U.S. patent application number 14/472917 was filed with the patent office on 2014-12-18 for golf club assembly and golf club with aerodynamic features.
The applicant listed for this patent is NIKE, Inc.. Invention is credited to Robert Boyd, John T. Stites, Gary G. Tavares.
Application Number | 20140371000 14/472917 |
Document ID | / |
Family ID | 43301146 |
Filed Date | 2014-12-18 |
United States Patent
Application |
20140371000 |
Kind Code |
A1 |
Tavares; Gary G. ; et
al. |
December 18, 2014 |
GOLF CLUB ASSEMBLY AND GOLF CLUB WITH AERODYNAMIC FEATURES
Abstract
A golf club head includes a body member having a ball striking
face, a crown, a toe, a heel, a sole, a back and a hosel region,
located at the intersection of the ball striking face, the heel,
the crown and the sole. The body member may have a first
cross-section having a first airfoil-shaped surface in the heel.
The first cross-section may be oriented at approximately 90.degree.
from the centerline of the club head. The body member may have a
second cross-section having a second airfoil-shaped surface. The
second cross-section may be oriented at approximately 45.degree. or
at approximately 70.degree.. The airfoil-shaped surfaces may be
defined by spline points or by equations. A golf club including the
golf club head is also provided.
Inventors: |
Tavares; Gary G.;
(Southbridge, MA) ; Boyd; Robert; (Flower Mound,
TX) ; Stites; John T.; (Weatherford, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NIKE, Inc. |
Beaverton |
OR |
US |
|
|
Family ID: |
43301146 |
Appl. No.: |
14/472917 |
Filed: |
August 29, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13740394 |
Jan 14, 2013 |
8821311 |
|
|
14472917 |
|
|
|
|
12779669 |
May 13, 2010 |
8366565 |
|
|
13740394 |
|
|
|
|
12465164 |
May 13, 2009 |
8162775 |
|
|
12779669 |
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|
61298742 |
Jan 27, 2010 |
|
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Current U.S.
Class: |
473/324 |
Current CPC
Class: |
A63B 60/52 20151001;
A63B 53/04 20130101; A63B 53/0408 20200801; A63B 60/00 20151001;
A63B 53/0445 20200801; A63B 2225/01 20130101; A63B 53/0466
20130101; A63B 53/0433 20200801 |
Class at
Publication: |
473/324 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Claims
1. A golf club head comprising: a body member having a ball
striking face, a crown, a toe, a heel, a sole and a back, wherein
the body member is configured for attachment to a shaft having a
longitudinal axis, the body member including an apex point located
on the leading edge of the heel; the body member having a first
cross-section oriented generally parallel to a front face of the
club head, the first cross-section including the apex point and an
x.sub.1-axis extending from the apex point at a predetermined angle
relative to the ground surface, the first cross-section having a
first quasi-parabolic crown-side surface defined relative to the
x.sub.1-axis; the body member having a second cross-section
oriented at an angle rearwardly from the first cross-section, the
second cross-section including the apex point and an x.sub.2-axis
extending from the apex point at the same predetermined angle as
the x.sub.1-axis, the second cross-section having a second
quasi-parabolic crown-side surface defined relative to the
x.sub.2-axis, wherein the second quasi-parabolic crown-side surface
is flatter than the first quasi-parabolic crown-side surface in the
heel region.
2. The golf club head of claim 1, wherein the first cross-section
has a first quasi-parabolic sole-side surface defined relative to
the x.sub.1-axis, and wherein the first quasi-parabolic crown-side
surface is flatter than the first quasi-parabolic sole-side surface
in the heel region.
3. The golf club head of claim 1, wherein the second cross-section
has a second quasi-parabolic sole-side surface defined relative to
the x.sub.2-axis, and wherein the second quasi-parabolic crown-side
surface is flatter than the second quasi-parabolic sole-side
surface in the heel region.
4. The golf club head of claim 1, wherein the first cross-section
has a first quasi-parabolic sole-side surface defined relative to
the x.sub.1-axis, wherein the second cross-section has a second
quasi-parabolic sole-side surface defined relative to the
x.sub.2-axis, and wherein the second quasi-parabolic sole-side
surface is smaller than the first quasi-parabolic sole-side surface
in the heel region.
5. The golf club head of claim 4, wherein the coordinate values of
the second quasi-parabolic sole-side surface are within 10% of the
coordinate values of the first quasi-parabolic sole-side surface in
the heel region.
6. The golf club head of claim 1, wherein the first cross-section
has a first quasi-parabolic sole-side surface defined relative to
the x.sub.1-axis, wherein the second cross-section has a second
quasi-parabolic sole-side surface defined relative to the
x.sub.2-axis, and wherein the first quasi-parabolic crown-side
surface is flatter than the first quasi-parabolic sole-side surface
in the heel region, and wherein the second quasi-parabolic
crown-side surface is flatter than the second quasi-parabolic
sole-side surface in the heel region.
7. The golf club head of 1, wherein the second quasi-parabolic
crown-side surface is flatter than the first quasi-parabolic
crown-side surface within the first 24 mm from the apex point.
8. The golf club head of claim 1, wherein the body member has a
third cross-section oriented at an angle rearwardly from the second
cross-section, the third cross-section including the apex point and
an x.sub.3-axis extending from the apex point at the same
predetermined angle as the x.sub.1-axis, the third cross-section
having a third quasi-parabolic crown-side surface defined relative
to the x.sub.3-axis, wherein the third quasi-parabolic crown-side
surface is flatter than the second quasi-parabolic crown-side
surface in the heel region.
9. The golf club head of claim 1, wherein the apex point is located
approximately 10 mm to approximately 30 mm from the longitudinal
axis of the shaft.
10. The golf club head of claim 1, wherein the body member further
includes a groove extending at least partially along a horizontal
length of the toe and extending at least partially along a
horizontal length of the back.
11. The golf club head of claim 1, wherein the first cross-section
has a first concave-shaped surface opposed to the leading edge in
the heel.
12. The golf club head of claim 1, wherein the sole includes a
recess extending across the sole in a generally heel-to-toe
direction at an angle that ranges from approximately 10.degree. to
approximately 80.degree. from the centerline.
13. The golf club head of claim 1, wherein the club head has a
volume of 420 cc or greater, a club breadth-to-face length ratio of
0.92 or greater, and a face height of 53 mm or greater.
14. A golf club comprising: a shaft; and the golf club head
according claim 1, wherein the golf club head is secured to a first
end of the shaft.
15. A golf club head comprising: a body member having a ball
striking face, a crown, a toe, a heel, a sole and a back, wherein
the body member is configured for attachment to a shaft having a
longitudinal axis, the body member including an apex point located
on a leading edge of the heel; the body member having a first
cross-section oriented at approximately 90.degree. from a
centerline of the club head, wherein the first cross-section has a
first airfoil-shaped curvature in the heel, wherein the first
cross-section includes the apex point located in the heel, a first
crown-side surface curve extending from the apex point and a first
sole-side surface curve extending from the apex point, and wherein
the apex point represents an origin of a first x.sub.1- and
z.sub.1-coordinate system oriented in the plane of the first
cross-section at a roll angle of approximately 15.degree.; the body
member having a second cross-section oriented at approximately
70.degree. from the centerline of the club head, wherein the second
cross-section has a second airfoil-shaped curvature in the heel,
wherein the second cross-section includes the apex point located in
the heel, a second crown-side surface curve extending from the apex
point and a second sole-side surface curve extending from the apex
point, and wherein the apex point represents an origin of a second
x.sub.2- and z.sub.2-coordinate system oriented in the plane of the
second cross-section at a roll angle of approximately 15.degree.,
and wherein the second crown-side surface is flatter than the first
crown-side surface over the x.sub.1- and x.sub.2-coordinate ranges
of 0 mm to 48 mm.
16. The golf club head of claim 15, wherein the first crown-side
surface z.sub.1-coordinates over the x.sub.1-coordinate range of 0
mm to 24 mm, are greater than or equal to the second crown-side
surface z.sub.2-coordinates over the x.sub.2-coordinate range of 0
mm to 24 mm.
17. The golf club head of claim 15, wherein the first crown-side
surface z.sub.1-coordinates over the x.sub.1-coordinate range of 0
mm to 24 mm are within approximately 10% of the second crown-side
surface z.sub.2-coordinates over the x.sub.2-coordinate range of 0
mm to 24 mm.
18. The golf club head of claim 15, wherein the first crown-side
surface is flatter than the first sole-side surface over the
x.sub.1-coordinate range of 0 mm to 48 mm.
19. The golf club head of claim 15, wherein the second sole-side
surface is flatter than the first crown-side surface over the
x.sub.1- and x.sub.2-coordinate ranges of 0 mm to 48 mm.
20. The golf club head of claim 15, wherein the second crown-side
surface is flatter than the second sole-side surface over the
x.sub.2-coordinate range of 0 mm to 48 mm.
21. The golf club head of claim 15, wherein the body member has a
third cross-section oriented at approximately 45.degree. from a
centerline of the club head, wherein the third cross-section has a
third airfoil-shaped curvature in the heel, wherein the third
cross-section includes the apex point located in the heel, a third
crown-side surface curve extending from the apex point and a third
sole-side surface curve extending from the apex point, and wherein
the apex point represents an origin of a third x.sub.3- and
z.sub.3-coordinate system oriented in the plane of the third
cross-section at a roll angle of approximately 15.degree., wherein
the third crown-side surface is flatter than the third sole-side
surface over the x.sub.3-coordinate range of 0 mm to 48 mm.
22. The golf club head of claim 21, wherein the third crown-side
surface is flatter than the first crown-side surface over the
x.sub.1- and x.sub.3-coordinate ranges of 0 mm to 48 mm, and
wherein the third sole-side surface is flatter than the first
crown-side surface over the x.sub.1- and x.sub.3-coordinate ranges
of 0 mm to 48 mm.
23. The golf club head of claim 15, wherein the first sole-side
surface z.sub.1-coordinates over the x.sub.1-coordinate range of 0
mm to 24 mm are greater than or equal to the second sole-side
surface z.sub.2-coordinates over the x.sub.2-coordinate range of 0
mm to 24 mm.
24. The golf club head of claim 15, wherein the first sole-side
surface z.sub.1-coordinates over the x.sub.1-coordinate range of 0
mm to 24 mm are within approximately 10% of the second sole-side
surface z.sub.2-coordinates over the x.sub.2-coordinate range of 0
mm to 24 mm.
25. The golf club head of claim 15, wherein the body member is
configured for attachment to a shaft having a longitudinal axis,
and wherein the apex point is located approximately 10 mm to
approximately 30 mm from the longitudinal axis of the shaft.
26. The golf club head of claim 15, wherein the body member further
includes a groove extending at least partially along a horizontal
length of the toe and extending at least partially along a
horizontal length of the back.
27. The golf club head of claim 15, wherein the first cross-section
has a first concave-shaped surface opposed to the first
airfoil-shaped curvature in the heel.
28. The golf club head of claim 15, wherein the sole includes a
recess extending across the sole in a generally heel-to-toe
direction at an angle that ranges from approximately 10.degree. to
approximately 80.degree. from the centerline.
29. A golf club comprising: a shaft; and the golf club head
according to claim 15, wherein the golf club head is secured to a
first end of the shaft.
Description
RELATED APPLICATIONS
[0001] The present patent application is a continuation of U.S.
patent application Ser. No. 13/740,394, filed Jan. 14, 2013,
entitled "Golf Club Assembly and Golf Club With Aerodynamic
Features," and naming Gary Tavares, et al. as inventors, which is a
continuation of U.S. patent application Ser. No. 12/779,669, filed
May 13, 2010, now U.S. Pat. No. 8,366,565, entitled "Golf Club
Assembly and Golf Club With Aerodynamic Features," and naming Gary
Tavares, et al. as inventors, which is a continuation-in-part of
U.S. patent application Ser. No. 12/465,164, filed May 13, 2009,
now U.S. Pat. No. 8,162,775, entitled "Golf Club Assembly and Golf
Club With Aerodynamic Features," and naming Gary Tavares, et al. as
inventors, and which claims the benefit of priority of Provisional
Application No. 61/298,742, filed Jan. 27, 2010, entitled "Golf
Club Assembly and Golf Club With Aerodynamic Features," and naming
Gary Tavares, et al. as inventors. Each of these earlier filed
applications is incorporated herein by reference in its
entirety.
FIELD
[0002] Aspects of this invention relate generally to golf clubs and
golf club heads, and, in particular, to golf clubs and golf club
heads with improved aerodynamic features.
BACKGROUND
[0003] The distance a golf ball travels when struck by a golf club
is determined in large part by club head speed at the point of
impact with the golf ball. Club head speed in turn can be affected
by the wind resistance or drag provided by the club head during the
entirety of the swing, especially given the large club head size of
a driver. The club head of a driver or a fairway wood in particular
produces significant aerodynamic drag during its swing path. The
drag produced by the club head leads to reduced club head speed
and, therefore, reduced distance of travel of the golf ball after
it has been struck.
[0004] Air flows in a direction opposite to the golf club head's
trajectory over those surfaces of the golf club head that are
roughly parallel to the direction of airflow. An important factor
affecting drag is the behavior of the air flow's boundary layer.
The "boundary layer" is a thin layer of air that lies very close to
the surface of the club head during its motion. As the airflow
moves over the surfaces, it encounters an increasing pressure. This
increase in pressure is called an "adverse pressure gradient"
because it causes the airflow to slow down and lose momentum. As
the pressure continues to increase, the airflow continues to slow
down until it reaches a speed of zero, at which point it separates
from the surface. The air stream will hug the club head's surfaces
until the loss of momentum in the airflow's boundary layer causes
it to separate from the surface. The separation of the air streams
from the surfaces results in a low pressure separation region
behind the club head (i.e., at the trailing edge as defined
relative to the direction of air flowing over the club head). This
low pressure separation region creates pressure drag. The larger
the separation region, the greater the pressure drag.
[0005] One way to reduce or minimize the size of the low pressure
separation region is by providing a streamlined form that allows
laminar flow to be maintained for as long as possible, thereby
delaying or eliminating the separation of the laminar air stream
from the club surface.
[0006] Reducing the drag of the club head not only at the point of
impact, but also during the course of the entire downswing prior to
the point of impact, would result in improved club head speed and
increased distance of travel of the golf ball. When analyzing the
swing of golfers, it has been noted that the heel/hosel region of
the club head leads the swing during a significant portion of the
downswing and that the ball striking face only leads the swing at
(or immediately before) the point of impact with the golf ball. The
phrase "leading the swing" is meant to describe that portion of the
club head that faces the direction of swing trajectory. For
purposes of discussion, the golf club and golf club head are
considered to be at a 0.degree. orientation when the ball striking
face is leading the swing, i.e. at the point of impact. It has been
noted that during a downswing, the golf club may be rotated by
about 90.degree. or more around the longitudinal axis of its shaft
during the 90.degree. of downswing prior to the point of impact
with the golf ball.
[0007] During this final 90.degree. portion of the downswing, the
club head may be accelerated to approximately 65 miles per hour
(mph) to over 100 mph, and in the case of some professional
golfers, to as high as 140 mph. Further, as the speed of the club
head increases, typically so does the drag acting on the club head.
Thus, during this final 90.degree. portion of the downswing, as the
club head travels at speeds upwards of 100 mph, the drag force
acting on the club head could significantly retard any further
acceleration of the club head.
[0008] Club heads that have been designed to reduce the drag of the
head at the point of impact, or from the point of view of the club
face leading the swing, may not function well to reduce the drag
during other phases of the swing cycle, such as when the heel/hosel
region of the club head is leading the downswing.
[0009] It would be desirable to provide a golf club head that
reduces or overcomes some or all of the difficulties inherent in
prior known devices. Particular advantages will be apparent to
those skilled in the art, that is, those who are knowledgeable or
experienced in this field of technology, in view of the following
disclosure of the invention and detailed description of certain
embodiments.
SUMMARY
[0010] This application discloses a golf club head with improved
aerodynamic performance. In accordance with certain aspects, a golf
club head may include a body member having a ball striking face, a
crown, a toe, a heel, a sole, a rear, and a hosel region located at
the intersection of the ball striking face, the heel, the crown and
the sole. A drag reducing structure on the body member may be
configured to reduce drag for the club head during at least a
portion of a golf downswing from an end of a backswing through a
point-of-impact with the golf ball, and optionally, through at
least the last 90.degree. of the downswing up to and immediately
prior to impact with the golf ball.
