Patent Publication Number: US-10786718-B2

Title: Artificial shuttlecock feather and shuttlecock

Description:
RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 16/300,221 filed on Nov. 9, 2018, which is the U.S. National Phase under 35 U.S.C. § 371 of International Application No. PCT/JP2017/016888, filed Apr. 28, 2017, which in turn claims the benefit of Japanese Application No. 2016-093666, filed May 9, 2016, the contents of which are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an artificial shuttlecock feather and a shuttlecock. 
     BACKGROUND ART 
     Badminton shuttlecocks include those that employ feathers (natural feathers) of waterfowl for their feathers (natural feather shuttlecocks), and those that employ artificial feathers synthetically manufactured from a nylon resin or the like therefor (artificial feather shuttlecocks). 
     As is widely known, natural feather shuttlecocks have a structure using 16 or so natural feathers from a goose, duck, or the like, with a base end of the rachis of each feather implanted into a hemispherical mounting block (base) configured from leather-covered cork or the like. The feathers employed in natural feather shuttlecocks have a low relative density and are extremely light in weight. The rachises of such feathers also have high rigidity. Natural feather shuttlecocks therefore have a distinctive flight performance and a satisfying sensation is obtained when they are hit. 
     Although artificial feather shuttlecocks provided with feathers made from resin integrally molded into a ring shape are well known, the feathers are not able to move individually independently of each other in such artificial feather shuttlecocks in the same manner as in natural feather shuttlecocks. This makes it difficult to obtain flight performance similar to that of natural feather shuttlecocks. 
     There are accordingly proposals for artificial feathers modelled on feathers, as described in Patent Literature 1 below. Namely, there is a proposal for an artificial feather shuttlecock with artificial feathers including a vane section and a rachis section to support the vane section. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP 2012-24157 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     In artificial feather shuttlecocks employing artificial feathers modelled on feathers, if an attempt is made to match the weight of the artificial feathers to that of natural feathers then there is insufficient rigidity and durability deteriorates. Moreover, if an attempt is made to match rigidity, then the weight increases and flight performance deteriorates. Even if a balance is found between weight and rigidity, flight performance is inferior due to the rigidity being lower and the weight being heavier than that of natural feathers. 
     In consideration of the above issues, an object of the invention is to improve flight performance. 
     Solution to Problem 
     A main aspect for achieving the object is an artificial shuttlecock feather that is to be implanted in a circular ring shape into a base of a shuttlecock, the artificial shuttlecock feather including: 
     a vane section; and 
     a rachis section having one end in an axial direction of the rachis section fixed to the base and supporting the vane section provided to another end side of the rachis section, 
     a plurality of holes being formed in the vane section so as to penetrate the vane section, and 
     a porosity of a first region of the vane section being lower than a porosity of a second region of the vane section, the first region spanning from an edge on the one end side in the axial direction to a predetermined position further toward the one end side than a center of the vane section in the axial direction, the second region spanning from the predetermined position to an edge on the other end side in the axial direction. 
     Other features of this invention will become clear from descriptions of this specification and drawings. 
     Advantageous Effects of Invention 
     The artificial shuttlecock feather of the invention is capable of improving flight performance. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating an artificial feather shuttlecock, as viewed from a base side. 
         FIG. 2  is a perspective view illustrating an artificial feather shuttlecock, as viewed from an artificial feather side. 
         FIG. 3  is an external view of an artificial feather. 
         FIG. 4  is a diagram illustrating an artificial feather, as viewed from a back side. 
         FIG. 5  is a schematic explanatory diagram relating to aerodynamic characteristics of an artificial feather shuttlecock. 
         FIG. 6  is an explanatory diagram relating to pressures acting on an artificial feather during flight of an artificial feather shuttlecock. 
         FIG. 7  is a diagram illustrating an artificial feather of a present embodiment, as viewed from the back side. 
