EP3932500A1

EP3932500A1 - Shuttlecock

Info

Publication number: EP3932500A1
Application number: EP19916934.3A
Authority: EP
Inventors: Takumi Sakaguchi; Shogo Maeda
Original assignee: Yonex KK
Current assignee: Yonex KK
Priority date: 2019-02-28
Filing date: 2019-12-24
Publication date: 2022-01-05
Also published as: JP7267035B2; TWI770456B; JP2020137804A; TW202033245A; CN113631235A; EP3932500A4; WO2020174854A1

Abstract

A shuttlecock 1 includes: a base portion 2; and a plurality of artificial feathers 10 arranged in an annular shape on the base portion 2. The artificial feathers 10 each includes a feather portion 12 and a feather shaft portion 14 that supports the feather portion 12. Letting a rotation direction be a counterclockwise direction centered about a central axis of the shuttlecock in a view from a side opposite to the base portion 2, a virtual straight line M is outward with respect to a virtual straight line N, on a downstream side of the feather shaft portion 14 in the rotation direction; the virtual straight line M is a line connecting a downstream end of the feather portion 12 in the rotation direction and a central portion of the feather shaft portion 14, and the virtual straight line N is a line connecting an upstream end of the feather portion 12 in the rotation direction and the central portion of the feather shaft portion 14.

Description

[Technical Field]

The present invention relates to a shuttlecock that uses artificial feathers.

[Background Art]

Shuttlecocks for badminton include shuttlecocks that use waterfowl feathers (natural feathers) for the feathers (i.e., natural shuttlecocks) and shuttlecocks that use artificial feathers artificially manufactured using nylon resin or the like (i.e., artificial shuttlecocks).
As is well known, a natural shuttlecock uses around 16 natural feathers from geese, ducks, or the like, and has a structure in which the base ends of the feather shafts of the feathers are planted in a hemispherical base (base portion) that is made of cork and covered with a leather. The feathers used in a natural shuttlecock are characterized by having a low specific gravity and being extremely light weight. The feathers are highly rigid, and a natural shuttlecock provides unique flight performance and a comfortable shot feeling.
On the other hand, a well-known example of an artificial shuttlecock is provided with feathers that are made of resin and integrally molded in an annular shape, but because the feathers of such an artificial shuttlecock do not move independently on their own like those of a natural shuttlecock, it is difficult to obtain flight performance similar to that of a natural shuttlecock.
In view of this, as described in Patent Document 1 below, artificial feathers that mimic natural feathers have been proposed. Specifically, there has been a proposal for a shuttlecock that has artificial feathers that include a feather portion and a feather shaft portion that supports the feather portion.

[Citation List]

[Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2008-206970

[Summary of Invention]

[Technical Problem]

Even a shuttlecock (artificial shuttlecock) that has artificial feathers such as those described above is inferior in flight stability to a natural shuttlecock. The main reasons for this are that artificial feathers are denser and heavier than natural feathers, and it is not possible to exhibit the same aerodynamic characteristics as natural shuttlecocks.
If the weight of the shaft (feather shaft portion) is reduced in order to reduce the weight of the artificial feathers, the rigidity may not be sufficient to withstand a strong hit such as a smash. On the other hand, if the area of the feather portion is reduced, the aerodynamic characteristics further deteriorate.
Even if the overall weight of an artificial shuttlecock is the same as the weight of a natural shuttlecock, the position of the center of gravity is different from that of the natural shuttlecock, and therefore the stability is poor when the attitude is disrupted (it takes time to return to the correct attitude). In particular, in a "hairpin net shot", which is a known shot in badminton, the difference in attitude stability from that of a natural shuttlecock is exhibited remarkable. A hairpin net shot is a technique for hitting the shuttlecock so as to float in the air and draw a unique flight trajectory. During a hairpin net shot, the attitude of the shuttlecock is greatly disrupted.
The present invention has been made in view of the foregoing circumstances, and an aspect of the present invention is to provide a shuttlecock capable of having improved aerodynamic characteristics for a shot that involves a greatly disrupted attitude.

