2  without departing from the scope and content of the present invention. As for MOI about the Y axis (MOI-Y), the present inventive golf club head  200  may generally have a MOI about the Y axis that is greater than about 400 kg-mm 2 , more preferably greater than about 410 kg-mm 2 , and most preferably greater than about 420 kg-mm 2  all without departing from the scope and content of the present invention. 
     While the large MOI number about the X and Y axis discussed previously are not necessarily new in the world of golf club head  200  designs, the ability to maintain those number while decreasing the MOI about the Z axis (MOI-Z) and holding the MOI about the Shaft axis (MOI-SA) to a minimum is what makes the present invention. While the majority of the golf industry are focusing their attention so intently on the ability of the golf club head  200  to offer forgiveness on off center hits by trying to increase the MOI-Y to astronomical numbers, they have failed to recognize the ability of the golf club head  200  to offer more club head speed and more ball speed by decreasing the MOI about the Z axis (MOI-Z) in concert with the minimization of MOI about the Shaft axis (MOI-SA). The present invention focuses its attention on that very specific unrecognized characteristic, and has developed a golf club head  200  design to take advantage and maximize the performance of the golf club head  200  by focusing on the MOI about the Z axis. More specifically, a golf club head  200  in accordance with the present invention may generally have a MOI about a Z axis that is less than about 268 kg-mm 2 , more preferably less than about 260 kg-mm 2 , and most preferably less than about 250 kg-mm 2 . Additionally, the golf club head  200  may generally have a MOI about a Shaft axis that is less than about 850 kg-mm 2 . 
     It should be noted here that the low MOI-Z numbers mentioned above cannot by itself accurately depict and describe the current invention; as old school golf club heads with much smaller footprint may inherently have a low MOI-Z number, combined with a low MOI-X and MOI-Y number. Hence, it is important to recognize here that the present invention is predicated on the interrelationship between the different numbers achieved by the MOI-X and MOI-Y numbers as it relates to MOI-Z and MOI-SA, in combination with the CG location articulated above. 
     In order to capture the essence of the present invention, a ratio can be created between the MOI-X, MOI-Y, and MOI-Z to help provide one way to quantify this relationship. In one first example, a MOI-X to MOI-Z Ratio can be created to help quantify the current golf club head  200  as illustrated by Eq. (1) below. In one exemplary embodiment of the present invention, the MOI-X to MOI-Z Ratio is greater than about 1.10, more preferably greater than about 1.20, and most preferably greater than about 1.28. 
     
       
         
           
             
               
                 
                   
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     Similarly, a comparable ratio can be established called a MOI-Y to MOI-Z Ratio to quantify the current golf club head  200  as illustrate by Eq. (2) below. In one exemplary embodiment of the present invention, the MOI-Y to MOI-Z ratio is greater than about 1.50, more preferably greater than about 1.57, and most preferably greater than about 1.68. 
     
       
         
           
             
               
                 
                   
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     As it can be seen from the relationship established by the Eqs (1) and (2) above, the present invention relates to a specific relationship between the MOI of the golf club head  200  with an extra focus on minimizing the MOI-Z about the Z axis while maintaining a high MOI-Y. In order to further illustrate this, a graphical representation of the relationship is provided as  FIG. 4 . 
       FIG. 4  of the accompanying drawings shows a plot of various data points of various golf club head and their respective MOI-Z numbers as well as their MOI-Y number. In  FIG. 4  the X-axis represents the MOI-Y while the Y-axis represents the MOI-Z. The data points shown in  FIG. 4  have been separated into circular dots and asterisks. The circular dots are representative of the data of “prior art” golf club heads, whereas the asterisk data points represent the current invention. 
     A closer examination of the prior art data points will show that none of the golf club heads in the prior art are capable of achieving a MOI-Z number of lower than 268 kg-mm 2 , for all modern day golf club heads that have a MOI-Y of greater than 420 kg-mm 2 . However, an even closer examination of the graph of  FIG. 4  will show that as the MOI-Y numbers of the golf club heads exceeds 500 kg-mm 2 , an additional relationship can be established to quantify the ability of the present invention to achieve the optimal MOI-Z to MOI-Y relationship. In fact, that relationship is shown in  FIG. 4  as Y≤0.47x+33. Combining the two conditions articulated above can result in another unique way to quantify the present invention whereas, for golf club heads having a MOI-Y of between 420 kg-mm 2  and 500 kg-mm 2 , the golf club head generally has a MOI-Z of less than about 268 kg-mm 2 ; however, for golf club heads having a MOI-Y of greater than 500 kg-mm 2 , the golf club head may have a MOI-Z that satisfies Eq. (3) below: 
       MOI-Z≤(0.47*MOI-Y)+33  Eq. (3)
 
