U.S. patent application number 12/404701 was filed with the patent office on 2010-09-16 for high launch and low spin golf ball and golf club combination.
Invention is credited to Steven Aoyama, Andrew Curtis, Daniel Stone.
Application Number | 20100234125 12/404701 |
Document ID | / |
Family ID | 42731159 |
Filed Date | 2010-09-16 |
United States Patent
Application |
20100234125 |
Kind Code |
A1 |
Aoyama; Steven ; et
al. |
September 16, 2010 |
HIGH LAUNCH AND LOW SPIN GOLF BALL AND GOLF CLUB COMBINATION
Abstract
The present invention is directed to a golf club and golf ball
combination that maximizes the distance of travel when the golf
club strikes the golf ball. More specifically, a golf club and golf
ball combination capable of generating a higher launch angle
combined with the lower spin rate to maximize the distance. The
golf club in accordance with the present invention may generally
have a lower center of gravity, a higher loft angle, or may even
have a coating on the club face that optimizes the coefficient of
friction between the golf club and the golf ball. The golf ball in
accordance with the present invention may generally have a ratio of
the coefficient of lift (C.sub.L) near the beginning of flight to
the coefficient of lift near the end of the flight within a range
that maximizes flight distance, with similar ratios in appropriate
ranges for the coefficient of drag (C.sub.D) and the lift-to-drag
ratio (C.sub.L/C.sub.D).
Inventors: |
Aoyama; Steven; (Marion,
MA) ; Curtis; Andrew; (Carlsbad, CA) ; Stone;
Daniel; (Carlsbad, CA) |
Correspondence
Address: |
ACUSHNET COMPANY
333 BRIDGE STREET, P. O. BOX 965
FAIRHAVEN
MA
02719
US
|
Family ID: |
42731159 |
Appl. No.: |
12/404701 |
Filed: |
March 16, 2009 |
Current U.S.
Class: |
473/324 ;
473/409 |
Current CPC
Class: |
A63B 37/0066 20130101;
A63B 37/0087 20130101; A63B 53/0408 20200801; A63B 53/0466
20130101; A63B 37/0003 20130101; A63B 37/0047 20130101; A63B 53/005
20200801; A63B 37/0076 20130101 |
Class at
Publication: |
473/324 ;
473/409 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Claims
1. A golf club and golf ball combination comprising: a golf club
and a golf ball; wherein said golf ball achieves a launch angle
(.alpha.) and an initial spin rate (.omega..sub.i) satisfying a
relationship defined as 86.alpha.+.omega..sub.i.ltoreq.4310 when
struck by said golf club.
2. The golf club and golf ball combination of claim 1, wherein said
golf club is swung at an exemplary swing; and wherein said
exemplary swing is further comprising: a velocity of about 110
miles per hour; an attack angle of about 2 degrees; an effective
loft of about 13 degrees; and a static loft of about 9.5 degrees;
wherein said golf ball contacts said golf club at the geometric
center of the face of said golf club.
3. The golf club and ball combination of claim 2, wherein said
launch angle (.alpha.) is at least about 15 degrees.
4. The golf club and ball combination of claim 2, wherein said
launch angle (.alpha.) is at least about 18 degrees.
5. The golf club and ball combination of claim 2, wherein said
launch angle (.alpha.) is at least about 20 degrees.
6. The golf club and ball combination of claim 3, wherein said
launch angle (.alpha.) and said initial spin rate (.omega..sub.i)
relationship is defined as 86.alpha.+.omega..sub.i.ltoreq.4310 when
struck by said golf club.
7. The golf club and ball combination of claim 3, wherein said
launch angle (.alpha.) and said initial spin rate (.omega..sub.i)
relationship is defined as 86.alpha.+.omega..sub.i.ltoreq.3710 when
struck by said golf club.
8. The golf club and ball combination of claim 3, wherein said
launch angle (.alpha.) and said initial spin rate (.omega..sub.i)
relationship is defined as 86.alpha.+.omega..sub.i.ltoreq.3310 when
struck by said golf club.
9. The golf club and ball combination of claim 3, wherein said golf
club head has a center of gravity located about 10 mm to about 30
mm above a ground level of said golf club.
10. The golf club and ball combination of claim 3, wherein said
golf club head has a center of gravity located about 15 mm to about
25 mm above a ground level of said golf club.
11. The golf club and ball combination of claim 9, wherein said
golf ball has a beginning to end coefficient of lift ratio of about
0.64 to about 3.20; a beginning to end coefficient of drag ratio of
about 0.76 to about 0.99; and a beginning to end ratio of lift to
drag ratio of about 0.65 to about 3.40.
12. The golf club and ball combination of claim 9, wherein said
golf ball has a beginning to end coefficient of lift ratio of about
0.72 to about 2.03; a beginning to end coefficient of drag ratio of
about 0.82 to about 0.96; and a beginning to end ratio of lift to
drag ratio of about 0.76 to about 2.25.