         FIG. 8  is a graph illustrating a relationship between a porosity of a vane section and pitching moment. 
         FIG. 9  is a diagram illustrating an artificial feather of a first modified example, as viewed from the back side. 
         FIG. 10  is a diagram illustrating an artificial feather of a second modified example, as viewed from the back side. 
         FIG. 11  is a diagram illustrating an artificial feather of a third modified example, as viewed from the back side. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Overview 
     At least the below matters will become clear from descriptions of this specification and drawings. 
     An artificial shuttlecock feather that is to be implanted in a circular ring shape into a base of a shuttlecock will become clear, the artificial shuttlecock feather including: a vane section; and a rachis section having one end in an axial direction of the rachis section fixed to the base and supporting the vane section provided to another end side of the rachis section, a hole being formed in the vane section so as to penetrate the vane section, and a porosity of a first region of the vane section being lower than a porosity of a second region of the vane section, the first region spanning from an edge on the one end side in the axial direction to a predetermined position further toward the one end side than a center of the vane section in the axial direction, the second region spanning from the predetermined position to an edge on the other end side in the axial direction. 
     Such an artificial shuttlecock feather is capable of raising an aerodynamic characteristic (pitching moment), and is capable of achieving improved flight performance. 
     According to the artificial shuttlecock feather, wherein preferably the porosity of the first region is 0%. 
     Such an artificial shuttlecock feather is capable of further improving flight performance. 
     According to the artificial shuttlecock feather, wherein preferably the predetermined position is a position of greatest pressure difference between one surface of the vane section and another surface of the vane section during flight of the shuttlecock. 
     Such an artificial shuttlecock feather is capable of suppressing a reduction in lift. 
     According to the artificial shuttlecock feather, wherein preferably a plurality of the holes are formed, and a length from the edge on the one end side of the vane section to the predetermined position is greater than a separation between adjacent holes out of the holes. 
     According to the artificial shuttlecock feather, wherein preferably the hole is an elongated hole. 
     Such an artificial shuttlecock feather enables an airflow to pass efficiently through from a surface on one side thereof to a surface on the other side thereof, enabling separation of airflow to be suppressed as well as enabling lift to be increased. 
     According to the artificial shuttlecock feather, wherein preferably the porosity of the vane section taken as a whole is from 5% up to, but not including, 30%. 
     Such an artificial shuttlecock feather is capable of obtaining flight performance close to that of a natural feather shuttlecock, and is also capable of securing durability. 
     A shuttlecock employing the above artificial shuttlecock feather is also made clear. 
     EMBODIMENTS 
     &lt;Basic Structure of Artificial Feather Shuttlecock&gt; 
       FIG. 1  and  FIG. 2  are external views to explain the basic structure of an artificial feather shuttlecock  1  provided with artificial feathers  10 .  FIG. 1  is a perspective view illustrating the artificial feather shuttlecock  1 , as viewed from a base  2  side.  FIG. 2  is a perspective view illustrating the artificial feather shuttlecock  1 , as viewed from the artificial feather  10  side. 
     The artificial feather shuttlecock  1  includes a base  2 , plural of the artificial feathers  10  modelled on natural feathers, and cord shaped members  3  for fixing the artificial feathers  10  together. The base  2  is configured by, for example, covering a cork mounting block with thin leather. The shape of the base  2  is a hemispherical shape having a diameter of from 25 mm to 28 mm and including a flat face. Basal portions (base ends: corresponds to one end) of the plural artificial feathers  10  are embedded in a circular ring shape around the circumference of the flat face. The plural artificial feathers  10  are arranged such that separations therebetween widen on progression away from the base  2 . As illustrated in the drawings, each of the artificial feathers  10  is arranged so as to overlap with the respective adjacent artificial feathers  10 . A skirt section  4  is thereby formed with the plural artificial feathers  10 . The plural artificial feathers  10  are fixed together with the cord shaped members  3  (for example cotton threads). 