[Solution to Problem]

A main aspect of the invention for achieving the aforementioned object is a shuttlecock including a base portion and a plurality of artificial feathers arranged in an annular shape on the base portion, wherein the artificial feathers each include a feather portion and a feather shaft portion that supports the feather portion, wherein the feather portion includes an overlapping portion that overlaps an inward side of an adjacent feather portion, at a position on a one side of the feather shaft portion in a width direction that is orthogonal to an axial direction, and wherein the feather portion includes an inclined portion that is inclined outward relative to the surface of the overlapping portion, at a position on the other side of the feather shaft portion in the width direction.
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[Advantageous Effects of Invention]

According to the present invention, it is possible to provide a shuttlecock capable of having improved aerodynamic characteristics for a shot that involves a greatly disrupted attitude.

[Brief Description of the Drawings]

FIG. 1 is a perspective view of an artificial shuttlecock 100 (comparative example) seen from one side of a base portion 2.
FIG. 2 is a perspective view of the artificial shuttlecock 100 (comparative example) seen from one side of artificial feathers 110.
FIG. 3A is a perspective view of an artificial feather 110 of the comparative example. FIG. 3B is a schematic view of an artificial feather 110 as viewed from above.
FIG. 4 is a schematic view of a plurality of artificial feathers 110 arranged on the artificial shuttlecock 100 of the comparative example as viewed from above.
FIG. 5 is a schematic view of an artificial feather 10 of a first embodiment as viewed from above.
FIG. 6 is a schematic view of a plurality of artificial feathers 10 arranged on an artificial shuttlecock 1 of the first embodiment as viewed from above.
FIG. 7 is a diagram showing evaluation results of drag of the artificial shuttlecock 1.
FIG. 8 is a diagram showing evaluation results of the pitching moment of the artificial shuttlecock 1.
FIG. 9 is a diagram showing evaluation results of an effect confirmation test.
FIG. 10A is a schematic view of an artificial feather 10a of a first variation as viewed from above. FIG. 10B is a schematic view of a plurality of artificial feathers 10a arranged on the artificial shuttlecock 1 as viewed from above.
FIG. 11 is a schematic view of an artificial feather 10b of a second variation as viewed from above.
FIG. 12 is a schematic view of an artificial feather 10c of a third variation as viewed from above.
FIG. 13 is a schematic view of an artificial feather 10d of a fourth variation as viewed from above.
FIG. 14 is a schematic view of an artificial feather 10' of a second embodiment as viewed from above.

[Description of Embodiments]

Overview

At least the following matter will become apparent from the description of the present specification and the drawings.
Clarified is a shuttlecock including: a base portion; and a plurality of artificial feathers arranged in an annular shape on the base portion, the artificial feathers each including a feather portion and a feather shaft portion that supports the feather portion, letting a rotation direction be a counterclockwise direction centered about a central axis of the shuttlecock in a view from a side opposite to the base portion, a first virtual straight line being outward with respect to a second virtual straight line, on a downstream side of the feather shaft portion in the rotation direction, the first virtual straight line being a line connecting a downstream end of the feather portion in the rotation direction and a central portion of the feather shaft portion, the second virtual straight line being a line connecting an upstream end of the feather portion in the rotation direction and the central portion of the feather shaft portion.
According to this shuttlecock, the projected area at a high angle of attack (when the attitude is disrupted) is large, and drag and the pitching moment can be increased. As a result, it is possible to improve the aerodynamic characteristics for a shot in which the attitude is greatly disrupted (hairpin net shot).
In such a shuttlecock, it is desirable that the feather portion includes an inclined portion at a position between the downstream end of the feather portion in the rotation direction and the feather shaft portion, the inclined portion being a portion that is inclined outward with respect to the second virtual straight line, and that in a view of the feather portion from an extension of an axial direction of the feather shaft portion, a length of the inclined portion is longer than half of a length from the downstream end of the feather portion in the rotation direction to the feather shaft portion.
According to this shuttlecock, the projected area is larger, thus making it possible to further improve the aerodynamic characteristics.
In such a shuttlecock, it is acceptable that the feather portion includes an overlapping portion that overlaps an inward side of an adjacent feather portion, at a position on an upstream side of the feather shaft portion in the rotation direction, and that the overlapping portion of the feather portion is in contact with the adjacent feather portion.
According to this shuttlecock, it is possible to easily suppress rotational movement around the central axis during normal flight (at a low angle of attack).
In such a shuttlecock, it is acceptable that the feather portion includes an overlapping portion that overlaps an inward side of an adjacent feather portion, at a position on an upstream side of the feather shaft portion in the rotation direction, and that the overlapping portion of the feather portion is not in contact with the adjacent feather portion.
According to this shuttlecock, it is possible to increase the inclination angle of the inclined portion, making it possible to further increase the projected area.
Clarified is a shuttlecock including: a base portion; and a plurality of artificial feathers arranged in an annular shape on the base portion, the artificial feathers each including a feather portion and a feather shaft portion that supports the feather portion, letting a rotation direction be a counterclockwise direction centered about a central axis of the shuttlecock in a view from a side opposite to the base portion, the feather portion including a protruding portion between a downstream end of the feather portion in the rotation direction and a position overlapped with the feather shaft portion, the protruding portion being a portion that protrudes outward from an outer surface. According to this shuttlecock, it is possible to improve the aerodynamic characteristics for a shot in which the attitude is greatly disrupted (hairpin net shot).