13. The golf club and ball combination of claim 9, wherein said
golf ball has a beginning to end coefficient of lift ratio of about
0.80 to about 0.86; a beginning to end coefficient of drag ratio of
about 0.87 to about 0.93; and a beginning to end ratio of lift to
drag ratio of about 0.86 to about 1.10.
14. A golf club and ball combination comprising: a golf club with a
center of gravity located about 10 mm to about 30 mm above a ground
level; and a golf ball that has a beginning to end coefficient of
lift ratio of about 0.64 to about 3.20; a beginning to end
coefficient of drag ratio of about 0.76 to about 0.99; and a
beginning to end ratio of lift to drag ratio of about 0.65 to about
3.40 when struck by said golf club.
15. The golf club and ball combination of claim 14, wherein said
golf ball achieves a launch angle (.alpha.) and an initial spin
rate (.omega..sub.i) satisfying a relationship defined as
86.alpha.+.omega..sub.i.ltoreq.3710 when struck by said golf
club.
16. The golf club and ball combination of claim 15, wherein said
golf club is swung at an exemplary swing; and wherein said
exemplary swing is further comprising: a velocity of about 110
miles per hour; an attack angle of about 2 degrees; an effective
loft of about 13 degrees; and a static loft of about 9.5 degrees;
wherein said golf ball contacts said golf club at the geometric
center of the face of said golf club.
17. The golf club and ball combination of claim 14, wherein said
golf ball achieves a launch angle (.alpha.) and an initial spin
rate (.omega..sub.i) satisfying a relationship defined as
86.alpha.+.omega..sub.i.ltoreq.3310 when struck by said golf
club.
18. The golf club and ball combination of claim 17, wherein said
golf club is swung at an exemplary swing; and wherein said
exemplary swing is further comprising: a velocity of about 110
miles per hour; an attack angle of about 2 degrees; an effective
loft of about 13 degrees; and a static loft of about 9.5 degrees;
wherein said golf ball contacts said golf club at the geometric
center of the face of said golf club.
19. The golf club and ball combination of claim 16, wherein said
launch angle (.alpha.) is at least about 18 degrees.
20. The golf club and ball combination of claim 16, wherein said
launch angle (.alpha.) is at least about 20 degrees.
21. A method of maximizing a travel distance of a golf ball
comprising: adjusting a center of gravity of a golf club to be
located about 10 mm to about 30 mm above a ground level of said
golf club; adjusting a beginning to end coefficient of lift ratio
for said golf ball to be about 0.64 to about 3.20; adjusting a
beginning to end coefficient of drag ratio of said golf ball to be
about 0.76 to about 0.99; and adjusting a beginning to end ratio of
lift to drag ratio of said golf ball to be about 0.65 to about
3.40; wherein said golf ball achieves a launch angle (.alpha.) and
an initial spin rate (.omega..sub.i) satisfying a relationship
defined as 86.alpha.+.omega..sub.i.ltoreq.4310 when struck by said
golf club.
22. The method of maximizing said travel distance of said golf ball
according to claim 21, further comprising of swinging said golf
club at an exemplary swing; wherein said exemplary swing is further
comprising: a velocity of about 110 miles per hour; an attack angle
of about 2 degrees; an effective loft of aboutl3 degrees; and a
static loft of about 9.5 degrees; wherein said golf ball contacts
said golf club at a center of a face of said golf club.
23. The method of maximizing said travel distance of said golf ball
according to claim 21, wherein said launch angle (.alpha.) is at
least about 18 degrees.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a golf club and golf ball
combination that creates high launch and low spin characteristics
that maximize the travel distance of a golf ball after impact with
a golf club. More specifically, the present invention relates to a
golf club capable of generating a high launch angle and a low spin
rate via a lower center of gravity. Additionally the present
invention also relates to a golf ball having an unusually low spin
rate along with certain ratios of the coefficient of lift
(C.sub.L), coefficient of drag (C.sub.D), and the lift-to-drag
ratio (C.sub.L/C.sub.D) measured near the beginning of the flight
to the same parameters measured later in flight.
BACKGROUND OF THE INVENTION
[0002] The complexities of golf club design are known; further, the
complexities of golf ball design are also known. The design
specifications for a golf club and a golf ball directly impact the
launch conditions generated by a golf swing. Designed separately,
the design of a golf club and a golf ball can both individually
contribute to improved performance characteristics such as high
launch and low spin. However, these designs, although effective in
maximizing launch angle and minimizing spin rate individually, fail
to take into consideration the additional performance gains that
are possible by correctly matching a golf club and a golf ball.
Thus, varying the performance characteristics of a golf club in
parallel with the performance characteristic of a golf ball can
produce a synergistic improvement in the performance
characteristics of both of the components.