     Alternatively speaking, it can be said that in one embodiment of the present invention, the golf club head  200  may have a MOI-Z that satisfies the relationship MOI-Z≤(0.47*MOI-Y)+0.33 if the MOI-Y number is greater than 500 kg-mm 2 , and a MOI-Z that is less than 268 kg-mm 2  if the MOI-Y number is between 420 kg-mm 2  and 500 kg-mm 2 . 
       FIG. 5  of the accompanying drawing introduces another MOI value relating to a golf club head not previously discussed named MOI-Shaft Axis (MOI-SA). The MOI of a golf club head as it relates to the shaft axis is defined as the ability of the golf club head to resist twisting upon impact with a golf ball at a location that is not aligned with the shaft axis. A golf club head in accordance with the present invention may generally have a MOI-SA of less than about 850 kg-mm 2 , more preferably less than about 800 kg-mm 2 , and most preferably less than about 750 kg-mm 2 . The relationship between the MOI-SA and MOI-Z is highlighted in  FIG. 5  and is important to the present invention.  FIG. 5  of the accompanying drawings shows that irrespective of the MOI-SA numbers, all of the prior art golf club heads have a MOI-Z of greater than about 268 kg-mm 2 , while all of the current inventive golf club heads have a MOI-Z of less than about 268 kg-mm 2 . 
       FIG. 6  of the accompanying drawings establishes a graphical relationship between the MOI-Y of the golf club head with the newly introduced MOI-SA. As a closer examination of the graph shown in  FIG. 6  will show, the current invention is capable of achieving a higher than average MOI-Y, all while keeping a relatively small MOI-SA. Similar to previous plots, the circular points on the plot will refer to prior art golf club heads, while the asterisks will refer to the current invention. Hence, it can be seen that the present invention occupies a previously unachieved space delineated by an equation Y≥0.52x+147, which when put into context with the variables used in this plot, yields Eq. (4) below: 
       MOI-Y≥(0.52*MOI-SA)+147  Eq. (4)
 
       FIG. 7  of the accompanying drawings establishes a graphical relationship between the MOI-X of the golf club head with now a familiar MOI-SA. As a closer examination of the graph shown in  FIG. 7  will show, the current invention is capable of achieving a higher than average MOI-X, all while keeping a relatively small MOI-SA. Hence, it can be seen that the present invention occupies a previously unachieved space delineated by an equation Y≥0.40x+50, which when put into context with the variables used in this plot, yields Eq. (5) below: 
       MOI-X≥(0.40*MOI-SA)+50  Eq. (5)
 
       FIG. 8  of the accompanying drawings establishes a graphical relationship between the MOI-Z of the golf club head with a ratio of CG-B/Face Width. Both the measurement for CG-B and Face Width can be found in  FIG. 3  of the accompanying drawings as well as the accompanying discussion in paragraphs [0022] and [0023]. The CG-B measurement is explicitly shown in  FIG. 3 , while the Face Width referred to by the chart in  FIG. 8  is shown as W 2 . A closer examination of the graph shown in  FIG. 8  will show that the current invention is capable of achieving a lower MOI-Z, while keeping the CG-B/Face Width number fairly consistent above 0.4. CG-B/Face Width is indicative of the location of the center of gravity while keeping a moderately sized face golf club head. 
     In the chart shown in  FIG. 8 , it can be seen that the present invention occupies a previously unachieved space delineated by an equation Y≤1000x−150, which when put into context with the variable used in this plot, yields Eq. (6) below: 
     
       
         
           
             
               
                 
