Patent Application
20130090189
1. Field of the Invention
The embodiments described herein relate generally to golf balls and are specifically concerned with a kit for a driver and a golf ball to create desired flight characteristics.
2. Related Art
Golf ball dimple pattern design has long been considered a critical factor in ball flight distance. A golf ball's velocity, launch angle, and spin rate is determined by the impact between the golf club and the golf ball, but the ball's trajectory after impact is controlled by gravity and aerodynamics of the ball. Dimples on a golf ball affect both drag and lift, which in turn determine how far the ball flies.
The aerodynamic forces acting on a golf ball during flight may be determined according to well-understood laws of physics. Scientists have created mathematical models so as to understand these laws and predict the flight of a golf ball. Using these models along with several readily determined values such as the golf ball's weight, diameter and lift and drag coefficients, scientists have been able to resolve these aerodynamic forces into the orthogonal components of lift and drag. The lift coefficient relates to the aerodynamic force component acting perpendicular to the path of the golf ball during flight while the drag coefficient relates to the aerodynamic force component acting parallel to the flight path. The lift and drag coefficients vary by golf ball design and are generally a function of the speed and spin rate of the golf ball and for the most part do not depend on the orientation of the golf ball on the tee for a spherically symmetrical or “conforming” golf ball.
The maximum height a golf ball achieves during flight is directly related to the lift generated by the ball, while the direction that the golf ball takes, specifically how straight a golf ball flies, is related to several factors, some of which include spin and spin axis orientation of the golf ball in relation to the golf ball's direction of flight. Further, the spin and spin axis are important in specifying the direction and magnitude of the lift force vector. The lift force vector is a major factor in controlling the golf ball flight path in the x, y and z directions. Additionally, the total lift force a golf ball generates during flight depends on several factors, including spin rate, velocity of the ball relative to the surrounding air and the surface characteristics of the golf ball. A golf ball that is not hit squarely off the tee will tend to drift off-line and disperse away from its intended trajectory. This is often the case with recreational golfers who impart a slice or a hook spin on the golf ball when striking the ball.
In order to overcome the drawbacks of a hook or a slice, some golf ball manufacturers have modified the construction of a golf ball in ways that tend to lower the spin rate. Some of these modifications include utilizing hard two-piece covers and using higher moment of inertia golf balls. Other manufacturers have resorted to modifying the ball surface to decrease the lift characteristics on the ball. These modifications include varying the dimple patterns in order to affect the lift and drag on the golf ball.
Some prior golf balls have been designed with non-conforming or non-symmetrical dimple patterns in an effort to offset the effect of imperfect hits, so that the unskilled golfer can hit a ball more consistently in a straighter path. Although such balls do not conform to the United States Golf Association (USGA) Rules of Golf, they are very helpful for the recreational golfer in making the shots fly straighter and the game more fun. One such ball is described in U.S. Pat. No. 3,819,190 of Nepela et al. This ball is also known as a Polara™ golf ball, and has regions with different types and numbers of dimples or no dimples. A circumferential band extending around the spherical ball has a plurality of dimples, while polar areas on opposite sides of the band have more shallow, fewer or no dimples at all. For this asymmetric golf ball, the measured lift and drag coefficients are strongly influenced by the orientation of the rotating golf ball. This is evidenced by the fact that the trajectory of the golf ball is strongly influenced by how the golf ball is oriented on the tee. For this ball to work properly, it must be placed on the tee with the poles of the ball oriented such that they are in the plane that is pointed in the intended direction of flight. In this orientation, the ball produces the lowest lift force and thus is less susceptible to hooking and slicing.
U.S. patent application Ser. Nos. 12/765,762 (the '762 application), 13/423,028 (the '028 application), and 13/097,013 (the '013 application) each describe a golf ball that creates low lift relative to conventional golf balls in order to help golfers address the problems of hooking and slicing and can be included in the kits described herein. The '762 application describes a low lift conforming golf ball, while the '028 and '013 applications each describe a low lift, nonconforming golf ball design. Golf balls designed in accordance with the techniques described in these applications have been demonstrated to reduce hooks and slices; however, because such balls exhibit low lift, they tend to not fly as far as a normal golf ball struck with a normal club, such as a conventional driver. It should be noted that it has been demonstrated that certain of these balls will fly as far or even further than a conventional golf ball when hit with certain clubs, but almost uniformly these balls do not fly as far when hit with the driver. Driver distance is something most golfers, even amateur and high handicap players are very sensitive to and in general providing the maximum distance, while correcting hooks and slices to the greatest degree possible is desirable.
In golf, the club that is usually used on the tee for par 4 and 5 holes is the driver club. Drivers were once made of wood, but today they are made of metal or are a composite of metal and other materials. Standard driver golf clubs for men in the USA are generally labeled 8-12 degrees loft, with the majority of driver lofts being labeled by the manufacturer as being in the range of 9.5-10.5 degrees loft. However, these drivers are actually higher loft than they are labeled because the golf industry is aware that many golfers aspire to use the same equipment that professional golfers use, which are drivers with a loft of <9 degrees so the manufacturers purposely mislabel the actual loft on a driver. Still, drivers with conventional lofts, e.g., 9-12 degrees, will often result in shorter distance off the tee when used with a low lift golf ball, such as those described in the '762, '028, and '013 applications.
But much of the distance lost due to the low loft of such balls can be reclaimed if a driver with the appropriate loft is used. But most golfers have no idea how to determine the best fit of golf ball and golf club, or golf club parameters. Moreover, e.g., conventional drivers may not provide the needed loft, as conventional clubs are designed for conventional or high lift balls and are marketed to appeal to a golfer's desire to be like the pros.
Certain embodiments as disclosed herein provide for a kit comprising a golf club and a golf ball where the golf club loft is selected in order to improve or optimize the distance that the golf ball travels when hit.
In one aspect, the kit comprises a golf club with predetermined club loft based on a golfer's swing and a golf ball which is designed to have a lower flight trajectory than other golf balls, as a result of lower lift, higher drag, higher weight, smaller size, or any combination of factors that cause the golf ball to have a lower flight trajectory.
In one aspect, the golf ball has a dimple pattern which has reduced or no dimple volume in a selected circumferential band around the ball and more dimple volume in other regions of the ball. This causes the ball to have a “preferred” spin axis because of the weight differences caused by locating different volume dimples in different areas across the ball. This in turn reduces the tendency for dispersion of the ball to the left or right (hooking and slicing) during flight. In one example, the circumferential band of lower dimple volume is around the equator with more dimple volume in the polar regions. This creates a preferred spin axis passing through the poles. The dimple pattern is also designed to exhibit relatively low lift when the ball spins in the selected orientation around its preferred spin axis. This golf ball is nonconforming or non-symmetrical under United States Golf Association rules.
A golf ball's preferred or selected spin axis may also be established by placing high and low density materials in specific locations within the core or intermediate layers of the golf ball, but has the disadvantage of adding cost and complexity to the golf ball manufacturing process.
Where a circumferential band of lower or zero dimple volume is provided about the equator and more dimple volume is provided in the polar regions, a ball is created which has a large enough moment of inertia (MOI) difference between the poles horizontal (PH) orientation and other orientations that the ball has a preferential spin axis going through the poles of the ball. The preferred spin axis extends through the lowest weight regions of the ball. If these are the polar regions, the preferred axis extends through the poles. If the ball is oriented on the tee so that the “preferred axis” or axis through the poles is pointing up and down (pole over pole or POP orientation), it is less effective in correcting hooks and slices compared to being oriented in the PH orientation when struck.
The lower volume dimples do not have to be located in a single circumferential band to create a preferred spin axis. The lower volume dimples can be located outside the one or more bands, planes or regions, so long as the presence of the lower volume dimple bands, regions or planes are situated such that the ball in one rotational orientation has a higher MOI than in any other rotational orientations. In some of the designs described above and below, the dimple design results in a ball which has a highest MOI in one rotational orientation and a lower and nearly equal MOI in the two other rotational orientations that are orthogonal to the highest MOI rotational orientation. For clarification purposes and for example, the 3 orthogonal axes of rotation would be geometrically similar to the x-y-z axes in a three dimensional Cartesian coordinate system where any two axes are perpendicular to each other. So in the example where the ball has a lower or zero dimple volume provided about the equator and more dimple volume provided in the polar regions, which results in a ball which has a large enough moment of inertia (MOI) difference between the poles horizontal (PH) orientation and other orientations that the ball has a preferential spin axis going through the poles of the ball—this axis going through the poles could be named the x-axis and the MOI when the ball rotated about the x-axis would be higher than when it rotated about the y or z axes. In this particular design the MOI rotating about the y and z axes would be the same. The volume of the dimples could also be controlled so that the ball has a higher MOI in one orientation and a lower MOI in one of the other orthogonal axes of rotation and an even lower MOI in the third orthogonal axis of rotation. The preferred spin axis is still the highest MOI rotational configuration of all the possible rotational orientations.
In another aspect, the ball may have no dimples in a band about the equator (a land area) and deep dimples in the polar regions. The dimple-less region may be narrow, like a wide seam, or may be wider, i.e. equivalent to removing one or more rows of dimples on each side of the equator.
