【The Geometry of GOLF】 2. How to aim at the target by fade or draw ball
Curving the ball and aiming it to the pin is not easy. Curving the ball is not so difficult, but aiming to the pin, many factors must ne considered, e.g. distance, club loft, and wind etc. First of all, considering the element that the ball curves, there are cases where the ball is hit in the crosswind or at the outside of the sweet spot of the face, or hit from a slope such as rising forward, but here, only the spin axis tilt according to the D Plane theory is considering. The spin axis tilt is caused by the difference between the two directions of the club path and the face angle. If the face angle is to the right of the club path, the spin axis will tilt to the right and the ball will turn to the right. Conversely, if the face angle is to the left of the club path, the spin axis will tilt to the left and the ball will curve to the left. The difference between the face angle and the club path is called [face to path]. The easiest way to make a face to path is to change the grip to close or open the face, while swinging it as normal straight shot. To change the club path without changing the swing, just change the direction of the address. Changing the club path without changing the direction of the address will change the swing, and cause to difficult to hit the ball accurately. The direction in which the ball goes out (the direction in which the ball comes out) is almost the direction of the face. Strictly speaking, it is said that irons account for about 70% of the face to path, but this ratio is generally not determined because it is determined by the coefficient of friction of the face surface. Therefore, here, we think that the ball launch direction is the direction of the face. In the case of a draw ball, the direction of the ball launch is to the right of the target and turn left toward the target. Fade balls, on the other hand, launch to the left of the target and turn to the right. In order for the ball to go in the target direction, the club path will be further to the right of the launch direction in the case of a draw ball. How much the club path should be turned to the right to move the ball toward the target depends on the angle between the target and the ball’s exit direction, the distance to the target, and the spin loft. The difference between the face angle and the club path, that is, the larger the face to path, the greater the curving of the ball. Also, the longer the distance, the longer the flight time, so the curving width of the ball will increase accordingly. Also, the smaller the spin loft, the smaller the back spin, cause the larger the spin axis tilt. Since the spin axis tilt is caused by a combination of backspin and lateral spin, the spin axis tilt increases as the backspin decreases. In other words, if you hit with a club with a small loft even at the same distance, the curve will be larger even with the same face to path. Once the distance to the target, the launch direction, and the spin loft are determined, a club path for landing near the target is found.