[0011] In accordance with certain aspects, a golf club head for a
driver, having a volume of 400 cc or greater and a club
breadth-to-face length ratio of 0.90 or greater, includes a body
member having a crown, a sole, and a heel. A leading edge may be
included on the heel, the leading edge defined as the surface of
the heel having a vertical slope when the club head is in a 60
degree lie angle position. The body member may further have a first
cross-section, wherein the first cross-section includes an apex
point located on the leading edge, a first crown-side surface
extending from the apex point, and a first sole-side surface
extending from the apex point. The first cross-section may be
oriented perpendicular to a centerline of the club head. The apex
point may represent an origin of a first x.sub.1- and
z.sub.1-coordinate system oriented in the plane of the first
cross-section at a roll angle of approximately 15.degree.. The
first crown-side surface may be defined by the following spline
points:
TABLE-US-00001 x.sub.1-coordinate (mm) 0 6 12 24 36 48
z.sub.1U-coordinate (mm) 0 11 16 22 25 26
[0012] According to certain aspects, the first sole-side surface
may be defined by the following spline points:
TABLE-US-00002 x.sub.1-coordinate (mm) 0 6 12 24 36 48
z.sub.1L-coordinate (mm) 0 -14 -19 -25 -29 -32
[0013] According to other aspects, the body member further may have
a second cross-section, wherein the second cross-section includes
the apex point located on the leading edge, a second crown-side
surface extending from the apex point, and a second sole-side
surface extending from the apex point. The second cross-section may
be oriented at approximately 70.degree. from the centerline of the
club head. The apex point further may represent an origin of a
second x.sub.2- and z.sub.2-coordinate system oriented in the plane
of the second cross-section at a roll angle of approximately
15.degree.. The second crown-side surface may be defined by the
following spline points:
TABLE-US-00003 x.sub.2-coordinate (mm) 0 6 12 24 36 48
z.sub.2u-coordinate (mm) 0 11 16 21 24 25
[0014] The second sole-side surface may be defined by the following
spline points:
TABLE-US-00004 x.sub.2-coordinate (mm) 0 6 12 24 36 48
z.sub.2L-coordinate (mm) 0 -13 -18 -24 -28 -30
[0015] According to even other aspects, the body member may be
configured for attachment to a shaft having a longitudinal axis,
and the apex point may be located approximately 15 mm to
approximately 25 mm from the longitudinal axis of the shaft.
Alternatively, the apex point may be located approximately 20 mm
from the longitudinal axis of the shaft.
[0016] According to certain aspects, the club head may have a
volume greater than or equal to 420 cc. The club head may have a
face height greater than or equal to 53 mm. Further, the club
breadth-to-face length ratio of 0.92 or greater.
[0017] According to certain aspects, the body member may further
include a groove extending at least partially along a length of the
toe and extending at least partially along a length of the back.
The groove may be a Kammback feature.
[0018] According to even other aspects, the body member may even
further include a diffuser located on the sole and oriented at an
angle from the centerline of the club head of from approximately
10.degree. to approximately 80.degree.. Alternatively, the diffuser
may be oriented at an angle from the centerline of the club head of
from approximately 50.degree. to approximately 70.degree..
[0019] According to certain aspects, a golf club head may include a
first cross-section oriented perpendicular to a centerline of the
club head, and x.sub.1- and z.sub.1-coordinates of a first
crown-side surface curve of the first cross-section may be defined
by the following Bezier equations:
x.sub.1U=3(17)(1-t)t.sup.2+(48)t.sup.3
z.sub.1U=3(10)(1-t).sup.2t+3(26)(1-t)t.sup.2+(26)t.sup.3 [0020]
over the range of: 0.ltoreq.t.ltoreq.1.
[0021] According to other aspects, x.sub.1- and z.sub.1-coordinates
of a first sole-side surface curve of the first cross-section may
be defined by the following Bezier equations:
x.sub.1L=3(11)(1-t)t.sup.2+(48)t.sup.3
z.sub.1L=3(-10)(1-t).sup.2t+3(-26)(1-t)t.sup.2+(-32)t.sup.3 [0022]
over the range of: 0.ltoreq.t.ltoreq.1.
[0023] The golf club head may further include a second
cross-section, wherein the second cross-section is oriented at
approximately 70.degree. from the centerline of the club head. The
x.sub.2U- and z.sub.2U-coordinates of a second crown-side surface
curve of the second cross-section may be defined by the following
Bezier equations:
x.sub.2U=3(19)(1-t)t.sup.2+(48)t.sup.3
z.sub.2U=3(10)(1-t).sup.2t+3(25)(1-t)t.sup.2+(25)t.sup.3 [0024]
over the range of: 0.ltoreq.t.ltoreq.1.
[0025] Further, the x.sub.1L- and z.sub.1L-coordinates of a second
sole-side surface curve of the second cross-section may be defined
by the following Bezier equations:
x.sub.2L=3(13)(1-t)t.sup.2+(48)t.sup.3
z.sub.2L=3(-10)(1-t).sup.2t+3(-26)(1-t)t.sup.2+(-30)t.sup.3 [0026]
over the range of: 0.ltoreq.t.ltoreq.1.
[0027] According to even other aspects, the body member may have a
first cross-section oriented at approximately 90.degree. from a
centerline of the club head and a second cross-section oriented at
approximately 45.degree. from the centerline of the club head. The
first and second cross-sections may each include the apex point
located on the heel and may each have a respective crown-side
surface extending from the apex point and a respective sole-side
surface extending from the apex point. The first cross-section may
have a first airfoil-shaped surface in the heel and a first
concave-shaped surface opposed to the first airfoil-shape surface.
The second cross-section may have a second airfoil-shaped surface
in the heel and a second concave-shaped surface opposed to the
second airfoil-shape surface.
[0028] The first and the second concave-shaped surfaces may be
formed by a continuous groove extending at least partially along
the length of the toe and at least partially along the length of
the back.
[0029] According to certain aspects, golf clubs including the
disclosed golf club heads are also provided.
[0030] These and additional features and advantages disclosed here
will be further understood from the following detailed disclosure
of certain embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1A is a perspective view of a golf club with a groove
formed in its club head according to an illustrative aspect.
[0032] FIG. 1B is a close up of the club head of FIG. 1A with
orientation axes provided.
[0033] FIG. 2 is a side perspective view of the club head of the
golf club of FIG. 1A.
[0034] FIG. 3 is a back elevation view of the club head of the golf
club of FIG. 1A.
[0035] FIG. 4 is a side elevation view of the club head of the golf
club of FIG. 1A, viewed from a heel side of the club head.
[0036] FIG. 5 is a plan view of the sole of the club head of the
golf club of FIG. 1A.
[0037] FIG. 6 is a bottom perspective view of the club head of the
golf club of FIG. 1A.
[0038] FIG. 7 is a side elevation view of an alternative embodiment
of the club head of the golf club of FIG. 1A, viewed from a toe
side of the club head.
[0039] FIG. 8 is a back elevation view of the club head of FIG.
7.
[0040] FIG. 9 is a side elevation view of the club head of FIG. 7,
viewed from a heel side of the club head.
[0041] FIG. 10 is a bottom perspective view of the club head of
FIG. 7.
[0042] FIG. 11 is a schematic, time-lapsed, front view of a typical
golfer's downswing.
[0043] FIG. 12A is a top plan view of a club head illustrating yaw;
FIG. 12B is a heel-side elevation view of a club head illustrating
pitch; and FIG. 12C is a front elevation view of a club head
illustrating roll.
[0044] FIG. 13 is a graph of representative yaw, pitch and roll
angles as a function of position of a club head during a typical
downswing.
[0045] FIGS. 14A-14C schematically illustrate a club head 14 (both
top plan view and front elevation view) and typical orientations of
the air flow over the club head at points A, B and C of FIG. 11,
respectively.
[0046] FIG. 15 is a top plan view of a club head according to
certain illustrative aspects.
[0047] FIG. 16 is a front elevation view of the club head of FIG.
15.
[0048] FIG. 17 is a toe-side elevation view of the club head of
FIG. 15.
[0049] FIG. 18 is a rear-side elevation view of the club head of
FIG. 15.
[0050] FIG. 19 is a heel-side elevation view of the club head of
FIG. 15.
[0051] FIG. 20A is a bottom perspective view of the club head of
FIG. 15.
[0052] FIG. 20B is a bottom perspective view of an alternative
embodiment of a club head that is similar to the club head of FIG.
15, but without a diffuser.
[0053] FIG. 21 is a top plan view of a club head according to other
illustrative aspects.
[0054] FIG. 22 is a front elevation view of the club head of FIG.
21.
[0055] FIG. 23 is a toe-side elevation view of the club head of
FIG. 21.
[0056] FIG. 24 is a rear-side elevation view of the club head of
FIG. 21.
[0057] FIG. 25 is a heel-side elevation view of the club head of
FIG. 21.
[0058] FIG. 26A is a bottom perspective view of the club head of
FIG. 21.
[0059] FIG. 26B is a bottom perspective view of an alternative
embodiment of a club head that is similar to the club head of FIG.
21, but without a diffuser.
[0060] FIG. 27 is a top plan view of the club head of FIGS. 1-6,
without a diffuser, in a 60 degree lie angle position, showing
cross-sectional cuts taken through point 112.
[0061] FIG. 28 is a front elevation view of the club head of FIG.
27 in the 60 degree lie angle position.
[0062] FIGS. 29A and 29B are cross-sectional cuts taken through
line XXIX-XXIX of FIG. 27.
[0063] FIGS. 30A and 30B are cross-sectional cuts taken through
line XXX-XXX of FIG. 27.
[0064] FIGS. 31A and 31B are cross-sectional cuts taken through
line XXXI-XXXI of FIG. 27.
[0065] FIGS. 32A and 32B are schematics (top plan view and front
elevation) of a club head illustrating certain other physical
parameters.
[0066] The figures referred to above are not drawn necessarily to
scale, should be understood to provide a representation of
particular embodiments of the invention, and are merely conceptual
in nature and illustrative of the principles involved. Some
features of the golf club head depicted in the drawings may have
been enlarged or distorted relative to others to facilitate
explanation and understanding. The same reference numbers are used
in the drawings for similar or identical components and features
shown in various alternative embodiments. Golf club heads as
disclosed herein would have configurations and components
determined, in part, by the intended application and environment in
which they are used.
DETAILED DESCRIPTION
[0067] An illustrative embodiment of a golf club 10 is shown in
FIG. 1A and includes a shaft 12 and a golf club head 14 attached to
the shaft 12. Golf club head 14 may be a driver, as shown in FIG.
1A. The shaft 12 of the golf club 10 may be made of various
materials, such as steel, aluminum, titanium, graphite, or
composite materials, as well as alloys and/or combinations thereof,
including materials that are conventionally known and used in the
art. Additionally, the shaft 12 may be attached to the club head 14
in any desired manner, including in conventional manners known and
used in the art (e.g., via adhesives or cements at a hosel element,
via fusing techniques (e.g., welding, brazing, soldering, etc.),
via threads or other mechanical connectors (including releasable
and adjustable mechanisms), via friction fits, via retaining
element structures, etc.). A grip or other handle element 12a may
be positioned on the shaft 12 to provide a golfer with a slip
resistant surface with which to grasp golf club shaft 12. The grip
element 12a may be attached to the shaft 12 in any desired manner,
including in conventional manners known and used in the art (e.g.,
via adhesives or cements, via threads or other mechanical
connectors (including releasable connectors), via fusing
techniques, via friction fits, via retaining element structures,
etc.).
[0068] In the example structure of FIG. 1A, the club head 14
includes a body member 15 to which the shaft 12 is attached at a
hosel or socket 16 for receiving the shaft 12 in known fashion. The
body member 15 includes a plurality of portions, regions, or
surfaces as defined herein. This example body member 15 includes a
ball striking face 17, a crown 18, a toe 20, a back 22, a heel 24,
a hosel region 26 and a sole 28. Back 22 is positioned opposite
ball striking face 17, and extends between crown 18 and sole 28,
and further extends between toe 20 and heel 24. This particular
example body member 15 further includes a skirt or Kammback feature
23 and a recess or diffuser 36 formed in sole 28.
[0069] Referring to FIG. 1B, the ball striking face region 17 is a
region or surface that may be essentially flat or that may have a
slight curvature or bow (also known as "bulge"). Although the golf
ball may contact the ball striking face 17 at any spot on the face,
the desired-point-of-contact 17a of the ball striking face 17 with
the golf ball is typically approximately centered within the ball
striking face 17. For purposes of this disclosure, a line L.sub.T
drawn tangent to the surface of the striking face 17 at the
desired-point-of-contact 17a defines a direction parallel to the
ball striking face 17. The family of lines drawn tangent to the
surface of the striking face 17 at the desired-point-of-contact 17a
defines a striking face plane 17b. Line L.sub.P defines a direction
perpendicular to the striking face plane 17b. Further, the ball
striking face 17 may generally be provided with a loft angle
.alpha., such that at the point of impact (and also at the address
position, i.e., when the club head is positioned on the ground
adjacent to the golf ball prior to the initiation of the backswing)
the ball striking plane 17b is not perpendicular to the ground.
Generally, the loft angle .alpha. is meant to affect the initial
upward trajectory of the golf ball at the point of impact. Rotating
the line L.sub.P drawn perpendicular to the striking face plane 17b
through the negative of the loft angle .alpha. defines a line
T.sub.0 oriented along the desired club-head-trajectory at the
point of impact. Generally, this point-of-impact
club-head-trajectory direction T.sub.0 is perpendicular to the
longitudinal axis of the club shaft 12.
[0070] Still referring to FIG. 1B, a set of reference axes
(X.sub.0, Y.sub.0, Z.sub.0) associated with a club head oriented at
a 60 degree lie angle position with a face angle of zero degrees
(see, e.g., USGA Rules of Golf, Appendix II and see also, FIG. 28)
can now be applied to the club head 14. The Y.sub.0-axis extends
from the desired-point-of-contact 17a along the point-of-impact
club-head-trajectory line in a direction opposite to the T.sub.0
direction. The X.sub.0-axis extends from desired-point-of-contact
17a generally toward the toe 20 and is perpendicular to the
Y.sub.0-axis and parallel to the horizontal with the club at a 60
degree lie angle position. Thus, the line L.sub.T, when drawn
parallel to the ground, is coincident with the X.sub.0-axis. The
Z.sub.0-axis extends from desired-point-of-contact 17a generally
vertically upward and perpendicular to both the X.sub.0-axis and
the Y.sub.0-axis. For purposes of this disclosure, the "centerline"
of the club head 14 is considered to coincide with the Y.sub.0-axis
(and also with the T.sub.0 line). The term "rearwardly" as used
herein generally refers to a direction opposite to the
point-of-impact club-head trajectory direction T.sub.0, i.e., in
the positive direction of the Y.sub.0-axis.
[0071] Referring now to FIGS. 1-6, the crown 18, which is located
on the upper side of the club head 14, extends from the ball
striking face 17 back toward the back 22 of the golf club head 14.
When the club head 14 is viewed from below, i.e., along the
Z.sub.0-axis in the positive direction, the crown 18 cannot be
seen.
[0072] The sole 28, which is located on the lower or ground side of
the club head 14 opposite to the crown 18, extends from the ball
striking face 17 back to the back 22. As with the crown 18, the
sole 28 extends across the width of the club head 14, from the heel
24 to the toe 20. When the club head 14 is viewed from above, i.e.,
along the Z.sub.0-axis in the negative direction, the sole 28
cannot be seen.
[0073] Referring to FIGS. 3 and 4, the back 22 is positioned
opposite the ball striking face 17, is located between the crown 18
and the sole 28, and extends from the heel 24 to the toe 20. When
the club head 14 is viewed from the front, i.e., along the
Y.sub.0-axis in the positive direction, the back 22 cannot be seen.
In some golf club head configurations, the back 22 may be provided
with a skirt or with a Kammback feature 23.
[0074] The heel 24 extends from the ball striking face 17 to the
back 22. When the club head 14 is viewed from the toe side, i.e.,
along the X.sub.0-axis in the positive direction, the heel 24
cannot be seen. In some golf club head configurations, the heel 24
may be provided with a skirt or with a Kammback feature 23 or with
a portion of a skirt or with a portion of a Kammback feature
23.
