A golf club comprising a supersize head and a shaft tip with a diameter of 9.40 mm (0.370 inches) or larger.

A portion near a ball (3) and a club head (12) is photographed by a high speed camera (4) and a portion near a top-of-swing of a golfer (1) is photographed by a high speed camera. These images are then recorded on a high speed video tape recorder (6), and the recorded images are reproduced so that a swing time, a swing speed and a head speed can be detected by a personal computer (15), and a shaft having a optimum flex can be selected on the basis of the swing time, the swing speed, the swing time and the head speed, and the swing speed and the head speed.

The invention provides a simple alignment device which is mounted on the golf club and which enables the golfer to determine when the club face is properly aligned without the assistance of another person. The alignment device comprises a linearoptic or lenticular screen (28) which provides a three-dimensional visual image of an indicating mark below the surface of the screen. When the position of the screen changes relative to the golfer's eyes, the position of the indicating mark (34) changes at a magnified rate, thereby providing a readily apparent indication of the position of the club face. In one embodiment of the alignment device the screen provides the image of a line (34) which is aligned with lines (35,36) on the club above and below the screen when the club face is aligned square to the target. When the club shaft and club face are rotated slightly out of alignment, the line on the screen moves out of alignment with the lines on the club. In another embodiment of the alignment device no image is visible on the screen when the club face is properly aligned, but an indicating mark or color becomes visible if the club is rotated out of alignment in either direction.

It is a casing that is formed around a solid -1-, thanks to the fact that it is provided with hairs, in such a way that the jet or layer of flowing medium released -5- shapes the aforementioned casing, causing a wall to be formed which prevents the passage of energy to the captive masses of flowing medium -4- achieving an energy savings and doing away with vibration by means of this arrangement.

An iron golf club (1) has a club length L measured in accordance with 60-degrees method of at least 36.5 inches, and it includes: a carbon shaft (3); a weight (5) attached to said carbon shaft (3); a grip (2) attached to one end of said carbon shaft (3); and a head (4) attached to the other end of said carbon shaft (3). Sum total of mass of the carbon shaft (3), the weight (5), the grip (2) and the head (4) is at least 0.3996 kg and at most 0.4197 kg. A value r/L, where r represents a distance from an upper end (2a) of the grip (2) to the center of gravity of the iron golf club (1), is at least 0.765 and at most 0.795. Thus, an iron golf club realizing improved easiness of swing can be provided.

A method for manufacturing an object having a potential {x} that is generated in response to a field {f} applied thereto. A computerized mathematical model (801) of the object is generated by discretizing a geometric model of the object into a plurality of finite elements (802) and specifying values for the field {f} and potential {x} relative to the finite elements (802). The material properties (804) of the finite elements (802) are specified to have a particular symmetry and a material property (804) matrix [k] is calculated based on the relationship {f}=[k]{x} and the specified symmetry. Material property (804) coefficients are extracted from the material property (804) matrix [k] for each finite element (802) in the computerized mathematical model (801) and the extracted material property (804) coefficients are compared to material property (804) coefficients for known materials to match the extracted material property (804) coefficients to the material property (804) coefficients for known materials. Manufacturing parameters (805) for controlling manufacturing equipment are determined based on the matched material property (804) coefficients and the manufacturing equipment is controlled in accordance with the determined manufacturing parameters (805) to thereby manufacture the object.