WO1994000203A1 - Raquette de tennis a structure de surface conçue pour reduire la resistance a l'air - Google Patents

Raquette de tennis a structure de surface conçue pour reduire la resistance a l'air Download PDF

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Publication number
WO1994000203A1
WO1994000203A1 PCT/CA1993/000257 CA9300257W WO9400203A1 WO 1994000203 A1 WO1994000203 A1 WO 1994000203A1 CA 9300257 W CA9300257 W CA 9300257W WO 9400203 A1 WO9400203 A1 WO 9400203A1
Authority
WO
WIPO (PCT)
Prior art keywords
depressions
frame
pattern
string
protrusions
Prior art date
Application number
PCT/CA1993/000257
Other languages
English (en)
Original Assignee
Velke, Willi, H.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Velke, Willi, H. filed Critical Velke, Willi, H.
Priority to AU44139/93A priority Critical patent/AU4413993A/en
Publication of WO1994000203A1 publication Critical patent/WO1994000203A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15D—FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS
    • F15D1/00—Influencing flow of fluids
    • F15D1/10—Influencing flow of fluids around bodies of solid material
    • F15D1/12—Influencing flow of fluids around bodies of solid material by influencing the boundary layer
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B49/00—Stringed rackets, e.g. for tennis
    • A63B49/02—Frames
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B60/00—Details or accessories of golf clubs, bats, rackets or the like
    • A63B60/48—Details or accessories of golf clubs, bats, rackets or the like with corrugated cross-section
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63B—APPARATUS FOR PHYSICAL TRAINING, GYMNASTICS, SWIMMING, CLIMBING, OR FENCING; BALL GAMES; TRAINING EQUIPMENT
    • A63B60/00—Details or accessories of golf clubs, bats, rackets or the like
    • A63B60/006—Surfaces specially adapted for reducing air resistance