[0075] The toe 20 is shown as extending from the ball striking face
17 to the back 22 on the side of the club head 14 opposite to the
heel 24. When the club head 14 is viewed from the heel side, i.e.,
along the X.sub.0-axis in the negative direction, the toe 20 cannot
be seen. In some golf club head configurations, the toe 20 may be
provided with a skirt or with a Kammback feature 23 or with a
portion of a skirt or with a portion of a Kammback feature 23.
[0076] The socket 16 for receiving the shaft is located within the
hosel region 26. The hosel region 26 is shown as being located at
the intersection of the ball striking face 17, the heel 24, the
crown 18 and the sole 28 and may encompass those portions of the
heel 24, the crown 18 and the sole 28 that lie adjacent to the
hosel 16. Generally, the hosel region 26 includes surfaces that
provide a transition from the socket 16 to the ball striking face
17, the heel 24, the crown 18 and/or the sole 28.
[0077] Thus it is to be understood that the terms: the ball
striking face 17, the crown 18, the toe 20, the back 22, the heel
24, the hosel region 26 and the sole 28, refer to general regions
or portions of the body member 15. In some instances, the regions
or portions may overlap one another. Further, it is to be
understood that the usage of these terms in the present disclosure
may differ from the usage of these or similar terms in other
documents. It is to be understood that in general, the terms toe,
heel, ball striking face and back are intended to refer to the four
sides of a golf club, which make up the perimeter outline of a body
member when viewed directly from above when the golf club is in the
address position.
[0078] In the embodiment illustrated in FIGS. 1-6, body member 15
may generally be described as a "square head." Although not a true
square in geometric terms, crown 18 and sole 28 of square head body
member 15 are substantially square as compared to a traditional
round-shaped club head.
[0079] Another embodiment of a club head 14 is shown as club head
54 in FIGS. 7-10. Club head 54 has a more traditional round head
shape. It is to be appreciated that the phrase "round head" does
not refer to a head that is completely round but, rather, one with
a generally or substantially round profile.
[0080] FIG. 11 is a schematic front view of a motion capture
analysis of at least a portion of a golfer's downswing. As shown in
FIG. 11, at the point of impact (I) with a golf ball, the ball
striking face 17 may be considered to be substantially
perpendicular to the direction of travel of the club head 14. (In
actuality, the ball striking face 17 is usually provided with a
loft of from approximately 2.degree. to 4.degree., such that the
ball striking face 17 departs from the perpendicular by that
amount.) During a golfer's backswing, the ball striking face 17,
which starts at the address position, twists outwardly away from
the golfer (i.e., clockwise when viewed from above for a
right-handed golfer) due to rotation of the golfer's hips, torso,
arms, wrists and/or hands. During the downswing, the ball striking
face 17 rotates back into the point-of-impact position.
[0081] In fact, referring to FIGS. 11 and 12A-12C, during the
downswing the club head 14 experiences a change in yaw angle
(ROT-Z) (see FIG. 12A) (defined herein as a rotation of the club
head 14 around the vertical Z.sub.0-axis), a change in pitch angle
(ROT-X) (see FIG. 12B) (defined herein as a rotation of the club
head 14 around the X.sub.0-axis), and a change in roll angle
(ROT-Y) (see FIG. 12C) (defined herein as a rotation of the club
head 14 around the Y.sub.0-axis).
[0082] The yaw, pitch, and roll angles may be used to provide the
orientation of the club head 14 with respect to the direction of
air flow (which is considered to be the opposite direction from the
instantaneous trajectory of the club head). At the point of impact
and also at the address position, the yaw, pitch and roll angles
may be considered to be 0.degree.. For example, referring to FIG.
12A, at a measured yaw angle of 45.degree., the centerline L.sub.0
of the club head 14 is oriented at 45.degree. to the direction of
air flow, as viewed along the Z.sub.0-axis. As another example,
referring to FIG. 12B, at a pitch angle of 20.degree., the
centerline L.sub.0 of the club head 14 is oriented at 20.degree. to
the direction of air flow, as viewed along the X.sub.0-axis. And,
referring to FIG. 12C, with a roll angle of 20.degree., the
X.sub.0-axis of the club head 14 is oriented at 20.degree. to the
direction of air flow, as viewed along the Y.sub.0-axis.
[0083] FIG. 13 is a graph of representative yaw (ROT-Z), pitch
(ROT-X) and roll (ROT-Y) angles as a function of position of a club
head 14 during a typical downswing. It can be seen by referring to
FIG. 11 and to FIG. 13, that during a large portion of the
downswing, the ball striking face 17 of the golf club head 14 is
not leading the swing. At the beginning of a golfer's downswing,
due to an approximately 90.degree. yaw rotation, the heel 24 may be
essentially leading the swing. Even further, at the beginning of a
golfer's downswing, due to an approximately 10.degree. roll
rotation, the lower portion of the heel 24 is essentially leading
the swing. During the downswing, the orientation of the golf club
and club head 14 changes from the approximately 90.degree. of yaw
at the beginning of the downswing to the approximately 0.degree. of
yaw at the point of impact.
[0084] Moreover, referring to FIG. 13, typically, the change in yaw
angle (ROT-Z) over the course of the downswing is not constant.
During the first portion of the downswing, when the club head 14
moves from behind the golfer to a position approximately at
shoulder height, the change in yaw angle is typically on the order
of 20.degree.. Thus, when the club head 14 is approximately
shoulder high, the yaw is approximately 70.degree.. When the club
head 14 is approximately waist high, the yaw angle is approximately
60.degree.. During the last 90.degree. portion of the downswing
(from waist height to the point of impact), the golf club generally
travels through a yaw angle of about 60.degree. to the yaw angle of
0.degree. at the point of impact. However, the change in yaw angle
during this portion of the downswing is generally not constant,
and, in fact, the golf club head 14 typically closes from
approximately a 20.degree. yaw to the 0.degree. yaw at the point of
impact only over the last 10.degree. degrees of the downswing. Over
the course of this latter 90.degree. portion of the downswing, yaw
angles of 45.degree. to 60.degree. may be considered to be
representative.
[0085] Similarly, still referring to FIG. 13, typically, the change
in roll angle (ROT-Y) over the course of the downswing is also not
constant. During the first portion of the downswing, when the club
head 14 moves from behind the golfer to a position approximately at
waist height, the roll angle is fairly constant, for example, on
the order of 7.degree. to 13.degree.. However, the change in roll
angle during the portion of the downswing from approximately waist
height to the point of impact is generally not constant, and, in
fact, the golf club head 14 typically has an increase in roll angle
from approximately 10.degree. to approximately 20.degree. as the
club head 14 swings from approximately waist height to
approximately knee height, and then a subsequent decrease in roll
angle to 0.degree. at the point of impact. Over the course of a
waist-to-knee portion of the downswing, a roll angle of 15.degree.
may be considered to be representative.
[0086] The speed of the golf club head also changes during the
downswing, from 0 mph at the beginning of the downswing to 65 to
100 mph (or more, for top-ranked golfers) at the point of impact.
At low speed, i.e., during the initial portion of the downswing,
drag due to air resistance may not be very significant. However,
during the portion of the downswing when club head 14 is even with
the golfer's waist and then swinging through to the point of
impact, the club head 14 is travelling at a considerable rate of
speed (for example, from 60 mph up to 130 mph for professional
golfers). During this portion of the downswing, drag due to air
resistance causes the golf club head 14 to impact the golf ball at
a slower speed than would be possible without air resistance.
[0087] Referring back to FIG. 11, several points (A, B and C) along
a golfer's typical downswing have been identified. At point A, the
club head 14 is at a downswing angle of approximately 120.degree.,
i.e., approximately 120.degree. from the point-of-impact with the
golf ball. At this point, the club head may already be traveling at
approximately 70% of its maximum velocity. FIG. 14A schematically
illustrates a club head 14 and a typical orientation of the air
flow over the club head 14 at point A. The yaw angle of the club
head 14 may be approximately 70.degree., meaning that the heel 24
is no longer substantially perpendicular to the air flowing over
the club head 14, but rather that the heel 24 is oriented at
approximately 20.degree. to the perpendicular to the air flowing
over the club head 14. Note also, that at this point in the
downswing, the club head 14 may have a roll angle of approximately
7.degree. to 10.degree., i.e., the heel 24 of the club head 14 is
rolled upwards by 7.degree. to 10.degree. relative to the direction
of air flow. Thus, the heel 24 (slightly canted to expose the lower
(sole side) portion of the heel 24), in conjunction with the
heel-side surface of the hosel region 26, leads the swing.
[0088] At point B shown on FIG. 11, the club head 14 is at a
downswing angle of approximately 100.degree., i.e., approximately
100.degree. from the point-of-impact with the golf ball. At this
point, the club head 14 may now be traveling at approximately 80%
of its maximum velocity. FIG. 14B schematically illustrates a club
head 14 and a typical orientation of the air flow over the club
head 14 at point B. The yaw angle of the club head 14 may be
approximately 60.degree., meaning that the heel 24 is oriented at
approximately 30.degree. to the perpendicular to the air flowing
over the club head 14. Further, at this point in the downswing, the
club head 14 may have a roll angle of approximately 5.degree. to
10.degree.. Thus, the heel 24 is again slightly canted to the
expose the lower (sole side) portion of the heel 24. This portion
of the heel 24, in conjunction with the heel-side surface of the
hosel region 26, and now also with some minor involvement of the
striking face-side surface of the hosel region 26, leads the swing.
In fact, at this yaw and roll angle orientation, the intersection
of the heel-side surface with the striking face-side surface of the
hosel region 26 provides the most forward surface (in the
trajectory direction). As can be seen, the heel 24 and the hosel
region 26 are associated with the leading edge, and the toe 20, a
portion of the back 22 adjacent to the toe 20, and/or their
intersection are associated with the trailing edge (as defined by
the direction of air flow).
[0089] At point C of FIG. 11, the club head 14 is at a downswing
position of approximately 70.degree., i.e., approximately
70.degree. from the point of impact with the golf ball. At this
point, the club head 14 may now be traveling at approximately 90%
or more of its maximum velocity. FIG. 14C schematically illustrates
a club head 14 and a typical orientation of the air flow over the
club head 14 at point C. The yaw angle of the club head 14 is
approximately 45.degree., meaning that the heel 24 is no longer
substantially perpendicular to the air flowing over the club head
14, but rather is oriented at approximately 45.degree. to the
perpendicular to the air flow. Further, at this point in the
downswing, the club head 14 may have a roll angle of approximately
20.degree.. Thus, the heel 24 (canted by approximately 20.degree.
to expose the lower (sole side) portion of the heel 24) in
conjunction with the heel-side surface of the hosel region 26, and
with even more involvement of the striking face-side surface of the
hosel region 26 leads the swing. At this yaw and roll angle
orientation, the intersection of the heel-side surface with the
striking face-side surface of the hosel region 26 provides the most
forward surface (in the trajectory direction). As can be seen, the
heel 24 and the hosel region 26 are again associated with the
leading edge and a portion of the toe 20 adjacent to the back 22,
the portion of the back 22 adjacent to the toe 20 and/or their
intersection are associated with the trailing edge (as defined by
the direction of air flow).
[0090] Referring back to FIGS. 11 and 13, it can be understood that
the integration or summation of the drag forces during the entire
downswing provides the total drag work experienced by the club head
14. Calculating the percent reduction in the drag work throughout
the swing can produce a very different result than calculating the
percent reduction in drag force at the point of impact only. The
drag-reducing structures described below provide various means to
reduce the total drag, not just reducing the drag at the
point-of-impact (I).
[0091] A further embodiment of the club head 14 is shown as club
head 64 in FIGS. 15-20A. Club head 64 is a generally "square head"
shaped club. Club head 64 includes ball-striking surface 17, crown
18, a sole 28, a heel 24, a toe 20, a back 22 and a hosel region
26.
[0092] A Kammback feature 23, located between the crown 18 and the
sole 28, continuously extends from a forward portion (i.e., a
region that is closer to the ball striking face 17 than to the back
22) of the toe 20 to the back 22, across the back 22 to the heel 24
and into a rearward portion of the heel 24. Thus, as best seen in
FIG. 17, the Kammback feature 23 extends along a majority of the
length of the toe 20. As best seen in FIG. 19, the Kammback feature
extends along a minority of the length of the heel 24. In this
particular embodiment, Kammback feature 23 is a concave groove
having a maximum height (H) that may range from approximately 10 mm
to approximately 20 mm and a maximum depth (D) that may range from
approximately 5 mm to approximately 15 mm.
[0093] One or more diffusers 36 may be formed in sole 28, as shown
in FIG. 20A. In an alternative embodiment of club head 14 as shown
as club head 74 in FIG. 20B, the sole 28 may be formed without a
diffuser.
[0094] Referring back to FIGS. 16, 18 and 19, in the heel 24, from
the tapered end of the Kammback feature 23 to the hosel region 26,
a streamlined region 100 having a surface 25 that is generally
shaped as the leading surface of an airfoil may be provided. As
disclosed below in greater detail, this streamlined region 100 and
the airfoil-like surface 25 may be configured so as to achieve
aerodynamic benefits as the air flows over the club head 14 during
a downswing stroke of the golf club 10. In particular, the
airfoil-like surface 25 of the heel 24 may transition smoothly and
gradually into the crown 18. Further, the airfoil-like surface 25
of the heel 24 may transition smoothly and gradually into the sole
28. Even further, the airfoil-like surface 25 of the heel 24 may
transition smoothly and gradually into the hosel region 26.
[0095] A further embodiment of the club head 14 is shown as club
head 84 in FIGS. 21-26A. Club head 84 is a generally "round head"
shaped club. Club head 84 includes ball-striking surface 17, crown
18, a sole 28, a heel 24, a toe 20, a back 22 and a hosel region
26.
[0096] Referring to FIGS. 23-26, a groove 29, located below the
outermost edge of the crown 18, continuously extends from a forward
portion of the toe 20 to the back 22, across the back 22 to the
heel 24 and into a forward portion of the heel 24. Thus, as best
seen in FIG. 23, the groove 29 extends along a majority of the
length of the toe 20. As best seen in FIG. 25, the groove 29 also
extends along a majority of the length of the heel 24. In this
particular embodiment, groove 29 is a concave groove having a
maximum height (H) that may range from approximately 10 mm to
approximately 20 mm and a maximum depth (D) that may range from
approximately 5 mm to approximately 10 mm. Further, as best shown
in FIG. 26A, sole 28 includes a shallow step 21 that generally
parallels groove 29. Step 21 smoothly merges into the surface of
the hosel region 26.
[0097] A diffuser 36 may be formed in sole 28, as shown in FIGS.
20A and 26A. In these particular embodiments, diffuser 36 extends
from a region of the sole 28 that is adjacent to the hosel region
26 toward the toe 20, the back 22 and the intersection of the toe
22 with the back 22. In an alternative embodiment of club head 14
as shown in FIG. 26B as club head 94, the sole 28 may be formed
without a diffuser.
[0098] Some of the example drag-reducing structures described in
more detail below may provide various means to maintain laminar
airflow over one or more of the surfaces of the club head 14 when
the ball striking face 17 is generally leading the swing, i.e.,
when air flows over the club head 14 from the ball striking face 17
toward the back 22. Additionally, some of the example drag-reducing
structures described in more detail below may provide various means
to maintain laminar airflow over one or more surfaces of the club
head 14 when the heel 24 is generally leading the swing, i.e., when
air flows over the club head 14 from the heel 24 toward the toe 20.
Moreover, some of the example drag-reducing structures described in
more detail below may provide various means to maintain laminar
airflow over one or more surfaces of the club head 14 when the
hosel region 26 is generally leading the swing, i.e., when air
flows over the club head 14 from the hosel region 26 toward the toe
20 and/or the back 22. The example drag-reducing structures
disclosed herein may be incorporated singly or in combination in
club head 14 and are applicable to any and all embodiments of club
head 14.
[0099] According to certain aspects, and referring, for example, to
FIGS. 3-6, 8-10, 15-31, a drag-reducing structure may be provided
as a streamlined region 100 located on the heel 24 in the vicinity
of (or adjacent to and possibly including a portion of) the hosel
region 26. This streamlined region 100 may be configured so as to
achieve aerodynamic benefits as the air flows over the club head 14
during a downswing stroke. As described above with respect to FIGS.