[0003] With respect to the improvements in golf club heads, the
current industry has been focused primarily on creating a golf club
head that controls and improves the flight characteristics of a
golf ball after impact with the golf club head. Amongst the
prominent considerations in golf club head design are loft, lie,
face angle, horizontal face bulge, vertical face roll, center of
gravity, rotational moment of inertia, material selection, and
overall head weight. In addition to the above mentioned design
variations, the center of gravity is often adjusted to be moved to
various locations within the golf club head to increase launch
angle and control the spin of the golf ball. One example is
described in U.S. Pat. No. 7,407,447 to Beach et al. for a Movable
Weight for a Golf Club Head. In that example, embodiments of
movable weights, such as weight assemblies and weight screws, for a
golf club head are disclosed. More specifically, in one
configuration, the club head CG is in a center-back location,
resulting in a high launch angle and a relatively low initial spin
rate for optimal distance.
[0004] Another example is described in U.S. Pat. App. 2007/0155532
to Adams for a Golf Club Head. In that example, a golf club head
includes a club head body having a striking face, a soleplate, a
toe, a heel and a hosel, wherein at least a portion of the body
shell is composed of a flexible material having a density of less
than approximately 2.5 g/cm.sup.3, and a tensile strength of at
least approximately 465 MPa/(g/cm.sup.3). More specifically, one
may position the weight member(s) on the soleplate, but position it
all the way back to increase launch angle while keeping the
backspin relatively low (High Launch/Low Spin) or position it all
the way forward to control launch angle, lower spin and also lower
the amount of gear effect spin caused by off-center hits.
[0005] With respect to golf ball design, the golfing industry has
been struggling between the two dichotomies of golf ball designs to
either create a hard ball with enhanced flight characteristics or a
soft ball with enhanced feel and control. Hard golf balls that have
good flight characteristics as well as good rebounding
characteristics that minimize spin can tend to sacrifice feel and
control. Soft golf balls on the other hand, although capable of
providing great feel and control, have less than optimal rebounding
characteristics, and generally create too much spin to maximize
distance.
[0006] One example of a hard ball design can be seen in U.S. Pat.
No. 6,743,124 to Tsunoda et al. for a Golf Ball. In that example, a
golf ball with a low spin rate, a high launch angle, and an
increased flight distance is characterized by a ratio of primary
natural frequency of the golf ball in a direction in which the ball
deforms to a primary natural frequency of the ball in vibration
mode along a direction of torsion (f.sub.c/f.sub.n) being in the
range of 2.22 to 2.45. More specifically, the solid core can
effectively be formed from a plurality of layers having a complex
modulus smallest at the inner core, larger at the intermediate
layer(s) and the largest at the outermost layer to achieve a value
(f.sub.c/f.sub.n) in the range of 2.22 to 2.45.
[0007] Alternatively, other examples attempt to strike a balance
between a hard golf ball having increased distance and a soft golf
ball having increased feel and control. For example, in U.S. Pat.
No. 7,232,383 to Kato et al. for a Three-Piece Solid Golf Ball, a
three-piece solid golf ball having long flight distance by
accomplishing low ball rotation rate and high launch angle at the
time of hitting while maintaining good shot feel is disclosed. More
specifically, a three-piece solid golf ball comprising a core
composed of a center and an intermediate layer formed on the
center, and a cover covering the core and having many dimples on
the surface thereof is disclosed.
[0008] In another example described by U.S. Pat. No. 7,354,357 to
Sullivan et al., a Multi-Layer Core Golf Ball having an improved
multi-layer construction displaying enhanced playing
characteristics including high speed, high launch, and low spin is
disclosed. More specifically, a golf ball that displays improved
performance in areas such as distance and feel for lower swing
speed players having a relatively large solid inner core, with at
least one solid outer core layer surrounding the inner core, and a
thin cover layer surrounding the outermost core layer is
disclosed.
[0009] Despite numerous attempts to improve ball flight
characteristics in terms of high launch and low spin, the current
art has been focused on addressing each of the two important
components separately. More specifically, the current art utilizes
shifting of weights in a golf club head as well as shifts in the
center of gravity location within a golf club head without any
consideration for a matching ball design. Alternatively, the
current art has also attempted to address the problem by focusing
on golf ball design utilizing multiple materials having different
hardnesses, different core constructions, or even different complex
modulus variations with little consideration for matching the golf
club head.
[0010] Hence, it can be seen that there is a need in the field for
a golf club and golf ball combination that work in conjunction to
optimize and enhance the performance characteristics of the
respectively paired equipment. More specifically, there is a need
for a golf club that optimizes its design characteristics around
that of a golf ball to maximize high launch and low spin; and for a
golf ball that optimizes its design characteristics around that of
a golf club to maximize high launch and low spin, while providing
matching aerodynamics to optimize the overall flight
performance.