First Embodiment

Before giving a description of an artificial shuttlecock 1 of the present embodiment, the following first describes a comparative example.

Basic structure of artificial shuttlecock (comparative example)

FIGS. 1 and 2 are external views for describing the basic structure of an artificial shuttlecock 100 provided with artificial feathers 110 according to a comparative example. FIG. 1 is a perspective view of the artificial shuttlecock 100 (comparative example) seen from one side of a base portion 2. FIG. 2 is a perspective view of the artificial shuttlecock 100 (comparative example) seen from one side of the artificial feathers 110.
The artificial shuttlecock 100 includes a base portion 2, a plurality of artificial feathers 110 that mimic natural feathers, and string-shaped members 3 for fixing the artificial feathers 110 to each other. The base portion 2 is constituted by covering a cork base with a thin leather, for example. The base portion 2 is shaped as a hemisphere having a diameter of 25 mm to 28 mm, and has a flat surface. The roots (base ends) of the artificial feathers 110 are embedded in the flat surface in an annular shape along the periphery of the flat surface. The artificial feathers 110 are arranged such that the distance between them becomes wider as the distance from the base portion 2 increases. Also, as shown in the figures, each artificial feather 110 is arranged so as to be overlapped with the adjacent artificial feathers 110. As a result, a skirt portion 4 is formed by the artificial feathers 110. The artificial feathers 110 are fixed to each other by the string-shaped members 3 (e.g., cotton strings).
The artificial shuttlecock 100 rotates in a predetermined direction (rotation direction) around the central axis of the shuttlecock during normal flight (at a low angle of attack described later). In the present embodiment, the rotation direction is the counterclockwise direction when viewed from the artificial feather 110 side in FIG. 2 (the side opposite to the base portion 2), or in other words the clockwise direction when viewed from the base portion 2. Note that the central axis of the shuttlecock is the axis that passes through the center of the ring formed by the artificial feathers (here, the artificial feathers 110), or in other words the center of the skirt portion 4, as well as the center of the base portion 2.

Structure of artificial feather (comparative example)

