【The Geometry of GOLF】 1. CP shift
CP (club path) shift is a phenomenon in which the swing direction and the club path at impact shift when the attack angle is not zero. The size of the shift is ⊿ Club Path ≒-(Attack Angle) / tan (Swing Plane) For example, if the attack angle is -5 degrees and the swing plane is 60 degrees, it will be about 3 degrees in to out. This 3 degree angle is equivalent to 5 yards off at 100 yards. What this means is that as long as you hit with a down blow, if the swing direction is straight (parallel to the target direction), the club path at impact will be in to out, so you cannot hit a straight ball with the straight swing direction. In other words, ”even if you swing straight, the ball will not fly straight.” If the attack angle is -5 degrees, it is impossible to hit straight ball to the target direction unless the swing direction is turned to the left by about 3 degrees. This 3 degrees mean that about 5 yards shifts at 100 yards, about 8 yards shifts at 150 yards, and about 10 yards shifts at 200 yards. If you align this line with an alignment stick and address it, you’ll feel horribly pointing to the left of the target. That’s why you can’t straighten the club path unless you turn the swing direction to the left. Of course, even if the club path is facing to the right, you can aim at the target with a draw ball by closing the face angle, but it is not easy to bend the ball and aim at the target as described later. When hitting the upper blow with a driver, on the contrary, the club path at impact will not be straight in the target direction unless the swing direction is turned to the right. For example, if the upper blow is 2 degrees and the swing plane is 50 degrees, the deviation of the club path will be about 2 degrees to the left. 2 degrees means that you’ll be off to the left by about 8 yards at 250 yards away. If you don’t turn to the right that much, the club path will not be straight. When you actually address it, you will feel that it is facing way to far right than you imagined.