Abstract: A method of configuring a stepped, cylindrical golf club shaft to achieve an optimum shaft impact angle is diclosed. A predetermined portion in the middle of the shaft is selected as are the number of steps to be used, the wall thickness of each step and the outer diameter. For each configuration which has the selected number of steps the deflection at a predetermined point is calculated when a load is applied at another point. For those deflections which fall within a desired predetermined range of deflections, the slope of the bending angle of the shaft is calculated at the point of deflection. A configuration is then selected which has a desired slope and a golf club shaft is made with the middle portion configured to provide the desired bending angle. Specific configurations for maximum bending angle are provided for both wood-type and iron-type golf clubs.

Abstract: A trajectory calculator receiving data indicating initial values of golf ball flight angle, velocity and spin, calculates the apparent elevation and deflection angles at which the golf ball would be seen by an observer at the launch point. An optical object projector projects an image representing the golf ball on a screen. The size of the image decreases with time to yield the apparent perspective size decrease with range. An optional exerciser console enables input of changeable environmental quantities.

Abstract: An improved light emitter assembly for use in biomechanical electro-optical systems is disclosed. The device comprises a curved rigid or semi-rigid body to which at least three spaced light emitting diodes are affixed. The body is preferably cylindrical or hemispherical.

Abstract: A measurement system obtains and stores digital data on the positions of golf club and significant human body parts during a golf club swing. An interactive display allows later display of the measured performance for use in instruction or review. A coordinate transformer allows the viewing of a displayed simulated golfer from any aspect and at variable speeds and stop action. A generator such as an alphanumeric or graphic generator displays suggested display options, graphics, informative labels, and alphanumeric tabular data. Permanent copies of any displayed picture can be made for later home study.