BRIEF SUMMARY OF THE INVENTION
[0011] In one aspect of the present invention, a golf club and ball
combination may comprises a golf club and a golf ball; wherein said
golf ball achieves a launch angle (.alpha.) and an initial spin
rate (.omega..sub.i) relationship defined as
86.alpha.+.omega..sub.i.ltoreq.4310 (where .alpha. is in degrees
and .omega..sub.i is in rpm) when struck by the golf club.
[0012] In another aspect of the present invention, a golf club and
ball combination comprises a golf ball with a beginning to end
coefficient of lift ratio of 0.64 to 3.20, a beginning to end
coefficient of drag ratio of 0.76 to 0.99, and a beginning to end
ratio of lift to drag ratio of 0.65 to 3.40; and a golf club with a
center of gravity located 10 mm to 30 mm above a ground level.
"Beginning to end" coefficient ratios, as used in the current
invention may generally refer to the coefficient measured during
the beginning (ascent) portion of the flight divided by the
coefficient measured during the end (descent) portion of the
flight.
[0013] In a further aspect of the present invention, a method of
maximizing travel distance of a golf ball comprises adjusting a
center of gravity of a golf club to be located 10 mm to 30 mm above
a ground level of the golf club, adjusting a beginning to end
coefficient of lift ratio for the golf ball to be 0.64 to 3.20,
adjusting a beginning to end coefficient of drag ratio of the golf
ball to be 0.76 to 0.99, and adjusting a beginning to end ratio of
lift to drag ratio of the golf ball to be 0.65 to 3.40; wherein the
golf ball achieves a launch angle (.alpha.) and an initial spin
rate (.omega..sub.i) relationship defined as
86.alpha.+.omega..sub.i.ltoreq.3710 when struck by the golf
club.
[0014] These and other features, aspects and advantages of the
present invention will become better understood with references to
the following drawings, description and claims.
BRIEF DESCRIPTION OF DRAWINGS
[0015] The foregoing and other features and advantages of the
invention will be apparent from the following description of the
invention as illustrated in the accompanying drawings. The
accompanying drawings, which are incorporated herein and form a
part of the specification, further serve to explain the principles
of the invention and to enable a person skilled in the pertinent
art to make and use the invention.
[0016] FIG. 1 shows a perspective view of a golf club head and a
golf ball in accordance with an embodiment of the present
invention;
[0017] FIG. 2 shows a perspective view of a golf club in accordance
with an embodiment of the present invention;
[0018] FIG. 3 shows a graphical representation of the effect of the
center of gravity (CG) location on initial backspin;
[0019] FIG. 4 shows a graphical representation of the effect of the
center of gravity (CG) location on launch angle;
[0020] FIG. 5 shows the forces acting on a golf ball in flight;
[0021] FIG. 6 shows a cross-sectional view of a golf ball in
accordance with an embodiment of the present invention; and
[0022] FIG. 7 shows a further cross-sectional view of a golf ball
in accordance with a further alternative embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The following detailed description is of the best currently
contemplated modes of carrying out the invention. The description
is not to be taken in a limiting sense, but is made merely for the
purpose of illustrating the general principles of the invention,
since the scope of the invention is best defined by the appended
claims.
[0024] Various inventive features are described below and can each
be used independently of one another or in combination with other
features. However, any single inventive feature may not address any
or all of the problems discussed above or may only address one of
the problems discussed above. Further, one or more of the problems
discussed above may not be fully addressed by any of the features
described below.
[0025] The present invention generally relates to a golf club and
golf ball combination that create a high launch and low spinning
golf ball upon impact with a golf club. More specifically, the
present invention relates to a golf club and golf ball combination
wherein the golf ball achieves a launch angle .alpha. and an
initial spin rate .omega..sub.i that satisfy the following
relationship when struck by the golf club:
86.alpha.+.omega..sub.i.ltoreq.4310 (Eq. 1)
where
[0026] .alpha. is in degrees
[0027] .omega..sub.i is in rpm
Even more specifically the present invention relates to a golf club
having a lower center of gravity and/or a higher loft combined with
a golf ball having a beginning to end coefficient of lift ratio of
0.64 to 3.20, a beginning to end coefficient of drag ratio of 0.76
to 0.99, and a beginning to end ratio of lift to drag ratio of 0.65
to 3.40. The current invention is unlike the prior art approaches
on creating a high launch and low spinning golf ball that only
focuses on the individual components such as a golf cub or a golf
ball separately. Focusing on the individual components without
taking in consideration of the additional performance enhancement
capabilities that can be achieved by simultaneously adjusting and
pairing the performance characteristics of both the golf club and
the golf ball may not maximize the performance characteristics that
can be achieved when the two components are designed in parallel
with one another.
[0028] FIG. 1 shows a golf club 100 and golf ball 102 combination
in accordance with an embodiment of the present invention. More
specifically, FIG. 1 shows the initial spin rate .omega..sub.i of
the golf ball 102 and the launch angle .alpha. of the golf ball 102
relative to the flat ground surface 108 as it is struck by golf
club 100.