                   
                     MOI 
                     ⁢ 
                     
                       - 
                     
                     ⁢ 
                     Z 
                   
                   ≤ 
                   
                     
                       ( 
                       
                         1 
                         ⁢ 
                         0 
                         ⁢ 
                         0 
                         ⁢ 
                         0 
                         * 
                         
                           
                             CG 
                             ⁢ 
                             
                               - 
                             
                             ⁢ 
                             B 
                           
                           
                             Face 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             Width 
                           
                         
                       
                       ) 
                     
                     - 
                     
                       1 
                       ⁢ 
                       5 
                       ⁢ 
                       0 
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     6 
                     ) 
                   
                 
               
             
           
         
       
     
       FIG. 9  of the accompanying drawings establishes a graphical relationship between the MOI-Z of the golf club head with a ratio of CG-B/Head Width. Both the measurement for CG-B and Head Width can be found in  FIG. 3  of the accompanying drawings as well as the accompanying discussion above in paragraph [0022] and [0023]. The CG-B measurement is explicitly shown in  FIG. 3 , while the Head Width referred to by the chart in  FIG. 9  is shown as W 1 . A closer examination of the graph shown in  FIG. 9  will show that the current invention is capable of achieving a lower MOI-Z, while keeping the CG-B/Head Width number fairly consistent above 0.34. CG-B/Head Width is indicative of the location of the center of gravity while keeping a moderately sized head width of the golf club head. 
     In the chart shown in  FIG. 9 , it can be seen that the present invention occupies a previously unachieved space delineated by a MOI-Z number that is lower than 320 kg-mm 2  combined with a CG-B/Head Width number that is greater than about 0.34. 
       FIG. 10  of the accompanying drawings establishes another graphical relationship of the performance of a golf club in accordance with an embodiment of the present invention. More specifically,  FIG. 10  of the accompanying drawings shows a relationship between MOI-X/MOI-Z and CG-Z. (MOI-X is used interchangeably with Ixx, MOI-Y is used interchangeably with Iyy, and finally MOI-Z is used interchangeably with Izz) The definition and measurement for CG-Z of a golf club head can be found in the earlier discussion relating to  FIG. 2  of the accompanying drawings, while the background information establishing MOI-X and MOI-Z have already been discussed previously. Although the selection of the plot for the X and Y axis may appear random initially to a person not versed in golf club design, but a closer examination will reveal that the relationship created here is absolutely critical to the proper performance of the present invention. On the Y axis of the plot shown in  FIG. 10 , a ratio between MOI-X and MOI-Z is created here. This ratio created illustrates the ability of the current inventive golf club head to maximize the value of one variable (MOI-X) while minimizing the value of another variable (MOI-Z); which resonates with the theme of the present invention. The CG-Z used in the X axis of the plot shown in  FIG. 10  is indicative of the CG location of the golf club head rearward from the front of the golf club head, and it is desirable to maintain that in the range described above. 
     A further examination of the plot shown in  FIG. 10  will show that the present invention occupies a portion of the graph that was previously unachieved. This portion of the graph is delineated from other prior art data points by an equation Y≥6.7501x−99.30, which when put into context with the variable used in this plot, yields Eq. (7) below: 
     
       
         
           
             
               
                 
                   
                     
                       MOI 
                       ⁢ 
                       
                         - 
                       
                       ⁢ 
                       X 
                     
                     
                       MOI 
                       ⁢ 
                       
                         - 
                       
                       ⁢ 
                       Z 
                     
                   
                   ≥ 
                   
                     
                       ( 
                       
                         
                           6 
                           . 
                           7 
                         
                         ⁢ 
                         5 
                         ⁢ 
                         0 
                         ⁢ 
                         1 
                         * 
                         CG 
                         ⁢ 
                         
                           - 
                         
                         ⁢ 
                         Z 
                       
                       ) 
                     
                     - 
                     
                       9 
                       ⁢ 
                       
                         9 
                         . 
                         3 
                       
                       ⁢ 
                       0 
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     7 
                     ) 
                   
                 
               
             
           
         
       