By creating a golf ball with a dimple pattern that has less dimple volume in a band around the equator and by removing more dimple volume from the polar regions adjacent to the low-dimple-volume band, a ball can be created with a large enough moment of inertia (MOI) difference between the poles-horizontal (PH) and other orientations that the ball has a “preferred” spin axis going through the poles of the ball and this preferred spin axis tends to reduce or prevent hooking or slicing when a golfer aligns the ball in the PH orientation on the tee (poles pointing right and left and the equatorial plane aligned in the intended direction of flight) and then hits the ball in a manner which would generate other than pure backspin on a normal symmetrically designed golf ball. In other words, when this ball is hit in manner which would normally cause hooking or slicing in a symmetrical or conforming ball, the ball tends to rotate about the selected spin axis and thus not hook or slice as much as a symmetrical ball with no selected or “preferred” spin axis. In one embodiment, the dimple pattern is designed so that it generates relatively low lift when rotating in the preferred spin axis PH orientation. The resulting golf ball displays enhanced hook and slice correcting characteristics.
The low volume dimples do not have to be located in a continuous band around the ball's equator. The low volume dimples could be interspersed with higher volume dimples, the band could be wider in some parts than others, the area in which the low volume dimples are located could have more land area (lack of dimples) than in other areas of the ball. The high volume dimples located in the polar regions could also be inter-dispersed with lower volume dimples; and the polar regions could be wider in some spots than others. The main idea is to create a higher moment of inertia for the ball when it is rotating in one configuration and to do this by manipulating the volume of the dimples across the surface of the ball. This difference in MOI then causes the ball to have a preferred spin axis. The golf ball is then placed on the tee so that the preferred spin axis is oriented approximately horizontally and perpendicular to the intended direction of flight so that when the ball is hit with a hook or slice action, the ball tends to rotate about the initial horizontal spin axis orientation and thus not hook or slice as much as a symmetrical ball with no preferred spin axis would hook or slice. In some embodiments, the preferred spin axis is the PH orientation.
Another way to create the preferred spin axis would be to place two or more regions of lower volume or zero volume regions on the ball's surface and make the regions somewhat co-planar so that they create a preferred spin axis. For example, if two areas of lower volume dimples were placed opposite each other on the ball, then a dumbbell-type weight distribution would exist. In this case, the ball has a preferred spin axis equal to the orientation of the ball when it is rotating end-over-end with the “dumbbell areas”.
The ball can also be oriented on the tee with the preferred spin axis tilted up to about 45 degrees to the right and then the ball still resists slicing, but does not resist hooking as much. If the ball is tilted 45 degrees to the left it reduces or prevents hook dispersion, but does not reduce or prevent slice dispersion as much. This may be helpful for untrained golfers who tend to hook or slice a ball. When the ball is oriented so that the preferred axis is pointing up and down on the tee (POP orientation for a preferred spin axis in the PH orientation), the ball is much less effective in correcting hooks and slices compared to being oriented in the PH orientation.
In other cases, the kit may include a conforming ball with no preferred spin axis but with first and second areas of dimples of different dimensions designed to exhibit relatively low lift. Or the kit may include a ball that exhibits relatively low lift because of the design of the dimple characteristics such as depth, shape, diameter, edge radius and their arrangement on the golf ball.
Other features and advantages will become more readily apparent to those of ordinary skill in the art after reviewing the following detailed description and accompanying drawings.
The details of the present embodiments, both as to structure and operation, may be gleaned in part by study of the accompanying drawings, in which like reference numerals refer to like parts, and in which:
After reading this description it will become apparent to one skilled in the art how to implement the embodiments in various alternative implementations and alternative applications. Further, although various embodiments will be described herein, it is understood that these embodiments are presented by way of example only, and not limitation. As such, this detailed description of various alternative embodiments should not be construed to limit the scope or breadth of the appended claims.
The embodiments described herein involve a series of drivers with lofts ranging from about 12 to 24.5 degrees. However, the ideas and technology described here could be used for drivers of lower or higher loft than the range of lofts actually produced and shown here. The USGA has set limits driver specification, including size (less than or equal to 460 cc), coefficient of restitution (0.83), characteristic time (256 micro seconds). Certain of the clubs described herein were designed to have increased volume that will improve several playability characteristics for certain golfers. The larger size can enable the drivers to be made more forgiving for off-center hits, for example. Further, the drivers can have a coefficient of restitution higher than that of the USGA limits.
The embodiments described herein are directed to a combination or kit of a low lift, symmetric or asymmetric ball that reduces hooks or slices and combined with a driver of high loft, increased volume add high spring-like effect to maximize distance, wherein the driver and the ball are paired to produce the best results, i.e., maximum distance and control for a specific golfer. In order to select the correct kit, the golfer's swing must be characterized. Accordingly, systems and methods for characterizing golfer's swing are also disclosed.
Overall, the kits described herein are a combination of a driver and ball to maximize distance and game improvement reduction of hooks and slices. As noted, lower lift golf balls have the advantage that they are less prone to hook or slice when mishit, but due to their lower lift they can also end up flying shorter distance off shots with the driver. To overcome the disadvantage of shorter distance, a higher loft driver is needed to maximize distance with low lift golf balls. The exact loft depends on several factors including the lift and drag characteristics of the ball and the golfers swing speed. Descriptions of example low lift golf balls, including lift and drag characteristic information are provided below.
In one embodiment, the kit will include drivers having a loft range of 12 degrees to 25 degrees. In order to match a driver and a low lift golf ball to a player, a fitting scheme will be employed. Players with slower swing speeds in the 70 to 80 mph range will be fitted to drivers with higher lofts. Conversely, players with faster swing speeds will need drivers with not quite as much loft. Overall, swing speed is the major factor in determining driver loft for a given golf ball and swing speed is considered a macro-adjustment.
But, e.g., another factor influencing the driver loft selected is the natural ball flight tendencies of shots hit by the player. Players with higher ball flights (often caused by higher backspin or higher launch angle) will tend to be fitted with slightly lower driver lofts and players with lower ball flights will be fitted with slightly higher driver lofts.
A third factor influencing the driver loft is the golf ball selected. The present invention is a kit for a driver and golf ball combination. A low lift ball such as the Polara Ultimate Straight or the 28-1, described below, are low flying balls that develop low lift and exhibit excellent hook and slice reducing characteristics. A higher driver loft is needed for this low-lift type of ball. For a slightly higher lift golf ball such as the Polara XD, which does not correct hooks and slices as much as the Polara Ultimate Straight or the 28-1, a slightly lower loft driver will be selected than would be used by the same player for the Polara Ultimate Straight golf ball for example.
More specifically, referring to the table below it can be seen that a player with a 77 mph swing speed, using a low lift golf ball such as the Polara Ultimate Straight will be fitted with a driver with 22 degrees loft in order to maximize the overall distance the player hits the ball. A 24.5 degree driver would be needed to maximize the total carry distance for this same player-ball combination.
Conversely, if a player with a 77 mph swing speed wants to optimize total distance using a high lift golf ball like the Titleist Pro V1, then this golfer would choose a 12 degree driver and would choose an 18 degree driver to maximize carry distance.
The optimum driver loft for different combinations of balls and player swing speeds can bee seen in the table and chart in
In order to identify the correct kit, several aspects of the golfer's game can first be determined. For example, it can be determined how far the golfer hits his driver. This can be determined by asking the golfer; however, most golfers over estimate how far they hit the ball generally and specifically overestimate how far they hit their driver. Accordingly, it is preferable to measure, e.g., using a launch monitor how far the golfer can hit his or her driver. It should be noted that distance is not the only issue, as ball flight or trajectory can play an important role as well. Thus, preferably, the ball flight information would be measured as well.
If it is not possible to measure driver distance, then other determinations relating to what club the golfer uses from certain distances can be made. For example, if the golfer normally hits an 8 iron from 150 yards, then this is an indication that they have a relatively high swing speed and high trajectory. Whereas, if they hit a 4 iron, then they likely have a relatively low swing speed and trajectory.
It is also important to determine whether the golfer normally hooks or slices and by how much.
The above information can then be correlated with swing speed, launch angle, and spin rate, which can then be used to identify a correct kit. For example, if a golfer slices significantly, then they will tend to have a higher launch angle and a higher spin rate if they use a conventional golf ball such as the ProV1. Accordingly, a very low lift ball such as the Polara Ultimate Straight may be selected. But this will significantly reduce the maximum trajectory height and carry distance of the ball. Tables such as that below can be used to determine what the relative maximum trajectory heights and carry distances may be if the golfer were to use the Polara Ultimate Straight and then this information used to select the correct club or kit.
Computer modeling capability using a golf ball trajectory model, as well as measurement capabilities using a Trackman™ Net System™ to measure actual golf shots allows one to better understand the effect between club loft, ball spin, and carry distance.
Using the trajectory model, pre-determined launch conditions can be set up and evaluated in order to understand the effect of varying club loft on the resultant trajectory. A first series of tests used the following initial launch parameters: ball speed=200 fps (simulating approximately a 90 mph swing speed), initial spin=3000 rpm. The vertical launch angle was varied from 5 to 45 degrees and the resultant overlaid trajectories are shown in
The maximum height and carry distance both vary as the launch angle in increased. But while the maximum height simply increases with increasing vertical launch angle, the carry distance starts out relatively short (5 deg launch=approx 170 yds carry), reaches a maximum (20 & 25 deg vertical launch=approx 195 yds carry), and then the carry actually decreases as the vertical launch continues to be increased. At 40 deg vertical launch, the carry is actually shorter than at 5 deg vertical launch, at about 165 yds.