     &lt;Artificial Feather Structure&gt; 
       FIG. 3  is an perspective view of an artificial feather  10 .  FIG. 4  is a diagram illustrating an artificial feather, as viewed from a back side. The same reference signs are appended in the drawings to members that have already been described. 
     Each of the artificial feathers  10  includes a vane section  12  and a rachis section  14 . The vane section  12  is a portion corresponding to vanes of a natural feather, and the rachis section  14  is a portion corresponding to the rachis of a natural feather. In the drawings there is a defined top-to-bottom direction (corresponding to an axial direction) running along the length of the rachis section  14 , with the side of the vane section  12  being an upper (distal end side), and the opposite side thereto being a lower (base end side). In the drawings there is also a defined left-to-right direction (corresponding to a width direction) which runs along the direction of extension of the vane section  12  from the rachis section  14 . Front and back in the drawings are defined according to the attached state of the artificial feathers  10  to the base  2 . Note that a front-to-back direction corresponds to a direction normal to the vane section  12 . In a state in which the artificial feathers  10  are arranged in a circular ring shape on the base  2 , the front corresponds to the outside and the back corresponds to the inside. Each of the respective configuration elements will now be described using upper/lower, left/right, and front/back as defined in the drawings. 
     The vane section  12  is a member modelled on the shape of vanes of a natural feather. The vane section  12  may, for example, be configured by a nonwoven cloth, a resin, or the like. In cases in which a nonwoven cloth is employed, a reinforcement covering layer is formed on a front face thereof in order to prevent fibers of the nonwoven cloth from fraying when hit. The reinforcement covering layer may be formed by applying a resin coating. Various coating methods may be employed therefor, such as a dipping method, a spraying method, or a roll-coating method, for example. The reinforcement covering layer may be formed to a single face of the vane section  12 , or may be formed to both faces thereof. The reinforcement covering layer may be formed over the entire surface of the vane section  12 , or may be formed to part of the vane section  12 . The shape of the vane section  12  is not limited to the shape illustrated in the drawings. An elliptical shape may, for example, be adopted therefor. 
     The rachis section  14  is a long and thin member modelled on the shape of the rachis of a natural feather, and is a member supporting the vane section  12 . The rachis section  14  includes a vane support portion  14   a  supporting the vane section  12  over a region from an upper side edge (the position P 4  in  FIG. 4 ) to a lower side edge (the position P 1  in  FIG. 4 ), and a calamus portion  14   b  projecting beyond the vane section  12 . The calamus portion  14   b  is a portion corresponding to the calamus (this location is also referred to as the quill) of a natural feather. A base end of the rachis section  14  (lower end of the calamus portion  14   b ) is embedded in the base  2  so as to be fixed to the base  2 . The distal end of the rachis section  14  (corresponds to other end) is aligned with an upper end of the vane section  12 . Although cross-section profiles of the rachis section  14  are illustrated as being quadrangle in the drawings, there is no limitation thereto, and other cross-section profiles may be employed. 
     The rachis section  14  and the vane section  12  may be configured by separate bodies, or may be configured by a single body. For example, when a resin is employed as the material for the rachis section  14  and the vane section  12 , the rachis section  14  and the vane section  12  may be molded as a single body by injection molding using a mold. The rachis section  14  and the vane section  12  may also be formed as a single body with different materials for each by injection molding (two-color molding) employing two types of material (resin). 
     The vane section  12  may be supported in the front side of the vane support portion  14   a , and the vane section  12  may be supported on the back side of the vane support portion  14   a . The vane section  12  may also be configured by two sheets, configured such that the vane support portion  14   a  is sandwiched between the two sheet vane section  12 . The vane section  12  may also be embedded within the vane support portion  14   a.    
     &lt;Flight Performance&gt; 
     The feathers employed in natural feather shuttlecocks have a low relative density and are extremely light in weight. The rachises of these feathers also have high rigidity, and return to their original shape irrespective of the cumulative number of times they have been hit. Natural feather shuttlecocks therefore obtain a distinctive flight. 