FIG. 3A is a perspective view of the artificial feather 110 of the comparative example, and FIG. 3B is a schematic view of the artificial feather 110 as viewed from above. In these figures, the members that have already been described are denoted by the same reference signs.
The artificial feather 110 includes a feather portion 120 and a feather shaft portion 14. The feather portion 120 is a portion corresponding to the vane of a natural feather, and the feather shaft portion 14 is a portion corresponding to the rachis of a natural feather.
In these figures, the vertical direction (corresponding to the axial direction) is defined along the lengthwise direction of the feather shaft portion 14, the side with the feather portion 120 is the upper side (tip), and the opposite side is the lower side (base). Also, in these figures, the front and the back are defined based on the state in which the artificial feather 110 is attached to the base portion 2. Note that the front-back direction corresponds to a normal direction of the feather portion 120, and the front and the back respectively correspond to the outer side and the inner side in the state where the artificial feathers 110 are arranged in an annular shape on the base portion 2. Also, in these figures, the left-right direction is defined along the direction in which the feather portion 120 extends from the feather shaft portion 14 (the direction orthogonal to the vertical direction). In the left-right direction, "right" refers to the right side in a view of the front side (outer side) from the back side (inner side), and "left" is the left side in the same view. Note that the left-right direction will also be referred to as the width direction. Also, relative to the feather shaft portion 14, the right side corresponds to the upstream side in the rotation direction, and the left side corresponds to the downstream side in the rotation direction. In the following, constituent elements may be described according to the terms upper, lower, left, right, front, and back as defined in the figures.
The feather portion 120 is a member that mimics the shape of the vane of a natural feather. The feather portion 120 can be constituted by nonwoven fabric or resin, for example. In the case where nonwoven fabric is used, a reinforcing film is formed on the surface in order to prevent the fibers of the nonwoven fabric from coming loose during a hit. The reinforcing film can be formed by applying a resin, and various coating methods such as a dipping method, a spraying method, and a roll coating method are adopted. Note that the reinforcing film may be formed on one side of the feather portion 120 or on both sides. Also, the reinforcing film may be formed on the entire surface of the feather portion 120 or a part of the surface. Moreover, the shape of the feather portion 120 is not limited to the shape shown in the figures (the same applies to a feather portion 12 described later). For example, an elliptical shape may be adopted.
The feather shaft portion 14 is an elongated member that mimics the shape of the rachis of a natural feather, and is a member that supports the feather portion 120. The feather shaft portion 14 has a feather support portion 14a that supports a region from the upper edge of the feather portion 120 to the lower edge thereof, and a calamus portion 14b that protrudes from the feather portion 120. The calamus portion 14b is a portion corresponding to the calamus (note that this is sometimes called the quill) of a natural feather. The base end of the feather shaft portion 14 (the lower end of the calamus portion 14b) is embedded in the base portion 2 and fixed to the base portion 2. On the other hand, the tip of the feather shaft portion 14 coincides with the upper end of the feather portion 12. Note that in this example, the cross-sectional shape of the feather shaft portion 14 is a quadrangle (rectangle), but the cross-sectional shape is not limited to this, and other shapes (circle, ellipse, polygon, etc.) may be used.
Also, the feather shaft portion 14 and the feather portion 120 may be separate bodies or may be integrated. For example, if resin is used as the material for the feather shaft portion 14 and the feather portion 120, the feather shaft portion 14 and the feather portion 120 can be integrally molded by injection molding using a mold. Also, the feather shaft portion 14 and the feather portion 120 can be integrally formed using different materials by performing injection molding (twocomponent molding) using two kinds of materials (resins).
The feather portion 120 may be supported on the front side of the feather support portion 14a, or the feather portion 120 may be supported on the back side of the feather support portion 14a. Also, a configuration is possible in which the feather portion 120 is constituted by two sheets, and two feather portions 120 sandwich the feather support portion 14a. Moreover, the feather portion 120 may be embedded inside the feather support portion 14a.
FIG. 4 is a schematic view of artificial feathers 110 arranged on the artificial shuttlecock 100 of the comparative example as viewed from above. As shown in this figure, the feather portions 120 are arranged such that the feather portions 120 overlap each other with slightly different angles. More specifically, the right end portion of each feather portion 120 overlaps the inward side of the left end portion of the adjacent feather portion 120. This portion of the right end portion (the portion that overlaps the adjacent feather portion 120) will be referred to as an overlapping portion S. Also, in this example, each feather portion 120 (specifically, the end portion of the overlapping portion S) is in contact with the adjacent feather portion 120.
In the above-described artificial shuttlecock 100 (comparative example), the weight of the artificial feather 110 is heavier than that of a natural feather. If the feather shaft portion 14 is made thinner and lighter, there is a possibility that the rigidity is not sufficient to withstand a strong hit such as a smash, and if the area of the feather portion 120 is reduced, there is a possibility that the aerodynamic characteristics deteriorate. Even if the total weight of the artificial shuttlecock 100 is adjusted to match that of a natural shuttlecock, it is difficult to match the center of gravity, and the position of the center of gravity is rearward (away from the base portion 2) of that of a natural shuttlecock. Therefore, stability deteriorates when the attitude is greatly disrupted.
In particular, in a hairpin net shot in which the shuttlecock is hit so as to float in the air, the attitude is greatly disrupted, and therefore the difference in attitude stability from that of a natural shuttle is exhibited remarkable.
In view of this, in the present embodiment, the aerodynamic characteristics are improved for a shot (hairpin net shot) in which the attitude is greatly disrupted. Note that in the following description, an attitude close to normal flight (flying with the base portion 2 facing the direction of travel) is referred to as "low angle of attack", and a state in which the attitude is greatly disrupted with respect to the direction of travel is referred to as "high angle of attack".