Clearly there is an “optimal” trajectory that maximizes carry distance. In the simulated trajectories of
In general, golf companies label a driver with 11-12 or greater loft as a “High Loft” or “High Trajectory” driver. Several companies make drivers labeled as 13.5 degrees loft. There is one company named Thomas Golf that makes degree labeled “16 degree”. The USGA has set limits driver specification, including size (less than or equal to 460 cc), coefficient of restitution (0.83), characteristic time (256 micro seconds). As a golfer' club head speed slows, and with all other things being constant, the golf ball needs to launch higher in order to maintain distance. Similarly with backspin—as the club head speed slows, a higher backspin is desired.
It should also be noted that the kits described herein can include non-conforming golf balls, as noted, as well as non-conforming clubs. Parameters such as club length, club head size, shaft flex, etc., will also affect distance and accuracy. Because the kits described herein include equipment that a typical golfer has never used and for which there is not significant data available, it is even more important to provide a method for fitting a golfer with the correct kit.
Conventional USGA conforming drivers are all designed to be 460 cc in volume or less. However, increasing the volume can improve several playability characteristics for certain golfers so it is anticipated that the drivers could easily be made over 500 cc and even as high as 600 cc or even 700 cc or higher. The larger size will enable the driver to be made more forgiving for off-center hits, for example. Making the driver larger volume will also enable the driver to be made with a larger breadth (dimension E in attached diagram). The USGA restricts the breadth to be less than the width. For some of the drivers described herein, the breadth is greater than the width for all models. Making the ratio of breadth to width even larger will also benefit the playability of the driver. For the current models the breadth/width is 1.04 (12 degree loft) to 1.136 (24.5 degree loft). The breadth-width ratio could be increased to 1.3 or even as high as 1.6 in order to improve the playability for the golfer.
The loft of the driver is important in getting the ball to launch higher in the air. Even though the highest loft made was 24.5 degrees, tests show that many golfers like the 24.5 degree driver and could further benefit from even higher loft drivers. Especially for golf balls like the Polara Ultimate Straight (has about half the lift of a normal golf ball) a higher lofted club is required for getting the ball to fly higher and thus maximize the carry distance. Thus a driver loft of up to 40 degree would be useful, even as high as 55 degrees would be useful for some golfers, especially those with very slow swing speeds.
The face of these clubs can comprise beta-titanium (Beta-Ti). This can be done to increase the CT and COR. Beta Ti is stronger than normal titanium alloy so the face can be made thinner and thus have a higher “spring effect”. It should also be noted that as the driver loft is increased the face thickness is decreased because the direct force on the face decreases. This allows the face to have a higher COR than would be found with a standard club design. In certain embodiments, the thinnest face can be 2.3 mm. This lower limit can be selected to cause the face to have a certain level of strength. In other embodiments, however, the face can be even thinner, especially for golfers with a lower swing speed. The face can be made less than 2 mm, lower than 1.9 mm and even as low as 1.5 mm for slower swing speed golfers and lofts greater than 12 degrees.
In certain embodiments, the face height for the clubs can be 56 mm. In larger volume versions the face can be even higher (greater than 56 mm tall). Even for similar volume versions the face can be higher by making the rear portion of the club less voluminous. The face width can be increased to over 119 mm and this would improve the performance for off-center hits. Making the face width 25-75% greater would help improve performance for some golfers.
In certain embodiments, the shafts used on the drivers can all be cut to 45.75″. Because some of the drivers are higher loft and are designed to be more forgiving w/ slice and hook shots than a normal driver, the shaft length can be longer and adding 0.25-6.0 inches should help golfers generate considerably more club head velocity and thus more ball distance. Adding even 6-12 inches would even be possible and with the higher loft (>12 degrees) the mis-hits would be lessened because of the fact that the higher backspin caused by the higher loft would prevent the spin axis on slices and hooks from being as tilted to the right or left as would be the case with a lower loft driver (<12 degrees). The shafts were made by UST-Mamiya and were their model “6000 series”. The shafts were in flexes stiff, regular, A (senior) and L (ladies)
In certain embodiments, the drivers use variable face thickness. For example, the entire face can be very thin (2.3-2.6 mm thickness), but can include “ramps” on the lower portion of the face escalate from 2.3 mm to 2.9 mm. For comparison, most constant conforming face thicknesses are in the range of 2.9-3.1 mm thick depending on the face size and head volume (for 6-4 titanium). These drivers have beta-Ti (15-3-3-3) faces and use 2.9 mm ramps to help reinforce the strength of the face. The ramps or reinforcement bars are variable width—wider at the base than at the top. The following Table 2 illustrates some example club characteristics that include such ramps.
To look at the effect that increased launch angle has on the carry distance for the Polara Ultimate Straight, several tests were performed. These tests involved expert golfers hitting balls while data was recorded with the Trackman™ Net System™. The Appendix attached hereto includes data garnered from these and other tests.
For the first test (see complete report attached as Appendix A) the only parameters varied were club type and tee height (ball impact club face location). Three clubs were used: 8.5 deg driver, 11.5 deg driver, 13 deg 3-wood. For each club, 3 groups of shots (all using the Polara Ultimate Straight in the Poles Horizontal orientation) were hit with a mid-level tee-height (standard position, center of club face), a low tee height (approx 1 cm lower), and a high tee height (approx 1 cm higher). Typically the face of a driver or any of the woods such as the 3-wood, is not perfectly flat. These clubs have faces that are convex (bulging outward) and thus the upper portion of the club face has an effectively higher loft than the middle section, which in turn is higher loft than the lower section. The objective of this test was to vary only the launch angle (spin would also be expected to vary) while keeping the golf swing (per club) itself unchanged. In this way, the primary effect of launch angle on carry distance could be observed. The results of this test are shown in
These results clearly showed that for all 3 clubs increasing the vertical launch angle resulted in increased carry distance for all cases. The chart in
As can be seen, there appears to be a direct correlation of increasing carry distance with increasing vertical launch angle for the Polara Ultimate Straight, PH orientation. The increased scatter for low tee height with the 3-wood and 8.5 deg driver was due to the fact that for these clubs, lowering the tee height from standard position resulted in a more challenging shot to hit solidly for the golfer.
Data for another on-course player test shows very clearly that increasing driver club loft results in significant improvement in the carry distance of the Polara Ultimate Straight, PH orientation while actually decreasing the carry distance of a more traditional ball, in this case the Titleist™ ProV1. This is due to the combination of the higher lofted club and the unique aerodynamic performance of the Polara Ultimate Straight golf ball.
The player hit several groups of shots using a 9 deg loft driver and a 16 deg loft driver. Balls were randomly mixed between ProV1 and Polara Ultimate Straight (PH orientation). Data was recorded with the Trackman™ Net System™ and some results are presented below. (See full report, Appendix B). The data for the vertical launch angles is illustrated in the chart of
The spin has increased dramatically for both balls using the 16 deg lofted driver relative to the 9 deg. Since the ProV1 is a relatively high-lift ball, this increased spin would generate even more lift. Even though the Polara Ultimate Straight is a much lower lift ball under comparable spin conditions compared to the Pro V1, the increased lift generated by the increased spin and the increased vertical launch angle would still be expected to increase maximum height and flight time. The combination of the higher spin and higher vertical launch angle is what is observed in the trajectory data illustrated in the charts of
At 9 deg driver loft, the maximum height for the ProV1 is about 36 yds, while the Polara Ultimate Straight is only about 21 yds. When the loft is increased to 16 degrees, the maximum height for the ProV1 has increased to about 52 yds, while the Polara Ultimate Straight has increased to a maximum height of about 40 yds. This effect on flight time is similar and is illustrated in the chart of
With a 9 deg loft, the Polara Ultimate Straight is in the air a full 2 seconds shorter than ProV1, while with the 16 deg loft, the difference has dropped to 1 second. Also, the flight time for the Polara Ultimate Straight with 16 deg loft is very similar to the flight time for the ProV1 at 9 deg loft. Carry distance in yards is shown in the chart of
Of interest here is that the carry distance for the ProV1 decreased dramatically (by about 30 yards) when going from the 9 deg lofted driver to the 16 deg lofted driver, while the carry for the Polara surprisingly increased 30 yards by going to the higher lofted driver.
Here is the data from above summarized in table form:
The above data suggests that the higher lofted club is resulting in shorter carry for the ProV1 because the higher spin generate by the higher loft club, combined with the relatively high lift of the ball and the higher launch angle, cause the ball to “balloon” above it's optimal trajectory, and carry distance is lost.
However, for the Polara Ultimate Straight ball (in PH orientation), the increased spin resulting from the higher lofted club gives extra lift to the relatively low lift Polara, and this combined with the higher launch angle causes the ball to climb higher as it attempts to reach it's optimal trajectory, and carry distance is gained.
