Golf club, jetdrv driver for increased distance and accuracy

Abstract

A golf club, a driver, designed to provide an inprovement in the accuracy of ball control as club head speeds are increased from 100 miles per hour to the level of a semipro at 120 miles per hour. Most forces on the club head increase as the square of the velocity, representing a forty four percent increase. A detailed analysis has been made of forces generated during the collision of the ball and club head and their effect on trajectory of the ball. The design proposed greatly reduces the aerodynamic drag of the clubhead, increases the allowable tolerance to angular misalignment of the club striking face from two degrees to ten degrees and reduces the torque that twists the club head causing an angular misalignment prior to contact with the ball.

Description

U.S. PATENT DOCUMENTS

	3,595,577	July 1971	Hodge
	3,625,518	December 1971	Solheim
	3,941,390	March 1976	Hussey
	4,471,961	September 1984	Masghati
	5,354,059	October 1994	Stuff
	5,366,223	November 1994	Werner
	5,511,786	April 1996	Antonious
	5,735,754	April 1998	Antonious
	5,971,868	October 1999	Kosmatka
	5,997,413	December 1999	Wood
	6,139,445	October 2000	Werner
	6,190,267	February 2001	Marlowe
	6,312,534	November 2001	Grensing
	6,319,437	November 2001	Elsner
	6,371,868	April 2002	Galloway
	6,402,636	June 2002	Chang
	6,478,692	November 2002	Kosmatka

BACKGROUND OF THE INVENTION

Golf has become a very popular sport for both the amateur and the professional resulting in rapid improvements in courses, hazzards, clubs and balls. The two clubs which account for the most strokes on the score card are the driver and the putter. The driver is responsible for covering the the majority of the yardage on most courses, and consequently is responsible for getting its owner into the most difficult to impossible lies. Recent trend in driver design has been to get more distance by increasing head speed. This improved range has been accomplished by the combination of a reducion in clubhead weight, increased shaft length to make the increased club head speed possible. Clubhead speeds of 120 miles per hour could result in 260 yard drives, however, if the clubhead is only two degrees off normal when striking the ball, this will cause the drive to be off the aiming point by this angular error of at least nine yards. The induced side spin on ball will add a hook or slice to this error. For accuracy, it is essential that the player develop his swing to repeatedly align the velocity vector at the clubhead center of gravity pointed directly at the desired location. For the weekend golfer to improve his driving from a clubhead velocity of 100 MPH to 120 MPH he has to contend with a 144 percent increases in drag, centrifugal force and inertia force. It is not practical to swing the same club at the higher speed without introducing an uncontrollable slice.

The proposed driver design is capable of obtaining higher swing speeds by the reduction in the weight and a more accurate control of the clubhead twist by reducing the unbalanced moments that result from the sum of the aerodynamic drag inertia loading. The decrease in the pendulum action by reducing its offset moment will ensure more hets on the sweet spot, resulting in obtaining added distance with an increased accuracy.

Various efforts have been made to increase the clubhead speed by creating a controlled, favorable turbulance which reduces the area of reduced pressure at the rear of the club thereby reducing the aerodynamic drag as shown in U.S. Pat. Nos. 3,468,544, 4,828,265, 5,511,786, and 5,735,754 by Antonious.

A clubhead design has been proposed to have been multi-angularly streamlined to reduce aerodynamic drag when swung through the entire 120 degrees prior to impact in U.S. Pat. No. 5,997,413. Aerodynamic drag varies as the square of the speed and is only significant at the latter part of the swing. Efforts have been made to eliminate the twisting or turning of a golf club head during the golf swing in U.S. Pat. Nos. 3,595,577 and 3,941,390 by Hodge and Woodridge. This has been accomplished in their proposed designs by the addition of a large hosel to control the center of gravity or the installation of high-density materials.