11-14, in the latter portion of the downswing, where the velocity
of the club head 14 is significant, the club head 14 may rotate
through a yaw angle of from approximately 70.degree. to 0.degree..
Further, due to the non-linear nature of the yaw angle rotation,
configurations of the heel 24 designed to reduce drag due to
airflow when the club head 14 is oriented between the yaw angles of
approximately 70.degree. to approximately 45.degree. may achieve
the greatest benefits.
[0100] Thus, due to the yaw angle rotation during the downswing, it
may be advantageous to provide a streamlined region 100 in the heel
24. For example, providing the streamlined region 100 with a
smooth, aerodynamically-shaped leading surface may allow air to
flow past the club head with minimal disruption. Such a streamlined
region 100 may be shaped to minimize resistance to airflow as the
air flows from the heel 24 toward the toe 20, toward the back 22,
and/or toward the intersection of the back 22 with the toe 20. The
streamlined region 100 may be advantageously located on the heel 24
adjacent to, and possibly even overlapping with, the hosel region
26. This streamlined region of the heel 24 may form a portion of
the leading surface of the club head 14 over a significant portion
of the downswing. The streamlined region 100 may extend along the
entire heel 24. Alternatively, the streamlined region 100 may have
a more limited extent.
[0101] Referring to FIGS. 27 and 28, according to certain aspects,
the streamlined region 100 as, for example, referenced in FIGS.
3-6, 8-10 and 15-31 may be provided at least along the length of
the heel 24 from approximately 15 mm to approximately 70 mm in the
Y-direction, as measured from a longitudinal axis of the shaft 12
or from where the longitudinal axis of the shaft 12 meets the
ground, i.e., at the "ground-zero" point, when the club is at a 60
degree lie angle position with a face angle of zero degrees. In
these embodiments, the streamlined region 100 may also optionally
extend beyond the enumerated range. For certain other embodiments,
the streamlined region 100 may be provided at least from
approximately 15 mm to approximately 50 mm in the Y-direction along
the length of the heel 24, as measured from the ground-zero point.
For further embodiments, the streamlined region 100 may be provided
at least from approximately 15 mm to approximately 30 mm, or even
at least from approximately 20 mm to approximately 25 mm, in the
Y-direction along the length of the heel 24, as measured from the
ground-zero point.
[0102] FIG. 27 is shown with three cross-section cuts. The
cross-section at line XXIX-XXIX is shown in FIGS. 29A and 29B. The
cross-section at line XXX-XXX is shown in FIGS. 30A and 30B. The
cross-section at line XXXI-XXXI is shown in FIGS. 31A and 31B. The
cross-sections shown in FIGS. 29-31 are used to illustrate specific
characteristics of club head 14 of FIGS. 1-6 and are also used to
schematically illustrate characteristics of the club head
embodiments shown in FIGS. 7-10, FIGS. 15-20 and FIGS. 21-26.
[0103] According to certain aspects and referring to FIGS. 29A and
29B, the streamlined region 100 may be defined by a cross-section
110 in the heel 24. FIGS. 29A and 29B illustrate a cross-section
110 of club head 14 taken through line XXIX-XXIX of FIG. 27. A
portion of the cross-section 110 cuts through the sole 28, the
crown 18 and the heel 24. Further, at least a portion of the
cross-section 110 lies within the streamlined region 100, and thus,
as discussed above, the leading portion of the cross-section 110
may resemble an airfoil. The cross-section 110 is taken parallel to
the X.sub.0-axis (i.e., approximately 90 degrees from the
Y.sub.0-axis (i.e., within a range of .+-.5 degrees)) in a vertical
plane located approximately 20 mm in the Y-direction as measured
from the ground-zero point. In other words, the cross-section 110
is oriented perpendicular to the Y.sub.0-axis. This cross-section
110 is thus oriented for air flowing over the club head 14 in a
direction from the heel 24 to the toe 20.
[0104] Referring to FIGS. 27, 29A and 29B, a leading edge 111 is
located on the heel 24. The leading edge 111 extends generally from
the hosel region 26 toward the back 22 and lies between the crown
18 and the sole 28. If air were to flow parallel to the
X.sub.0-axis over the club head 14 from the heel 24 toward the toe
20, the leading edge 111 would be the first portion of the heel 24
to experience the air flow. Generally, at the leading edge 111, the
slope of the surface of the cross-section 110 is perpendicular to
the X.sub.0-axis, i.e., the slope is vertical when the club head 14
is at the 60 degree lie angle position.
[0105] An apex point 112, which lies on the leading edge 111 of the
heel 24 may be defined at Y=20 mm (see FIG. 27). Further, a local
coordinate system associated with the cross-section 110 and the
apex point 112 may be defined: x- and z-axes extending from the
apex point 112 are oriented in the plane of the cross-section 110
at an angle of 15.degree. from the X.sub.0- and Z.sub.0-axes,
respectively, associated with the club head 14. This orientation of
the axes at 15.degree. corresponds to the roll angle of 15.degree.,
which was considered to be representative over the course of a
waist-to-knee portion of the downswing (i.e., when the club head 14
approaches its greatest velocity).
[0106] Thus, according to certain aspects, the airfoil-like surface
25 of the streamlined region 100 may be described as being
"quasi-parabolic." As used herein, the term "quasi-parabolic"
refers to any convex curve having an apex point 112 and two arms
that smoothly and gradually curve away from the apex point 112 and
from each other on the same side of the apex point. The first arm
of the airfoil-like surface 25 may be referred to as a crown-side
curve or upper curve 113. The other arm of the airfoil-like surface
25 may be referred to as a sole-side curve or lower curve 114. For
example, a branch of a hyperbolic curve may be considered to be
quasi-parabolic. Further, as used herein, a quasi-parabolic
cross-section need not be symmetric. For example, one arm of the
quasi-parabolic cross-section may be most closely represented by a
parabolic curve, while the other arm may be most closely
represented by a hyperbolic curve. As another example, the apex
point 112 need not be centered between the two arms. In which case,
the term "apex point" refers to the leading point of the
quasi-parabolic curve, i.e., the point from which the two curves
113, 114 curve away from each other. In other words, a
"quasi-parabolic" curve oriented with the arms extending
horizontally in the same direction has a maximum slope at the apex
point 112 and the absolute values of the slope of the curves 113,
114 gradually and continuously decrease as the horizontal distance
from the apex point 112 increases.
[0107] FIGS. 30A and 30B illustrate a cross-section 120 of club
head 14 taken through line XXX-XXX of FIG. 27. According to certain
aspects and referring to FIGS. 30A and 30B, the streamlined region
100 may be defined by its cross-section 120 in the heel 24. The
cross-section 120 is taken at an angle of approximately 70 degrees
(i.e., within a range of .+-.5 degrees) to the Y.sub.0-axis,
rotated around the apex point 112, as shown in FIG. 27. This
cross-section 120 is thus also oriented for air flowing over the
club head 14 in a direction from the heel 24 to the toe 20, but now
with the direction of airflow angled more toward the intersection
of the toe 20 with the back 22 as compared to the cross-section 110
(refer to FIG. 14 A). Similar to the cross-section 110, the
cross-section 120 includes a crown-side curve or upper curve 123
extending from the apex point 112 and a sole-side curve or lower
curve 124 also extending from the apex point. The apex point 112,
which is associated with the leading edge 111 of the heel 24 at
Y=20 mm, is shown.
[0108] The x- and z-axes associated with cross-section 120 are
oriented in the plane of the cross-section 120 at an angle of
15.degree. from the X.sub.0- and Z.sub.0-axes, respectively,
associated with the club head 14. Once again, this orientation of
the cross-sectional axes at 15.degree. corresponds to a roll angle
of 15.degree., which was considered to be representative over the
course of a waist-to-knee portion of the downswing (i.e., when the
club head 14 approaches its greatest velocity).
[0109] FIGS. 31A and 31B illustrate a cross-section 130 of club
head 14 taken through line XXXI-XXXI of FIG. 27. According to
certain aspects and referring to FIGS. 31A and 31B, the streamlined
region 100 may be defined by its cross-section 130 in the heel 24.
As discussed above, the cross-section 130 of the streamlined region
100 may resemble the leading edge of an airfoil. The cross-section
130 is taken at an angle of approximately 45 degrees (i.e., within
a range of .+-.5 degrees) to the Y-axis, rotated around the apex
point 112, as shown in FIG. 27. This cross-section 130 is thus
oriented for air flowing over the club head 14 generally in a
direction from the heel 24 to the back 22 (refer to FIG. 14C).
Similar to the cross-sections 110 and 120, the cross-section 130
also includes a crown-side curve or upper curve 133 extending from
the apex point 112 and a sole-side curve or lower curve 134 also
extending from the apex point. The apex point 112, which is
associated with the leading edge 111 of the heel 24 at Y=20 mm, as
measured from the ground-zero point, is shown.
[0110] The x- and z-axes associated with cross-section 130 are
oriented in the plane of the cross-section 130 at an angle of
15.degree. from the X.sub.0- and Z.sub.0-axes, respectively,
associated with the club head 14. Once again, this orientation of
the cross-sectional axes at 15.degree. corresponds to a roll angle
of 15.degree., which was considered to be representative over the
course of a waist-to-knee portion of the downswing (i.e., when the
club head 14 approaches its greatest velocity).
[0111] Referring to FIGS. 29A, 30A and 31A, a person of ordinary
skill in the art would recognize that one way to characterize the
shape of a curve is by providing a table of spline points. For
purposes of these spline point tables, the apex point 112 is
defined at (0, 0) and all of the coordinates of the spline points
are defined relative to the apex point 112. FIGS. 29A, 30A and 31A
include x-axis coordinate lines at 12 mm, 24 mm, 36 mm, 48 mm at
which spline points may be defined. Although spline points may be
defined at other x-axis coordinates, for example, at 3 mm, 6 mm and
18 mm, such coordinate lines are not included in FIGS. 29A, 30A and
31A for purposes of clarity.
[0112] As shown in FIGS. 29A, 30A and 31A, the z.sub.U-coordinates
are associated with the upper curves 113, 123, 133; the
z.sub.L-coordinates are associated with the lower curves 114, 124,
134. The upper curves are generally not the same as the lower
curves. In other words, the cross-sections 110, 120, 130 may be
non-symmetric. As can be seen from examining FIGS. 29A, 30A and
31A, this non-symmetry, i.e. the differences between the upper and
lower curves, may become more pronounced as the cross-sections
swing toward the back of the club head. Specifically, the upper and
lower curves of the cross-section taken at an angle of
approximately 90 degrees to the centerline (see, e.g., FIG. 29A)
may be more symmetrical than the upper and lower curves of the
cross-section taken at an angle of approximately 45 degrees to the
centerline (see, e.g., FIG. 31A). Furthermore, again referring to
FIGS. 29A, 30A and 31A, the lower curves may, for some example
embodiments, remain relatively constant as the cross-section swings
toward the back of the club head, while the upper curves may
flatten out.
[0113] Referring to FIGS. 29B, 30B and 31B, a person of ordinary
skill in the art would recognize that another way to characterize a
curve is by fitting the curve to one or more functions. For
example, because of the asymmetry of the upper and lower curves as
discussed above, the upper and lower curves of cross-sections 110,
120, 130 may be independently curve fit using polynomial functions.
Thus, according to certain aspects, second-order or third-order
polynomials, i.e., quadratic or cubic functions, may sufficiently
characterize the curves.
[0114] For example, a quadratic function may be determined with the
vertex of the quadratic function being constrained to be the apex
point 112, i.e., the (0, 0) point. In other words, the curve fit
may require that the quadratic function extend through the apex
point 112. Further the curve fit may require that the quadratic
function be perpendicular to the x-axis at the apex point 112.
[0115] Another mathematical technique that may be used to curve fit
involves the use of Bezier curves, which are parametric curves that
may be used to model smooth curves. Bezier curves, for example, are
commonly used in computer numerical control (CNC) machines for
controlling the machining of complex smooth curves.
[0116] Using Bezier curves, the following generalized parametric
curves may be used to obtain, respectively, the x- and
z-coordinates of the upper curve of the cross-section:
x.sub.U=(1-t).sup.3Pxu.sub.0+3(1-t).sup.2tPxu.sub.1+3(1-t)t.sup.2Pxu.sub-
.2+t.sup.3Pxu.sub.3 Equ. (1a)
z.sub.U=(1-t).sup.3Pzu.sub.0+3(1-t).sup.2tPzu.sub.0+3(1-t)t.sup.2Pzu.sub-
.2+t.sup.3Pzu.sub.3 Equ. (1b) [0117] over the range of:
0.ltoreq.t.ltoreq.1.
[0118] Pxu.sub.0, Pxu.sub.1, Pxu.sub.2 and Pxu.sub.3 are the
control points for the Bezier curve for the x-coordinates
associated with the upper curve, and Pzu.sub.0, Pzu.sub.1,
Pzu.sub.2 and Pzu.sub.3 are the control points for the Bezier curve
for the z-coordinates associated with the upper curve.
[0119] Similarly, the following generalized parametric Bezier
curves may be used to obtain, respectively, the x- and
z-coordinates of the lower curve of the cross-section:
x.sub.L=(1-t).sup.3PXL.sub.0+3(1-t).sup.2tPXL.sub.1+3(1-t)t.sup.2PXL.sub-
.2+t.sup.3PXL.sub.3 Equ. (2a)
z.sub.L=(1-t).sup.3PZL.sub.0+3(1-t).sup.2tPZL.sub.1+3(1-t)t.sup.2PZL.sub-
.2+t.sup.3PZL.sub.3 Equ. (2b) [0120] over the range of:
0.ltoreq.t.ltoreq.1.
[0121] PXL.sub.0, PXL.sub.1, PXL.sub.2 and PXL.sub.3 are the
control points for the Bezier curve for the x-coordinates
associated with the lower curve, and PZL.sub.0, PZL.sub.1,
PZL.sub.2 and PZL.sub.3 are the control points for the Bezier curve
for the z-coordinates associated with the lower curve.
[0122] Since curve fits are used to generally fit the data, one way
to capture the data may be to provide curves that bound the data.
Thus, for example, referring to FIGS. 29B, 30B, 31B, each of the
upper and lower curves of cross-sections 110, 120, 130 may be
characterized as residing within a region bounded by a pair of
curves (115a, 115b), (116a, 116b), (125a, 125b), (126a, 126b),
(135a, 135b), (136a, 136b) wherein the pairs of curves may, for
example, represent a variation in the z-coordinates of the curves
113, 114, 123, 124, 133 and 134, respectively, of up to .+-.10%, or
even up to 20%.
[0123] Further, it is noted that the cross-sections 110, 120 and
130 presented in FIGS. 29-31 are for a club head 14 without a
diffuser 36 provided on the sole 28. According to certain aspects,
a diffuser 36 may be provided on the sole 28, and as such, the
lower curves of the cross-sections 110, 120 and/or 130 would vary
from the shapes presented in FIGS. 29-31. Even further, according
to certain aspects, each of the cross-sections 110, 120 and 130 may
include a Kammback feature 23 at their trailing edge.
[0124] Referring back to FIGS. 27 and 28, it is noted that the apex
point 112, which is associated with the leading edge 111 of the
heel 24 at Y=20 mm (see FIG. 27), was used to assist in the
description of the cross-sections 110, 120 and 130 (see FIGS.
29-31). However, the apex point 112 need not be positioned
precisely at Y=20 mm. In the more general case, according to
certain aspects, the apex point 112 may be position from
approximately 10 mm to approximately 30 mm in the Y-direction as
measured from the "ground-zero" point. For some embodiments, the
apex point 112 may be position from approximately 15 mm to
approximately 25 mm in the Y-direction as measured from the
"ground-zero" point. A variation of plus or minus a millimeter in
the location of the apex point may be considered acceptable.
According to certain embodiments, the apex point 112 may be
positioned on the leading edge 111 of the heel 24 in the forward
half of the club head 14.
[0125] According to certain aspects and as best shown in FIG. 20B,
the sole 28 may extend across the width of the club head 14, from
the heel 24 to the toe 20, with a generally convex, gradual,
widthwise curvature. Further, the smooth and uninterrupted,
airfoil-like surface 25 of the heel 24 may continue into, and even
beyond, a central region of the sole 28. The sole's generally
convex, widthwise, curvature may extend all the way across the sole
28 to the toe 20. In other words, the sole 28 may be provided with
a convex curvature across its entire width, from the heel 24 to the
toe 20.