One distinction should be made between a higher lofted driver and a 3 wood. Although a 3 wood club usually has a loft of approximately 15 degrees, it also has a lower volume and lower mass head. The 3 wood also has a shorter shaft. These mass, volume and length characteristics contribute to shorter distance and thus when a higher lofted driver is recommended for use with the Polara Ultimate Straight golf ball, it is preferred that the higher lofted driver have a club head size and mass that is at least that of typical modern drivers (460 cc limit by USGA). Another preferred driver design is to make a driver with a loft greater than 10.5 degrees and to have the head larger than the USGA limit of 460 cc and to also exceed the USGA COR (coefficient of restitution) and CT (Characteristic Time) limits. A driver with these criteria included in its design would deliver even longer golf ball flight distance.
Armed with these data, a kit can be assembled that matches a driver, or other club or clubs, with certain parameters, in particular loft, with a golf ball such as the Polara Ultimate Straight golf ball based on the swing characteristics of a certain golfer. For example, this can be as simple as producing a kit with a driver that has, e.g., a 16 degree loft to be sold with a golf ball such as described above that is for golfers with swing speeds under 90 mph, or 80 mph, or basically whatever the data shows. Kits can then also be produced pairing, e.g., drivers with lower lofts with golf balls such as those described above for golfers with higher swings speeds. For example there may be kits for golfers with swing speeds under 80 mph, between 80 and 90 mph, between 90 and 100 mph, and over 100 mph.
More variations can also be produced, to provide more granularity. In addition, other parameters, such as angle of attack, smash factor, spin rate, etc., can also be taken into account when producing kits. Thus, a salesperson can measure a few parameters related to a golfer's swing and then quickly identify the correct kit, i.e., club and ball pairing.
Appendices A-C include the results of various tests performed in order to obtain data to verify the above. Appendix A is a summary of data for tests performed using a Trackman™ where the tee heights were varied for various lofted clubs. Appendix B is a summary of data for tests performed using a Trackman™ where 9 degree and 16 degree drivers were used with various golf balls. Appendix C is a summary of data for tests performed using a Trackman™ where the tee height were varied or clubs with 10.5 degree and 8.5 degree lofted drivers were used.
The very different aerodynamics of the Polara Ultimate Straight golf ball are so different from normal golf balls that they have never been extensively studied before and until the new Polara Ultimate Straight golf ball was introduced people did not have the occasion to even study a ball with this range of aerodynamic performance. So it is not a surprise that nobody until this time has demonstrated the benefits or ever recommended using a higher lofted driver than normal with a ball that exhibits lower lift than normal. Balls with similar aerodynamic performance to the Polara Ultimate straight that exhibit low lift will similarly benefit from the use of a higher lofted driver—generally greater than 10.5 degrees loft, for example balls with symmetrical dimple patterns which are also designed for a lower flight trajectory, as described in detail below, as well as other golf balls which have lower than normal flight trajectories, such as golf balls with higher drag, higher weight, or smaller size. A kit can be assembled in a similar matter to that described above for the Polara Straight golf ball, using any of the conforming or symmetrical low lift or low trajectory golf balls described below in connection with
Thus, a low lift ball does not have to have an asymmetric dimple pattern, like the Polara Ultimate Straight, in order to benefit from the higher lofted driver. Any golf ball with an asymmetrical or symmetrical dimple pattern that flies lower than another golf ball benefits in general from a higher lofted driver as compared to a driver that provides the optimum distance for a higher lift golf ball. It should also be mentioned that a ball with higher drag also exhibits shorter distance than a ball with lower drag, when all other factors are equal. So in this case, the ball with the higher drag also benefits from the higher lofted driver because it helps the ball stay in the air longer and fly faster than it could roll on the ground.
In the embodiments of
It should also be understood that the terms equator or equatorial region and poles can be defined with respect to the gyroscopic center plane. In other words, the equator is in the gyroscopic center plane and the preferred spin axis goes through the poles.
In fact it has been determined that making dimples more shallow within the region inside the approximately 45 degree point 1803 on the circumference of the ball 10 with respect to the gyroscopic center plane 1801, as illustrated in
Shown in Table 1 are the dimple radius, depth and dimple location information for making a hemispherical injection molding cavity to produce the dimple pattern 28-1 on one hemisphere of the ball, with the other injection molding cavity being identical. As illustrated in Table 1, the ball has a total of 410 dimples (205 in each hemisphere of the ball). The truncated dimples 12 are each of the same radius and truncated chord depth, while the larger and smaller spherical dimples are each of three different sizes (Smaller dimples 1, 2 and 3 and larger dimples 5, 6, 7 in Table 1 of the '013 application). The locations of the truncated dimples and each of the different size spherical dimples on one hemisphere of the ball are illustrated in detail in Table 1 of the '013 application.
As seen in
With this dimple arrangement, significantly more material is removed from the polar regions of the ball to create the larger, deeper spherical dimples, and less material is removed to create the band of shallower, truncated dimples around the equator. In testing described in more detail below, the 28-1 dimple pattern of
The dimple radius, depth and dimple location information for making an injection molding cavity to produce the dimple pattern 25-1 of
It will be understood that a similar type of mold, or set of molds, is used for all of the embodiments described herein, and that mold 23 is shown by way of example only.
Table 4 of the '013 application lists dimple shapes, dimensions, and coordinates or locations on a ball for a dimple pattern 28-2 which is very similar to the dimple pattern 28-1 and is therefore not shown separately in the drawings. The ball with dimple pattern 28-2 has three larger spherical dimples of different dimensions, numbered 5, 6 and 7 in Table 4 of the '013 application, and three smaller spherical dimples of different dimensions, numbered 1, 2 and 3, and the dimensions of these dimples are identical to the corresponding dimples of the 28-1 ball in Table 1 of the '013 application, as are the dimensions of truncated dimples numbered 4 in Table 4 of the '013 application. The dimple pattern 28-2 is nearly identical to dimple pattern 28-1, except that the seam that separates the two hemispheres of the ball is wider in the 28-2 ball, and the coordinates of some of the dimples are slightly different, as can be determined by comparing Tables 1 and 4 of the '013 application.
The dimple coordinates for pattern 28-2 are illustrated in detail in Table 4 of the '013 application.
Ball 30 or 25-2 of
Ball 40 or 25-3 of
Ball 50 or 25-4 of
As indicated in Tables 5, 6, and 7 of the '013 application, the balls 25-2 and 25-3 each have three different sizes of truncated dimple in the equatorial region and two different sizes of spherical dimple in the polar region, while ball 25-4 has three different sizes of truncated dimple as well as three different sizes of spherical dimple. The polar region of dimples is largest in ball 25-2, which has four rows of truncated dimples (two rows per hemisphere) in the equatorial region, and smallest in ball 25-3, which has eight rows of truncated dimples in the equatorial region. In alternative embodiments, balls may be made with a single row of truncated dimples in each hemisphere, as well as with a land area having no dimples in an equatorial region, the land area or band having a width equal to two, four or more rows of dimples, or with a band having regions with dimples alternating with land regions with no dimples spaced around the equator.
Dimple patterns 25-2, 25-3 and 25-4 are similar to pattern 2-9 in that they have truncated dimples around the equatorial region and deeper dimples around the pole region, but the truncated dimples in patterns 25-2, 25-3 and 25-4 are of larger diameter than the truncated dimples of patterns 28-1, 25-1 and 2-9. The larger truncated dimples near the equator mean that more weight is removed from the equator area. With all other factors being equal, this means that there is a smaller MOI difference between the PH and POP orientations for balls 25-2, 25-3 and 25-4 than for balls 28-1, 28-2, 25-1 and 2-9.
As indicated in Table 8 of the '013 application and
The dimple parameters and coordinates for making one hemisphere of the 28-3 ball are illustrated in detail in Table 8 of the '013 application.
In one example, the seam widths for balls 28-1, 28-2, and 28-3 was 0.0088″ total (split on each hemisphere), while the seam widths for balls 25-2, 25-3, and 25-4 was 0.006″, and the seam width for ball 25-1 was 0.030″.
Each of the dimple patterns described above and illustrated in
V1=volume of truncated dimple,
V1+V2=volume of spherical dimple,
V1+V2+V3=volume of cover removed to create spherical dimple, and
V1+V3=volume of cover removed to create truncated dimple.
For dimples that are based on the same radius and spherical chord depth, the moment of inertia difference between a ball with truncated dimples and spherical dimples is related to the volume V2 below line or plane A-A which is removed in forming a spherical dimple and not removed for the truncated dimple. A ball with all other factors being the same except that one has only truncated dimples and the other has only spherical dimples, with the difference between the truncated and spherical dimples being only the volume V2 (i.e. all other dimple parameters are the same), the ball with truncated dimples is of greater weight and has a higher MOI than the ball with spherical dimples, which has more material removed from the surface to create the dimples.
The approximate moment of inertia can be calculated for each of the balls illustrated in
The MOI for each ball was calculated based on the dimple pattern information and the physical information in Table 4. Table 5 shows the MOI calculations.
With the Polara™ golf ball as a standard, the MOI differences between each orientation were compared to the Polara golf ball in addition to being compared to each other. The largest difference between any two orientations is called the “MOI Delta”, shown in table 5. The two columns to the right quantify the MOI Delta in terms of the maximum % difference in MOI between two orientations and the MOI Delta relative to the MOI Delta for the Polara ball. Because the density value used to calculate the mass and MOI was lower than the average density of a golf ball, the predicted weight and MOI for each ball is relative to each other, but not exactly the same as the actual MOI values of the golf balls that were made, robot tested and shown in Table 5. Generally a golf ball weighs about 45.5-45.9 g. Comparing the MOI values of all of the balls in Table 5 is quite instructive, in that it predicts the relative order of MOI difference between the different designs, with the 25-3 ball having the smallest MOI difference and ball 28-2 having the largest MOI difference.