Artificial shuttlecock 1 of present embodiment

FIG. 5 is a schematic view of an artificial feather 10 of the first embodiment as viewed from above. Also, FIG. 6 is a schematic view of a plurality of artificial feathers 10 arranged on the artificial shuttlecock 1 of the first embodiment as viewed from above. Note that portions that have the same configuration as those in the comparative example are designated by the same reference numerals, and the description thereof will be omitted. Also, the definitions of directions are the same as those of the comparative example. A straight line (dashed-dotted line) connecting the left end of the feather portion 12 (downstream end in the rotation direction) and the central portion of the feather shaft portion 14 is a virtual straight line M (corresponding to a first virtual straight line). And a straight line (dashed line) connecting the right end (upstream end in the rotation direction) of the feather portion 12 and the central portion of the feather shaft portion 14 is a virtual straight line N (corresponding to a second virtual straight line). Note that the central portion of the feather shaft portion 14 is a portion at the axial center of the feather shaft portion 14, such as the intersection of diagonal lines in the case where the cross-sectional shape of the feather shaft portion 14 is rectangular as in the present embodiment. As another example, if the cross-sectional shape of the feather shaft portion 14 is elliptical, the central portion is the intersection of the long axis and the short axis.
As shown in FIG. 6, the artificial shuttlecock 1 of the present embodiment includes a plurality of artificial feathers 10. Similarly to the artificial feather 110 of the comparative example, the artificial feathers 10 are arranged in an annular shape along the circumference of the flat surface of the base portion 2 (not shown here).

Structure of artificial feather 10

As shown in FIGS. 5 and 6, the artificial feathers 10 of the artificial shuttlecock 1 of the present embodiment each have the feather portion 12 and the feather shaft portion 14. In the present embodiment, the shape of the feather portion 12 is different from that of the feather portion 120 (see FIG. 3B) of the above-described comparative example.
The feather portion 12 is supported by the feather shaft portion 14 similarly to the comparative example (FIG. 3A).
The end portion of the feather portion 12 on the right side of the feather shaft portion 14 overlaps the inward side of the left end portion of the adjacent feather portion 12 (overlapping portion S), similarly to the comparative example.
Also, the feather portion 12 has an inclined portion 12a on the left side of the feather shaft portion 14. The inclined portion 12a is inclined outward (toward the front side) at an angle θ (corresponding to an inclination angle) with respect to the virtual straight line N (second virtual straight line). Therefore, the widthwise length of the overlapping portion S is shorter than that of the comparative example (FIG. 4) . Also, as shown in FIG. 6, the right end (overlapping portion S) of the feather portion 12 is not in contact with the left end (inclined portion 12a) of the adjacent feather portion 12.
Also, because the inclined portion 12a is provided in the present embodiment, the virtual straight line M (first virtual straight line) is outward (on the front side) with respect to the virtual straight line N, on the left side (downstream side in the rotation direction) of the feather shaft portion 14.
With such a shape, the artificial shuttlecock 1 of the present embodiment has a larger projected area at a high angle of attack than the artificial shuttlecock 100 of the comparative example. Note that the projected area is the area of the "shadow" created when a three-dimensional object is projected in two dimensions (here, the area when the shuttlecock is viewed from the side) . As a result, as will be described later, the artificial shuttlecock 1 has higher air resistance (drag) at a high angle of attack, and therefore when compared with the comparative example (artificial shuttlecock 100), it is possible to suppress unstable behavior (staggering, etc.) when the attitude is greatly disrupted, making it more easier to stabilize the attitude.