     
       FIG. 11  of the accompanying drawings establishes another graphical relationship of a golf club in accordance with an embodiment of the present invention by creating a relationship between the MOI-Y/MOI-Z and CG-Z. The definition and measurement for CG-Z of a golf club head can be found in the earlier discussion relating to  FIG. 2  of the accompanying drawings, while the background information establishing MOI-Y and MOI-Z have already been discussed previously. Similar to the previous discussion, the relationship between MOI-Y and MOI-Z is indicative of the ability of a golf club to achieve great forgiveness along the MOI-Y axis, while minimizing the MOI-Z of a golf club head to achieve a higher ball speed, as previously discussed. Similar to previous discussion,  FIG. 11  of the accompanying drawings shows that the present invention is capable of achieving performance characteristics that was previously unachieved. This portion of the graph is delineated from other prior art data points by an equation Y≥11.349 x−175.76, which when put into context with the variable used in this plot, yields Eq. (8) below: 
     
       
         
           
             
               
                 
                   
                     
                       MOI 
                       ⁢ 
                       
                         - 
                       
                       ⁢ 
                       Y 
                     
                     
                       MOI 
                       ⁢ 
                       
                         - 
                       
                       ⁢ 
                       Z 
                     
                   
                   ≥ 
                   
                     
                       ( 
                       
                         1 
                         ⁢ 
                         
                           1 
                           . 
                           3 
                         
                         ⁢ 
                         4 
                         ⁢ 
                         9 
                         * 
                         CG 
                         ⁢ 
                         
                           - 
                         
                         ⁢ 
                         Z 
                       
                       ) 
                     
                     - 
                     
                       1 
                       ⁢ 
                       7 
                       ⁢ 
                       
                         5 
                         . 
                         7 
                       
                       ⁢ 
                       6 
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     8 
                     ) 
                   
                 
               
             
           
         
       
     
       FIG. 12  of the accompanying drawings establishes another graphical relationship of a golf club in accordance with an embodiment of the present invention by creating a relationship between the (MOI-X+MOI-Y)/MOI-Z and CG-Z. The definition and measurement for CG-Z of a golf club head can be found in the earlier discussion relating to  FIG. 2  of the accompanying drawings, while the background information establishing MOI-X, MOI-Y, and MOI-Z have already been discussed previously. Similar to the previous discussion, the relationship between MOI-X, MOI-Y, and MOI-Z is indicative of the ability of a golf club to achieve great forgiveness along both the MOI-X and MOI-Y axes, while minimizing the MOI-Z of a golf club head to achieve a higher ball speed, as previously discussed. Similar to previous discussion,  FIG. 12  of the accompanying drawings shows that the present invention is capable of achieving performance characteristics that was previously unachieved. This portion of the graph is delineated from other prior art data points by an equation Y≥18.67x−296.63, which when put into context with the variable used in this plot, yields Eq. (9) below: 
     
       
         
           
             
               
                 
                   
                     
                       ( 
                       
                         
                           MOI 
                           ⁢ 
                           
                             - 
                           
                           ⁢ 
                           X 
                         
                         + 
                         
                           MOI 
                           ⁢ 
                           
                             - 
                           
                           ⁢ 
                           Y 
                         
                       
                       ) 
                     
                     
                       MOI 
                       ⁢ 
                       
                         - 
                       
                       ⁢ 
                       Z 
                     
                   
                   ≥ 
                   
                     
                       ( 
                       
                         1 
                         ⁢ 
                         
                           8 
                           . 
                           6 
                         
                         ⁢ 
                         7 
                         * 
                         CG 
                         ⁢ 
                         
                           - 
                         
                         ⁢ 
                         Z 
                       
                       ) 
                     
                     - 
                     
                       2 
                       ⁢ 
                       9 
                       ⁢ 
                       
                         6 
                         . 
                         6 
                       
                       ⁢ 
                       3 
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     9 
                     ) 
                   
                 
               
             
           
         
       