Table 6 shows that a ball's MOI Delta does strongly influence the ball's dispersion control. In general as the relative MOI Delta of each ball increases, the dispersion distance for a slice shot decreases. The results illustrated in Table 6 also include data obtained from testing a known TopFlite XL straight ball, and were obtained during robot testing under standard laboratory conditions, as discussed in more detail below.
As illustrated in Table 6, balls 28-3, 25-1, 28-1 and 28-2 all have higher MOI deltas relative to the Polara, and they all have better dispersion control than the Polara. This MOI difference is also shown in
The aerodynamic force acting on a golf ball during flight can be broken down into three separate force vectors: Lift, Drag, and Gravity. The lift force vector acts in the direction determined by the cross product of the spin vector and the velocity vector. The drag force vector acts in the direction opposite of the velocity vector. More specifically, the aerodynamic properties of a golf ball are characterized by its lift and drag coefficients as a function of the Reynolds Number (Re) and the Dimensionless Spin Parameter (DSP). The Reynolds Number is a dimensionless quantity that quantifies the ratio of the inertial to viscous forces acting on the golf ball as it flies through the air. The Dimensionless Spin Parameter is the ratio of the golf ball's rotational surface speed to its speed through the air.
The lift and drag coefficients of a golf ball can be measured using several different methods including an Indoor Test Range such as the one at the USGA Test Center in Far Hills, N.J. or an outdoor system such as the Trackman™ Net System™ made by Interactive Sports Group in Denmark. The test results described below and illustrated in
For right-handed golfers, particularly higher handicap golfers, a major problem is the tendency to “slice” the ball. The unintended slice shot penalizes the golfer in two ways: 1) it causes the ball to deviate to the right of the intended flight path and 2) it can reduce the overall shot distance. A sliced golf ball moves to the right because the ball's spin axis is tilted to the right. The lift force by definition is orthogonal to the spin axis and thus for a sliced golf ball the lift force is pointed to the right.
The spin-axis of a golf ball is the axis about which the ball spins and is usually orthogonal to the direction that the golf ball takes in flight. If a golf ball's spin axis is 0 degrees, i.e., a horizontal spin axis causing pure backspin, the ball does not hook or slice and a higher lift force combined with a 0-degree spin axis only makes the ball fly higher. However, when a ball is hit in such a way as to impart a spin axis that is more than 0 degrees, it hooks, and it slices with a spin axis that is less than 0 degrees. It is the tilt of the spin axis that directs the lift force in the left or right direction, causing the ball to hook or slice. The distance the ball unintentionally flies to the right or left is called Carry Dispersion. A lower flying golf ball, i.e., having a lower lift, is a strong indicator of a ball that has lower Carry Dispersion.
The amount of lift force directed in the hook or slice direction is equal to: Lift Force*Sine (spin axis angle). The amount of lift force directed towards achieving height is: Lift Force*Cosine (spin axis angle).
A common cause of a sliced shot is the striking of the ball with an open clubface. In this case, the opening of the clubface also increases the effective loft of the club and thus increases the total spin of the ball. With all other factors held constant, a higher ball spin rate in general produces a higher lift force and this is why a slice shot often has a higher trajectory than a straight or hook shot.
The table 7 below shows the total ball spin rates generated by a golfer with club head speeds ranging from approximately 85-105 mph using a 10.5 degree driver and hitting a variety of prototype golf balls and commercially available golf balls that are considered to be low and normal spin golf balls:
Table 9 below illustrates results from slice testing the 25-1, 28-1, and 2-9 balls as well as the Titleist ProV1 and the TopFlite XL Straight balls, with the 25-1, 28-1 and 2-9 balls tested in both the PH and POP orientations. In this table, the average values for carry dispersion, carry distance, total dispersion, total yards, and roll yards are indicated. This indicates that the 25-1, 28-1 and 2-9 balls have significantly less dispersion in the PH orientation than in the POP orientation, and also have less dispersion than the known symmetrical ProV1 and TopFlite balls which were tested.
Golf balls 25-1, 28-1, 2-9, Polara 2p 4/08, Titleist ProV1 and TopFlite XL Straight were subjected to several tests under industry standard laboratory conditions to demonstrate the better performance that the dimple patterns described herein obtain over competing golf balls. In these tests, the flight characteristics and distance performance of the golf balls 25-1, 28-1 and 2-9 were conducted and compared with a Titleist Pro V1® made by Acushnet and TopFlite XL Straight made by Callaway Golf and a Polara 2p 4/08 made by Pounce Sports LLC. Also, each of the golf balls 25-1, 28-1, 2-9, Polara 2p 4/08, were tested in the Poles-Forward-Backward (PFB), Pole-Over-Pole (POP) and Pole Horizontal (PH) orientations. The Pro V1® and TopFlite XL Straight are USGA conforming balls and thus are known to be spherically symmetrical, and were therefore tested in no particular orientation (random orientation). Golf balls 25-1 and 28-1 were made from basically the same materials and had a DuPont HPF 2000 based core and a Surlyn™ blend (50% 9150, 50% 8150) cover. The cover was approximately 0.06 inches thick.
The tests were conducted with a “Golf Laboratories” robot and hit with the same Taylor Made® driver at varying club head speeds. The Taylor Made® driver had a 10.5° R9 460 club head with a Motore 65 “S” shaft. The golf balls were hit in a random order. Further, the balls were tested under conditions to simulate an approximately 15-25 degree slice, e.g., a negative spin axis of 15-25 degrees.
The curves in
CL
Regression
=a
1
*Re+a
2
*W+a
3
*Rê2+a4*Ŵ2+a5*ReW+a6
CD
Regression
=b
1
*Re+b
2
*W+b
3
*Rê2+b4*Ŵ2+b5*ReW+b6
Where ai with i=1-6 are regression coefficients for Lift Coefficient and
Typically the predicted CD and CL values within the measured Re and W space (interpolation) were in close agreement with the measured CD and CL values. Correlation coefficients of 96-99% were typical.
Below in Tables 10A and 10B are the regression constants for each ball shown in
As can be determined from
Under typical slice conditions, with spin rates of 3,000 rpm or greater, the 2-9, 25-1, 28-1 in PH orientation and the Polara 2p in PFB orientation exhibit lower lift coefficients than the commercial balls: ProV1 and TopFlite XL Straight. Lower lift coefficients translate into lower trajectory for straight shots and less dispersion for slice shots. Balls with dimple patterns 2-9, 25-1, 28-1 in PH orientation have approximately 10-40% lower lift coefficients than the ProV1 and TopFlite XL Straight under Re and spin conditions characteristics of slice shots.
Tables 11-13 are the Trackman™ Report from the Robot Test. The robot was set up to hit a slice shot with a club path of approximately 7 degrees outside-in and a slightly opened club face. The club speed was approximately 98-100 mph, initial ball spin ranged from about 3,800-5,200 rpm depending on ball construction and the spin axis was approximately 13-21 degrees.
The non-conforming golf balls described above which have dimple patterns including areas of less dimple volume along at least part of a band around the equator and more dimple volume in the polar regions have a large enough moment of inertia (MOI) difference between the poles horizontal (PH) or maximum orientation and other orientations that the ball has a preferred spin axis extending through the poles of the ball. As described above, this preferred spin axis helps to prevent or reduce the amount of hook or slice dispersion when the ball is hit in a way which would normally produce hooking or slicing in a conventional, symmetrically designed golf ball. This reduction in dispersion is illustrated for the embodiments described above in
Although the illustrated embodiments all have reduced dimple volume in a band around the equator as compared to the dimple volume in the polar regions, other dimple patterns which generate preferred spin axis may be used in alternative embodiments to achieve similar results. For example, the low volume dimples do not have to be located in a continuous band around the ball's equator. The low volume dimples could be interspersed with larger volume dimples about the equator, the band could be wider in some parts of the circumference than others, part of the band could be dimple-less around part or all of the circumference, or there may be no dimples at all around the equatorial region. Another embodiment may comprise a dimple pattern having two or more regions of lower or zero dimple volume on the surface of the ball, with the regions being somewhat co-planar. This also creates a preferred spin axis. In one example, if the two areas of lower volume dimples are placed opposite one another on the ball, then a dumbbell-like weight distribution is created. This results in a ball with a preferred spin axis equal to the orientation of the ball when rotating end-over-end with the “dumbbell” areas.
Although the dimples in the embodiments illustrated in
As noted above a golf ball's flight trajectory depends on a number of factors, which can be broken down into two major categories: 1) the mechanical interaction between the ball and club and 2) the golf ball's aerodynamic performance.
The ball-club impact (dynamic mechanical interaction) can be thought of as the event that specifies the initial conditions for the aerodynamic flight of the golf ball to follow. Thus it is common when describing the performance of one golf ball versus the other to first describe in detail the specific club used to impact each ball and then to describe the resulting initial conditions of the golf ball flight at the instant the ball leaves the club face, using the terms “vertical launch angle”, “horizontal launch angle”, “initial velocity”, “initial spin”, and “initial spin axis”. Once the ball leaves the face of the club, it is then these initial conditions plus the aerodynamics of the golf ball, its weight, and its size, and the environmental conditions that determine the flight path of the golf ball. The aerodynamics of a golf ball are highly dependent on the ball's dimple pattern and individual dimple characteristics as well as the ball's speed, spin rate, size and mass.