     If the rigidity of the rachis section  14  were to be raised in the artificial feather shuttlecock  1  employing the artificial feathers  10  then this would lead to an increase in weight of the rachis section  14  and a worse weight balance. This would make the flight performance such as that of a natural feather shuttlecock unobtainable. If, however, the weight of the rachis section  14  were to be reduced and the rigidity lowered, then this would result in slower recovery when hit. The flight performance would accordingly deteriorate. The reason flight performance deteriorates as the weight of the rachis section  14  increases is thought to be as follows. 
     After being hit, the artificial feather shuttlecock  1  gradually stabilizes while the skirt section  4  repeatedly performs a pendulum motion, with the base  2  acting as the pivot point. When the weight is heavier, the position of the center of gravity shifts toward the skirt section  4  side, and the moment of inertia about the pivot point of the base  2  increases. This acts against attenuation of the pendulum motion, leading to weaving in flight and a loss of directionality (namely, a deterioration in flight performance). 
       FIG. 5  is a schematic explanatory diagram relating to aerodynamic characteristics of the artificial feather shuttlecock  1 . The basic aerodynamic characteristics of the artificial feather shuttlecock  1  can be explained in terms of drag, lift, and pitching moment. 
     Of forces acting on the artificial feather shuttlecock  1  when placed in an airflow, drag is a component (component force) parallel to the direction of airflow. Lift is a component (component force) perpendicular to the direction of airflow. 
     Pitching moment is a force attempting to return the orientation of the artificial feather shuttlecock  1  when a difference has arisen between the airflow direction and the direction of the base  2  (namely, when the artificial feather shuttlecock  1  is angled with respect to the airflow). The greater the pitching moment, the faster the motion in a direction to return orientation. 
     It is desirable to shift the position of the center of gravity of the artificial feather shuttlecock  1  toward the base  2  side in order to stabilize flight performance. However if, hypothetically, a weight were to be placed in the base  2 , then the overall weight of the artificial feather shuttlecock  1  would increase, resulting in an inferior hitting sensation and making the correct flight distance no longer achievable. 
     The present embodiment achieves improved flight performance by enhancing the aerodynamic characteristics (pitching moment), while at the same time suppressing an increase in weight. Specifically, in an artificial feather  10  of the present embodiment, plural holes (holes  122 , described later) are provided in the vane section  12 , so as to penetrate the vane section  12 . An improvement in the pitching moment is thereby achieved. However, providing holes uniformly over the entire surface of the vane section  12  might reduce the lift acting on the artificial feather shuttlecock  1 . 
       FIG. 6  is a graph illustrating a difference in pressure that occurs between the two surfaces (front surface and back surface) of the artificial feather  10  during flight of the artificial feather shuttlecock  1  (see Journal of Fluids and Structures 41, 89 to 98). 
     The position on the artificial feather shuttlecock  1  is shown on the horizontal axis of the graph, and a pressure difference (ΔCp) between the positive pressure surface (the front surface in this example) and the negative pressure face (the back surface in this example) is shown on the vertical axis. The positions P 1  to P 4  on the horizontal axis in  FIG. 6  correspond to the respective positions on the vane section  12  (on the vane support portion  14   a ) in  FIG. 4 , with the calamus portion  14   b  lying to the left of the position P 1  in  FIG. 4 . The position P 3  is a center of the vane section  12  in the top-to-bottom direction (the center point between the position P 1  and the position P 4 ). 