[0126] Further, the sole 28 may extend across the length of the
club head 14, from the ball striking face 17 to the back 22, with a
generally convex smooth curvature. This generally convex curvature
may extend from adjacent the ball striking surface 17 to the back
22 without transitioning from a positive to a negative curvature.
In other words, the sole 28 may be provided with a convex curvature
along its entire length from the ball striking face 17 to the back
22.
[0127] Alternatively, according to certain aspects, as illustrated,
for example, in FIGS. 5, 20A and 26A, a recess or diffuser 36 may
be formed in sole 28. In the illustrated embodiment of FIG. 5,
recess or diffuser 36 is substantially V-shaped with a vertex 38 of
its shape being positioned proximate ball striking face 17 and heel
24. That is, vertex 38 is positioned close to ball striking face 17
and heel 24 and away from skirt or Kammback feature 23 and toe 20.
Recess or diffuser 36 includes a pair of legs 40 extending to a
point proximate toe 20 and away from ball striking face 17, and
curving toward skirt or Kammback feature 23 and away from ball
striking face 17.
[0128] Still referring to FIG. 5, a plurality of secondary recesses
42 may be formed in a bottom surface 43 of recess or diffuser 36.
In the illustrated embodiment, each secondary recess 42 is a
regular trapezoid, with its smaller base 44 closer to heel 24 and
its larger base 46 closer to toe 20, and angled sides 45 joining
smaller base 44 to larger base 46. In the illustrated embodiment a
depth of each secondary recess 42 varies from its largest amount at
smaller base 44 to larger base 46, which is flush with bottom
surface 43 of recess or diffuser 36.
[0129] Thus, according to certain aspects and as best shown in
FIGS. 5, 20A and 26A, diffuser 36 may extend from adjacent the
hosel region 26 toward the toe 20, toward the intersection of the
toe 20 with the back 22 and/or toward the back 22. The
cross-sectional area of the diffuser 36 may gradually increase as
the diffuser 36 extends away from the hosel region 26. It is
expected than any adverse pressure gradient building up in an air
stream flowing from the hosel region 26 toward the toe 20 and/or
toward the back 22 will be mitigated by the increase in
cross-sectional area of the diffuser 36. Thus, it is expected that
any transition from the laminar flow regime to the turbulent flow
regime of the air flowing over the sole 28 will be delayed or even
eliminated altogether. In certain configurations, the sole 28 may
include multiple diffusers.
[0130] The one or more diffusers 36 may be oriented to mitigate
drag during at least some portion of the downswing stroke,
particularly as the club head 14 rotates around the yaw axis. The
sides of the diffuser 36 may be straight or curved. In certain
configurations, the diffuser 36 may be oriented at an angle from
the Y.sub.0-axis in order to diffuse the air flow (i.e., reduce the
adverse pressure gradient) when the hosel region 26 and/or the heel
24 lead the swing. The diffuser 36 may be oriented at angles that
range from approximately 10.degree. to approximately 80.degree.
from the Y.sub.0-axis. Optionally, the diffuser 36 may be oriented
at angles that range from approximately 20.degree. to approximately
70.degree., or from approximately 30.degree. to approximately
70.degree., or from approximately 40.degree. to approximately
70.degree., or even from approximately 45.degree. to approximately
65.degree. from the T.sub.0 direction. Thus, in certain
configurations, the diffuser 36 may extend from the hosel region 26
toward the toe 20 and/or toward the back 22. In other
configurations, the diffuser 36 may extend from the heel 24 toward
the toe 20 and/or the back 22.
[0131] Optionally, as shown in FIGS. 5, 20A and 26, the diffuser 36
may include one or more vanes 32. The vane 32 may be located
approximately centered between the sides of the diffuser 36. In
certain configurations (not shown), the diffuser 36 may include
multiple vanes. In other configurations, the diffuser 36 need not
include any vane. Even further, the vane 32 may extend
substantially along the entire length of the diffuser 36 or only
partially along the length of the diffuser 36.
[0132] As shown, according to one embodiment, in FIGS. 1-4 and 6,
the club head 14 may include the "Kammback" feature 23. The
Kammback feature 23 may extend from the crown 18 to the sole 28. As
shown in FIGS. 3 and 6, the Kammback feature 23 extends across the
back 22 from the heel 24 to the toe 20. Further, as shown in FIGS.
2 and 4, the Kammback feature 23 may extend into the toe 22 and/or
into the heel 24.
[0133] Generally, Kammback features are designed to take into
account that a laminar flow, which could be maintained with a very
long, gradually tapering, downstream (or trailing) end of an
aerodynamically-shaped body, cannot be maintained with a shorter,
tapered, downstream end. When a downstream tapered end would be too
short to maintain a laminar flow, drag due to turbulence may start
to become significant after the downstream end of a club head's
cross-sectional area is reduced to approximately fifty percent of
the club head's maximum cross section. This drag may be mitigated
by shearing off or removing the too-short tapered downstream end of
the club head, rather than maintaining the too-short tapered end.
It is this relatively abrupt cut off of the tapered end that is
referred to as the Kammback feature 23.
[0134] During a significant portion of the golfer's downswing, as
discussed above, the heel 24 and/or the hosel region 26 lead the
swing. During these portions of the downswing, either the toe 20,
portion of the toe 20, the intersection of the toe 20 with the back
22, and/or portions of the back 22 form the downstream or trailing
end of the club head 14 (see, e.g., FIGS. 27 and 29-31). Thus, the
Kammback feature 23, when positioned along the toe, at the
intersection of the toe 20 with the back 22, and/or along the back
22 of the club head 14, may be expected to reduce turbulent flow,
and therefore reduce drag due to turbulence, during these portions
of the downswing.
[0135] Further, during the last approximately 20.degree. of the
golfer's downswing prior to impact with the golf ball, as the ball
striking face 17 begins to lead the swing, the back 22 of the club
head 14 becomes aligned with the downstream direction of the
airflow. Thus, the Kammback feature 23, when positioned along the
back 22 of club head 14, is expected to reduce turbulent flow, and
therefore reduce drag due to turbulence, most significantly during
the last approximately 20.degree. of the golfer's downswing.
[0136] According to certain aspects, the Kammback feature 23 may
include a continuous groove 29 formed about a portion of a
periphery of club head 14. As illustrated in FIGS. 2-4, groove 29
extends from a front portion 30 of toe 20 completely to a rear edge
32 of toe 20, and continues on to rear portion 22. Groove 29 then
extends across the entire length of back 22. As can be seen in FIG.
4, groove 29 tapers to an end in a rear portion 34 of heel 24. In
certain embodiments (see FIG. 2), groove 29 at front portion 30 of
toe 20 may turn and continue along a portion of sole 28.
[0137] In the illustrated embodiment of FIGS. 2-4, groove 29 is
substantially U-shaped. In certain embodiments, groove 29 has a
maximum depth (D) of approximately 15 mm. It is to be appreciated
however, that groove 29 may have any depth along its length, and
further that the depth of groove 29 may vary along its length. Even
further, it is to be appreciated that groove 29 may have any height
(H), although a height of from one-quarter to one-half of the
maximum sole-to-crown height of the club head 14 may be most
advantageous. The height of the groove 29 may vary over its length,
as shown in FIGS. 2-4, or alternatively, the height of the groove
29 may be uniform over some or all of its length.
[0138] As air flows over crown 18 and sole 28 of body member 15 of
club head 14, it tends to separate, which causes increased drag.
Groove 29 may serve to reduce the tendency of the air to separate,
thereby reducing drag and improving the aerodynamics of club head
14, which in turn increases club head speed and the distance that
the ball will travel after being struck. Having groove 29 extend
along toe 20 may be particularly advantageous, since for the
majority of the swing path of golf club head 14, the leading
portion of club head 14 is heel 24 with the trailing edge of club
head 14 being toe 20, as noted above. Thus, the aerodynamic
advantage provided by groove 29 along toe 20 is realized during the
majority of the swing path. The portion of groove 29 that extends
along the back 22 may provide an aerodynamic advantage at the point
of impact of club head 14 with the ball.
[0139] An example of the reduction in drag during the swing
provided by groove 29 is illustrated in the table below. This table
is based on a computer fluid dynamic (CFD) model for the embodiment
of club head 14 as shown in FIGS. 1-6. In the table, drag force
values are shown for different degrees of yaw throughout the golf
swing for both a square head design and for the square head design
incorporating the drag-reducing structure of groove 29.
TABLE-US-00005 Drag Force Yaw.fwdarw. 90.degree. 70.degree.
60.degree. 45.degree. 20.degree. 0.degree. Standard 0 3.04 3.68
8.81 8.60 8.32 W/Groove 0 1.27 1.30 3.25 3.39 4.01
[0140] From the results of the computer model, it can be seen that
at the point of impact, where the yaw angle is 0.degree., the drag
force for the square club head with groove 29 is approximately
48.2% (4.01/8.32) of that of the square club head. However, an
integration of the total drag during the entire swing for the
square club head provides a total drag work of 544.39, while the
total drag work for the square club head with groove 29 is 216.75.
Thus the total drag work for the square club head with groove 29 is
approximately 39.8% (216.75/544.39) of that of the square club
head. Thus, integrating the drag force throughout the swing can
produce a very different result than calculating the drag force at
the point of impact only.
[0141] Referring to FIGS. 7-10, continuous groove 29 is formed
about a portion of a periphery of club head 54. As illustrated in
FIGS. 7-10, groove 29 extends from a front portion 30 of toe 20
completely to a rear edge 32 of toe 20, and continues on to rear
portion 22. Groove 29 then extends across the entire length of rear
portion 22. As can be seen in FIG. 9, groove 29 tapers to an end in
a rear portion 34 of heel 24.
[0142] One or more of the drag-reducing structures, such as the
streamlined portion 100 of the heel 24, the diffuser 36 of the sole
28, and/or the Kammback feature 23, may be provided on the club
head 14 in order to reduce the drag on the club head during a
user's golf swing from the end of a user's backswing throughout the
downswing to the ball impact location. Specifically, the
streamlined portion 100 of the heel 24, the diffuser 36, and the
Kammback feature 23 may be provided to reduce the drag on the club
head 14 primarily when the heel 24 and/or the hosel region 26 of
the club head 14 are generally leading the swing. The Kammback
feature 23, especially when positioned within the back 22 of the
club head 14, may also be provided to reduce the drag on the club
head 14 when the ball striking face 17 is generally leading the
swing.
[0143] Different golf clubs are designed for the different skills
that a player brings to the game. For example, professional players
may opt for clubs that are highly efficient at transforming the
energy developed during the swing into the energy driving the golf
ball over a very small sweet spot. In contrast, weekend players may
opt for clubs designed to forgive less-than-perfect placement of
the club's sweet spot relative to the struck golf ball. In order to
provide these differing club characteristics, clubs may be provided
with club heads having any of various weights, volumes,
moments-of-inertias, center-of-gravity placements, stiffnesses,
face (i.e., ball-striking surface) heights, widths and/or areas,
etc.
[0144] The club heads of typical modern drivers may be provided
with a volume that ranges from approximately 420 cc to
approximately 470 cc. Club head volumes, as presented herein, are
as measured using the USGA "Procedure for Measuring the Club Head
Size of Wood Clubs" (Nov. 21, 2003). The club head weight for a
typical driver may range from approximately 190 g to approximately
220 g. Referring to FIGS. 32A and 32B, other physical properties of
a typical driver can be defined and characterized. For example, the
face area may range from approximately 3000 mm.sup.2 to
approximately 4800 mm.sup.2, with a face length that may range from
approximately 110 mm to approximately 130 mm and a face height that
may range from approximately 48 mm to approximately 62 mm. The face
area is defined as the area bounded by the inside tangent of a
radius which blends the ball striking face to the other portions of
the body member of the golf club head. The face length is measured
from opposed points on the club head as shown in FIG. 32B. The face
height is defined as the distance measured at the face center (see
USGA, "Procedure for Measuring the Flexibility of a Golf ClubHead,"
Section 6.1 Determination of Impact Location, for determining the
location of the face center) from the ground plane to the midpoint
of the radius which blends the ball striking face and crown of the
club as measured when the club is sitting at a lie angle of 60
degrees with a face angle of zero degrees. The club head breadth
may range from approximately 105 mm to approximately 125 mm. The
moment-of-inertia at the center-of-gravity around an axis parallel
to the X.sub.0-axis may range from approximately 2800 g-cm.sup.2 to
approximately 3200 g-cm.sup.2. The moment-of-inertia at the
center-of-gravity around an axis parallel to the Z.sub.0-axis may
range from approximately 4500 g-cm.sup.2 to approximately 5500
g-cm.sup.2. For typical modern drivers, the location of the
center-of-gravity in the X.sub.0 direction of the club head (as
measured from the ground-zero point) may range from approximately
25 mm to approximately 33 mm; the location of the center-of-gravity
in the Y.sub.0 direction may also range from approximately 16 mm to
approximately 22 mm (also as measured from the ground-zero point);
and the location of the center-of-gravity in the Z.sub.0 direction
may also range from approximately 25 mm to approximately 38 mm
(also as measured from the ground-zero point).
[0145] The above-presented values for certain characteristic
parameters of the club heads of typical modern drivers are not
meant to be limiting. Thus, for example, for certain embodiments,
club head volumes may exceed 470 cc or club head weights may exceed
220 g. For certain embodiments, the moment-of-inertia at the
center-of-gravity around an axis parallel to the X.sub.0-axis may
exceed 3200 g-cm.sup.2. For example, the moment-of-inertia at the
center-of-gravity around an axis parallel to the X.sub.0-axis may
be range up to 3400 g-cm.sup.2, up to 3600 g-cm.sup.2, or even up
to or over 4000 g-cm.sup.2. Similarly, for certain embodiments, the
moment-of-inertia at the center-of-gravity around an axis parallel
to the Z.sub.0-axis may exceed 5500 g-cm.sup.2. For example, the
moment-of-inertia at the center-of-gravity around an axis parallel
to the Z.sub.0-axis may be range up to 5700 g-cm.sup.2, up to 5800
g-cm.sup.2, or even up to 6000 g-cm.sup.2.
[0146] The design of any given golf club always involves a series
of tradeoffs or compromises. The following disclosed embodiments
illustrate some of these tradeoffs.
Example Embodiment (1)
[0147] In a first example, a representative embodiment of a club
head as shown in FIGS. 1-6 is described. This first example club
head is provided with a volume that is greater than approximately
400 cc. Referring to FIGS. 32A and 32B, other physical properties
can be characterized. The face height ranges from approximately 53
mm to approximately 57 mm. The moment-of-inertia at the
center-of-gravity around an axis parallel to the X.sub.0-axis
ranges from approximately 2800 g-cm.sup.2 to approximately 3300
g-cm.sup.2. The moment-of-inertia at the center-of-gravity around
an axis parallel to the Z.sub.0-axis is greater than approximately
4800 g-cm.sup.2. As an indication of the aspect ratio of the club,
the club breadth-to-face length ratio is 0.94 or greater.
[0148] In addition, the club head of this first example embodiment
may have a weight that ranges from approximately 200 g to
approximately 210 g. Referring again to FIGS. 32A and 32B, the face
length may range from approximately 114 mm to approximately 118 mm
and the face area may range from approximately 3200 mm.sup.2 to
approximately 3800 mm.sup.2. The club head breadth may range from
approximately 112 mm to approximately 114 mm. The location of the
center-of-gravity in the X.sub.0 may range from approximately 28 mm
to approximately 32 mm; the location of the center-of-gravity in
the Y.sub.0 direction may range from approximately 17 mm to
approximately 21 mm; and the location of the center-of-gravity in
the Z.sub.0 direction may range from approximately 27 mm to
approximately 31 mm (all as measured from the ground-zero
point).
[0149] For this example club head, Table I provides a set of
nominal spline point coordinates for the upper curve 113 and lower
curve 114 of cross-section 110. As discussed, these nominal spline
point coordinates may vary, in some instances, within a range of
.+-.10%.
