Based on a surface shape appearing at a predetermined point moment by moment during rotation of a golf ball having numerous dimples on its surface, a data constellation regarding a parameter dependent on a surface shape of the golf ball is calculated. Preferably, the parameter is a distance between an axis of the rotation and the surface of the golf ball. Another preferable parameter is a volume of space between a surface of a phantom sphere and the surface of the golf ball. Based on a maximum value and a minimum value of the data constellation, a fluctuation range is calculated. By dividing the fluctuation range by a total volume of the dimples, an evaluation value is calculated. This value is calculated for each of PH rotation and POP rotation.
1. A process for designing a golf ball comprising the steps of:
using a computer to provide a phantom surface of a golf ball;
determining positions and shapes of numerous dimples on the phantom surface of the golf ball;
placing the numerous dimples on the phantom surface of the golf ball;
calculating a first data constellation regarding a parameter dependent on a surface shape of the golf ball, based on a surface shape appearing at a predetermined point moment by moment during rotation of the golf ball about a first axis;
calculating a second data constellation regarding a parameter dependent on a surface shape of the golf ball, based on a surface shape appearing at a predetermined point moment by moment during rotation of the golf ball about a second axis, the second axis being different from the first axis;
determining an aerodynamic symmetry of the golf ball based on a difference between a value obtained from the first data constellation and a value obtained from the second data constellation; and
changing the positions or the shapes of the dimples if the difference between the value obtained from the first data constellation and the value obtained from the second data constellation exceeds a predetermined value.
2. The process according to claim 1 , wherein in the step of determining the aerodynamic symmetry of the golf ball, the aerodynamic characteristic of the golf ball is determined based on fluctuation ranges of the first and second data constellations.
3. The process according to claim 1 , wherein in the step of calculating the first and second data constellations, the first and second data constellations are calculated throughout one rotation of the golf ball.
4. The process according to claim 1 , wherein in the step of calculating the first and second data constellations, the first and second data constellations are calculated based on a shape of a surface near a great circle orthogonal to a corresponding axis of the rotation.
5. The process according to claim 1 , wherein in the step of calculating the first and second data constellations, the first and second data constellations are calculated based on a parameter dependent on a distance between a corresponding axis of the rotation and the surface of the golf ball.
6. The process according to claim 1 , wherein in the step of calculating the first and second data constellations, the first and second data constellations are calculated based on a parameter dependent on a volume of space between a surface of a phantom sphere and the surface of the golf ball.