     
       FIGS. 13 through 15  show different exploded and cross-sectional view of golf club heads and their internal components that are used to achieve the performance characteristics described above.  FIG. 13  shows an exploded perspective view of an exemplary design of a golf club head  1300  in capable of achieving the performance characteristics previously discussed. The golf club head  1300  is made out of the essential components previously discussed in  FIG. 1  in terms of a frontal portion  1304  and a rear portion  1306 . However, this exploded view of golf club head  1300  allows additional components to be shown in more detail. More specifically,  FIG. 13  illustrates that, as often the case in a golf club head construction, the frontal portion  1304  may further be comprised out of a separate component called the striking face insert  1320  to form the striking portion of the golf club head  1300 . The rear portion  1306  of the golf club head  1300  is where it gets more interesting. In order to achieve the performance numbers above of a higher MOI-Y, a higher MOI-X, and a lower MOI-Z, a significant amount of mass is re-allocated towards the center of the golf club head away from the perimeter. In order to achieve this, the present invention utilizes four weighting members that are all comprised out of a high density material that have a higher density than the frontal portion  1304  or the rear portion  1306 . The four weighting members can be separated into a frontal sole weight  1322 , frontal internal weight  1324 , rear internal weight  1326 , and rear sole weight  1328 , and these weighting members may all generally have a material density of greater than 13 g/cc, more preferably greater than about 15 g/cc, and most preferably greater than about 17 g/cc. 
     It should be noted that in this exemplary embodiment of the present invention, all of the weighting members  1322 ,  1324 ,  1326 , and  1328  are all made out of the same material having the same heavy density discussed previously. However, in alternative embodiments of the present invention, different densities of tungsten may be used for different weighting members depending on the design criteria and desired CG location all without departing from the scope and content of the present invention. 
       FIG. 14  of the accompanying drawings shows a cross-sectional view of a golf club head  1400  in accordance with an exemplary embodiment of the present invention. The cross-sectional view of the golf club head taken across a horizontal plane across the face of the golf club head  1400  to allow some of the relationship between the golf club head  1400  and the various weighting member  1422 ,  1424 ,  1426 , and  1428  to be shown more clearly. In addition to the weighting members, the cross-sectional view of the golf club head  1400  shown in  FIG. 14  also allows the face center  1402  and the CG location  1410  to be re-introduced as it relates to the weighting members. It can be seen from this view that at least one weighting member is located near a central portion of the golf club head in a heel to toe direction, and substantially in line with and behind said face center. 
       FIG. 15  of the accompanying drawings shows a cross-sectional view of a golf club head  1500  in accordance with an exemplary embodiment of the present invention taken along a vertical plane that passes through the center of the face. This cross-sectional view of the golf club head  1500  shown in  FIG. 15  provides a little more information on the interworking relationship between the components. More specifically,  FIG. 15  shows a striking face insert  1520  being located in the frontal portion  1504  of the golf club head  1500 . In addition to the above,  FIG. 15  also shows that the frontal sole weight  1522  is located in a receptacle that is created within the frontal portion  1504 . Although not shown in this cross-sectional view in  FIG. 15 , the frontal internal weight is also located in the frontal portion  1504 . Attached to the rear of the frontal portion  1504  is the rear portion  1506 . The rear portion  1506  forms the aft body portion of the golf club head  1500 , and contains the rear internal weight  1526  and the rear sole weight  1528 . These weighting members, combined with the unique materials used to form the frontal portion  1504  and the rear portion  1506 , allow the golf club head  1500  to achieve the unique performance characteristics outlined previously. 
       FIGS. 16 through 20  show various perspective and cross-sectional views of a golf club head  1600  in accordance with an alternative embodiment of the present invention that is capable of achieving the performance goals previously mentioned. Similar to the previous embodiment illustrated by  FIGS. 1-3 and 13-15 , a lot of weighting member is located near the center of the golf club head  1600  in a heel to toe orientation along the x-axis behind the face center  1602  to help minimize the MOI-Z of the golf club head  1600 . 
     More specifically,  FIG. 16  of the accompanying drawings shows a perspective view of a golf club head  1600  in accordance with this alternative embodiment of the present invention. Although not much can be gleamed from this perspective view of the golf club head  1600 , it does lay the ground work for the subsequent discussion relating to this particular embodiment of the present invention. Finally,  FIG. 16 , similar to previous figures that illustrate a golf club head, provides a coordinate system  1601  to guide the subsequent discussions. 
       FIG. 17  of the accompanying drawings shows a top view of a golf club head  1600  in accordance with this alternative embodiment of the present invention. In this top view, a couple of familiar dimensions are reintroduced here. First and foremost, the top view of the golf club head  1600  shown in  FIG. 17  allows the relationship between the face center  1602  and the CG  1610  to be shown in more detail. When measured along the Z-axis, the measurement CG-Z is shown as  1612 . The location of the CG, when referenced against the shaft axis  1615  yields another way to measure the CG location along the Z-axis called CG-C  1614 . The number ranges for the CG-Z  1612  and CG-C  1614  measurements are not much different from previous discussions, but this embodiment of the present invention provides an alternative way to achieve those targets with a slightly different construction without the need for a multi-material chassis. 