[0029] Here, in the current exemplary embodiment, a golf club 100
and golf ball 102 combination may merge to provide launch angles
and initial spin rates that satisfy Equation 1 when the golf ball
102 is struck by golf club 100. More preferably, the launch angles
and spin rates satisfy Equation 2:
86.alpha.+.omega..sub.i.ltoreq.4010 (Eq. 2)
Still more preferably, the launch angles and spin rates satisfy
Equation 3:
86.alpha.+.omega..sub.i.ltoreq.3710 (Eq. 3)
Most preferably, the launch angles and spin rates satisfy Equation
4:
86.alpha.+.omega..sub.i.ltoreq.3310 (Eq. 4)
Equations 1 through 4 characterize the initial conditions of the
golf ball 102's flight performance and ultimately affect the total
distance of travel of the golf ball 102. When the initial spin rate
is too high for a given launch angle, the trajectory is not optimal
and distance is lost.
[0030] In accordance with the present invention, the greatest
distance improvements are achieved with unusually high launch
angles in combination with initial spin rates that satisfy Equation
1, 2, 3, or 4. Launch angles are preferably about 15 degrees or
greater, more preferably about 18 degrees or greater, and most
preferably about 20 degrees or greater.
[0031] Here, in the current exemplary embodiment, in order to
achieve the maximum golf ball 102 travel distance, golf club 100
may generally be modeled in accordance to an "exemplary swing" in
accordance with the present invention. The "exemplary swing", as
described in the current invention may generally have a velocity of
approximately 110 miles per hour (mph), with an attack angle of
approximately 2 degrees and an effective loft of approximately 13
degrees, while maintaining the static loft angle of approximately
9.5 degrees and impacting the golf ball at the geometric center of
the face to achieve .omega..sub.i and .alpha. values that satisfy
Equation 1, 2, 3, or 4 in accordance with the exemplary embodiment
of the present invention.
[0032] FIG. 2 shows a golf club 200 designed to satisfy Equation 1,
2, 3, or 4 when striking a golf ball that is in accordance with an
exemplary embodiment of the present invention. Two very important
variables such as the center of gravity 212 and loft angle 216 may
generally affect the performance characteristics of a golf club 200
in conjunction with a golf ball 102. Golf club 200, as shown in
this current exemplary embodiment may contain a head 202 at a
distal end of the golf club 200, a hosel 204 connected to head 202,
a shaft 206 connected to the hosel 204, and a grip 208 connected to
the shaft 206. FIG. 2 also shows a ground level 210 on which the
head 202 rests, along with the center of gravity 212 of golf club
head 202 located at a distance 214 from the ground level 210.
[0033] Head 202 in this current exemplary embodiment may generally
be applicable towards a driver type head and have a preferable
volume range of approximately 300 cubic centimeters to
approximately 600 cubic centimeters, and more preferably in the
volume range of approximately 350 cubic centimeters to
approximately 550 cubic centimeters, even more preferably in the
volume range of approximately 375 cubic centimeters to
approximately 475 cubic centimeters, and most preferably
approximately 420 centimeters to approximately 460 centimeters; all
without departing from the scope of the present invention. Head
202, being generally applicable towards drivers, may generally have
loft angles 216 ranging from approximately 8.5 degrees to
approximately 15.0 degrees.
[0034] Hosel 204 in this current exemplary embodiment may be used
to connect the head 202 to shaft 206, and may generally be made
from a low density material such as aluminum located substantially
above a plane located at a peak of the crown section of head 202.
The hosel 204 may also provide interchangeability between various
head 202 and various shafts 206 without the need for extensive
tooling without departing from the scope and content of the present
invention.
[0035] Shaft 206 in this current exemplary embodiment may be used
to connect the head 202 and the hosel 204 to the grip 208 to
complete the golf club 200; however, various other components in
addition to shaft 206 may be used to complete golf club 200 such as
a ferrule, a grip tape, a glue, or any other components that may
typically be used within a golf club 200 without departing from the
scope of the present invention.
[0036] Golf club 200 and more specifically head 202, as shown in
the current exemplary embodiment, may generally rest on a ground
level 210 in an address position to create a reference point from
where the center of gravity 212 may be measured to yield a distance
214. Distance 214, as shown in the current exemplary embodiment
refers to a height in the y-direction as indicated by the axis of
orientation 201 in FIG. 2; however, other identifiers may be used
to identify this distance away from the ground level 220 such as
x-direction, or z-direction without departing from the scope and
content of the present invention. In this current exemplary
embodiment distance 214 may generally be in the range of
approximately 5 millimeters to approximately 35 millimeters, more
preferably in the range of approximately 10 millimeters to
approximately 30 millimeters, most preferably in the range of
approximately 15 millimeters to approximately 25 millimeters all
without departing from the scope and content of the present
invention.