Definitions

  • a racquet is a hand held device, and is used by players in games such as tennis, squash, racquetball, etc. , to move a ball from one player to another. All such racquets basically consist of a frame with string woven into it to provide a resilient surface. This resilient tightly woven surface is the part of the racquet making contact with the ball during the motion of swing, propelling the ball in its desired direction.
  • the object of the present invention is to provide a racquet frame which noticeably reduces the amount of drag it normally encounters during the motion of swing, thereby increasing the speed a racquet can be moved with, and hence increasing the force a ball can be hit with.
  • the scope of the present invention generally embraces all types of racquets, consisting of a racquet frame and tensioned string, used in a variety of racquet sports and games.
  • a racquet frame and its string webbing experiences drag forces inherent in flow mechanics of all bodies moving through air.
  • drag forces divide into two basic forms. Firstly, drag resulting from a slow-down or non-slip condition of air moving adjacent a surface of a body, usually referred to as frictional drag or positive surface pressure, and secondly, drag resulting from a low pressure condition existing at the rear of a body moving though air, usually referred to as negative surface pressure or base drag.
  • the present invention deals with the effects of negative surface pressure or base drag and the means to provide significant reduction of such base drag as experienced by all racquet frames during the motion of swing.
  • the surface of the frame and string of such racquet is modified to include a surface structure which increases operating efficiency during the motion of swing, by altering fluid flow behaviour across such racquet frame and string surface, reducing or eliminating, as the case may be, negative surface pressure or base drag.
  • the present invention therefore comprises a racquet frame, including its tensioned string webbing, which includes in its surface a structure in the form of a pattern of distinct surface depressions, such as rows of dimples or grooves.
  • Such structure covers at least part of a racquet frame and all of its string surface and preferably consists of, in the case of dimpled shapes, a pattern of generally spheroidal depressions, and in the case of grooves, a pattern of generally channel-like depressions, which, in order to be fully effective, must be arranged at 90° to the mean flow direction experienced by a racquet frame surface during the motion of swing.
  • spherical shapes are especially preferred, although oblate and prolate shapes, as well as cylindrical, pyramidal, cubic and multi-faceted, as well as irregularly shaped depressions are also contemplated.
  • grooves in the racquet frame surface When employing grooves in the racquet frame surface, generally straight channels, with a radius floor, and parallel sidewalls perpendicular to the adjacent land area, are especially preferred, although flat or irregularly shaped floor channels, as well as channels with asymmetrical sidewalls, which may be arranged other than parallel to each other, or, for that matter, other than parallel in relation to adjacent channels, if a pattern consists of more than one channel, are also contemplated.
  • dimples or discrete symmetrical depressions have the added advantage of dealing uniformly with changing flow directions and operate independently of the mean flow direction across the surface of a racquet frame and string webbing equipped with such a structure.
  • the structure consisting of a pattern of depressions as herebefore described may be included in the surface of a racquet frame and string webbing as part of its original forming or moulding process, or may be attached to, or wrought into, or included in the frame or string surface as part of a later or separate manufacturing phase.
  • a certain level of performance enhancement may be achieved using surface protrusions, and therefore, a surface structure consisting of protrusions rather than depressions may be a desirable alternative for some racquet frame or string manufacturing methods.
  • Such surface protrusions in order to be at all effective, must be of a height not to protrude much beyond the unseparated boundary layer, or its first adjacent laminar flow layer, proximal the racquet frame or string surface over which they protrude, otherwise surface drag as well as base drag will be increased.
  • surface protrusions may be employed in the form of patterns of discrete protrusions or reverse dimples, or in the form of ridges or reverse channels, in all the variations and applications as previously described.
  • reduced base drag can be realized by changing fluid flow over the surface of a racquet frame and string webbing, through including in such racquet frame and string surface a certain surface structure.
  • Such surface structure must be operable to cause interruptions in the unseparated boundary layer flow proximal the racquet frame or string surface, along the mean direction of flow, changing surface frictional qualities with the direction of the adjacent without interfering with the direction of the adjacent laminar flow conditions, which reduce or eliminate, as the case may be, base drag normally occuring behind a racquet frame and string during the motion of swing.
  • the surface structure according to the present invention is located in the surface of a racquet frame between two points along the mean direction of flow across it, in which a point upstream of the flow across the surface of a racquet frame is located more or less ahead of the line where surface pressure changes from positive to neutral, and downstream of the flow across the surface of a racquet frame where a point is located more or less beyond the line where surface pressure changes from neutral to negative.
  • a surface structure according to the present invention is only of benefit to reduce base drag, if such structure is located in surface areas where, during relative motion, fluid pressure across the surface exceeds fluid pressure against the surface.
  • SUBSTITUTE SHEET advantage available through the use of the surface structure on racquet frames and strings as disclosed herein, and a comparison was made between modified and unmodified racquet frames and frame tube shapes. For that purpose a back-to-back testing technique was chosen so as to ensure that identical conditions applied to both test samples and to provide reliable data. This method supplied measurements of the difference in drag between two test samples simultaneously.
  • the two test samples were mounted on levers of the test apparatus, side by side, and each lever was attached to a diaphragm unit, which in turn was connected to each side of a "U" tube manometer.
  • This system supplied measurements of the difference in aerodynamic loads on the two samples under test in a scale of centimeters of manometer fluid (speci ic gravity of 1.8).
  • the various velocities at which pressure readings were taken were then indicated by the velocity meter of the drag unit.
  • the testing procedure was to first open an isolator valve to supply air to both load cells at rest, record the manometer reading and close the isolator valve. Readings of the pressure differential shown by the manometer where then recorded at selected air velocities to which the test samples were subjected and the recorded data from these tests were as follows.
  • One tubing section was modified to include a surface structure according to the present invention, while the other tubing section remained plain.
  • the surface modification in this case consisted of a pattern of shallow dimples or discrete depressions of circular configuration, with a diameter of 3.5 mm and a dept of 1.5 mm.
  • the pattern of depressions allowed for a land area versus dimpled area of 30% land area to 70% dimpled area.
  • the manometer high column readings (lowest pressure- representing the drag reduction) were as follows:
  • Tube section plain 5.5 cm 16.5 cm 32.5 cm 45.0 cm
  • Tube section modified 3.5 cm 12.0 cm 23.5 cm 34.5 cm