A golf club for minimizing spin of the golf ball and reducing hooks and slices by the addition of a lubricant to the striking face of the club in U.S. Pat. No. 6,402,636. The present study shows the spin is to introduce to the ball by a rolling action with friction not required. A proposed Pat. No. 5,366,223, addresses the persistent problem of the failure to hit the golf ball fully on the strike face by analyzing the location of the 11 hits by each of 28 golfers. Study had shown there was a pronounced elliptical distribution pattern of impacts over that many swings, they called this pattern the “hit pattern”. The driver faces were then recommended to be oriented to take advantage of the shape of the hit pattern. The present study shows on FIG. 5 that this movement is due to the centrifuge force causing a pendulum motion about the wrist cock axis. Reducing the offcet center of gravity will eliminate most of this movement.

In U.S. Pat. No. 6,190,267 this invention claims to be able to control the location of the center of percussion to within 0.500 inch of the outer toe end portion of the clubhead. This claim is impossible since the center of precussion is close to the club center of gravity. The inventors error is in the selection of the shaft centerline as the pivot point in the analysis rather than at the wrist-cock-axis.

In U.S. Pat. No. 6,139,445 this invention claims to have face surface shapes which are designed to reduce the scatter of the points where a ball stops after a hit. This patent differs from the proposed patent that claims that a greater tolerance is introduced for an angularly misaligned clubhead at point of contact with the ball and accounting for the extensive distortion of the ball during impact.

In U.S. Pat. No. 6,371,868 this invention is a golf club having an interior hosel that is disposed inward from a striking plate to allow for compliance of the striking plate during impact with the golf ball. It claims to have a striking plate or face with a coefficient of restitution approaching 0.93. This coefficient of restitution represents a seven percent loss of velocity and a 14 percent loss in kinetic energy resulting from the flexible striking plate. This patent differs from the proposed patent which has an airfoil shaped hosel for a significant reduction in aerodynamic drag of the round shaft. The proposed design has a crowned, thick striking face giving a coefficient of restitution of nearly 1.0. To eliminate the danger associated with the failure of the dissimilar material bonded joint of shaft to clubhead a roll pin is used for an additional mechanical attachment.

In U.S. Pat. No. 6,478,692 this invention proposes a compliant golf club head to permit a more efficient impact between a golf ball and the golf head. It is stated that material and geometry constraints of a striking plate of the golf club head can reduce energy losses caused by large strain and strain rate values of the golf ball. The inventor presents an extensive static analysis of a simulated elliptical striking plate, varying thickness and materials with contact force as a variable. The selected force used in the comparison is F=2500 lbs. This is nearly half of the contact force required to accelerate the ball to the observed speed that has been measured experimentally. Any deflection of the striking plate will reduce the kinetic energy in the ball rather than reduce the energy losses as stated. AU analysis was conducted considering contact at the “sweet spot”, the deflection during an off center hit will introduce an error in the directional trajectory of the ball. The proposed patent is of aluminum with a minum thickness locally of 0.25 inch as well as a significantly smaller striking face. The design is based on controlling the deflective shape of the ball by contact with a rigid contoured striking face.

SUMMARY OF THE INVENTION

The present invention relates to a golf club, the driver, that has been designed to provide the golfer with a club capable of producing an increased accuracy as he attains greater distance with the increased clubhead speed. There is a tremendous amount of information published on how to grip and swing a golf club.

In Jack Nicklaus's book “Golf My Way” published by Simon and Schuster he says “The overall swings of golfers like Ben Hogan, Bobby Jones and myself may appear different, but, because basically there is only one correct way to deliver the club to the ball, they look almost identical at impact”. “The three elements of power: 1, clubhead speed; 2, on-line delivery of clubhead relative to target line; 3, square impacting of clubface on ball. Distance is diminshed anytime any of the these three elements is missing”.

The second extremely valuable book “Search for Perfect Swing” by Alastair Cochran and John Stubbs, published by Triumph Books. This book is a condensed account of a wide and fascinating exploration of golf, made possible by the imagination and support of Sir Aynsly Bridgland and the Golf Society of Great Britian (G.S.G.B.).