[0037] FIG. 3 shows a graphical representation of the effect of the
location of the center of gravity 212 with respect to changes in
the initial spin rate .omega..sub.i in accordance with an exemplary
embodiment of the present invention. FIG. 3 shows that the initial
spin rate .omega..sub.i on a golf ball can be dramatically reduced
as the center of gravity 212 moves closer and closer to the ground
level 210.
[0038] FIG. 4 shows a graphical representation of the effect of the
location of the center of gravity 212 with respect to changes in
launch angle .alpha. in accordance with an exemplary embodiment of
the present invention. FIG. 4 shows that the launch angle .alpha.
increases as the center of gravity 212 moves closer and closer to
the ground level 210.
[0039] As it can be seen from FIG. 3 and FIG. 4 above, decreasing
the distance 214 moves the location of the center of gravity 212
closer to the ground level 210; which will decrease the initial
spin rate .omega..sub.i and increase the launch angle .alpha. in
accordance with an exemplary embodiment of the present invention.
The increased launch angle .alpha. combined with the decrease in
initial spin rate .omega..sub.i may allow the golf club head 202 to
impart to the golf ball launch conditions that satisfy Equation 1,
2, 3, or 4 in accordance with an exemplary embodiment of the
present invention.
[0040] Although adjusting the location, and more specifically, the
height distance 214 of the center of gravity 212 may generally be
the preferable methodology to satisfy Equation 1, 2, 3, or 4 in
accordance with an exemplary embodiment of the present invention,
other variables may also be adjusted to affect .omega..sub.i and
.alpha.. For example, adjustments may also be made to the loft
angle 216 to significantly increase a without departing from the
scope of the present invention. More specifically, loft angle 216
may be adjusted to range from approximately 8.5 degrees to
approximately 15.0 degrees for a driver type golf head to satisfy
Equation 1, 2, 3, or 4 in accordance with an exemplary embodiment
of the present invention.
[0041] In a further alternative embodiment of the present
invention, loft angle 216 may be further increased to achieve a
higher launch angle .alpha. through adjustments in the shaft 206.
In this alternative embodiment, shaft 206 may effective increase a
higher launch angle .alpha. without changing the loft angle 216 by
adjusting the way shaft 206 whips and snaps at the point of impact.
More specifically, shaft 206 in accordance with an embodiment of
the present invention may generally have a softer tip at the tip
section of shaft 206 in order to crease a lower kick point that may
effectively increase launch angle .alpha. without adjusting the
loft angle 216 without departing from the scope and content of the
present invention. In essence, shaft 206 may allow golf club 200 to
be swinging up on a golf ball, which effectively adds launch angle
.alpha. without adding loft angle 216. Alternatively, shaft 206 may
also contain a swing hinge, a higher kick point, a difference in
stiffness variation, or any other mechanism capable of increasing
launch angle .alpha. without adding loft angle 216 all without
departing from the scope and content of the present invention.
[0042] FIG. 5 shows the forces acting during flight on a golf ball
500 in accordance with an exemplary embodiment of the present
invention. The total aerodynamic force F.sub.A acting on a golf
ball 500 is typically resolved into orthogonal components of lift
(F.sub.L) and drag (F.sub.D). Lift is defined as the aerodynamic
force component acting perpendicular to the flight path, and it
results from a difference in pressure created by a distortion in
the air flow that is caused by the backspin .omega. of the ball.
Drag is defined as the aerodynamic force component acting parallel
to the ball flight direction. As the ball travels through the air,
the pressure at the front of the ball is greater than the pressure
at the rear of the ball, the difference being primarily responsible
for the drag force.
[0043] More particularly, FIG. 5 shows the various forces as
enumerated in Equation 5 below.
F=F.sub.L+F.sub.D+F.sub.G (Eq. 5)
where
[0044] F=total force vector acting on the ball
[0045] F.sub.L=lift force vector 508
[0046] F.sub.D=drag force vector 512
[0047] F.sub.G=gravity force vector 514
[0048] The lift force vector (F.sub.L) 508 acts in a direction
dictated by the cross product of the spin vector and the velocity
vector. The drag force vector (F.sub.D) 512 acts in a direction
that is directly opposite the velocity vector. The magnitudes of
the lift and drag forces of Equation 5 are calculated in Equations
6 and 7, respectively:
F.sub.L=0.5C.sub.L.rho.AV.sup.2 (Eq. 6)
F.sub.D=0.5C.sub.D.rho.AV.sup.2 (Eq. 7)
where
[0049] .rho.=density of air(slugs/ft.sup.3)
[0050] A=projected area of the ball (ft.sup.2)
((.pi./4)D.sup.2)
[0051] D=ball diameter (ft)
[0052] V=ball speed (ft/s)
[0053] C.sub.L=dimensionless lift coefficient
[0054] C.sub.D=dimensionless drag coefficient
[0055] Lift and drag coefficients are typically used to quantify
the aerodynamic forces imparted to a ball in flight and are
dependent on air density, air viscosity, ball speed, and spin rate.