Evaluation of characteristics of artificial shuttlecock 1

Of basic aerodynamic characteristics of the artificial shuttlecock 1 of the present embodiment, drag and pitching moment were evaluated.
Of components of the force acting on the shuttlecock placed in the airflow, drag is a component (component force) parallel to the direction of an airflow. Note that the component (component force) perpendicular to the direction of the airflow is called lift.
Pitching moment is the force of attempting to return to the original attitude (to a low angle of attack) when there is a difference between the direction of the airflow and the orientation of the base portion (i.e., when the shuttlecock is inclined with respect to the airflow). The larger the pitching moment is, the faster the movement in the direction of restoring the attitude is.
In the present embodiment, the drag and the pitching moment were measured by using a plurality of (five here) samples (artificial shuttlecocks 1) that had different bending angles θ (corresponding to the inclination angle) of the inclined portion 12a of the feather portion 12. Note that the sample with a bending angle of 0 degrees corresponds to the artificial shuttlecock 100 of the comparative example.
FIG. 7 is a diagram showing evaluation results for drag of the artificial shuttlecock 1. In this figure, the horizontal axis shows the bending angle (inclination angle), and the vertical axis shows the ratio of the relative drag if drag when the bending angle is 0 degrees is considered to 100. A normal wind tunnel test was conducted when performing the evaluation. Specifically, the artificial shuttlecock 1 was placed in the airflow of the wind tunnel device, and the drag acting on the artificial shuttlecock 1 was measured by a load cell. Also, in FIG. 7, a comparison is made measured value totals for angles of attack from 0 to 140 degrees at measurement intervals of 10 degrees.
As shown in the figure, samples that have a large bending angle θ also have high drag. This is because when the bending angle θ is large, the projected area at a high angle of attack is large, which increases the air resistance (drag).
FIG. 8 is a diagram showing evaluation results for the pitching moment of the artificial shuttlecock 1. In this figure, the horizontal axis shows the bending angle (inclination angle), and the vertical axis shows the ratio of the relative pitching moment if a pitching moment when the bending angle is 0 degrees is considered to 100. The method for evaluating the pitching moment was the same as in the case of drag described above.
In FIG. 8, there is almost no difference between the two samples that have a small bending angle θ, but it can be said that when the bending angle θ is large, the pitching moment improves due to an increase in drag. These results were used to calculate the bending angle (inflection point) at which the effect of an improvement in the pitching moment appears. In the present embodiment, calculation was performed to find the intersection of a straight line passing through two points where there is almost no difference in pitching moment (the bending angle θ is small) and a straight line passing through two points where the effect is achieved (the bending angle is large). As a result, the bending angle at which the effect appears was 9.6 degrees. Note that the method of calculating the inflection point is not limited to this. For example, the following method is also acceptable: increasing the number of samples (the number of set bending angles θ) for small bending angles θ and large bending angle θ, the intersection (inflection point) is obtained by using the least squares method or the like.

Confirmation of effect

The effect was confirmed using the above-mentioned five samples that had different bending angles θ. The effect was confirmed by a method of comparing hairpin net shots hit by three experienced badminton players. Specifically, all five samples were evaluated by a paired comparison method and scored. Note that the paired comparison method is a method in which two samples (a pair) are extracted, 1 point is given to a good sample, 0 points are given in the case of equivalency, and -1 point is given to a bad sample. All pairs were evaluated through round robin and statistically processed.
FIG. 9 is a diagram showing evaluation results of the effect confirmation test. In this figure, the horizontal axis shows the bending angle θ, and the vertical axis shows the evaluation score.
As shown in this figure, results close to the pitching moment were obtained. In other words, there was almost no difference between the two samples with a small bending angle θ, but the evaluation score increased as the bending angle θ increased.
Here, similarly to the case of the pitching moment described above, the bending angle (inflection point) at which the effect appears was calculated. Specifically, calculation was performed to find the intersection of a straight line passing through two points with a small bending angle and a straight line passing through two points with a large bending angle. As a result, the bending angle (inflection point) at which the effect appears was 12.2 degrees.
Based on the above results, it was confirmed that the artificial shuttlecock 1 of the present embodiment can have a higher drag and pitching moment than the artificial shuttlecock 100 (bending angle of 0 degrees) of the comparative example due to increasing the bending angle θ of the inclined portion 12a to a certain extent. Therefore, compared with the comparative example (sample with a bending angle of 0 degrees), the artificial shuttlecock 1 of the present embodiment can suppress unstable behavior when the attitude is greatly disrupted, making it possible to further stabilize the attitude.
Note that although the feather portion 12 is provided with the overlapping portion S in the present embodiment, the overlapping portion S may be omitted. In other words, adjacent feather portions 12 do not need to overlap each other in the width direction (the same applies to the following embodiments).

