Golf clubs are available featuring a wide variety of variations in design and construction, all of which se directed to achieve any number of desired results including improved performance and control. These variations include variations in the design, construction and weight of the club head, club shaft and club grip. Golf club heads are designed and manufactured separate and apart from the wide variety of different types of club shafts and club grips which are attached thereto to form assembled golf club. Golf club heads are typically designed so as to place the center of gravity of such club head at or near the center of the club face. In this regard, all wood club heads and some iron club heads are marked with appropriate markings such as a notch, line, V-shaped index type mark, circle or other mark to indicate the center of the club head face. Instructions, training and other golf aids typically remind the golfer to contact the ball at the center, or "sweet spot", of the club face. In golf terminology, the center of the club head face is supposed to be the center of percussion location. In actuality, this is not true as will be hereinafter explained.
It is commonly known that the optimal location on any club head for striking a golf ball corresponds to a location on the club head face, known as the center of percussion. The center of percussion is defined as that point located on the club face at which a body free to move as a compound pendulum about an axis of rotation can be struck so that the only motion imparted to the body will be a purely rotational motion around the body's axis of rotation. These concepts are more fully discussed and explained in Applicant's U.S. Pat. Nos. 5,094,101 and 5,277,059. Based upon the above assumption, striking a golf ball with a golf club using a compound pendulum motion at a location on the club head face corresponding to the center of percussion will impart a force to the golf ball which will be tangential to the arc of the pendulum motion of the club and which will direct the golf ball along a truer line corresponding to the intended direction of flight. This will also impart the best distance and direction/control characteristics to the ball since hitting the ball at the center of percussion location on the club face imparts no twisting or torsional motion to the ball. This results in maximum transfer of energy to the ball for a given golf swing. Striking a golf ball at club head face locations which do not correspond to the center of percussion location, even though using the same swinging motion, will cause a twisting or torsional motion to occur, which twisting or torsional motion will be imparted to the ball upon contact. This twisting motion will significantly affect the velocity, direction and effective force imparted to the ball and will produce widely varying results in ball distance, speed and direction.
When a particular club shaft and grip are affixed to a particular club head, the weight of the club shaft and grip shifts the center of gravity of the club head and, consequently, the center of percussion of the assembled golf club toward the heel of the club head. This shift in center of percussion away from the center of the club head face is not taken into account by the majority of golf club manufacturers and, as a result, the so-called "sweet spot" typically marked on a club head at the center of the club face, in actuality, does not coincide with the center of percussion location on such club face for the assembled golf club. This means that when a golfer makes contact with the ball at the center of the club head face, maximum transfer of energy is not imparted to the ball as explained above and, in total contrast to the desired goal, such contact will impart a twisting motion to the ball.
Because of this known misconception, professional golfers take the time to find the "sweet spot" or center of percussion associated with each individual golf club in their particular set of clubs since contacting the ball at the center of percussion location on each respective club head produces optimal results. Finding the center of percussion associated with each individual golf club can be achieved through trial and practice, or as explained hereinafter. Importantly, as discussed above, the actual location of the center of percussion for each individual golf club in a particular set of clubs does not coincide with the center of the respective club head faces and, in many instances, such centers of percussion are located at different locations for each respective club in a particular set. In a typical set of golf clubs, it has been observed that the center of percussion or "sweet spot" is actually located approximately 3/8 inch or more towards the heel of the club head from the center of the club face. Club performance is tied directly to the location of the center of percussion on the club head face and if the center of percussion location is offset from the center of the club head face, it becomes increasingly more difficult for an average golfer to consistently strike a golf ball at the center of percussion location. Also, depending upon how far the center of percussion is actually offset from the center of the club head face, the mass concentration in such area of the club head may likewise be less desirable. It is therefore desirable to have the center of percussion of art assembled golf club lie substantially at the center of the club head face for all of the reasons discussed above.