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# Ball distance and symetry info
- URL: https://peargolf.com/ball-distance-and-symetry-info/
- Published: 2011-10-26T01:00:04.000Z
- Updated: 2011-10-26T01:00:04.000Z
- Author: Chien Lung Ho
- Tags: 新聞, #imported, #Import 2026-08-19 20:27

Summary of Method

\-Using equipment at the USGA Research  
and Test Center, currently referred to as the  
Indoor Test Range (ITR), the aerodynamic  
properties of a sample lot of golf balls are  
completely characterized by the coefficient  
of lift (CL), and coefficient of drag (CD).  
\-Using the aerodynamic coefficients, the  
overall distance (carry plus roll) of a  
sample lot, as well as its spherical  
symmetry, is determined for a specific  
combination of launch conditions (ball  
speed, spin rate and launch angle) as  
determined by a mechanical golfer.

Significance

\-This method is used to determine the  
overall distance and symmetry of golf balls  
for a given set of launch conditions. The  
data obtained from this method is used to  
ascertain the conformance of the golf balls  
to the Overall Distance and Symmetry  
Standards as stated in the Rules of Golf

\-The overall distance of the ball shall not be  
greater than 317.0 yards. A maximum test  
tolerance of 3.0 yards is associated with this  
test.

In addition, the ball must not be designed,  
manufactured or intentionally modified to  
have properties that differ from those of a  
spherically symmetric ball. A spherically  
symmetric ball shall not exhibit statistically  
significant differences in carry distance  
greater than 4.0 yards or in flight time of  
more than 0.40 seconds regardless of which  
axis the ball is spinning about when  
launched.

\-Only those balls that have already passed  
the conformance tests for Weight, Size, and  
Initial Velocity will be tested for  
conformance to the Overall Distance and  
Symmetry Standards.

Launch Conditions

Launch Condition Mean Acceptable Range  
Angle 10° +0.5°  
Spin 42 rps +2.0 rps  
Swing Speed 120 mph +0.5 mph  
Ball Speed 256 fps Reference\*

The reference ball speed of 256 fps represents the speed  
after initial aging to a near steady-state condition