Golf ball having reduced side spin
A golf ball has one or more grooves in the ball surface. When the ball is initially struck by a golf club at an oblique angle the ball can have an undesired side spin. Each groove in the ball surface interacts with the air stream to absorb some of the side spin energy. The grooves act like miniature turbine blades, or vanes on an in-flight arrow, to decelerate side spin velocity so as to reduce the tendency of the ball to hook or slice.
This is a continuation-in-part of my co-pending U.S. patent application Ser. No. 11/975,556 filed on Oct. 22, 2007. Any patent issued hereon will date from Oct. 22, 2007, i.e. the filing date of the co-pending patent application.
FIELD OF INVENTIONThis invention relates to golf balls and particularly to golf ball having reduced side spin. Side spin is a spin generated around the golf ball center in a plane oblique to the flight path of the ball. Side spin is produced when the face of the golf club strikes the ball at an oblique angle to the path of the club. The present invention relates to a golf ball that is constructed to oppose side spin forces generated by the oblique angle striking force of the club face.
DESCRIPTION OF THE RELATED ARTSide spin of a golf ball is undesired because it causes the ball to take a curved path after it leaves the club face, so that the ball goes off course from the direction intended by the golfer. With a right-handed golfer a curvature to the right is termed a slice, and a curvature to the left is termed a hook.
U.S. Pat. No. 7,041,011 issued to M. J. Sullivan et al on May 9, 2006 discloses a golf ball designed to have a relatively low spin rate, with an associated lowered tendency to hook or slice. The golf ball has an outer layer containing regions of weighting material that provides perimeter weighting for the ball. Such perimeter weighting increases the moment of inertia of the ball, which the patentees believe causes the ball to have a lower spin rate, compared to a conventional golf ball.
SUMMARY OF THE INVENTIONThe present invention relates to a golf ball having one or more grooves in its spherical outer surface. Each groove has a sufficient width and depth dimension so that when the ball is airborne a ball-related laminar air flow is achieved in each groove, thereby generating resistance to side spin of the ball. Each groove acts as a miniature air vane that has a turbine-like resistance to the side spin force. The turbine-like resistance exerts a braking action to reduce the side spin and minimize the ball slice or hook (depending on the direction of the side spin).
The action of the groove in the golf ball surface is somewhat similar to the action of the fletches or vanes on an in-flight arrow. In each case the vane reacts to a disturbing force to stabilize the in-flight object (golf ball or arrow). In the case of the arrow the vane reacts to the disturbing force to produce stabilizing spinning motion of the arrow around the arrow axis. In the case of the golf ball the vane (groove) reacts to the side spin force so as to absorb the side spin energy, thereby reducing the undesired side spin.
Referring to
The ball can have a diameter of 1.68 inches, as required by the U.S. Golf Association. Each dimple 21 can typically be a circular depression having a diameter 23 of about 0.13 inch and a depth 25 of about 0.010 inch. Cover 18 may have a thickness on the order of 0.1 inch. The ball interacts with the stagnant air in the path of the ball to form an air separation point 22 in front of the ball, an air attachment zone 24 downstream from air separation point 22, and a turbulent wake area W downstream from air attachment zone 24.
The function of dimples 21 is to promote attachment of the air to the spherical surface of ball 10 so as to lengthen air attachment zone 24 (along path line 12).
In air attachment zone 24 dimples 21 generate localized boundary layer turbulence that interacts with the relative laminar flow of air spaced from the ball spherical surface 20, such that the laminar flow is attached to the ball surface.
The term “relative laminar air flow” is used herein to mean a flow relative to ball 10. In actual terms the air is relatively stagnant in the directions of ball movement; however the air is considered to move relative to the ball.
The present invention relates to a modification of the conventional golf ball (
One of the side surfaces of each groove 28 functions as a miniature turbine blade (or arrow vane) to oppose the side spin forces designated by arrow 26. Each groove 28 absorbs some of the side spin force so that during the course of ball travel the side spin rate decreases appreciably, thereby eliminating or reducing the undesired slicing or hooking action. In this context, a slice is associated with side spin in one direction, whereas a hook is associated with side spin in the opposite direction. Grooves 28 resist side spin in either direction. The grooves act cumulatively.
As the air in the air attachment zone 24 enters each groove 28 it has zero velocity in the arrow 26 direction. Spinning movement of the golf ball in the arrow 26 direction causes one side wall of each groove 28 to accelerate the air in the arrow 26 direction from a zero velocity condition up to the side spins velocity of the golf ball. The acceleration energy is absorbed by the golf ball so that eventually the side spins is eliminated or substantially reduced, as noted above.
When the ball is struck by the club head, grooves 28 can have a random orientation (not necessarily aligned with the ball flight path or air movement direction). During the initial stage of the ball travel grooves 28 interact with the air in air attachment zone 24 to turn the ball to a position where the grooves are aligned with the air stream in zone 24. Again, “air stream” means flow relative to the moving golf ball.
It will be seen from
Grooves 28 are of similar length, as shown in
Each groove 28 has sufficient depth and width to accommodate a desired volume of laminar velocity air in zone 24.
The width and depth dimensions for each groove 28 are several times the depth dimension of each dimple, whereby the groove has sufficient cross sectional area to accommodate laminar air flow. The turbulent boundary layer on the groove side walls and groove bottom wall is insufficient to choke off laminar air flow through the groove. As noted above,
Dimples 21 are not shown in
End areas of each groove merge gradually with the spherical surface of the golf ball, as shown in
Claims
1. A golf ball having a center and an outer spherical surface concentric around said center so that when the ball is airborne the air in the path of the ball interacts with the ball to form an air separation point in front of the ball, an air attachment zone downstream from the air separation point, and a turbulent wake area downstream from the air attachment zone; multiple elongated grooves in said spherical surface adapted to interact with air in the attachment zone so as to be aligned with the stream of air attached to the ball spherical surface; each said groove having a depth dimension and a width dimension causing the ball-attached air in said groove to have a laminar flow velocity relative to the ball, whereby each said groove generates a resistance to side spin of the golf ball; each said groove extending along the ball surface between two imaginary points located on a diametrical line passing through the golf ball center, each groove having a length that is a major portion of the distance between the two imaginary points, whereby each said groove is in contact with essentially the entire length dimension of the air attachment zone; the non-grooved areas of said spherical surface being covered with turbulence-generating dimples; each dimple having a depth dimension; the groove depth dimension and width dimension each being at least five times the dimple dimension so that air in each groove has a laminar flow relative to the ball.
Type: Application
Filed: Jul 14, 2009
Publication Date: Nov 12, 2009
Inventor: Thomas A. Doot (Commerce TWP., MI)
Application Number: 12/460,057