A number of math models have been developed to simulate the trajectory of a golf ball, including those published by T. Mizota, et al in Science and Golf IV Proceedings of the World Scientific Congress of Golf and by A, J. Smits and D. R. Smith in Science and Golf II Proceedings of the World Scientific Congress of Golf These models both calculate the ball's trajectory as a function of the aerodynamic factors and the initial conditions include the ball-club impact factors specified above.
The difference in aerodynamic forces from one commercially available ball to another are relatively small compared to the Polara Ultimate Straight golf ball made by Aero-X Golf, Inc and sold under the Polara Golf Brand, which includes dimple patterns such as those described above in connection with
Conventional golf balls have been designed for low initial drag and high lift toward the end of flight in order to increase distance. For example, U.S. Pat. No. 6,224,499 to Ogg teaches and claims a lift coefficient greater than 0.18 at a Reynolds number (Re) of 70,000 and a spin of 2000 rpm, and a drag coefficient less than 0.232 at a Re of 180,000 and a spin of 3000 rpm. One of skill in the art will understand that and Re of 70,000 and spin of 2000 rpm are industry standard parameters for describing the end of flight. Similarly, one of skill in the art will understand that a Re of greater than about 160,000, e.g., about 180,000, and a spin of 3000 rpm are industry standard parameters for describing the beginning of flight for a straight shot with only back spin.
The lift (CL) and drag coefficients (CD) vary by golf ball design and are generally a function of the velocity and spin rate of the golf ball. For a spherically symmetrical golf ball the lift and drag coefficients are for the most part independent of the golf ball orientation. The maximum height a golf ball achieves during flight is directly related to the lift force generated by the spinning golf ball while the direction that the golf ball takes, specifically how straight a golf ball flies, is related to several factors, some of which include spin rate and spin axis orientation of the golf ball in relation to the golf ball's direction of flight. Further, the spin rate and spin axis are important in specifying the direction and magnitude of the lift force vector.
The lift force vector is a major factor in controlling the golf ball flight path in the x, y, and z directions. Additionally, the total lift force a golf ball generates during flight depends on several factors, including spin rate, velocity of the ball relative to the surrounding air and the surface characteristics of the golf ball.
For a straight shot, the spin axis is generally parallel to the ground and orthogonal to the direction the ball is traveling and the ball rotates with perfect backspin. In this situation, the spin axis is 0 degrees. But if the ball is not struck perfectly, then the spin axis will be either positive (hook) or negative (slice). When the spin axis is negative, indicating a slice, the spin rate of the ball increases. Similarly, when the spin axis is positive, the spin rate decreases initially but then remains essentially constant with increasing spin axis.
The increased spin imparted when the ball is sliced, increases the lift coefficient (CL). This increases the lift force in a direction that is orthogonal to the spin axis. In other words, when the ball is sliced, the resulting increased spin produces an increased lift force that acts to “pull” the ball to the right. The more negative the spin axis, the greater the portion of the lift force acting to the right, and the greater the slice.
Thus, in order to reduce this slice effect, the ball must be designed to generate a relatively lower lift force at the greater spin rates generated when the ball is sliced.
Referring to
As can be seen, regions 110 and 115 stand out on the surface of ball 100 unlike conventional golf balls. This is because the dimples in each region are configured such that they have high visual contrast. This is achieved for example by including visually contrasting dimples in each area. For example, in one embodiment, flat, truncated dimples are included in region 110 while deeper, round or spherical dimples are included in region 115. Additionally, the radius of the dimples can also be different adding to the contrast.
But this contrast in dimples does not just produce a visually contrasting appearance; it also contributes to each region having a different aerodynamic effect. Thereby, disturbing air flow in such a manner as to produce low lift as described herein.
While conventional golf balls are often designed to achieve maximum distance by having low drag at high speed and high lift at low speed, when conventional golf balls are tested, including those claimed to be “straighter,” it can be seen that these balls had quite significant increases in lift coefficients (CL) at the spin rates normally associated with slice shots. Whereas balls configured in accordance with the embodiments described herein exhibit lower lift coefficients at the higher spin rates and thus do not slice as much.
A ball configured in accordance with the embodiments described herein and referred to as the B2 Prototype, which is a 2-piece Surlyn-covered golf ball with a polybutadiene rubber based core and dimple pattern “273”, and the TopFlite® XL Straight ball were hit with a Golf Labs robot using the same setup conditions so that the initial spin rates were about 3,400-3,500 rpm at a Reynolds Number of about 170,000. The spin rate and Re conditions near the end of the trajectory were about 2,900 to 3,200 rpm at a Reynolds Number of about 80,000. The spin rates and ball trajectories were obtained using a 3-radar unit Trackman™ Net System.
The B2 prototype ball had dimple pattern design 273, shown in
This is illustrated in the graphs of
Under typical slice conditions, with spin rates of 3,500 rpm or greater, the 173 and 273 dimple patterns exhibit lower lift coefficients than the other golf balls. Lower lift coefficients translate into lower trajectory for straight shots and less dispersion for slice shots. Balls with dimple patterns 173 and 273 have approximately 10% lower lift coefficients than the other golf balls under Re and spin conditions characteristics of slice shots. Robot tests show the lower lift coefficients result in at least 10% less dispersion for slice shots.
For example, referring again to
As noted above, conventional golf ball design attempts to increase distance, by decreasing drag immediately after impact.
In
Returning to
Furthermore, the different regions and dimple patterns within each region are arranged such that the golf ball 100 is spherically symmetrical as defined by the United States Golf Association (“USGA”) Symmetry Rules. It should be appreciated that golf ball 100 may be formed in any conventional manner such as, in one non-limiting example, to include two pieces having an inner core and an outer cover. In other non-limiting examples, the golf ball 100 may be formed of three, four or more pieces.
Tables 19 and 20 below list some examples of possible spherical polyhedron shapes which may be used for golf ball 100, including the cuboctahedron shape illustrated in
Accordingly, a golf ball 100 designed in accordance with the embodiments described herein will have at least two different regions A and B comprising different dimple patterns and types. Depending on the embodiment, each region A and B, and C where applicable, can have a single type of dimple, or multiple types of dimples. For example, region A can have large dimples, while region B has small dimples, or vice versa; region A can have spherical dimples, while region B has truncated dimples, or vice versa; region A can have various sized spherical dimples, while region B has various sized truncated dimples, or vice versa, or some combination or variation of the above. Some specific example embodiments are described in more detail below.
It will be understood that there is a wide variety of types and construction of dimples, including non-circular dimples, such as those described in U.S. Pat. No. 6,409,615, hexagonal dimples, dimples formed of a tubular lattice structure, such as those described in U.S. Pat. No. 6,290,615, as well as more conventional dimple types. It will also be understood that any of these types of dimples can be used in conjunction with the embodiments described herein. As such, the term “dimple” as used in this description and the claims that follow is intended to refer to and include any type of dimple or dimple construction, unless otherwise specifically indicated.
It should also be understood that a golf ball designed in accordance with the embodiments described herein can be configured such that the average volume per dimple in one region, e.g., region A, is greater than the average volume per dimple in another regions, e.g., region B. Also, the unit volume in one region, e.g., region A, can be greater, e.g., 5% greater, 15% greater, etc., than the average unit volume in another region, e.g., region B. The unit volume can be defined as the volume of the dimples in one region divided by the surface area of the region. Also, the regions do not have to be perfect geometric shapes. For example, the triangle areas can incorporate, and therefore extend into, a small number of dimples from the adjacent square region, or vice versa. Thus, an edge of the triangle region can extend out in a tab like fashion into the adjacent square region. This could happen on one or more than one edge of one or more than one region. In this way, the areas can be said to be derived based on certain geometric shapes, i.e., the underlying shape is still a triangle or square, but with some irregularities at the edges. Accordingly, in the specification and claims that follow when a region is said to be, e.g., a triangle region, this should also be understood to cover a region that is of a shape derived from a triangle.
But first,
The dimples can be aligned along geodesic lines with six dimples on each edge of the square regions, such as square region 110, and eight dimples on each edge of the triangular region 115. The dimples can be arranged according to the three-dimensional Cartesian coordinate system with the X-Y plane being the equator of the ball and the Z direction passing through the pole of the golf ball 100. The angle Φ is the circumferential angle while the angle θ is the co-latitude with 0 degrees at the pole and 90 degrees at the equator. The dimples in the North hemisphere can be offset by 60 degrees from the South hemisphere with the dimple pattern repeating every 120 degrees. Golf ball 100, in the example of
The geometric and dimple patterns 172-175, 273 and 2-3 described above have been shown to reduce dispersion. Moreover, the geometric and dimple patterns can be selected to achieve lower dispersion based on other ball design parameters as well. For example, for the case of a golf ball that is constructed in such a way as to generate relatively low driver spin, a cuboctahedral dimple pattern with the dimple profiles of the 172-175 series golf balls, shown in Table 16, or the 273 and 2-3 series golf balls shown in Tables 10 and 11 of the '028 application, provides for a spherically symmetrical golf ball having less dispersion than other golf balls with similar driver spin rates. This translates into a ball that slices less when struck in such a way that the ball's spin axis corresponds to that of a slice shot. To achieve lower driver spin, a ball can be constructed from e.g., a cover made from an ionomer resin utilizing high-performance ethylene copolymers containing acid groups partially neutralized by using metal salts such as zinc, sodium and others and having a rubber-based core, such as constructed from, for example, a hard Dupont™ Surlyn® covered two-piece ball with a polybutadiene rubber-based core such as the TopFlite XL Straight or a three-piece ball construction with a soft thin cover, e.g., less than about 0.04 inches, with a relatively high flexural modulus mantle layer and with a polybutadiene rubber-based core such as the Titleist ProV1®.