       FIG. 18  of the accompanying drawings shows a frontal view of a golf club head  1600  in accordance with this alternative embodiment of the present invention. In this frontal view, we can see another feature utilized by the present embodiment to help achieve the performance criteria of the current invention. More specifically,  FIG. 18  shows that in this embodiment of the present invention, in order to minimize the MOI-Z of the golf club head  1600 , weight is removed from the extremities of the golf club head  1600  via a reshaping of the contour at the toe portion of the golf club head  1600 . This reshaping of the contour at the toe portion of the golf club head  1600  not only removes weight from the extremities, but also tightens up the face profile of the golf club head  1600  to create a unique performing golf club head  1600 . 
     In addition to illustrating this toe contour profiling,  FIG. 18  also shows a CG-B  1616  measurement relating to the shaft axis  1615  similar to the previous discussion. Once again, the CG-B  1616  measurement range is in line as the previous discussion have mentioned, and does not deviate much from the design intent of the present invention. 
       FIG. 19  of the accompanying drawings shows a cut open cross-sectional view of a golf club head  1600  in accordance with this alternative embodiment of the present invention taken along a horizontal plane. In this embodiment of the present invention, the overarching theme of placing the weights along the central portion of the golf club head  1600  reemerges again. More specifically, the golf club head  1600  further comprises of a frontal internal weight  1624  and a rear internal weight  1626 . These weights, however, different from prior embodiments of the present invention in that they can be made out of the same material as the body portion of the golf club head  1600  such as titanium and be directly cast into the body without departing from the scope and content of the present invention. These weighting members  1624  and  1626  may also be made out of a tungsten type material having a total weight of 20-23 grams to further improve the performance of the golf club head  1600  without departing from the scope and content of the present invention. 
       FIG. 20  of the accompanying drawings provides another cross-sectional cut open view of the golf club head  1600  in accordance with an alternative embodiment of the present invention taken along a vertical plane. Once again, the measurements here are very similar to the discussion previously relating to prior embodiments and the CG-Z  1612  number remain within the same range as the prior discussion. This cross-sectional cut open view of the golf club head  1600  taken along this line allows the profile and geometry of the frontal internal weight  1624  and the rear internal weight  1626  to be shown more clearly and their relationship together with the body portion of the golf club head  1600 . 
     Referring to  FIGS. 21-23  the golf club head  2000  has preferred mass and inertial properties as discussed below. Further, the golf club head  2000  comprises frontal portion comprising a striking face  2001  having a face center FC, a crown on the upper portion of the golf club head  2000  and a sole on the bottom portion of the golf club head  2000 . The golf club head  2000  further comprises a crown return  2002  and a sole return  2003  as part of the frontal portion and a central body member  2004  that are preferably all formed of metal. The central body member  2004  is located near the central portion of the golf club head  2000  in a heel-to-toe orientation, substantially in line along the z-axis, as set forth above, and extends from the sole return  2003  to a back edge  2005  of the golf club head. The golf club head  2000  is further comprised of a crown body member  2006  made of a non-metallic material and coupled to a toe side and heel side of the central body member  2004  and the crown return  2002  and the sole return  2003  to form an internal cavity  2007 . Preferably, as shown in  FIG. 23 , the central body member  2004  and striking face  2001  are formed of metal such as standard titanium materials such as TI-6-4, Ti-8-1-1, beta-titanium, and others that have a specific gravity of about 4 g/cc to 5 g/cc. Alternatively, the metal portions can preferably be formed of a standard steel materials such as stainless steel 450, that have a specific gravity of about 7 g/cc to 9 g/cc Most preferably, the central body member  2004  is cast from 450 ss and the striking face  2001  is formed from a forged, high-strength steel having a Ultimate Tensile Strength of greater than about 2000 MPa. The crown body member  2006  is preferably formed of a standard composite fiber composite laminate, chopped fiber composite generally referred to as fiber-reinforced plastic (FRP), or a composite material such as those disclosed in U.S. Publication No. 2015-0360094, which is incorporated by reference in its entirety herein. Alternatively, the crown body member  2006  is preferably formed of structural material having a density of less than 3.0 g/cc such as a thermoplastic material such as those disclosed in U.S. application Ser. No. 16/528,210, filed on Jul. 31, 2019, which is incorporated by reference in its entirety herein, polyetherimide (PEI), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSU), polyacryletherketone (PAEK), polyetherketoneketone (PEKK) and polyvinyl chloride (PVC). The crown body member  2006  is preferably formed by compression molding, injection molding or 3D printing. The crown body member  2006  is essentially u-shaped as shown in  FIG. 23  such that golf club head  2000  has reduced mass along the heel and toe portions and reduced MOI-Y. 