     As illustrated in the drawings, the pressure difference (ΔCp) between the positive pressure surface and the negative pressure surface is greatest at the position P 2  to the lower side (base end side) of the position P 3 . The artificial feather shuttlecock  1  generates the greatest lift in the position P 2 . In this example, the position P 2  is positioned from the position P 1  of the vane section  12  at a distance of approximately 15% of the total length of the vane section  12  in the top-to-bottom direction (i.e. of the distance between the position P 1  and the position P 4 ). The position where the pressure difference is greatest (position P 2 ) varies slightly according to the shape and material of the vane section  12 , the rigidity of the rachis section  14  and the like. However, this position is not thought to vary much (is to the lower side of the position P 3 ) in artificial feather shuttlecocks  1  employing the artificial feathers  10  modelled on feathers. In the present embodiment, holes are arranged such that there are no holes provided further toward the lower side than the position P 2  (a region from the position P 1  to the position P 2 ). 
     &lt;Improved Example of Artificial Feather (Present Embodiment)&gt; 
       FIG. 7  is a diagram illustrating an artificial feather  10  of the present embodiment, as viewed from the back side. A rachis section  14  of the artificial feather  10  in the present embodiment is the same as that of the above artificial feather  10  ( FIG. 4 ), and so description thereof is omitted. 
     Holes  122  are provided in a vane section  12  of the artificial feather  10  in the present embodiment so as to penetrate the vane section  12  in the front-to-back direction. The holes  122  are elongated holes each having a long and thin profile oriented in a direction angled with respect to (intersecting) the left-to-right direction (width direction) and the top-to-bottom direction (axial direction). More specifically, the holes  122  are each formed with a profile slanting upward (away from the base  2 ) on progression away from the rachis section  14 . Plural of the holes  122  are arranged in rows along the top-to-bottom direction at a prescribed separation from each other. The plural holes  122  are arranged with left-right symmetry about the rachis section  14 . This thereby enables good balance to be achieved in the left-to-right direction. 
     &lt;Positions for Forming Holes  122 &gt; 
     In the present embodiment, there are no holes  122  provided in a region spanning a range from the position P 1 , i.e. from a lower side (base end side) edge of the vane section  12 , to the position P 2  (hereafter this region is also referred to as the first region  12 A). The holes  122  are provided in a region spanning from the position P 2  to the position P 4 , i.e. to an upper side (distal end side) edge of the vane section  12  (hereafter this region is also referred to as the second region  12 B). The reason for forming the holes  122  in this manner is described below. 
     As described earlier with reference the  FIG. 6 , when the artificial feather shuttlecock  1  is in flight, the pressure difference between the positive pressure surface (the front surface in this example) and the negative pressure surface (the back surface in this example) of the vane section  12  is greatest in the position P 2  of the vane section  12 , and the greatest lift is generated in the position P 2 . 
     The pressure at the negative pressure surface rises toward the distal end side (i.e. the downstream side in relation to the direction of airflow) of the position P 2 , resulting in a countervailing pressure gradient. The airflow therefore separates at the distal end side (downstream side) of the position P 2 . There is, however, no separation of airflow over the region (first region  12 A) at the base end side (upstream side) of the position P 2 , and lift is generated therein. 
     Supposing the holes  122  were to be formed in the first region  12 A where lift is being generated, then there would be a reduction in lift, which might result in a worsening of flight performance. 
     By contrast, in the present embodiment, the holes  122  are not provided in the first region  12 A, and the holes  122  are provided in the second region  12 B. This enables a flow to be induced to flow efficiently from the front surface (positive pressure surface) side to the back surface (negative pressure surface) side. This enables separation of airflow to be suppressed and enables lift to be increased. This thereby enables an increase in the pitching moment about the vane section  12 , and an increase in the pitching moment of the artificial feather shuttlecock  1  taken as a whole. An improvement is accordingly able to be achieved in the flight performance of the artificial feather shuttlecock  1 . 
     The holes  122  of the present embodiment are elongated holes, and setting (optimizing) the length and angle of the holes  122  enables the airflow to pass from the front surface side to the back surface side with good efficiency. This thereby enables separation of the airflow to be further suppressed, and enables lift to be increased further. 