First Variation

FIG. 10A is a schematic view of an artificial feather 10a of a first variation as viewed from above. Also, FIG. 10B is a schematic view of a plurality of artificial feathers 10a arranged on the artificial shuttlecock 1 as viewed from above.
In the artificial feather 10a of the first variation, the feather portion 12 is inclined (bent) outward by an angle θ with respect to the virtual straight line N, at a position on the left side (downstream side in the rotation direction) of the feather shaft portion 14. In other words, on the side to the left of the feather shaft portion 14, the feather portion 12 has an inclined portion (inclined portion 12a) and a non-inclined portion (portion between the inclined portion 12a and the feather shaft portion 14).
Note that in the case of the first variation as well, the virtual straight line M is outward with respect to the virtual straight line N, on the left side (downstream side in the rotation direction) of the feather shaft portion 14.
For this reason, even in the artificial shuttlecock 1 of the first variation, the projected area is larger than that of the comparative example (artificial shuttlecock 100). Therefore, the attitude can stabilize more easily than in the case of the comparative example. Note that as shown in this figure, it is desirable that a length L1 of the inclined portion 12a when the feather portion 12 is viewed from above (on an extension of the axial direction) is longer than a length L2 of the non-inclined portion (in other words, the length L1 of the inclined portion 12a is longer than half of the length from the left end (downstream end in the rotation direction) of the feather portion 12 to the feather shaft portion 14). According to this configuration, the projected area is larger, and the attitude can be more stabile (the aerodynamic characteristics can be improved) in comparison with the opposite case (when L2 is longer than L1).
Note that the right end portion (overlapping portion S) of the feather portion 12 may be in contact with the adjacent feather portion 12. For example, the size of the feather portion 12 may be changed so as to come into contact with the adjacent feather portion 12. If adjacent feather portions 12 are in contact with each other in this way, it becomes easier to suppress rotation around the central axis during normal flight (at a low angle of attack). On the other hand, in the case of not coming into contact with the adjacent feather portion 12, the bending angle θ can be made larger, and therefore the projected area can be made larger.
Also, in the above-described embodiment, the bending angle θ (inclination angle) of the inclined portion 12a is constant regardless of the position in the vertical direction (axial direction). But the present invention is not limited to this, and the bending angle θ (inclination angle) may be different depending on the position in the vertical direction (axial direction). In particular, increasing the bending angle θ of the inclined portion 12a toward the upper side (tip side) in the vertical direction is effective in improving the aerodynamic characteristics. Also, in this case, since the bending angle θ is small on the side close to the base portion 2, the airflow entering the skirt portion 4 is not likely to escape to the outside.

Second Variation

FIG. 11 is a schematic view of an artificial feather 10b of a second variation as viewed from above.
As shown in this figure, in the artificial feather 10b of the second variation, the portion of the feather portion 12 on the right side (upstream side in the rotation direction) of the feather shaft portion 14 is curved in the front-back direction instead of being flat. In the case of the second variation as well, the inclined portion 12a is inclined outward with respect to the virtual straight line N, and the virtual straight line M is outward of the virtual straight line N on the left side (downstream side in the rotation direction) of the feather shaft portion 14.
As a result, the projected area is large, and the attitude can be stabilized (the aerodynamic characteristics can be improved), similarly to the above-described embodiment.

Third Variation

FIG. 12 is a schematic view of an artificial feather 10c of a third variation as viewed from above.
As shown in this figure, in the artificial feather 10c of the third variation, the right end portion of the feather portion 12 is bent inward (toward the back side). In the case of the third variation as well, the inclined portion 12a is inclined outward with respect to the virtual straight line N, and the virtual straight line M is outward of the virtual straight line N on the left side (downstream side in the rotation direction) of the feather shaft portion 14.
As a result, the projected area is large, and the attitude can be stabilized (the aerodynamic characteristics can be improved), similarly to the above-described embodiment.

Fourth Variation

FIG. 13 is a schematic view of an artificial feather 10d of a fourth variation as viewed from above.
As shown in this figure, in the artificial feather 10d of the fourth variation, the feather portion 12 is bent outward on the right side (upstream side in the rotation direction) of the feather shaft portion 14. In the case of the fourth variation as well, the inclined portion 12a is inclined outward with respect to the virtual straight line N, and the virtual straight line M is outward of the virtual straight line N on the left side (downstream side in the rotation direction) of the feather shaft portion 14.
As a result, the projected area is large, and the attitude can be stabilized (the aerodynamic characteristics can be improved), similarly to the above-described embodiment.