     In the preferred embodiment, the central body member  2004  is cast from 450 ss and the striking face  2001  is formed of forged AerMet 340 ss. Preferably, the central body member  2004 , the crown return  2002 , the sole return  2003 , and back edge  2005 , combined, have a mass of about 80 grams to 110 grams and, more preferably, from about 90 grams to 100 grams. The striking face  2001  preferably has a mass of about 40 grams to 50 grams including the weld to the frontal portion. Overall, the 400 cc golf club head  2000  preferably has a mass of about 190 grams to 200 grams for a 45 inch shaft and 200 grams to 210 grams for a 44 inch shaft. 
     The golf club head  2000  preferably has a volume of between 250 cc and 400 cc, and more preferably between about 300 cc and 400 cc. Most preferably, the golf club head  2000  has a volume of between 350 cc and 400 cc. Moreover, the golf club head  2000  has a center of gravity CG-Z that is located a distance back from the face center that is greater than or equal to 0.33 times the golf club head depth  2015 . Golf club head depth  2015 , as referred to in the present invention, is defined as a depth of the golf club head  2000  measured front to back, from the leading edge to the rear most point of the golf club head  2000 , along a Z-axis. More preferably, the CG-Z is located a distance back from the face center a distance that is at least 0.35 times the golf club head depth  2015 . Still further, the golf club head  2000  has numerous additional features that can help quantify the location of the center of gravity of the golf club head  2000  from various other reference points. The golf club head  2000  has a CG-Y measurement that is a center of gravity a vertical distance up from the ground plane. (shown in  FIG. 22 ) The golf club head also has a CG-B measurement that is the perpendicular distance of the CG, measured from the shaft axis. (Shown in  FIG. 22 ) Finally, the golf club head  2000  also has a CG-C measurement that is the distance of the CG location away from the shaft axis measured along the z-axis as shown in  FIG. 21 . In the current invention, the CG-Y is generally less than or equal to about 0.4 times the face height,  2011 , measured from the ground plane. More preferably, the CG-Y is also generally less than or equal to about 0.35 times the crown height  2013 , also measured from the ground plane. 
     As stated above, it is important that the strategic location of the CG rearward along the z-axis be correct, irrespective of whether it is measured from the face center FC or the shaft axis SA, for the proper functionality of the current inventive golf club head  2000 . If the CG location is too far forward, the golf club head  2000  can have a low MOI-X and MOI-Y and low backspin when contacting a golf ball. However, in the alternative, if the CG location is too far rearward or too high, the golf club head  2000  can produce too much spin to yield desirable results. Hence, the CG location rearward along the z-axis and y-axis is important for the performance of the golf club head  2000 . 
     As shown in  FIG. 22 , the golf club head  2000  can further include a central support member  2010  such as wall member  2010  that is coupled to the central body member  2004 . The wall member  2010  preferably has a thickness t that is between 0.2 mm and 5 mm, and more preferably, between about 0.4 mm and 2 mm. 
     As shown in  FIGS. 22 and 23 , the golf club head  2000  can further include at least one weight member  2008  and  2009 , and more preferably, includes at least two weight members  2008  and  2009 . The first weight member  2008  is located on the sole portion of the club head, forward, near the striking face  2001  and the second weight member  2009  is located on the sole portion of the club head, aft, near the back edge  2005 . At least one of the weight members may generally have a material density of greater than 13 g/cc, and more preferably greater than about 15 g/cc. In a preferred embodiment, the first weight member  2008  preferably has a mass of between about 10 grams and 30 grams, more preferably between about 15 grams and 25 grams. In a preferred embodiment, the first weight member  2008  is located a distance  2017  of less than or equal to 15 mm from the CG as measured parallel to the z-axis to reduce the MOI-Y. Also, the first weight member  2008 , preferably, has greater mass than the second weight member  2009 . Most preferably, the first weight member  2008  has a mass that is at least 2 grams greater than the mass of the second weight member  2009 . 
     In another embodiment of the invention, the second weight member  2009  preferably has a mass of between about 20 grams and 50 grams, more preferably between about 25 grams and 35 grams. The first weight member  2008  can have a mass of less than half the mass of the second weight member  2009 . More preferably, the weight member  2009  is preferably located a distance of less than 20 mm from the back edge  2005  along the z-axis so that it can have a maximum effect on the spin and launch characteristics of the club head. 
     The golf club head  2000  also achieves a relative low Moment of Inertia (MOI) about the z-axis (MOI-Z), a low MOI about the shaft axis (MOI-SA), all combined with a high MOI about the x-axis (MOI-X) and low MOI about the y-axis (MOI-Y) and maintaining a consistently and relatively low CG discussed above. Moreover, the preferred embodiment golf club head has an MOI-Y of less than or equal to about 400 kg-mm 2  and more preferably less than or equal to about 300 kg-mm 2 . Furthermore, the golf club head  2000  has a MOI-X, MOI-Y, MOI-Z, CG-Z and CG-Y numbers that satisfies a number of relationships with one another. In one embodiment, the golf club head  2000  can have a MOI-X to MOI-Y of greater than or equal to 0.65 and more preferably between about 0.69 and 0.85. More preferably, the golf club head  2000  also has a MOI-Y to MOI-Z of greater than 1.5, and more preferably greater than about 1.57. Still further, the golf club head  2000  preferably has a MOI-X to MOI-Z ratio of greater than about 1.1, and more preferably greater than about 1.2. The following table demonstrates the difference of the present invention and an all titanium driver, the 915 D5. 
     