The third most helpful book “The Physics of Golf”, by Theodore P. Jorgensen Department of Physics and Astronomy University of Nebraska. This book provides an excellent quantitave comparison of an analytical treatment of the golf club swing and corrolates these results with experimental measured data. Additionally a computer program is provided in Qbasic by The American Institute of Physics. This program was modified by the inventor to include the effects of the aerodynamic drag on the clubhead and shaft. Results of this analysis were used to study the clubhead-to-ball transfer of energy and how it can be controlled to improve strike accuracy. The ball is assumed to be a spherical spring and the clubhead a ridge anvil to deform the ball in a desirable manner, controlling ball spin and direction. Kinetic energy transferred from clubhead to ball is proportional to the square of the club velocity at impact and directly as the ratio of the mass of the clubhead to the mass of the ball. Clubhead mass and aerodynamic drag is reduced to provide a higher velocity for the same energy input by the golfer. The center of gravity of the clubhead is more closely alligned with the shaft axis to ensure contact alignment between center of gravity of the clubhead and the ball, namely the sweet spot.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 give the results of a detailed analysis of club-ball interchange of energy during collison of a seven ounce clubhead at a velocity of 165.8 ft/sec with a ball at rest accelerating it to 231.2 ft/sec in 0.000038 sec. Clubhead speed at end of contact was 102.8 ft/sec. Maximum force of contact is is 4403 lbs occuring 0.000010 sec after contact. During this contact period the ball rolls up the face of the club with a roll radius decreasing as the contact force increases. A driver with a face angle of 11 degrees has been computed to give the ball a rotation of 66 rev/sec and leave the club face at an angle of 8.77 degrees and 231.2 ft/sec.

FIG. 2A and FIG. 2D are the front and rear views of the proposed JETDRV golf club. FIG. 2B is the side view of the Cross Section B-B showing the striking face section and the hosel shaft interface. FIG. 2C is the top view of Cross Section A-A showing striking face detail and airflow passages.

FIG. 3A illustrates the airflow patterns around a conventional driver club head, in computing the aerodynamic drag it is considered a blunt body, 24. A blunt body with a low aspect ratio will have all of the air flowing around the exterior of the body, resulting in separation with the resulting turbulent vortex flow producing low pressures at the rear of the body. Seperation occurs when the surface air film can no longer follow the surface contour of the club head. The central streamline at the face of the club comes to rest with a resulting increase in pressure, while the seperated air at the rear of the club is at a greatly reduced pressure. The air drag on the club head is then equal to the difference in the integrated force of pressure times area on the leading face of the club minus the integral of the pressure times area of the trailing surface of the club. This resulted in a drag force of 7.45 lbs at 165.8 ft/sec. This force will vary for different swing speeds as the square of the club velocity at impact.

FIG. 3B illustrates the airflow patterns around the JETDRV driver when a nacelle, 20, is introduced around the club head, 22. The air within the capture area of the nacelle is diffused within the nacelle by the controlled area distribution, slowing the flow of air as it approaches the discharge nozzle. Since the amount of air leaving through the nozzle equals the amount of air entering its exit velocity will be equal to the ratio of the capture area to the discharge nozzle area times the inlet velocity, giving a discharge velocity of 732.4 ft/sec, close to sonic velocity. The drag coefficient on this type of flow is proportional to the product of the surface wetted area times the surface skin friction. The calculated drag at 165.8 ft/sec club head velocity was 0.0243 lbs.

FIG. 4A illustrates the shaft twisting torque generated by the combination of the aerodynamic drag and the inertia force as a result of the club head acceleration up to the 165.8 ft/sec, multiplied by the offset 1.008 inch from the center of gravity and the center of pressure giving 30.91 in lbs for the conventional club. This is compared with the JETDRV driver in FIG. 4B that gives a twist torque of 7.42 in lbs. This torque tends to open the club face, causing a misaligned shot and probably an uncontrollable slice. This results in a 4 to 1 improvement in the twist torque.

FIG. 5 illustrates the pendulum action driven by the centrifugal force of 75.54 lbs acting on the club head center of gravity with the offset distance of 1.008 in. for the conventional driver. The club will pivot about the wrist cock axis, as shown in the deflected position when the center of gravity is aligned with the shaft centerline. This offset distance has been reduced to 0.388 in. for the JETDRV driver. The centrifugal and inertia forces are related to the clubhead weight and the offset distance is critical to controlling the accuracy of the drive.