Second Embodiment

FIG. 14 is a schematic view of an artificial feather 10' of the artificial shuttlecock 1 of a second embodiment as viewed from above. The arrangement on the base portion 2 (not shown here) is the same as that of the first embodiment described above, and therefore will not be described.
The artificial feather 10' of the second embodiment includes a feather portion 12' and a feather shaft portion 14.
The feather portion 12' has a ground portion 12b and a protruding portion 12c. The ground portion 12b is the same member as the feather portion 120 of the comparative example (FIGS. 3 and 4), and is supported by the feather shaft portion 14. Also, the right end portion of the ground portion 12b (overlapping portion S) overlaps the inward side of the adjacent feather portion 12' (ground portion 12b).
The protruding portion 12c is provided so as to project outward from the outer surface of the ground portion 12b. Also, the protruding portion 12c is provided at a position overlapping the feather shaft portion 14 in the width direction (rotation direction).
As described above, the feather portion 12' of the second embodiment is provided with the protruding portion 12c on the outward side of the root portion 12b. As a result, in the second embodiment as well, the projected area at a high angle of attack is large, thus making it possible to suppress unstable behavior when the attitude is greatly disrupted, and the attitude can be more stable.
Note that the protruding portion 12c is not limited to being formed at the position described above. It is sufficient that the protruding portion 12c is formed at a position between the left end (downstream end in the rotation direction) of the feather portion 12' and the feather shaft portion 14. In other words, the protruding portion 12c may be provided on the left side (downstream side in the rotation direction) of the feather shaft portion 14. Note that if the protruding portion 12c is provided at a position overlapping the feather shaft portion 14 in the width direction (rotation direction) as in the present embodiment, the balance is improved and the feather shaft portion 14 can easily support the feather portion 12'.

Others

The above embodiments are to facilitate understanding of the present disclosure and are not in any way to be construed as limiting the present disclosure. The present disclosure may variously be changed or altered without departing from its gist and encompass equivalents thereof.

[Reference Signs List]

1: Artificial shuttlecock
2: Base portion
3: String-shaped member
4: Skirt portion
10, 10a, 10b, 10c, 10d, 10': Artificial feather
12, 12': Feather portion
12a: Inclined portion
12b: Ground portion
12c: Protruding portion
14: Feather shaft portion
14a: Feather support portion
14b: Calamus portion
100: Artificial shuttlecock (comparative example)
110: Artificial feather (comparative example)
120: Feather portion (comparative example)
S: Overlapping portion
M: Virtual straight line (first virtual straight line)
N: Virtual straight line (second virtual straight line)

Claims

A shuttlecock comprising:
a base portion; and

a plurality of artificial feathers arranged in an annular shape on the base portion,

the artificial feathers each including a feather portion and a feather shaft portion that supports the feather portion,

letting a rotation direction be a counterclockwise direction centered about a central axis of the shuttlecock in a view from a side opposite to the base portion,
a first virtual straight line being outward with respect to a second virtual straight line, on a downstream side of the feather shaft portion in the rotation direction,
the first virtual straight line being a line connecting a downstream end of the feather portion in the rotation direction and a central portion of the feather shaft portion,

the second virtual straight line being a line connecting an upstream end of the feather portion in the rotation direction and the central portion of the feather shaft portion.
The shuttlecock according to claim 1, wherein
the feather portion includes an inclined portion at a position between the downstream end of the feather portion in the rotation direction and the feather shaft portion,
the inclined portion being a portion that is inclined outward with respect to the second virtual straight line, and

in a view of the feather portion from an extension of an axial direction of the feather shaft portion,
a length of the inclined portion is longer than half of a length from the downstream end of the feather portion in the rotation direction to the feather shaft portion.
The shuttlecock according to claim 1 or 2, wherein
the feather portion includes an overlapping portion that overlaps an inward side of an adjacent feather portion, at a position on an upstream side of the feather shaft portion in the rotation direction, and

the overlapping portion of the feather portion is in contact with the adjacent feather portion.
The shuttlecock according to claim 1 or 2, wherein
the feather portion includes an overlapping portion that overlaps an inward side of an adjacent feather portion, at a position on an upstream side of the feather shaft portion in the rotation direction, and

the overlapping portion of the feather portion is not in contact with the adjacent feather portion.
A shuttlecock comprising:
a base portion; and

a plurality of artificial feathers arranged in an annular shape on the base portion,

the artificial feathers each including a feather portion and a feather shaft portion that supports the feather portion,

letting a rotation direction be a counterclockwise direction centered about a central axis of the shuttlecock in a view from a side opposite to the base portion,
the feather portion including a protruding portion between a downstream end of the feather portion in the rotation direction and a position overlapped with the feather shaft portion,
the protruding portion being a portion that protrudes outward from an outer surface.