Similarly, when certain dimple pattern and dimple profiles describe above are used on a ball constructed to generate relatively high driver spin, a spherically symmetrical golf ball that has the short iron control of a higher spinning golf ball and when imparted with a relatively high driver spin causes the golf ball to have a trajectory similar to that of a driver shot trajectory for most lower spinning golf balls and yet will have the control around the green more like a higher spinning golf ball is produced. To achieve higher driver spin, a ball can be constructed from e.g., a soft Dupont™ Surlyn® covered two-piece ball with a hard polybutadiene rubber-based core or a relatively hard Dupont™ Surlyn® covered two-piece ball with a plastic core made of 30-100% DuPont™ HPF 2000®, or a three-piece ball construction with a soft thicker cove, e.g., greater than about 0.04 inches, with a relatively stiff mantle layer and with a polybutadiene rubber-based core.
It should be appreciated that the dimple patterns and dimple profiles used for 172-175, 273, and 2-3 series golf balls causes these golf balls to generate a lower lift force under various conditions of flight, and reduces the slice dispersion.
Golf balls dimple patterns 172-175 were subjected to several tests under industry standard laboratory conditions to demonstrate the better performance that the dimple configurations described herein obtain over competing golf balls. In these tests, the flight characteristics and distance performance for golf balls with the 173-175 dimple patterns were conducted and compared with a Titleist Pro V1® made by Acushnet. Also, each of the golf balls with the 172-175 patterns were tested in the Poles-Forward-Backward (PFB) and Pole Horizontal (PH) orientations. The Pro V1® being a USGA conforming ball and thus known to be spherically symmetrical was tested in no particular orientation (random orientation). Golf balls with the 172-175 patterns were all made from basically the same materials and had a standard polybutadiene-based rubber core having 90-105 compression with 45-55 Shore D hardness. The cover was a Surlyn™ blend (38% 9150, 38% 8150, 24% 6320) with a 58-62 Shore D hardness, with an overall ball compression of approximately 110-115.
The tests were conducted with a “Golf Laboratories” robot and hit with the same Taylor Made® driver at varying club head speeds. The Taylor Made® driver had a 10.5° r7 425 club head with a lie angle of 54 degrees and a REAX 65 ‘R’ shaft. The golf balls were hit in a random-block order, approximately 18-20 shots for each type ball-orientation combination. Further, the balls were tested under conditions to simulate a 20-25 degree slice, e.g., a negative spin axis of 20-25 degrees.
The testing revealed that the 172-175 dimple patterns produced a ball speed of about 125 miles per hour, while the Pro V1® produced a ball speed of between 127 and 128 miles per hour.
The data for each ball with patterns 172-175 also indicates that velocity is independent of orientation of the golf balls on the tee.
The testing also indicated that the 172-175 patterns had a total spin of between 4200 rpm and 4400 rpm, whereas the Pro V1® had a total spin of about 4000 rpm. Thus, the core/cover combination used for balls with the 172-175 patterns produced a slower velocity and higher spinning ball.
Keeping everything else constant, an increase in a ball's spin rate causes an increase in its lift. Increased lift caused by higher spin would be expected to translate into higher trajectory and greater dispersion than would be expected, e.g., at 200-500 rpm less total spin; however, the testing indicates that the 172-175 patterns have lower maximum trajectory heights than expected. Specifically, the testing revealed that the 172-175 series of balls achieve a max height of about 21 yards, while the Pro V1® is closer to 25 yards.
The data for each of golf balls with the 172-175 patterns indicated that total spin and max height was independent of orientation, which further indicates that the 172-175 series golf balls were spherically symmetrical.
Despite the higher spin rate of a golf ball with, e.g., pattern 173, it had a significantly lower maximum trajectory height (max height) than the Pro V1®. Of course, higher velocity will result in a higher ball flight. Thus, one would expect the Pro V1® to achieve a higher max height, since it had a higher velocity. If a core/cover combination had been used for the 172-175 series of golf balls that produced velocities in the range of that achieved by the Pro V1®, then one would expect a higher max height. But the fact that the max height was so low for the 172-175 series of golf balls despite the higher total spin suggests that the 172-175 Vballs would still not achieve as high a max height as the Pro V1® even if the initial velocities for the 172-175 series of golf balls were 2-3 mph higher.
The maximum trajectory height data correlates directly with the CL produced by each golf ball. These results indicate that the Pro V1® golf ball generated more lift than any of the 172-175 series balls. Further, some of balls with the 172-175 patterns climb more slowly to the maximum trajectory height during flight, indicating they have a slightly lower lift exerted over a longer time period. In operation, a golf ball with the 173 pattern exhibits lower maximum trajectory height than the leading comparison golf balls for the same spin, as the dimple profile of the dimples in the square and triangular regions of the cuboctahedral pattern on the surface of the golf ball cause the air layer to be manipulated differently during flight of the golf ball.
Despite having higher spin rates, the 172-175 series golf balls have Carry Dispersions that are on average less than that of the Pro V1® golf ball. The data in
The overall performance of the 173 golf ball as compared to the Pro V1® golf ball is illustrated in
In operation and as illustrated in
Therefore, it should be appreciated that the cuboctahedron dimple pattern on the 173 golf ball with large truncated dimples in the square sections and small spherical dimples in the triangular sections exhibits low lift for normal driver spin and velocity conditions. The lower lift of the 173 golf ball translates directly into lower dispersion and, thus, more accuracy for slice shots.
“Premium category” golf balls like the Pro V1® golf ball often use a three-piece construction to reduce the spin rate for driver shots so that the ball has a longer distance yet still has good spin from the short irons. The 173 dimple pattern can cause the golf ball to exhibit relatively low lift even at relatively high spin conditions. Using the low-lift dimple pattern of the 173 golf ball on a higher spinning two-piece ball results in a two-piece ball that performs nearly as well on short iron shots as the “premium category” golf balls currently being used.
The 173 golf ball's better distance-spin performance has important implications for ball design in that a ball with a higher spin off the driver will not sacrifice as much distance loss using a low-lift dimple pattern like that of the 173 golf ball. Thus the 173 dimple pattern or ones with similar low-lift can be used on higher spinning and less expensive two-piece golf balls that have higher spin off a PW but also have higher spin off a driver. A two-piece golf ball construction in general uses less expensive materials, is less expensive, and easier to manufacture. The same idea of using the 173 dimple pattern on a higher spinning golf ball can also be applied to a higher spinning one-piece golf ball.
Golf balls like the MC Lady and MaxFli Noodle use a soft core (approximately 50-70 PGA compression) and a soft cover (approximately 48-60 Shore D) to achieve a golf ball with fairly good driver distance and reasonable spin off the short irons. Placing a low-lift dimple pattern on these balls allows the core hardness to be raised while still keeping the cover hardness relatively low. A ball with this design has increased velocity, increased driver spin rate, and is easier to manufacture; the low-lift dimple pattern lessens several of the negative effects of the higher spin rate.
The 172-175 dimple patterns provide the advantage of a higher spin two-piece construction ball as well as being spherically symmetrical. Accordingly, the 172-175 series of golf balls perform essentially the same regardless of orientation.
In an alternate embodiment, a non-Conforming Distance Ball having a thermoplastic core and using the low-lift dimple pattern, e.g., the 173 pattern, can be provided. In this alternate embodiment golf ball, a core, e.g., made with DuPont™ Surlyn® HPF 2000 is used in a two- or multi-piece golf ball. The HPF 2000 gives a core with a very high COR and this directly translates into a very fast initial ball velocity—higher than allowed by the USGA regulations.
In yet another embodiment, as shown in
As can be seen in
In other embodiments, the ball may have non-spherical aspects of various combinations of the core and cover parts which have different specific gravities. The different shaped ball parts combined with the different specific gravities of the materials for different ball parts is what causes the MOI differential between spin axes. The golf ball is spherical, but the inner layers are not necessarily completely spherical or symmetrical layers or parts.
In the embodiments illustrated in
In the embodiments of
In each embodiment, at least two components of the ball have different specific gravities. One is denser than the other. The cover can be more or less dense than the core. The mantle layer can be more of less dense than the cover, the mantle layer can be more or less dense than the core, two mantle layers can differ in density, two cover layers can differ in density, etc. In any case, the ball will have a MOI differential depending upon the shape of the core, cover and mantle layers and the density differences among them. A spherical inner core or uniform thickness cover or uniform thickness mantle layer can be higher or lower specific gravity compared to any of the other mantle, cover or core layers.