  • Such grooves were of a width of 1.2 mm and of a dept of 1.2 mm and were located at a distance of 1.2 mm apart, parallel to each other and parallel to the edge of the frame. This allowed for the placement of three rows of grooves on each side of the rows of string insert holes on both the inside as well as the outside of the frame head area, and six rows of grooves on the outside of the throat area of the frame, extending to the handle portion.
  • Figure 1 of the drawings appended hereto depicts a preferred embodiment of the present invention, comprising a portion of a typical racquet, in isometric view.
  • Figure 2 of the drawings depicts an isometric side view of a portion of the frame of a racquet.
  • Figure 3 of the drawings depicts a portion of string webbing of a racquet, in front view.
  • Figure 4 of the drawings depicts a section view through strings, as shown in figure 3 of the drawings.
  • Figure 5 of the drawings depicts a section view through a racquet frame with its modified exterior surface.
  • Figure 6 of the drawings depicts a typical surface area of either frame or string surface of a racquet, illustrating a variety of exterior surface structure shape.
  • FIG. 1 of the drawings there is shown a portion of a typical racquet, comprising part of the frame (1) and its strings (2), including in the surface (3) of such frame a surface structure in the form of dimples (4), grooves (5) and diamond-shaped depressions (6), all illustrated in isometric view.
  • Such surface structures cover at least a portion of the racquet frame surface and preferably all of the string surface.
  • Figure 2 of the drawings depicts a portion of a racquet frame in isometric view. This view illustrates surface structures in the surface (3) of such frame portion, depicting structure patterns consisting of a combination of depressions and protrusions in a cross- weave pattern (7), a pattern of triangular depressions (8), a pattern of square depressions (9), and a pattern
  • a racquet frame may not be equipped with the customary string insert channel and the coresponding string grommet inserts, in which case the pattern of surface structures employed would be designed to accomodate the location of string insert holes and their connecting bridges, as may be viewed in illustrations of Figure 2 and 5, showing number (15) located at the inside frame portion.
  • annular frame opening On the inside frame portion, forming the annular frame opening, are illustrated alternative surface structures in the form of a pattern combining V-grooves (12), and discrete spherical depressions or dimples (4), and a pattern placing a wide groove with a convex radius floor (13) adjacent a narrow groove with a concave radius floor (14), all arranged in rows adjacent the row of holes (15), through which the string is located to form the string webbing of the racquet.
  • All such rows of grooves, channels, discrete depressions and dimples must always be arranged at a more or less 90° angle to the direction of flow to which they are subjected, or, in other words, be located more or less parallel with the leading edge or trailing edge of the racquet frame.
  • Figure 3 of the drawings depicts a portion of a typical string webbing of a racquet, comprising strings (2a) and (2b), arranged into a webbing, thereby creating the surface which makes contact with the ball.
  • the string type preferred to incorporate the present invention is herein shown as a multi-filament string, usually consisting of an inner core string, which is surrounded by layers of finer string, or whiskers (16), arranged in a spiral fashion around such inner core string, to give a certain amount of elasticity as shown in string illustration (2a), or it may be surrounded by layers of finer string or whiskers, arranged in the outer most layer as a netting (17), again to give a certain amount of elasticity, as shown in string illustration (2b).
  • Such core string and its surrounding whiskers are all imbedded in a resin-type material which is then covered with an outer level of resin coating (18).
  • This resin coating is the final surface which incorporates the desired surface structure, and, in the case of string (2a), will receive its grooves or channels (5) by way of an extrusion process or by heat impression, while the surface structure in string (2b) will be heat impressed into the string surface coating, placing the pattern of dimples (4) precisely within the design pattern of the netting (19).
  • Figure 4 of the drawings depicts a view through string (2a and 2b) . Such section view shows the inner
  • SHEET core string (21) surrounded by whiskers (16) and/or (17), all imbedded in a resin compound (22), which is covered by the outer layer of resin skin (18), into which the surface structures according to the present invention are impressed or extruded.
  • the dimple shape (4) adjacent its land area (23) shows the preferred ratio of 80% for dimples and 20% for land area
  • the groove or channel shape (5) adjacent its land area (24) shows the preferred ratio of 50% for the groove and 50% for its land area.
  • the location (25), at which a groove sidewall meets the land area should consist of a sharp and precise edge, especially for lower velocity applications.
  • Locations (26) and (27) illustrate a surface structure consisting of protrusions rather than depressions, which must not exceed a height of 10% of the diameter of the string over which they protrude (28) .
  • Figure 5 of the drawings depicts a view through a racquet frame.
  • Both discrete depressions (4) and grooves (5) are moulded into the surface area as part of the racquet frame's cast moulding process, and the shape of the depressions in the exterior frame surface are therefore communicated to the interior surface of the racquet frame tube, as viewed at (4a) and (5a).
  • Depressions (4b - 5b), which may represent dimples or grooves, have been wrought into the surface at a later manufacturing phase and the thickness of the frame tube wall (20) has been increased above its average thickness during the original moulding process to allow for the reduction of material when carving out such depressions.
  • Frame wall area (29) is of average thickness, and has protrusions (30) added to its exterior surface, to
  • SUBSTITUTE SHEET form a surface structure according to the present invention, but as a separate phase, and included as part of a later manufacturing stage independently from the moulding process.
  • Such protrusions could be attached to the racquet frame exterior surface in the form of individual pieces or as part of a patterned, embossed surface covering.
  • the surface structure according to the present invention should never reach into the high pressure area of a racquet frame surface manifested during the motion of swing, as this would be completely counter-productive, and as a racquet is normally used in a swing motion in either direction, the high pressure area during one swing motion direction would therefore relocate to the opposite side of the frame during a reverse swing motion, or when a racquet is actually turned 180° in the player's hand.
  • a high pressure area at a racquet frame exterior surface is therefore defined as the area, where, during the motion of the frame in the direction as indicated by arrow (31), fluid flow attack would be anywhere between 90° (32) or 45 degrees (33) to the surface of the racquet frame.
  • the pressure point (33), where fluid attack occurs at 45 degrees, is a variable pressure line location, which will shift somewhat in either direction, that is to say, it will locate at a point higher or lower than 45°, depending on racquet swing velocity and racquet attitude during swing motion.
  • Figure 6 of the drawings depicts a view of the surface of either frame or string of a racquet, illustrating surface structures in a variety of shapes of depressions in section view, identified as a discrete depression or groove with asymmetrical side walls (34), a discrete shape or groove consisting of a combination of depression and protrusion (35), a
  • SUBSTITUTE SHEET variation of a discrete shape or groove consisting of a combination of depression and protrustion (36) and protrusions (37) and (38), which could represent either a discrete protrusion or reverse channels.