TABLE-US-00006 TABLE I Spline Points for Cross-Section 110 for
Example (1) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 7 11 16 19 22 25 26 (upper surface 113)
z.sub.L-coordinate (mm) 0 -10 -14 -19 -23 -25 -29 -32 (lower
surface 114)
[0150] Alternatively, for this example club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 113 of
cross-section 110 as follows:
x.sub.U=3(17)(1-t)t.sup.2+(48)t.sup.3 Equ. (113a)
z.sub.U=3(10)(1-t).sup.2t+3(26)(1-t)t.sup.2+(26)t.sup.3 Equ. (113b)
[0151] over the range of: 0.ltoreq.t.ltoreq.1.
[0152] Thus, for this particular curve 113, the Bezier control
points for the x-coordinates have been defined as: Pxu.sub.0=0,
Pxu.sub.1=0, Pxu.sub.2=17 and Pxu.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: Pzu.sub.0=0,
Pzu.sub.1=10, Pzu.sub.2=26 and Pzu.sub.3=26. As discussed, these
z-coordinates may vary, in some instances, within a range of
.+-.10%.
[0153] Similarly, for this example club head, the Bezier equations
(2a) and (2b) may be used to obtain, respectively, the x- and
z-coordinates of the lower curve 114 of cross-section 110 as
follows:
x.sub.L=3(11)(1-t)t.sup.2+(48)t.sup.3 Equ. (114a)
z.sub.L=3(-10)(1-t).sup.2t+3(-26)(1-t)t.sup.2+(-32)t.sup.3 Equ.
(114b) [0154] over the range of: 0.ltoreq.t.ltoreq.1.
[0155] Thus, for this particular curve 114, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=11 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-10, PZL.sub.2=-26 and PZL.sub.3=-32. These z-coordinates
may also vary, in some instances, within a range of .+-.10%.
[0156] It can be seen from an examination of the data and the
figures that the upper, crown-side curve 113 differs from the
lower, sole-side curve 114. For example, at 3 mm along the x-axis
from the apex point 112, the lower curve 114 has a z-coordinate
value that is approximately 40% greater than the z-coordinate value
of the upper curve 113. This introduces an initial asymmetry into
the curves, i.e., lower curve 114 starts out deeper than upper
curve 113. However, from 3 mm to 24 mm along the x-axis, the upper
curve 113 and the lower curve 114 both extend away from the x-axis
by an additional 15 mm (i.e., the .DELTA.z.sub.U=22-7=15 mm and the
.DELTA.z.sub.L=25-10=15 mm). And, from 3 mm to 36 mm along the
x-axis, the upper curve 113 and the lower curve 114 extend away
from the x-axis by an additional 18 mm and 19 mm, respectively--a
difference of less than 10%. In other words, from 3 mm to 36 mm
along the x-axis, the curvatures of the upper curve 113 and the
lower curve 114 are approximately the same.
[0157] As with curves 113 and 114 discussed above with respect to
FIG. 29A, referring now to FIG. 30A, upper and lower curves 123 and
124 for this first example club head each may be characterized by a
curve presented as a table of spline points. Table II provides a
set of spline point coordinates for the cross-section 120 for
Example (1). The z.sub.U-coordinates are associated with the upper
curve 123; the z.sub.L-coordinates are associated with the lower
curve 124.
TABLE-US-00007 TABLE II Spline Points for Cross-Section 120 for
Example (1) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 7 11 16 19 21 24 25 (upper surface 123)
z.sub.L-coordinate (mm) 0 -9 -13 -18 -21 -24 -28 -30 (lower surface
124)
[0158] Alternatively, for this example club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 123 of
cross-section 120 as follows:
x.sub.U=3(19)(1-t)t.sup.2+(48)t.sup.3 Equ. (123a)
z.sub.U=3(10)(1-t).sup.2t+3(25)(1-t)t.sup.2+(25)t.sup.3 Equ. (123b)
[0159] over the range of: 0.ltoreq.t.ltoreq.1.
[0160] Thus, it can be seen that for this particular curve 123, the
Bezier control points for the x-coordinates have been defined as:
Pxu.sub.0=0, Pxu.sub.1=0, Pxu.sub.2=19 and Pxu.sub.3=48, and the
Bezier control points for the z-coordinates have been defined as:
Pzu.sub.0=0, Pzu.sub.1=10, Pzu.sub.2=25 and Pzu.sub.3=25.
[0161] As above, for this example club head, the Bezier equations
(2a) and (2b) may be used to obtain, respectively, the x- and
z-coordinates of the lower curve 124 of cross-section 120 as
follows:
x.sub.L=3(13)(1-t)t.sup.2+(48)t.sup.3 Equ. (124a)
z.sub.L=3(-10)(1-t).sup.2t+3(-26)(1-t)t.sup.2+(-30)t.sup.3 Equ.
(124b) [0162] over the range of: 0.ltoreq.t.ltoreq.1.
[0163] Thus, for this particular curve 124, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=13 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-10, PZL.sub.2=-26 and PZL.sub.3=-30.
[0164] It can be seen from an examination of the data and the
figures that the upper, crown-side curve 123 differs from the
lower, sole-side curve 124. For example, at 3 mm along the x-axis
from the apex point 112, the lower curve 124 has a z-coordinate
value that is approximately 30% greater than the z-coordinate value
of the upper curve 123. This introduces an initial asymmetry into
the curves. However, from 3 mm to 18 mm along the x-axis, the upper
curve 123 and the lower curve 124 both extend away from the x-axis
by an additional 12 mm (i.e., the .DELTA.z.sub.U=19-7=12 mm and the
.DELTA.z.sub.L=21-9=12 mm). And, from 3 mm to 24 mm along the
x-axis, the upper curve 123 and the lower curve 124 extend away
from the x-axis by an additional 14 mm and 15 mm, respectively--a
difference of less than 10%. In other words, from 3 mm to 24 mm
along the x-axis, the curvatures of the upper curve 123 and the
lower curve 124 are approximately the same.
[0165] Again, as with surfaces 113 and 114 discussed above, the
upper and lower curves 133 and 134 may be characterized by curves
presented as a table of spline points. Table III provides a set of
spline point coordinates for the cross-section 130 for Example (1).
For purposes of this table, all of the coordinates of the spline
points are defined relative to the apex point 112. The
z.sub.U-coordinates are associated with the upper curve 133; the
z.sub.L-coordinates are associated with the lower curve 134.
TABLE-US-00008 TABLE III Spline Points for Cross-Section 130 for
Example (1) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 6 9 12 15 17 18 18 (upper surface 133)
z.sub.L-coordinate (mm) 0 -8 -12 -16 -20 -22 -26 -29 (lower surface
134)
[0166] Alternatively, for this example club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 133 of
cross-section 130 as follows:
x.sub.U=3(25)(1-t)t.sup.2+(48)t.sup.3 Equ. (133a)
z.sub.U=3(10)(1-t).sup.2t+3(21)(1-t)t.sup.2+(18)t.sup.3 Equ. (133b)
[0167] over the range of: 0.ltoreq.t.ltoreq.1.
[0168] Thus, for this particular curve 133, the Bezier control
points for the x-coordinates have been defined as: Pxu.sub.0=0,
Pxu.sub.1=0, Pxu.sub.2=25 and Pxu.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: Pzu.sub.0=0,
Pzu.sub.1=10, Pzu.sub.2=21 and Pzu.sub.3=18.
[0169] As above, for this example club head, the Bezier equations
(2a) and (2b) may be used to obtain, respectively, the x- and
z-coordinates of the lower curve 134 of cross-section 130 as
follows:
x.sub.L=3(12)(1-t)t.sup.2+(48)t.sup.3 Equ. (134a)
z.sub.L=3(-10)(1-t).sup.2t+3(-22)(1-t)t.sup.2+(-29)t.sup.3 Equ.
(134b) [0170] over the range of: 0.ltoreq.t.ltoreq.1.
[0171] Thus, for this particular curve 134, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=12 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-10, PZL.sub.2=-22 and PZL.sub.3=-29.
[0172] An analysis of the data for this Example (1) embodiment at
cross-section 130 shows that at 3 mm along the x-axis from the apex
point 112 the lower, sole-side curve 134 has a z-coordinate value
that is approximately 30% greater than the z-coordinate value of
the upper, crown-side curve 133. This introduces an initial
asymmetry into the curves. From 3 mm to 18 mm along the x-axis, the
upper curve 133 and the lower curve 134 extend away from the x-axis
by an additional 9 mm and 12 mm, respectively. In fact, from 3 mm
to 12 mm along the x-axis, the upper curve 133 and the lower curve
134 extend away from the x-axis by an additional 6 mm and 8 mm,
respectively--a difference of greater than 10%. In other words, the
curvatures of the upper curve 133 and the lower curve 134 for this
Example (1) embodiment are significantly different over the range
of interest. And it can be seen, by looking at FIG. 31A, that upper
curve 133 is flatter (less curved) than lower curve 134.
[0173] Further, when the curves of the cross-section 110 (i.e., the
cross-section oriented at 90 degrees from the centerline) are
compared to the curves of the cross-section 120 (i.e., the
cross-section oriented at 70 degrees from the centerline), it can
be seen that they are very similar. Specifically, the values of the
z-coordinates for the upper curve 113 are the same as the values of
the z-coordinates for the upper curve 123 at the x-coordinates of 3
mm, 6 mm, 12 mm and 18 mm, and thereafter, the values for the
z-coordinates of the upper curves 113 and 123 depart from each
other by less than 10%. With respect to the lower curves 114 and
124 for the cross-sections 110 and 120, respectively, the values of
the z-coordinates depart from each other by 10% or less over the
x-coordinate range from 0 mm to 48 mm, with the lower curve 124
being slightly smaller than the lower curve 114. When the curves of
the cross-section 110 (i.e., the cross-section oriented at 90
degrees from the centerline) are compared to the curves of the
cross-section 130 (i.e., the cross-section oriented at 45 degrees
from the centerline), it can be seen that the values of the
z-coordinates for the lower curve 134 of the cross-section 130
differ from the values of the z-coordinates for the lower curve 114
of the cross-section 110 by a fairly constant amount--either 2 mm
or 3 mm--over the x-coordinate range of 0 mm to 48 mm. On the other
hand, it can be seen that the difference in the values of the
z-coordinates for the upper curve 133 of the cross-section 130 from
the values of the z-coordinates for the upper curve 113 of the
cross-section 110 increases over the x-coordinate range of 0 mm to
48 mm. In other words, the curvature of the upper curve 133
significantly departs from curvature of the upper curve 113, with
upper curve 133 being significantly flatter than upper curve 113.
This can also be appreciated by comparing curve 113 in FIG. 29A
with curve 133 in FIG. 31A.
Example Embodiment (2)
[0174] In a second example, a representative embodiment of a club
head as shown in FIGS. 7-10 is described. This second example club
head is provided with a volume that is greater than approximately
400 cc. The face height ranges from approximately 56 mm to
approximately 60 mm. The moment-of-inertia at the center-of-gravity
around an axis parallel to the X.sub.0-axis ranges from
approximately 2600 g-cm.sup.2 to approximately 3000 g-cm.sup.2. The
moment-of-inertia at the center-of-gravity around an axis parallel
to the Z.sub.0-axis ranges from approximately 4500 g-cm.sup.2 to
approximately 5200 g-cm.sup.2. The club breadth-to-face length
ratio is 0.90 or greater.
[0175] In addition, the club head of this second example embodiment
may have a weight that ranges from approximately 197 g to
approximately 207 g. Referring again to FIGS. 32A and 32B, the face
length may range from approximately 122 mm to approximately 126 mm
and the face area may range from approximately 3200 mm.sup.2 to
approximately 3800 mm.sup.2. The club head breadth may range from
approximately 112 mm to approximately 116 mm. The location of the
center-of-gravity in the X.sub.0 direction may range from
approximately 28 mm to approximately 32 mm; the location of the
center-of-gravity in the Y.sub.0 direction may range from
approximately 17 mm to approximately 21 mm; and the location of the
center-of-gravity in the Z.sub.0 direction may range from
approximately 33 mm to approximately 37 mm (all as measured from
the ground-zero point).
[0176] For this Example (2) club head, Table IV provides a set of
nominal spline point coordinates for the upper and lower curves of
cross-section 110. As previously discussed, these nominal spline
point coordinates may vary, in some instances, within a range of
.+-.10%.
TABLE-US-00009 TABLE IV Spline Points for Cross-Section 110 for
Example (2) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 6 9 13 16 19 22 23 (upper surface 113)
z.sub.L-coordinate (mm) 0 -9 -13 -18 -21 -24 -30 -33 (lower surface
114)
[0177] Alternatively, for this example club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 113 of
cross-section 110 as follows:
x.sub.U=3(22)(1-t)t.sup.2+(48)t.sup.3 Equ. (213a)
z.sub.U=3(8)(1-t).sup.2t+3(23)(1-t)t.sup.2+(23)t.sup.3 Equ. (213b)
[0178] over the range of: 0.ltoreq.t.ltoreq.1.
[0179] Thus, for this particular curve 113, the Bezier control
points for the x-coordinates have been defined as: Pxu.sub.0=0,
Pxu.sub.1=0, Pxu.sub.2=22 and Pxu.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: Pzu.sub.0=0,
Pzu.sub.1=8, Pzu.sub.2=23 and Pzu.sub.3=23. As discussed, these
z-coordinates may vary, in some instances, within a range of
.+-.10%.
[0180] Similarly, for this example club head, the Bezier equations
(2a) and (2b) may be used to obtain, respectively, the x- and
z-coordinates of the lower curve 114 of cross-section 110 as
follows:
x.sub.L=3(18)(1-t)t.sup.2+(48)t.sup.3 Equ. (214a)
z.sub.L=3(-12)(1-t).sup.2t+3(-25)(1-t)t.sup.2+(-33)t.sup.3 Equ.
(214b) [0181] over the range of: 0.ltoreq.t.ltoreq.1.
[0182] Thus, for this particular curve 114, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=18 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-12, PZL.sub.2=-25 and PZL.sub.3=-33. These z-coordinates
may also vary, in some instances, within a range of .+-.10%.
[0183] It can be seen from an examination of the data of this
Example (2) embodiment at cross-section 110 that at 3 mm along the
x-axis from the apex point 112, the lower curve 114 has a
z-coordinate value that is 50% greater than the z-coordinate value
of the upper curve 113. This introduces an initial asymmetry into
the curves. However, from 3 mm to 24 mm along the x-axis, the upper
curve 113 extends away from the x-axis by an additional 13 mm
(i.e., .DELTA.z.sub.U=19-6=13 mm) and the lower curve 114 extends
away from the x-axis by an additional 15 mm (i.e.,
.DELTA.z.sub.L=24-9=15 mm). And, from 3 mm to 36 mm along the
x-axis, the upper curve 113 and the lower curve 114 extend away
from the x-axis by an additional 16 mm and 21 mm, respectively. In
other words, from 3 mm to 36 mm along the x-axis, the upper curve
113 is flatter than the lower curve 114.
[0184] As with curves 113 and 114 discussed above with respect to
FIG. 29A, referring now to FIG. 30A, upper and lower curves 123 and
124 for this second example club head may be characterized by a
curve presented as a table of spline points. Table V provides a set
of spline point coordinates for the cross-section 120 for Example
(2). For purposes of this table, the coordinates of the spline
points are defined as values relative to the apex point 112. The
z.sub.U-coordinates are associated with the upper curve 123; the
z.sub.L-coordinates are associated with the lower curve 124.
TABLE-US-00010 TABLE V Spline Points for Cross-Section 120 for
Example (2) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 6 8 12 15 17 20 21 (upper surface 123)
z.sub.L-coordinate (mm) 0 -9 -12 -17 -21 -24 -29 -33 (lower surface
124)
[0185] Alternatively, for this example club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 123 of
cross-section 120 as follows:
x.sub.U=3(28)(1-t)t.sup.2+(48)t.sup.3 Equ. (223a)
z.sub.U=3(9)(1-t).sup.2t+3(22)(1-t)t.sup.2+(21)t.sup.3 Equ. (223b)
[0186] over the range of: 0.ltoreq.t.ltoreq.1.
[0187] Thus, it can be sent that for this particular curve 123, the
Bezier control points for the x-coordinates have been defined as:
Pxu.sub.0=0, Pxu.sub.1=0, Pxu.sub.2=28 and Pxu.sub.3=48, and the
Bezier control points for the z-coordinates have been defined as:
Pzu.sub.0=0, Pzu.sub.1=9, Pzu.sub.2=22 and Pzu.sub.3=21.