As illustrated in
This embodiment and all other ball construction embodiments described below in connection with
In the case of the Polara Ultimate Straight dimple pattern combined with design “A1”, if the flat spot on the core was centered with the pole of the dimple pattern (the deep dimpled region), and the density of the materials for the core and cover mantle layer we chosen so that core was higher specific gravity than the cover, then the MOI differentials caused by the ball construction and dimple pattern would reinforce each other and create a larger MOI differential than when just the Polara dimple pattern was used on a symmetrical ball construction or when a symmetrical dimple pattern was combined with the ball construction of
Another example similar to the ball 10 of
In the above embodiments, the mantle density or specific gravity may be greater than the cover layer density, but that does not have to be the case in all embodiments. The cover density may also be higher than the mantle density in the above embodiments, and this structure still results in a MOI differential. As long as there is a difference in the core and mantle densities in any of designs A1 to E1 of
One consideration when having more than one band or recess in a core, mantle or cover is that the shape would be easier to injection mold and then remove from the mold if there were no undercut portions of the shape such that when the part was removed from the mold that it was caught on a protruding part of the mold that was closer to the parting line of the mold. The dimensions for some specific examples of Designs “A1” through “E1” are provided below. There could be many other examples, with an almost infinite combination of dimensions and the examples discussed above are just a few simple designs selected for illustration of the invention and some of its various aspects.
Table 17 below shows the dimensions of a 1.68″ outer diameter golf ball of embodiments A1 through E1 (labeled A1, B1 . . . . E1, respectively. In Table 1 the outer core is referred to as the “mantle”. The numbers in Table 1 are expressed in “inches”. For these particular examples, the width of the raised band for the mantle in ball designs D1 and E1 is 0.50 inches and the width of the flat area for the mantle on ball design B1 is 0.50 inches.
Tables 18 and 19 below provide the differential MOI data between the x, y and z spin axes for a combination of different specific gravity materials used with designs A1-E1. Any combination of specific gravities of materials could be used and this would in turn change the resulting MOI differential for the ball. It may be higher or lower than what is shown below.
Tables 18 and 19 above provide the MOI Differential for Designs A1-E1. The MOI for rotation about the x and y axes are the same, but the MOI for rotation about the z axis is different. The actual MOI differential for the entire ball design is given in the far right column of the last row for each ball design. The far right column is labeled “Ix vs Iz”. This is the MOI Differential defined as the MOI percent difference between the ball rotating around the X-axis versus rotating around the Z-axis. Whether the value is positive or negative does not matter, this is just a matter of which axis MOI value was subtracted from the other. What matters is the absolute value of the “Ix vs Iz” value. For example, E-1 design has almost 10× the Moment of Inertia Differential (MOI differential) as A-1 design. The formula for calculating the MOI differential is as follows:
Moment of Inertia Differential=(MOI X-axis−MOI Z-axis)/((MOI X-axis+MOI Z-Axis)/2).
In the embodiments of
In all of the embodiments of
The density, mass, volume and MOI values for a ball made with the wide X-band mantle or outer core layer 170 of
In the embodiments of
In the above embodiments, at least one inner layer or part of the ball is non-spherical and is asymmetrical in such a way that the MOI measured in three orthogonal axes is different for at least one of the axes. The non-spherical part in many of the above embodiments is described as an outer core layer or mantle, but could also be an inner cover layer of a two part cover. The design is such that at least one layer of the cover or core is non-uniform in thickness and non-uniform in radius. In one embodiment, the diameter of the entire core (including the inner core and any outer core layer) may be greater than 1.61 inches. At least one core or cover layer has a higher specific gravity than other layers. In one embodiment, the difference in the MOI of any two axes is less than about 3 gm cm2.
As noted above, various types of symmetric or asymmetric dimple patterns may be provided on the outer cover of the golf balls described above. Golf balls with asymmetric dimple patterns are described in described in co-pending patent application Ser. No. 13/097,013 of the same Applicant filed on Aug. 28, 2011, the entire contents of which are incorporated herein by reference. Any of the dimple patterns described in that application may be combined with any of the golf balls described above with different MOI on at least two of the three perpendicular spin axes or principal axes. Two examples of dimple patterns described in application Ser. No. 13/097,013 are illustrated in
Alternatively, the differential may result only from the asymmetry of the dimple pattern, as described application Ser. No. 13/097,013 referenced above. The MOI variations in several such balls are provided in Table 20 below.
With the original Polara™ golf ball dimple pattern (deep spherical dimples around the equator and shallow truncated dimples on the poles) as a standard, the MOI differences between each orientation of balls with different asymmetric dimple patterns are compared to the original Polara golf ball in addition to being compared to each other. In Table 20, the largest difference between any two orientations is called the “MOI Delta”. In this case the MOI Delta and the previously defined MOI Differentials are different quantities because they are calculated differently. However, they both define a difference in MOI between one rotational axis and the other. And it is this difference, no matter how it is defined, which is important to understand in order to make balls which will perform straighter when hit with a slice or hook type golf swing. In Table 20, the two columns to the right quantify the MOI Delta in terms of the maximum % difference in MOI between two orientations and the MOI Delta relative to the MOI Delta for the original Polara ball. Because the density value used to calculate the mass and MOI (using the solid works CAD program) was lower than the average density of a golf ball, the predicted weight and MOI for each ball are relative to each other, but not exactly the same as the actual MOI values of the golf balls that were made, robot tested and shown in Table 20. Generally a golf ball weighs about 45.5-45.9 g. Comparing the MOI values of all of the balls in Table 20 is quite instructive, in that it predicts the relative order of MOI difference between the different designs.
Design 25-1 of
Table 21 shows that a ball's MOI Delta does strongly influence the balls dispersion control. In general as the relative MOI Delta of each ball increases, for a slice shot the dispersion distance decreases. Balls 28-3, 25-1, 28-1 and 28-2 all have higher MOI deltas relative to the Polara, and they all have better dispersion control than the Polara. This is shown in Table 5 below.
Golf balls of the embodiments with asymmetrical dimple patterns described above exhibit lower aerodynamic lift properties in one orientation than in another. If these dimple patterns are provided on balls with core and cover layers constructed as described above in connection with the embodiments of
Any combination of symmetrical or asymmetrical dimple patterns, such as the dimple patterns of
The dimple co-ordinates for one embodiment of dimple pattern 95-3 of
The balls of
Any of the balls of
Tables 24, 25 and 26 contain the density, volume and mass information for each of the individual layers and the complete balls for all of the ball designs of
Tables 27, 28 and 29 contain the moment of inertia values for each of the principle axes of rotation for all of the individual layers of each ball design in
Tables 30, 31 and 32 contain the ball mass, ball volume, ball moment of inertia values for each of the principle axes of rotation and the MOI Differential for each of the complete ball designs of
If a ball is designed with an internal construction providing a preferred spin axis due to differential MOI between the spin axes, the dimple pattern can be designed to have the lowest lift or lift coefficient (CL) and drag or drag coefficient (CD) when the ball is spinning about the preferred spin axis, i.e. the spin axis corresponding to the highest MOI. This decouples the dimple pattern from the mechanism for creating a preferred spin axis. The differential MOI may be achieved by different specific gravity layers in the ball or by different non-spherical geometry in at least one layer, or both, as described in the above embodiments.
The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, it is to be understood that the description and drawings presented herein represent a presently preferred embodiment of the invention and are therefore representative of the subject matter which is broadly contemplated by the present invention. It is further understood that the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art and that the scope of the present invention is accordingly limited by nothing other than the appended claims.
In order to obtain a low L/D (lift/drag) ratio, high drag and low lift dimples may be employed. Balls with L/D ratios similar or less than the values measured for ProVI and other standard golf balls may be used in the kit described above, as well as any of the non-conforming or conforming golf balls described above in connection with
In other kit examples, golf balls are selected for the kit which have a L/D ratio of less than about 0.75, and preferably less than about 0.70, at a spin rate of 3,000 rpm and at a Reynolds number of about 160,000.
The above embodiments describe various examples of a kit combining a higher lofted driver with a golf ball which has a lower flight trajectory, which may result from lower lift due to predetermined dimple patterns, as described above in connection with
It should be understood that the term “dimples” is meant to include any and all of the surface modifications that are applied to the exterior of the golf ball in order to modify the flight characteristics of the golf ball.
The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, it is to be understood that the description and drawings presented herein represent a presently preferred embodiment of the invention and are therefore representative of the subject matter which is broadly contemplated by the present invention. It is further understood that the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art and that the scope of the present invention is accordingly limited by nothing other than the appended claims.
The application claims the benefit under 35 U.S.C. 119(e) to U.S. Provisional Patent Application Ser. No. 60/543,764, filed Oct. 5, 2011, entitled “A Kit for a Driver and Golf Ball That Provides Optimum Performance,” which is incorporated herein by reference in its entirety as if set forth in full. This application is also related to U.S. patent application Ser. No. 12/765,762, filed Apr. 22, 2010, entitled “A Low Lift Golf Ball,” and is also related to U.S. patent application Ser. No. 13/423,028, filed Mar. 16, 2012, entitled “Anti-Slice Golf Ball Construction,” and is also related to U.S. patent application Ser. No. 13/097,013, filed Apr. 28, 2011, entitled “A Nonconforming Anti-Slice Ball,” all of which are incorporated herein by reference in their entirety as if set forth in full.
| Number | Date | Country | |
|---|---|---|---|
| 61543764 | Oct 2011 | US |