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  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Physical Education & Sports Medicine (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Professional, Industrial, Or Sporting Protective Garments (AREA)

Abstract

Une modification de la surface d'une raquette de tennis est utilisée pour en augmenter la vitesse de retour ou swing. L'on obtient une telle augmentation de la vitesse de retour, dans une raquette destinée à des sports tels que le tennis, le squash, le badminton ou le raquetball, en réduisant la traînée de base à l'arrière du cadre et du tamis de la raquette. L'on réduit la traînée en incorporant dans la surface du cadre et du tamis une multiplicité de discontinuités de surface selon un motif choisi parmi plusieurs, afin de modifier l'écoulement de fluide sur la surface du cadre et à travers le tamis en un écoulement plus favorable à la vitesse que dans une raquette non modifiée.
PCT/CA1993/000257 1992-06-30 1993-06-30 Raquette de tennis a structure de surface conçue pour reduire la resistance a l'air WO1994000203A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU44139/93A AU4413993A (en) 1992-06-30 1993-06-30 Tennis racquet having a surface structure adapted for the reduction of air resistance

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US90638692A 1992-06-30 1992-06-30
US906,386 1992-06-30

Publications (1)

Publication Number Publication Date
WO1994000203A1 true WO1994000203A1 (fr) 1994-01-06

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PCT/CA1993/000257 WO1994000203A1 (fr) 1992-06-30 1993-06-30 Raquette de tennis a structure de surface conçue pour reduire la resistance a l'air

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AU (1) AU4413993A (fr)
WO (1) WO1994000203A1 (fr)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6162138A (en) * 1998-11-16 2000-12-19 Mckee; Roger W. Attachments presenting rotation aid surfaces for tennis racquet and method of attaching the same
US6447412B1 (en) * 2000-04-18 2002-09-10 Ef Composite Technologies, L.P. Sports racket with undulations in frame interior surface
US6761651B2 (en) * 2002-11-22 2004-07-13 Chin-Dong Pai Aluminum tennis racket
EP2003207A2 (fr) 2000-01-18 2008-12-17 Isis Pharmaceuticals, Inc. Inhibition anti-sens d'expression PTP1B
EP2133125A1 (fr) * 2008-06-13 2009-12-16 Renew Group Sweden AB Tige pour crosse de sport
EP2138207A1 (fr) * 2008-06-27 2009-12-30 Head Technology GmbH Batteur de jeux de balle
EP2174945A1 (fr) 2001-08-01 2010-04-14 Genzyme Corporation Modulation par anti-sense de l'expression de apolipoprotéine B
EP2272958A1 (fr) 2002-09-26 2011-01-12 ISIS Pharmaceuticals, Inc. Modulation de l'expression de la boîte Forkhead O1A
EP2280019A1 (fr) 2001-07-25 2011-02-02 ISIS Pharmaceuticals, Inc. Modulation antisens de l'expression de la protéine réactive C
EP2336318A1 (fr) 2002-11-13 2011-06-22 Genzyme Corporation Modulation anti-sens d'expression B apolipoprotéine
EP2336319A1 (fr) 2002-11-13 2011-06-22 Genzyme Corporation Modulation anti-sens d'expression B apolipoprotéine
EP2388318A1 (fr) 2001-12-10 2011-11-23 Isis Pharmaceuticals, Inc. Modulation antisens d'expression de facteur de croissance de tissu conjonctif
GB2514565A (en) * 2013-05-29 2014-12-03 Evan Alun Harrison Mackrill Design to reduce vibrations in a field hockey stick when striking the ball
WO2016033424A1 (fr) 2014-08-29 2016-03-03 Genzyme Corporation Méthodes de prévention et de traitement d'évènements indésirables cardiovasculaires majeurs à l'aide de composés modulant l'apolipoprotéine b
WO2016156485A1 (fr) 2015-04-01 2016-10-06 Babolat Vs Raquette de tennis
US20230105842A1 (en) * 2021-10-04 2023-04-06 Joon Bu Park Negative poisson`s ratio materials for racquets and golf tees