FIG. 6 illustrates the inital impact point of the clubface on the ball for an 11 degree angle of the driver clubface. This contact is initally 0.171 inch below the center of gravity of the ball, dropping to 0.138 inch at the maximum ball compressed deflection of 0.2448 inch resulting in a maximum contact force of 4403 lbs. This offset produces a torsional moment on the ball, causing it to roll up the face of the club. Because of the deflection of the ball this rolling radius changes from 0.84 inch initally to 0.57 inch at its maximum displacement. This rolling action accelerates the ball to 66 rps at separation with the ball leaving the club face at 231.2 ft/sec inclined to 8.77 degrees.

FIG. 7 illustrates that with a club head misalignment of as much as 10 degrees at contact with the ball it still does not produce a significant moment on the ball, which causes the ball to rotate horizontally, resulting in a slice.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the golf club proposed is illustrated in FIG. 2A, front view, and FIG. 2D, rear view, with the top view of the cross section FIG. 2C, and cross section of the side view FIG. 2B. The clubhead 20, with the striking face 25 has a plurality of score lines 23. An elliptical shaped nacelle 10, attached to the clubhead by four support struts of airfoil cross section 40. The leading edge of the nacelle has an elliptical cross section 55 for low drag in guiding the air past the nacelle leading edge. The club shaft 50 is attached to the hosel 35, the support strut 40 and the internal cylindrical shroud 35. The shaft 50, can be a hollow steel shaft or solid graphite filament that is bonded to the aluminum clubhead. For safety in reduncy, a roll pin or steel rivit 45 is inserted through the shaft attaching it to the cylindrical shroud 35. Air enters the passage 28 between the nacelle 10 and the clubhead 20 where the flow area change diffuses the flow reducing its velocity thereby increasing to over twice the ambient pressure. The air is then expanded as it passes through the exit nozzle 30 at near sonic velocity. The top of the club 60 is of ellipsoidal shape to present a low drag profile for the club as it rotates through a 90 degree angle as it travles from the top of the swing to the contact with the ball. FIG. 4B illustrates three recessed triangles 70, the larger central triangle designates the location of the sweet spot and the outer two represent a measured distance on the contoured striking face used for controlled slices and hooks.

Claims

1. A golf club, driver, is designed with a nacelle surrounding the clubhead. This nacelle is designed to capture a stream tube of air that enters the club head, the internal air passage shape provides an increasing diffusion volume, reducing the air velocity, thereby increasing its pressure. The air is then expanded by discharging it, at near sonic velocity, through the nozzle at the rear of the club. The ram drag of the air entering the club is balanced by the jet thrust resulting from the change in momentum. The drag is then limited to skin friction on surface area exposed to air flow. This drag is far less than the blunt body drag of a conventional clubhead.

2. A hosel of an aerodynamic airfoil design to reduce the drag.

3. Four symetrical airfoil shaped struts supporting the nacelle and capable of transmitting the inertia load of the nacelle to the striking head of the club. One strut is alligned with the hosel as an extention to attach the club shaft to the clubhead.

4. Clubhead with a external shape designed to provide the area distribution within the nacelle for diffusing the air as it passes through the club. The clubhead is hollow to control the weight and the center of gravity location relative to the shaft centerline.

5. The striking face of the clubhead is thick and contoured to make it rigid and give it a high natural frequency on impact with the ball. The deformation shape of the ball is controlled by the striking face acting as an anvil to deform the ball. Spin and spin direction and force to accelerate the ball is controlled by the shape of the striking surface. The magnitude of the force is dependent on the mass of the clubhead and its velocity at time of impact.

6. The contour of the striking face of the clubhead is designed to increase the tolerance to angular misalingment from about two degrees in the conventional driver to ten degrees for the proposed driver.

7. Three recessed triangles on the top surface of the clubhead define the location of the sweet spot and a measured distance on the contoured striking face that can be used by the highly proficient golfer for making controlled hooks and slices. They can also be used to compensate for high crosswinds giving a reduced drag and improved distances.

8. A roll pin is added to provide a mechanical attachment as backup to the cement bond of the dissimilar meterials in the shaft and clubhead.