The influence of all these parameters may be captured by two
dimensionless parameters: Spin Ratio (SR) and Reynolds Number
(N.sub.Re). Spin Ratio is the rotational surface speed of the ball
divided by ball speed. Reynolds Number quantifies the ratio of
inertial to viscous forces acting on the golf ball moving through
air. SR and N.sub.Re are calculated in Equations 8 and 9 below:
SR=.omega.(D/2)/V (Eq. 8)
N.sub.Re=DV.rho./.mu. (Eq. 9)
where
[0056] .omega.=ball rotation rate (radians/s) (2.pi.(rpm/60))
[0057] rpm=ball spin rate .omega. (revolution/min)
[0058] V=ball speed (ft/s)
[0059] D=ball diameter (ft)
[0060] .rho.=air density (slugs/ft.sup.3)
[0061] .mu.=absolute viscosity of air (lb sec/ft.sup.2)
[0062] There is a number of suitable methods for determining the
lift and drag coefficients for a given range of SR and N.sub.Re,
which include the use of indoor test ranges with ballistic screen
technology. U.S. Pat. No. 5,682,230, the entire disclosure of which
is incorporated by reference herein, teaches the use of a series of
ballistic screens to acquire lift and drag coefficients. U.S. Pat.
Nos. 6,186,002 and 6,285,445, also incorporated in their entirety
by reference herein, disclose methods for determining lift and drag
coefficients for a given range of velocities and spin rates using
an indoor test range, wherein the values for C.sub.L and C.sub.D
are related to SR and N.sub.Re for each shot. One skilled in the
art of golf ball aerodynamics testing may readily determine the
lift and drag coefficients through the use of an indoor test range,
or alternatively in a wind tunnel.
[0063] In order to better classify the above variables, it is often
more effective to characterize the aerodynamics of a golf ball 500
based on a ratio of the coefficient near the beginning of a flight
over the coefficient near the end of the flight, labeled here as a
"beginning to end coefficient ratio". This beginning to end
coefficient ratio can be applicable to the coefficient of lift
(C.sub.L), coefficient of drag (C.sub.D), and the lift-to-drag
ratio (C.sub.L/C.sub.D), yielding a beginning to end coefficient of
lift ratio (C.sub.L-Beg/C.sub.L-End), a beginning to end
coefficient of drag ratio (C.sub.D-Beg/C.sub.D-End), and beginning
to end ratio of lift to drag
ratio ( C L - Beg C D - Beg / C L - End C D - End ) .
##EQU00001##
[0064] For the purposes of this invention, a Reynolds Number
(N.sub.Re) of approximately 220,000 with a Spin Ratio (SR) of
approximately 0.054 is used to represent the exemplary aerodynamic
conditions during the beginning (ascent) portion of the golf ball
flight. These conditions generally translate into a golf ball 500
velocity of approximately 168 mph at a spin rate of approximately
1800 rpm.
[0065] Furthermore, a Reynolds Number (N.sub.Re) of approximately
80,000 with a Spin Ratio (SR) of approximately 0.120 is used to
represent the exemplary aerodynamic conditions during the end
(descent) portion of golf ball flight. These conditions generally
translate into a golf ball 500 velocity of approximately 61 mph at
a spin rate of approximately 1460 rpm.
[0066] In this current exemplary embodiment the beginning to end
coefficient of lift ratio (C.sub.L-Beg/C.sub.L-End) may be
approximately within the range of 0.64 to 3.20, more preferably
within the range of 0.72 to 2.03, most preferably within the range
of 0.80 to 0.86. Additionally, the beginning to end coefficient of
drag ratio (C.sub.D-Beg/C.sub.D-End) may be approximately within
the range of 0.76 to 0.99, more preferably within the range of 0.82
to 0.96, most preferably within the range of 0.87 to 0.93. Lastly,
the beginning to end lift to drag ratio
( C L - Beg C D - Beg / C L - End C D - End ) ##EQU00002##
may be approximately within the range of 0.65 to 3.40, more
preferably within the range of 0.76 to 2.25, most preferably within
the range of 0.86 to 1.10 all without departing from the scope and
content of the present invention.
[0067] The above discussion only provides a brief introduction to
the aerodynamic properties of a golf ball 500 that can be combined
with a golf club 200 to achieve the high launch and low spin
characteristics in accordance with an exemplary embodiment of the
present invention; more details regarding the above discussion
relating to the aerodynamic properties and forces acting on a golf
ball 500 may be found in U.S. Pat. No. 7,226,369, the disclosure of
which is incorporated by reference in its entirety herein.
[0068] FIG. 6 shows a multi-layered golf ball 600 capable of
achieving launch conditions that satisfy Equation 1, 2, 3, or 4 in
accordance with the exemplary embodiment of the present invention.