[0188] As above, for this example club head, the Bezier equations
(2a) and (2b) may be used to obtain, respectively, the x- and
z-coordinates of the lower curve 124 of cross-section 120 as
follows:
x.sub.L=3(13)(1-t)t.sup.2+(48)t.sup.3 Equ. (224a)
z.sub.L=3(-11)(1-t).sup.2t+3(-22)(1-t)t.sup.2+(-33)t.sup.3 Equ.
(224b) [0189] over the range of: 0.ltoreq.t.ltoreq.1.
[0190] Thus, for this particular curve 124, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=13 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PIL.sub.O=0,
PzL.sub.1=-11, PZL.sub.2=-22 and PzL.sub.3=-33.
[0191] At cross-section 120 at 3 mm along the x-axis from the apex
point 112, the lower curve 124 has a z-coordinate value that is 50%
greater than the z-coordinate value of the upper curve 123. This
introduces an initial asymmetry into the curves. However, from 3 mm
to 24 mm along the x-axis, the upper curve 123 extends away from
the x-axis by an additional 11 mm (i.e., .DELTA.z.sub.U=17-6=11 mm)
and the lower curve 124 extends away from the x-axis by an
additional 15 mm (i.e., .DELTA.z.sub.L=24-9=15 mm). And, from 3 mm
to 36 mm along the x-axis, the upper curve 123 and the lower curve
124 extend away from the x-axis by an additional 14 mm and 20 mm,
respectively. In other words, similar to the curves of
cross-section 110, from 3 mm to 36 mm along the x-axis, the upper
curve 123 is flatter than the lower curve 124.
[0192] As with surfaces 113 and 114 discussed above, the upper and
lower curves 133 and 134 may be characterized by curves presented
as a table of spline points. Table VI provides a set of spline
point coordinates for the cross-section 130 for Example (2). For
purposes of this table, all of the coordinates of the spline points
are defined relative to the apex point 112. The z.sub.U-coordinates
are associated with the upper curve 133; the z.sub.L-coordinates
are associated with the lower curve 134.
TABLE-US-00011 TABLE VI Spline Points for Cross-Section 130 for
Example (2) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 5 7 9 10 12 13 13 (upper surface 133)
z.sub.L-coordinate (mm) 0 -6 -10 -15 -18 -21 -26 -30 (lower surface
134)
[0193] Alternatively, for this example club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 133 of
cross-section 130 as follows:
x.sub.U=3(26)(1-t)t.sup.2+(48)t.sup.3 Equ. (233a)
z.sub.U=3(9)(1-t).sup.2t+3(14)(1-t)t.sup.2+(13)t.sup.3 Equ. (233b)
[0194] over the range of: 0.ltoreq.t.ltoreq.1.
[0195] Thus, for this particular curve 133, the Bezier control
points for the x-coordinates have been defined as: Pxu.sub.0=0,
Pxu.sub.1=0, Pxu.sub.2=26 and Pxu.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: Pzu.sub.0=0,
Pzu.sub.1=9, Pzu.sub.2=14 and Pzu.sub.3=13.
[0196] As above, for this example club head, the Bezier equations
(2a) and (2b) may be used to obtain, respectively, the x- and
z-coordinates of the lower curve 134 of cross-section 130 as
follows:
x.sub.L=3(18)(1-t)t.sup.2+(48)t.sup.3 Equ. (234a)
z.sub.L=3(-7)(1-t).sup.2t+3(-23)(1-t)t.sup.2+(-30)t.sup.3 Equ.
(234b) [0197] over the range of: 0.ltoreq.t.ltoreq.1.
[0198] Thus, for this particular curve 134, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=18 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-7, PZL.sub.2=-23 and PZL.sub.3=-30.
[0199] At cross-section 130, at 3 mm along the x-axis from the apex
point 112, the lower curve 134 has a z-coordinate value that is
only 20% greater than the z-coordinate value of the upper curve
133. This introduces an initial asymmetry into the curves. From 3
mm to 24 mm along the x-axis, the upper curve 133 extends away from
the x-axis by an additional 7 mm (i.e., .DELTA.z.sub.U=12-5=7 mm)
and the lower curve 134 extends away from the x-axis by an
additional 15 mm (i.e., .DELTA.z.sub.L=21-6=15 mm). And, from 3 mm
to 36 mm along the x-axis, the upper curve 133 and the lower curve
134 extend away from the x-axis by an additional 8 mm and 20 mm,
respectively. In other words, from 3 mm to 36 mm along the x-axis,
the upper curve 133 is significantly flatter than the lower curve
134.
[0200] Further, for this Example (2) embodiment, when the curves of
the cross-section 110 (i.e., the cross-section oriented at 90
degrees from the centerline) are compared to the curves of the
cross-section 120 (i.e., the cross-section oriented at 70 degrees
from the centerline), it can be seen that they are similar.
Specifically, the values of the z-coordinates for the upper curve
113 vary from the values of the z-coordinates for the upper curve
123 by approximately 10% or less. With respect to the lower curves
114 and 124 for the cross-sections 110 and 120, respectively, the
values of the z-coordinates depart from each other by less than 10%
over the x-coordinate range from 0 mm to 48 mm, with the lower
curve 124 being slightly smaller than the lower curve 114. When the
curves for this Example (2) embodiment of the cross-section 110
(i.e., the cross-section oriented at 90 degrees from the
centerline) are compared to the curves of the cross-section 130
(i.e., the cross-section oriented at 45 degrees from the
centerline), it can be seen that the values of the z-coordinates
for the lower curve 134 of the cross-section 130 differ from the
values of the z-coordinates for the lower curve 114 of the
cross-section 110 by a fairly constant amount--either 3 mm or 4
mm--over the x-coordinate range of 0 mm to 48 mm. On the other
hand, it can be seen that the difference in the values of the
z-coordinates for the upper curve 133 of the cross-section 130 from
the values of the z-coordinates for the upper curve 113 of the
cross-section 110 steadily increases over the x-coordinate range of
0 mm to 48 mm. In other words, the curvature of the upper curve 133
significantly departs from curvature of the upper curve 113, with
upper curve 133 being significantly flatter than upper curve
113.
Example Embodiment (3)
[0201] In a third example, a representative embodiment of a club
head as shown in FIGS. 15-20 is described. This third example club
head is provided with a volume that is greater than approximately
400 cc. The face height ranges from approximately 52 mm to
approximately 56 mm. The moment-of-inertia at the center-of-gravity
around an axis parallel to the X.sub.0-axis ranges from
approximately 2900 g-cm.sup.2 to approximately 3600 g-cm.sup.2. The
moment-of-inertia at the center-of-gravity around an axis parallel
to the Z.sub.0-axis is greater than approximately 5000 g-cm.sup.2.
The club breadth-to-face length ratio is 0.94 or greater.
[0202] This third example club head may also be provided with a
weight that may range from approximately 200 g to approximately 210
g. Referring to FIGS. 32A and 32B, a face length may range from
approximately 122 mm to approximately 126 mm and a face area may
range from approximately 3300 mm.sup.2 to approximately 3900
mm.sup.2. The club head breadth may range from approximately 115 mm
to approximately 118 mm. The location of the center-of-gravity in
the X.sub.0 direction may range from approximately 28 mm to
approximately 32 mm; the location of the center-of-gravity in the
Y.sub.0 direction may range from approximately 16 mm to
approximately 20 mm; and the location of the center-of-gravity in
the Z.sub.0 direction may range from approximately 29 mm to
approximately 33 mm (all as measured from the ground-zero
point).
[0203] For this Example (3) club head, Table VII provides a set of
nominal spline point coordinates for the upper and lower curves of
cross-section 110. As previously discussed, these nominal spline
point coordinates may vary, in some instances, within a range of
.+-.10%.
TABLE-US-00012 TABLE VII Spline Points for Cross-Section 110 for
Example (3) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 4 6 7 9 10 11 11 (upper surface 113)
z.sub.L-coordinate (mm) 0 -15 -20 -26 -31 -34 -40 -44 (lower
surface 114)
[0204] Alternatively, for this example club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 113 of
cross-section 110 as follows:
x.sub.U=3(17)(1-t)t.sup.2+(48)t.sup.3 Equ. (313a)
z.sub.U=3(5)(1-t).sup.2t+3(12)(1-t)t.sup.2+(11)t.sup.3 Equ. (313b)
[0205] over the range of: 0.ltoreq.t.ltoreq.1.
[0206] Thus, for this particular curve 113, the Bezier control
points for the x-coordinates have been defined as: Pxu.sub.0=0,
Pxu.sub.1=0, Pxu.sub.2=17 and Pxu.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: Pzu.sub.0=0,
Pzu.sub.1=5, Pzu.sub.2=12 and Pzu.sub.3=11. As discussed, these
z-coordinates may vary, in some instances, within a range of
.+-.10%.
[0207] Similarly, for this example club head, the Bezier equations
(2a) and (2b) may be used to obtain, respectively, the x- and
z-coordinates of the lower curve 114 of cross-section 110 as
follows:
x.sub.L=3(7)(1-t)t.sup.2+(48)t.sup.3 Equ. (314a)
z.sub.L=3(-15)(1-t).sup.2t+3(-32)(1-t)t.sup.2+(-44)t.sup.3 Equ.
(314b) [0208] over the range of: 0.ltoreq.t.ltoreq.1.
[0209] Thus, for this particular curve 114, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=7 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-15, PZL.sub.2=-32 and PZL.sub.3=-44. These z-coordinates
may also vary, in some instances, within a range of .+-.10%.
[0210] It can be seen from an examination of the data of this
Example (3) embodiment at cross-section 110 that at 3 mm along the
x-axis from the apex point 112, the lower curve 114 has a
z-coordinate value that is 275% greater than the z-coordinate value
of the upper curve 113. This introduces an initial asymmetry into
the curves. From 3 mm to 24 mm along the x-axis, the upper curve
113 extends away from the x-axis by an additional 6 mm (i.e.,
.DELTA.z.sub.U=10-4=6 mm) and the lower curve 114 extends away from
the x-axis by an additional 19 mm (i.e., .DELTA.z.sub.L=34-15=19
mm). And, from 3 mm to 36 mm along the x-axis, the upper curve 113
and the lower curve 114 extend away from the x-axis by an
additional 7 mm and 25 mm, respectively. In other words, from 3 mm
to 36 mm along the x-axis, the upper curve 113 is significantly
flatter than the lower curve 114.
[0211] As with curves 113 and 114 discussed above with respect to
FIG. 29A, referring now to FIG. 30A, upper and lower curves 123 and
124 for this third example club head may be characterized by a
curve presented as a table of spline points. Table VIII provides a
set of spline point coordinates for the cross-section 120 for
Example (3). For purposes of this table, the coordinates of the
spline points are defined as values relative to the apex point 112.
The z.sub.U-coordinates are associated with the upper curve 123;
the z.sub.L-coordinates are associated with the lower curve
124.
TABLE-US-00013 TABLE VIII Spline Points for Cross-Section 120 for
Example (3) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 4 4 5 6 7 7 7 (upper surface 123)
z.sub.L-coordinate (mm) 0 -14 -19 -26 -30 -34 -39 -43 (lower
surface 124)
[0212] Alternatively, for this Example (3) club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 123 of
cross-section 120 as follows:
x.sub.U=3(21)(1-t)t.sup.2+(48)t.sup.3 Equ. (323a)
z.sub.U=3(5)(1-t).sup.2t+3(7)(1-t)t.sup.2+(7)t.sup.3 Equ. (323b)
[0213] over the range of: 0.ltoreq.t.ltoreq.1.
[0214] Thus, it can be seen that for this particular curve 123, the
Bezier control points for the x-coordinates have been defined as:
Pxu.sub.0=0, Pxu.sub.1=0, Pxu.sub.2=21 and Pxu.sub.3=48, and the
Bezier control points for the z-coordinates have been defined as:
Pzu.sub.0=0, Pzu.sub.1=5, Pzu.sub.2=7 and Pzu.sub.3=7.
[0215] As above, for this example club head, the Bezier equations
(2a) and (2b) may be used to obtain, respectively, the x- and
z-coordinates of the lower curve 124 of cross-section 120 as
follows:
x.sub.L=3(13)(1-t)t.sup.2+(48)t.sup.3 Equ. (324a)
z.sub.L=3(-18)(1-t).sup.2t+3(-34)(1-t)t.sup.2+(-43)t.sup.3 Equ.
(324b) [0216] over the range of: 0.ltoreq.t.ltoreq.1.
[0217] Thus, for this particular curve 124, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=13 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-18, PZL.sub.2=-34 and PZL.sub.3=-43.
[0218] At cross-section 120 for Example (3) at 3 mm along the
x-axis from the apex point 112, the lower curve 124 has a
z-coordinate value that is 250% greater than the z-coordinate value
of the upper curve 123. This introduces an initial asymmetry into
the curves. From 3 mm to 24 mm along the x-axis, the upper curve
123 extends away from the x-axis by an additional 3 mm (i.e.,
.DELTA.z.sub.U=7-4=3 mm) and the lower curve 124 extends away from
the x-axis by an additional 20 mm (i.e., .DELTA.z.sub.L=34-14=20
mm). And, from 3 mm to 36 mm along the x-axis, the upper curve 123
and the lower curve 124 extend away from the x-axis by an
additional 3 mm and 25 mm, respectively. In other words, similar to
the curves of cross-section 110, from 3 mm to 36 mm along the
x-axis, the upper curve 123 is significantly flatter than the lower
curve 124. In fact, from 24 mm to 48 mm, the upper curve 123
maintains a constant distance from the x-axis, while the lower
curve 124 over this same range departs by an additional 9 mm.
[0219] As with surfaces 113 and 114 discussed above, the upper and
lower curves 133 and 134 may be characterized by curves presented
as a table of spline points. Table IX provides a set of spline
point coordinates for the cross-section 130 for Example (3). For
purposes of this table, all of the coordinates of the spline points
are defined relative to the apex point 112. The z.sub.U-coordinates
are associated with the upper curve 133; the z.sub.L-coordinates
are associated with the lower curve 134.
TABLE-US-00014 TABLE IX Spline Points for Cross-Section 130 for
Example (3) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 4 3 3 2 2 0 -2 (upper surface 133)
z.sub.L-coordinate (mm) 0 -11 -16 -22 -27 -30 -37 -41 (lower
surface 134)
[0220] Alternatively, for this example club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 133 of
cross-section 130 as follows:
x.sub.U=3(5)(1-t)t.sup.2+(48)t.sup.3 Equ. (333a)
z.sub.U=3(6)(1-t).sup.2t+3(5)(1-t)t.sup.2+(-2)t.sup.3 Equ. (333b)
[0221] over the range of: 0.ltoreq.t.ltoreq.1.
[0222] Thus, for this particular curve 133, the Bezier control
points for the x-coordinates have been defined as: Pxu.sub.0=0,
Pxu.sub.1=0, Pxu.sub.2=5 and Pxu.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: Pzu.sub.0=0,
Pzu.sub.1=6, Pzu.sub.2=5 and Pzu.sub.3=-2.
[0223] As above, for this Example (3) club head, the Bezier
equations (2a) and (2b) may be used to obtain, respectively, the x-
and z-coordinates of the lower curve 134 of cross-section 130 as
follows:
x.sub.L=3(18)(1-t)t.sup.2+(48)t.sup.3 Equ. (334a)
z.sub.L=3(-15)(1-t).sup.2t+3(-32)(1-t)t.sup.2+(-41)t.sup.3 Equ.
(334b) [0224] over the range of: 0.ltoreq.t.ltoreq.1.
[0225] Thus, for this particular curve 134, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=18 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-15, PZL.sub.2=-32 and PZL.sub.3=-41.
[0226] At cross-section 130 for Example (3), at 3 mm along the
x-axis from the apex point 112, the lower curve 134 has a
z-coordinate value that is 175% greater than the z-coordinate value
of the upper curve 133. This introduces an initial asymmetry into
the curves. From 3 mm to 24 mm along the x-axis, the upper curve
133 extends away from the x-axis by -2 mm (i.e.,
.DELTA.z.sub.U=2-4=-2 mm). In other words, the upper curve 133 has
actually approached the x-axis over this range. On the other hand,
the lower curve 134 extends away from the x-axis by an additional
19 mm (i.e., .DELTA.z.sub.L=30-11=19 mm). And, from 3 mm to 36 mm
along the x-axis, the upper curve 133 and the lower curve 134
extend away from the x-axis by an additional -4 mm and 26 mm,
respectively. In other words, from 3 mm to 36 mm along the x-axis,
the upper curve 133 is significantly flatter than the lower curve
134.