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1381897A (en) * 1972-03-20 1975-01-29 Acushnet Co Golf ball dimple spatial relationship
GB2012597A (en) * 1978-01-23 1979-08-01 Smith C G H Improvements in golf clubs
EP0446935A1 (fr) * 1990-03-15 1991-09-18 Mizuno Corporation Club de golf
US5150896A (en) * 1992-03-03 1992-09-29 David Holmes Game racket with incurvate contact surfaces

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1381897A (en) * 1972-03-20 1975-01-29 Acushnet Co Golf ball dimple spatial relationship
GB2012597A (en) * 1978-01-23 1979-08-01 Smith C G H Improvements in golf clubs
EP0446935A1 (fr) * 1990-03-15 1991-09-18 Mizuno Corporation Club de golf
US5150896A (en) * 1992-03-03 1992-09-29 David Holmes Game racket with incurvate contact surfaces

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6162138A (en) * 1998-11-16 2000-12-19 Mckee; Roger W. Attachments presenting rotation aid surfaces for tennis racquet and method of attaching the same
EP2003207A2 (fr) 2000-01-18 2008-12-17 Isis Pharmaceuticals, Inc. Inhibition anti-sens d'expression PTP1B
US6447412B1 (en) * 2000-04-18 2002-09-10 Ef Composite Technologies, L.P. Sports racket with undulations in frame interior surface
US6958104B1 (en) 2000-04-18 2005-10-25 Ef Composite Technologies, L.P. Sports racket with undulations in frame interior surface
EP2280019A1 (fr) 2001-07-25 2011-02-02 ISIS Pharmaceuticals, Inc. Modulation antisens de l'expression de la protéine réactive C
EP2174945A1 (fr) 2001-08-01 2010-04-14 Genzyme Corporation Modulation par anti-sense de l'expression de apolipoprotéine B
EP2336145A1 (fr) 2001-08-01 2011-06-22 Genzyme Corporation Modulation par anti-sense de l'expression de apolipoprotéine B
EP2388318A1 (fr) 2001-12-10 2011-11-23 Isis Pharmaceuticals, Inc. Modulation antisens d'expression de facteur de croissance de tissu conjonctif
EP2272958A1 (fr) 2002-09-26 2011-01-12 ISIS Pharmaceuticals, Inc. Modulation de l'expression de la boîte Forkhead O1A
EP2336319A1 (fr) 2002-11-13 2011-06-22 Genzyme Corporation Modulation anti-sens d'expression B apolipoprotéine
EP2336318A1 (fr) 2002-11-13 2011-06-22 Genzyme Corporation Modulation anti-sens d'expression B apolipoprotéine
US6761651B2 (en) * 2002-11-22 2004-07-13 Chin-Dong Pai Aluminum tennis racket
EP2133125A1 (fr) * 2008-06-13 2009-12-16 Renew Group Sweden AB Tige pour crosse de sport
EP2138207A1 (fr) * 2008-06-27 2009-12-30 Head Technology GmbH Batteur de jeux de balle
GB2514565A (en) * 2013-05-29 2014-12-03 Evan Alun Harrison Mackrill Design to reduce vibrations in a field hockey stick when striking the ball
WO2016033424A1 (fr) 2014-08-29 2016-03-03 Genzyme Corporation Méthodes de prévention et de traitement d'évènements indésirables cardiovasculaires majeurs à l'aide de composés modulant l'apolipoprotéine b
WO2016156485A1 (fr) 2015-04-01 2016-10-06 Babolat Vs Raquette de tennis
US10384101B2 (en) 2015-04-01 2019-08-20 Babolat Vs Tennis racket
US20230105842A1 (en) * 2021-10-04 2023-04-06 Joon Bu Park Negative poisson`s ratio materials for racquets and golf tees
WO2023060010A1 (fr) * 2021-10-04 2023-04-13 Joon Bu Park Matériaux à coefficient de poisson négatif pour raquettes et tees de golf

Also Published As

Publication number Publication date
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