Golf ball 600 may generally have an inner core 602, a cover layer
608, and at least one intermediate layer 604 between the inner core
602 and the cover layer 608. The inner core 602, the intermediate
layers 604, and the cover layer 608 may all be constructed to have
different properties. In an exemplary embodiment, the inner core
602 preferably has a low specific gravity, a low flexural modulus,
and low hardness; wherein the cover layer 608 has a higher specific
gravity, a higher flexural modulus, and a higher hardness than the
intermediate layer 604 and the core 602. The hardness of the cover
layer 608 may generally be in the range of 80 Shore C to 100 Shore
C, most preferably 90 Shore C, when measured in place on the ball
to achieve launch conditions that satisfy Equation 1, 2, 3, or 4 in
accordance with the exemplary embodiment of the present invention;
however, various other hardness ranges for cover layer 608 may also
be used so long as it adheres to the composition above without
departing from the scope and content of the present invention.
[0069] In another embodiment of the present invention, a
multi-layer golf ball that is substantially similar to the first
embodiment may be disclosed that provides a coefficient of
restitution (COR) gradient from slow to fast, e.g., the inner core
602 has a lower COR value, the intermediate layer 604 has a higher
COR value, and the cover layer 608 has an even higher COR value. In
a further alternative embodiment, the golf ball 600 may also
contain a higher moment of inertia wherein the inner core 602 may
have various fillers removed while other fillers may be adding
various fillers to the cover 608. The elimination of fillers from
inner core 602, combined with the addition of fillers to cover 608
may create additional mass towards the outer perimeter of the golf
ball 600; hence generating a higher moment of inertia within golf
ball 600 to create a lower initial spin rate .omega..sub.i without
departing from the scope and content of the present invention.
[0070] FIG. 6 also shows a further alternative embodiment of the
present invention wherein the golf ball 600 may have a relatively
low Atti compression in the range of 70 to 80 to achieve launch
conditions that satisfy Equation 1, 2, 3, or 4 in accordance with
the exemplary embodiment of the present invention. However, it
should be noted that a golf ball 600 with a really low compression
may create an undesirably soft feel for some golfers; thus creating
a preferable compression in the range of 80 to 90.
[0071] In a further alternative embodiment of the present
invention, golf ball 600 may have the cover 608 coated with a
material that optimizes a coefficient of friction to achieve launch
conditions that satisfy Equation 1, 2, 3, or 4 in accordance with
the exemplary embodiment of the present invention. The detail of
this film coating that optimizes the coefficient of friction may be
disclosed by U.S. Pat. No. 5,827,133; the disclosure of which is
incorporated here by reference in its entirety. It should be noted
that although this film that optimizes a coefficient of friction
may generally be applied to the golf ball, it could alternatively
be applied to the face of the golf club or to both the golf ball
and the face of the golf club to create the same effect or even
enhancing the reduction in coefficient of friction all without
departing from the scope and content of the present invention.
[0072] In an even further alternative embodiment of the present
invention, golf ball 600 may also be oversized to achieve launch
conditions that satisfy Equation 1, 2, 3, or 4 in accordance with
the exemplary embodiment of the present invention. The details of
this oversized golf ball with a diameter greater than the standard
1.68 inches may be found in U.S. Pat. No. 5,273,287; the disclosure
of which is incorporated by reference in its entirety.
[0073] FIG. 7 shows yet another embodiment of the present invention
directed at a multi-layer golf ball 700 comprising an inner core
702, at least one intermediate core layer 704, and outer core layer
706, and a cover layer 708. In this embodiment, a volume-decreasing
gradient is present, e.g., the volume of the inner core 702 is
larger than volume of the intermediate core layer 704, which is
larger than the volume of the outer core 706, which is larger than
the volume of the cover layer 708. A hardness-increasing gradient
may also be present in this alternative embodiment as shown in FIG.
7 resulting in a soft inner core 702, a slightly harder
intermediate core 704, a still harder outer core 706, and an even
harder cover layer 708. Finally, a specific gravity gradient may
also be present, progressing form an inner core 702 with a lower
specific gravity to an outer core 704 with a higher specific
gravity. However, it should be noted that in this alternative
embodiment the specific gravity gradient may not progress all the
way through the cover layer 708, as it may be preferred that the
specific gravity of the outer core layer 706 be higher than the
specific gravity of the cover layer 708.
[0074] The above discussion only provides a brief introduction to
the material properties of a golf ball 700 that can be combined
with a golf club 200 to achieve high launch angle .alpha. and low
initial spin .omega..sub.i characteristics in accordance with an
exemplary embodiment of the present invention; however, more
details regarding the above discussion relating to the material
properties of a golf ball 700 in accordance with the present
invention may be found in U.S. Pat. No. 7,354,357, the disclosure
of which is incorporated by reference in its entirety herein.
[0075] It should be understood, of course, that the foregoing
relates to exemplary embodiments of the invention and that
modifications may be made without departing from the scope and
content of the invention as set forth in the following claims.
* * * * *