[0227] Further, for this Example (3) embodiment, when the curves of
the cross-section 110 (i.e., the cross-section oriented at 90
degrees from the centerline) are compared to the curves of the
cross-section 120 (i.e., the cross-section oriented at 70 degrees
from the centerline), it can be seen that the upper curves vary
significantly, while the lower curves are very similar.
Specifically, the values of the z-coordinates for the upper curve
113 vary from the values of the z-coordinates for the upper curve
123 by up to 57% (relative to upper curve 123). Upper curve 123 is
significantly flatter than upper curve 113. With respect to the
lower curves 114 and 124 for the cross-sections 110 and 120,
respectively, the values of the z-coordinates depart from each
other by less than 10% over the x-coordinate range from 0 mm to 48
mm, with the lower curve 124 being slightly smaller than the lower
curve 114. When the curves for this Example (3) embodiment of the
cross-section 110 (i.e., the cross-section oriented at 90 degrees
from the centerline) are compared to the curves of the
cross-section 130 (i.e., the cross-section oriented at 45 degrees
from the centerline), it can be seen that the values of the
z-coordinates for the lower curve 134 of the cross-section 130
differ from the values of the z-coordinates for the lower curve 114
of the cross-section 110 by a fairly constant amount--either 3 mm
or 4 mm--over the x-coordinate range of 0 mm to 48 mm. Thus, the
curvature of lower curve 134 is approximately the same as the
curvature of lower curve 114, with respect to the x-axis, over the
x-coordinate range of 0 mm to 48 mm. On the other hand, it can be
seen that the difference in the values of the z-coordinates for the
upper curve 133 of the cross-section 130 from the values of the
z-coordinates for the upper curve 113 of the cross-section 110
steadily increases over the x-coordinate range of 0 mm to 48 mm. In
other words, the curvature of the upper curve 133 significantly
departs from curvature of the upper curve 113, with upper curve 133
being significantly flatter than upper curve 113.
Example Embodiment (4)
[0228] In a fourth example, a representative embodiment of a club
head as shown in FIGS. 21-26 is described. This fourth example club
head is provided with a volume that is greater than approximately
400 cc. The face height ranges from approximately 58 mm to
approximately 63 mm. The moment-of-inertia at the center-of-gravity
around an axis parallel to the X.sub.0-axis ranges from
approximately 2800 g-cm.sup.2 to approximately 3300 g-cm.sup.2. The
moment-of-inertia at the center-of-gravity around an axis parallel
to the Z.sub.0-axis ranges from approximately 4500 g-cm.sup.2 to
approximately 5200 g-cm.sup.2. The club breadth-to-face length
ratio is 0.94 or greater.
[0229] Additionally, this fourth example club head is provided with
a weight that may range from approximately 200 g to approximately
210 g. Referring to FIGS. 32A and 32B, the face length that may
range from approximately 118 mm to approximately 122 mm and the
face area may range from approximately 3900 mm.sup.2 to 4500
mm.sup.2. The club head breadth may range from approximately 116 mm
to approximately 118 mm. The location of the center-of-gravity in
the X.sub.0 direction may range from approximately 28 mm to
approximately 32 mm; the location of the center-of-gravity in the
Y.sub.0 direction may range from approximately 15 mm to
approximately 19 mm; and the location of the center-of-gravity in
the Z.sub.0 direction may range from approximately 29 mm to
approximately 33 mm (all as measured from the ground-zero
point).
[0230] For this Example (4) club head, Table X provides a set of
nominal spline point coordinates for the heel side of cross-section
110. These spline point coordinates are provided as absolute
values. As discussed, these nominal spline point coordinates may
vary, in some instances, within a range of .+-.10%.
TABLE-US-00015 TABLE X Spline Points for Cross-Section 110 for
Example (4) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 5 7 11 14 16 19 20 (upper surface 113)
z.sub.L-coordinate (mm) 0 -10 -14 -21 -26 -30 -36 -40 (lower
surface 114)
[0231] Alternatively, for this Example (4) club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 113 of
cross-section 110 as follows:
x.sub.U=3(31)(1-t)t.sup.2+(48)t.sup.3 Equ. (413a)
z.sub.U=3(9)(1-t).sup.2t+3(21)(1-t)t.sup.2+(20)t.sup.3 Equ. (413b)
[0232] over the range of: 0.ltoreq.t.ltoreq.1.
[0233] Thus, for this particular curve 113, the Bezier control
points for the x-coordinates have been defined as: Pxu.sub.0=0,
Pxu.sub.1=0, Pxu.sub.2=31 and Pxu.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: Pzu.sub.0=0,
Pzu.sub.1=9, Pzu.sub.2=21 and Pzu.sub.3=20. As discussed, these
z-coordinates may vary, in some instances, within a range of
.+-.10%.
[0234] Similarly, for this example club head, the Bezier equations
(2a) and (2b) may be used to obtain, respectively, the x- and
z-coordinates of the lower curve 114 of cross-section 110 as
follows:
x.sub.L=3(30)(1-t)t.sup.2+(48)t.sup.3 Equ. (414a)
z.sub.L=3(-17)(1-t).sup.2t+3(-37)(1-t)t.sup.2+(-40)t.sup.3 Equ.
(414b) [0235] over the range of: 0.ltoreq.t.ltoreq.1.
[0236] Thus, for this particular curve 114, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=30 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-17, PZL.sub.2=-37 and PZL.sub.3=-40. These z-coordinates
may also vary, in some instances, within a range of .+-.10%.
[0237] It can be seen from an examination of the data of this
Example (4) embodiment at cross-section 110 that at 3 mm along the
x-axis from the apex point 112, the lower curve 114 has a
z-coordinate value that is 100% greater than the z-coordinate value
of the upper curve 113. This introduces an initial asymmetry into
the curves. From 3 mm to 24 mm along the x-axis, the upper curve
113 extends away from the x-axis by an additional 11 mm (i.e.,
.DELTA.z.sub.U=16-5=11 mm) and the lower curve 114 extends away
from the x-axis by an additional 20 mm (i.e.,
.DELTA.z.sub.L=30-10=20 mm). And, from 3 mm to 36 mm along the
x-axis, the upper curve 113 and the lower curve 114 extend away
from the x-axis by an additional 14 mm and 26 mm, respectively. In
other words, from 3 mm to 36 mm along the x-axis, the upper curve
113 is significantly flatter than the lower curve 114.
[0238] As with curves 113 and 114 discussed above with respect to
FIG. 29A, referring now to FIG. 30A, upper and lower curves 123 and
124 for this first example club head may be characterized by a
curve presented as a table of spline points. Table XI provides a
set of spline point coordinates for the cross-section 120 for
Example (4). For purposes of this table, the coordinates of the
spline points are defined relative to the apex point 112. The
z.sub.U-coordinates are associated with the upper curve 123; the
z.sub.L-coordinates are associated with the lower curve 124.
TABLE-US-00016 TABLE XI Spline Points for Cross-Section 120 Example
(4) x-coordinate (mm) 0 3 6 12 18 24 36 48 z.sub.U-coordinate (mm)
0 4 5 8 10 12 14 14 (upper surface 123) z.sub.L-coordinate (mm) 0
-11 -15 -22 -27 -31 -37 -41 (lower surface 124)
[0239] Alternatively, for this Example (4) club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 123 of
cross-section 120 as follows:
x.sub.U=3(25)(1-t)t.sup.2+(48)t.sup.3 Equ. (423a)
z.sub.U=3(4)(1-t).sup.2t+3(16)(1-t)t.sup.2+(14)t.sup.3 Equ. (423b)
[0240] over the range of: 0.ltoreq.t.ltoreq.1.
[0241] Thus, it can be seen that for this particular curve 123, the
Bezier control points for the x-coordinates have been defined as:
Pxu.sub.0=0, Pxu.sub.1=0, Pxu.sub.2=25 and Pxu.sub.3=48, and the
Bezier control points for the z-coordinates have been defined as:
Pzu.sub.0=0, Pzu.sub.1=4, Pzu.sub.2=16 and Pzu.sub.3=14.
[0242] As above, for this example club head, the Bezier equations
(2a) and (2b) may be used to obtain, respectively, the x- and
z-coordinates of the lower curve 124 of cross-section 120 as
follows:
x.sub.L=3(26)(1-t)t.sup.2+(48)t.sup.3 Equ. (424a)
z.sub.L=3(-18)(1-t).sup.2t+3(-36)(1-t)t.sup.2+(-41)t.sup.3 Equ.
(424b) [0243] over the range of: 0.ltoreq.t.ltoreq.1.
[0244] Thus, for this particular curve 124, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=26 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-18, PZL.sub.2=-36 and PZL.sub.3=-41.
[0245] At cross-section 120 for Example (4) at 3 mm along the
x-axis from the apex point 112, the lower curve 124 has a
z-coordinate value that is 175% greater than the z-coordinate value
of the upper curve 123. This introduces an initial asymmetry into
the curves. From 3 mm to 24 mm along the x-axis, the upper curve
123 extends away from the x-axis by an additional 8 mm (i.e.,
.DELTA.z.sub.U=12-4=8 mm) and the lower curve 124 extends away from
the x-axis by an additional 20 mm (i.e., .DELTA.z.sub.L=31-11=20
mm). And, from 3 mm to 36 mm along the x-axis, the upper curve 123
and the lower curve 124 extend away from the x-axis by an
additional 10 mm and 26 mm, respectively. In other words, similar
to the curves of cross-section 110, from 3 mm to 36 mm along the
x-axis, the upper curve 123 is significantly flatter than the lower
curve 124.
[0246] As with surfaces 113 and 114 discussed above, the upper and
lower curves 133 and 134 may be characterized by curves presented
as a table of spline points. Table XII provides a set of spline
point coordinates for the cross-section 130 for Example (4). For
purposes of this table, all of the coordinates of the spline points
are defined relative to the apex point 112. The z.sub.U-coordinates
are associated with the upper curve 133; the z.sub.L-coordinates
are associated with the lower curve 134.
TABLE-US-00017 TABLE XII Spline Points for Cross-Section 130 for
Example (4) x-coordinate (mm) 0 3 6 12 18 24 36 48
z.sub.U-coordinate (mm) 0 4 4 5 6 7 7 5 (upper surface 133)
z.sub.L-coordinate (mm) 0 -8 -12 -18 -22 -26 -32 -37 (lower surface
134)
[0247] Alternatively, for this example club head, the Bezier
equations (1a) and (1b) presented above may be used to obtain,
respectively, the x- and z-coordinates of the upper curve 133 of
cross-section 130 as follows:
x.sub.U=3(35)(1-t)t.sup.2+(48)t.sup.3 Equ. (433a)
z.sub.U=3(6)(1-t).sup.2t+3(9)(1-t)t.sup.2+(5)t.sup.3 Equ. (433b)
[0248] over the range of: 0.ltoreq.t.ltoreq.1.
[0249] Thus, for this particular curve 133, the Bezier control
points for the x-coordinates have been defined as: Pxu.sub.0=0,
Pxu.sub.1=0, Pxu.sub.2=35 and Pxu.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: Pzu.sub.0=0,
Pzu.sub.1=6, Pzu.sub.2=9 and Pzu.sub.3=5.
[0250] As above, for this Example (4) club head, the Bezier
equations (2a) and (2b) may be used to obtain, respectively, the x-
and z-coordinates of the lower curve 134 of cross-section 130 as
follows:
x.sub.L=3(40)(1-t)t.sup.2+(48)t.sup.3 Equ. (434a)
z.sub.L=3(-17)(1-t).sup.2t+3(-35)(1-t)t.sup.2+(-37)t.sup.3 Equ.
(434b) [0251] over the range of: 0.ltoreq.t.ltoreq.1.
[0252] Thus, for this particular curve 134, the Bezier control
points for the x-coordinates have been defined as: PXL.sub.0=0,
PXL.sub.1=0, PXL.sub.2=40 and PXL.sub.3=48, and the Bezier control
points for the z-coordinates have been defined as: PZL.sub.0=0,
PZL.sub.1=-17, PZL.sub.2=-35 and PZL.sub.3=-37.
[0253] At cross-section 130 for Example (4), at 3 mm along the
x-axis from the apex point 112, the lower curve 134 has a
z-coordinate value that is 100% greater than the z-coordinate value
of the upper curve 133. This introduces an initial asymmetry into
the curves. From 3 mm to 24 mm along the x-axis, the upper curve
133 extends away from the x-axis by 3 mm (i.e.,
.DELTA.z.sub.U=7-4=3 mm). The lower curve 134 extends away from the
x-axis by an additional 18 mm (i.e., .DELTA.z.sub.L=26-8=18 mm).
And, from 3 mm to 36 mm along the x-axis, the upper curve 133 and
the lower curve 134 extend away from the x-axis by an additional 3
mm and 24 mm, respectively. In other words, from 3 mm to 36 mm
along the x-axis, the upper curve 133 is significantly flatter than
the lower curve 134.
[0254] Further, for this Example (4) embodiment, when the curves of
the cross-section 110 (i.e., the cross-section oriented at 90
degrees from the centerline) are compared to the curves of the
cross-section 120 (i.e., the cross-section oriented at 70 degrees
from the centerline), it can be seen that the upper curves vary
significantly, while the lower curves are very similar.
Specifically, the values of the z-coordinates for the upper curve
113 vary from the values of the z-coordinates for the upper curve
123 by up to 43% (relative to upper curve 123). Upper curve 123 is
significantly flatter than upper curve 113. With respect to the
lower curves 114 and 124 for the cross-sections 110 and 120,
respectively, the values of the z-coordinates depart from each
other by less than 10% over the x-coordinate range from 0 mm to 48
mm, with the lower curve 124 being slightly smaller than the lower
curve 114. When the curves for this Example (4) embodiment of the
cross-section 110 (i.e., the cross-section oriented at 90 degrees
from the centerline) are compared to the curves of the
cross-section 130 (i.e., the cross-section oriented at 45 degrees
from the centerline), it can be seen that the values of the
z-coordinates for the lower curve 134 of the cross-section 130
differ from the values of the z-coordinates for the lower curve 114
of the cross-section 110 by over a range of 2 mm to 4 mm--over the
x-coordinate range of 0 mm to 48 mm. Thus, for the Example (4)
embodiment, the curvature of lower curve 134 varies somewhat from
the curvature of lower curve 114. On the other hand, it can be seen
that the difference in the values of the z-coordinates for the
upper curve 133 of the cross-section 130 from the values of the
z-coordinates for the upper curve 113 of the cross-section 110
steadily increases from a difference of 1 mm to a difference of 15
mm over the x-coordinate range of 0 mm to 48 mm. In other words,
the curvature of the upper curve 133 significantly departs from
curvature of the upper curve 113, with upper curve 133 being
significantly flatter than upper curve 113.
[0255] It would be apparent to persons of ordinary skill in the
art, given the benefit of this disclosure, that a streamlined
region 100 similarly proportioned to the cross-sections 110, 120,
130 would achieve the same drag reduction benefits as the specific
cross-sections 110, 120, 130 defined by Tables I-XII. Thus, the
cross-sections 110, 120, 130 presented in Tables I-XII may be
enlarged or reduced to accommodate club heads of various sizes.
Additionally, it would be apparent to persons of ordinary skill in
the art, given the benefit of this disclosure, that a streamlined
region 100 having upper and lower curves that substantially accord
with those defined by Tables I-XII would also generally achieve the
same drag reduction benefits as the specific upper and lower curves
presented in Tables I-XII. Thus, for example, the z-coordinate
values may vary from those presented in Tables I-XII by up to
.+-.5%, up to .+-.10%, or even in some instances, up to
.+-.15%.
[0256] While there have been shown, described, and pointed out
fundamental novel features of various embodiments, it will be
understood that various omissions, substitutions, and changes in
the form and details of the devices illustrated, and in their
operation, may be made by those skilled in the art without
departing from the spirit and scope of the invention. For example,
the golf club head may be any driver, wood, or the like. Further,
it is expressly intended that all combinations of those elements
which perform substantially the same function, in substantially the
same way, to achieve the same results are within the scope of the
invention. Substitutions of elements from one described embodiment
to another are also fully intended and contemplated. It is the
intention, therefore, to be limited only as indicated by the scope
of the claims appended hereto.
* * * * *