       
         
           
               
               
               
             
               
                   
               
               
                   
                   
                 Comparative 
               
               
                 Parameter 
                 Inventive Embodiment 
                 Example 
               
               
                   
               
             
            
               
                 Volume (cc) 
                 400 
                 400 
               
            
           
           
               
               
               
               
            
               
                 CG-X 
                 0 mm to 2 mm 
                 1.5 
                 mm 
               
               
                 CG-Y 
                 24 mm to 27 mm 
                 28.3 
                 mm 
               
               
                 CG-Z 
                 −28 mm to −32 mm 
                 −32.3 
                 mm 
               
               
                 CG-C 
                 17 mm to 20 mm 
                 18 
                 mm 
               
               
                 MOI-Y (kg*mm 2 ) 
                 375 kg*mm 2  to 400 kg*mm 2   
                 418 
                 kg*mm 2   
               
               
                 MOI-X (kg*mm 2 ) 
                 250 kg*mm 2  to 300 kg*mm 2   
                 256 
                 kg*mm 2   
               
               
                 MOI-Z (kg*mm 2 ) 
                 220 kg*mm 2  to 240 kg*mm 2   
                 280 
                 kg*mm 2   
               
               
                 MOI-SA (kg*mm 2 ) 
                 625 kg*mm 2  to 675 kg*mm 2   
               
               
                   
               
            
           
         
       
     
     Other than in the operating example, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, moment of inertias, center of gravity locations, loft, draft angles, various performance ratios, and others in the aforementioned portions of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear in the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the above specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used. 
     It should be understood, of course, that the foregoing relates to exemplary embodiments of the present invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.