     Accordingly, the porosity of the first region  12 A is 0% due to there being no holes  122  provided in the first region  12 A of the vane section  12 , and is thus smaller than the porosity of the second region  12 B. Reference here to porosity means the proportion of surface area (openings) of the holes  122  with respect to the surface area of the front surface of the vane section  12  for each of the respective regions, and is expressed as a percentage. 
     Although in the present embodiment the holes  122  are formed regularly (at a prescribed separation) in the vane section  12 , the holes  122  are not necessarily formed regularly (namely, they may be formed irregularly). For example, in the present embodiment, a length of the first region  12 A in the top-to-bottom direction (the distance between the position P 1  and the position P 2 ) is greater than separations between the adjacent holes  122 , and greater than the length in the top-to-bottom direction of opening portions of the holes  122 . There may, however, be a location where the separation between adjacent holes  122  is greater than the length of the first region  12 A in top-to-bottom direction. 
     &lt;Quantity of Holes  122  Formed&gt; 
       FIG. 8  is a graph illustrating a relationship between porosity of the vane section  12  and pitching moment. The porosity of the vane section  12  taken as a whole is shown on the horizontal axis in  FIG. 8 . For example, the porosity is 0% for the vane section  12  of  FIG. 4  (a case in which no holes  122  are provided). The pitching moment is shown on the vertical axis in  FIG. 8 . The pitching moment is measured under the following conditions: wind speed 10 m/s; angle of attack ±24° (at intervals of 3°); no shuttlecock spin. 
     As illustrated in the graph, the pitching moment increases as the porosity increases over a range of from 0% to 25%. For example, when the porosity is 5%, the pitching moment is approximately 9% greater than that at a porosity of 0% ( FIG. 4 ). 
     The pitching moment of a natural feather shuttlecock is approximately 1.1, and a porosity of 5% is substantially equivalent to that of a natural feather shuttlecock. In order to obtain aerodynamic characteristics close to those of a natural feather shuttlecock it is accordingly preferable to have a porosity of 5% or greater for the vane section  12  as a whole. 
     However, when the porosity is 30% or greater, this might lead to too large gaps and not being able to secure durability. The porosity is accordingly preferably in a range of 5% up to, but not including, 30% (and more preferably up to, but not including, 20%). 
     As described above, plural of the holes  122  are provided in the second region  12 B on the upper side (distal end side) of the position P 2  of the vane section  12  in the artificial feather  10  of the present embodiment, but there are no holes  122  provided in the first region  12 A (i.e. the porosity of the first region  12 A is lower than the porosity of the second region  12 B). This thereby enables the pitching moment to be raised while suppressing a reduction in lift, thereby enabling an improvement in flight performance to be achieved. 
     MODIFIED EXAMPLES 
       FIG. 9  is a diagram illustrating an artificial feather  10  of a first modified example, as viewed from the back side. 
     Plural holes  124  are provided in a vane section  12  of the artificial feather  10  of the first modified example. Opening widths (top-to-bottom direction lengths) of the holes  124  are greater than the opening widths of the holes  122  of the above embodiment, and the separation between the adjacent holes  124  is also greater than the separation between the holes  122  in the above embodiment. Namely, the number of the holes  124  in the first modified example is fewer than in the above embodiment. Similarly to in the above embodiment, the holes  124  are provided in a second region  12 B to the upper side (distal end side) of the position P 2 . 
       FIG. 10  is a diagram illustrating an artificial feather  10  of a second modified example, as viewed from the back side. 
     Plural holes  126  are provided in a vane section  12  of the artificial feather  10  of the second modified example. In the second modified example, the forming positions where the holes  126  are formed are not arranged symmetrically with respect to a rachis section  14  (are asymmetrical in the left-to-right direction). Namely, irrespective of the position on the vane section  12 , the holes  126  are still provided so as to slant upward (away from the base  2 ) on progression toward the left, with the right end of each of the holes  126  being the lowermost position thereof (closest to the base  2 ). There is, however, no limitation thereto, and, for example, the direction of slanting may be left-right reversed. There are no holes (holes  122 , holes  124 ) formed in width direction end portions (left-to-right direction end portions) of the vane section  12  in the above embodiment. However, the holes  126  in the second modified example are also formed at positions closer to the end (specifically, at locations overlapping with the adjacent vane section  12 ). Similarly to in the above embodiment, the holes  126  are provided in the second region  12 B to the upper side (distal end side) of the position P 2 . 
       FIG. 11  is a diagram illustrating an artificial feather  10  of a third modified example, as viewed from the back side. 
     Plural holes  128   a  and  128   b  are each provided in a vane section  12  of the artificial feather  10  of the third modified example. The forming positions where the holes  128   a ,  128   b  are formed are also arranged asymmetrically with respect to the rachis section  14  in this example too. 
     The holes  128   a  are elongated holes each having a long and thin profile oriented in a direction angled with respect to (intersecting) the left-to-right direction (width direction) and the top-to-bottom direction (axial direction). 
     The holes  128   b  are formed parallel to the axis of the rachis section  14  (along the top-to-bottom direction). Namely, the holes  128   b  are elongated holes each having a long and thin profile oriented so as not to intersect with the top-to-bottom direction, but to intersect (orthogonally) with the left-to-right direction. 
     The vane section  12  of the third modified example includes a mix of both regions in which plural of the holes  128   a  are arrayed in rows along the top-to-bottom direction at a prescribed separation from each other, and regions in which plural of the holes  128   b  are arrayed in rows along the left-to-right direction at a prescribed separation from each other. The holes  128  (the holes  128   a  and the holes  128   b ) are also provided in the second region  12 B to the upper side (distal end side) of the position P 2  in this example too. 
     In each of the modified examples described above, the porosity of the first region  12 A is 0%, i.e. a lower porosity than that of the second region  12 B. This thereby enables an improvement in flight performance to be achieved, similarly to in the above embodiment ( FIG. 7 ). 
     Other Points 
     The above embodiment modes are to facilitate understanding of this invention, and are not for limiting this invention in any way. It is needless to say that this invention can be changed or modified without deviating from the scope, and this invention includes its equivalents. 
     Although the holes (the holes  122 ,  124 ,  126 ,  128   a ,  128   b ) that are provided to the vane section  12  in the above embodiments are each elongated holes that are long and thin, there is no limitation thereto. For example, holes with a circular profile (round holes) or holes with a polygonal profile may be provided. However, as described above, with elongated holes the airflow is able to pass efficiently from the front surface side to the back surface side, enabling separation of the airflow to be suppressed and also enabling lift to be increased. Elongated holes are therefore preferably employed. 
     Moreover, although plural holes are provided in the vane section  12  in the above embodiments, a configuration may be adopted in which at least one (a single) hole is provided. 
     Although the vane section  12  is sheet shaped in the above embodiment, there is no limitation thereto. For example, a three dimensional (3D) shape may be adopted therefor. 
     Although there are no holes provided in the first region  12 A in the above embodiments (i.e. the porosity is 0%), holes may be provided therein. In such cases, setting the porosity of the first region  12 A lower than the porosity of the second region  12 B enables better flight performance to be achieved than when holes are provided uniformly over the entire vane section  12 . However, setting porosity to 0% (providing no holes) in the first region  12 A, as in the present embodiment, enables a greater improvement to be achieved in flight performance. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  artificial feather shuttlecock, 
               2  base, 
               3  cord shaped member, 
               4  skirt section, 
               10  artificial feather, 
               12  vane section, 
               12 A first region, 
               12 B second region, 
               14  rachis section, 
               14   a  vane support portion, 
               14   b  calamus portion, 
               122 ,  124 ,  126 ,  128   a ,  128   b  hole