US2815956A - Shuttlecocks - Google Patents

Description

' Dec. 10, 1957 c. J. LASHILEY 9 3 SHUTTLECOCKS Filed Jan. 31, 1955i nited Claims priority, application Great Britain December 14, 1954 8 Claims. (Cl. 273-106) This invention relates to an improved construction of shuttlecocks, in particular to an improved shuttlecock skirt of plastic construction.

Shuttlecock skirts made of plastic material in place of natural feathers are known. Such skirts are usually outwardly flared in conical shape, as in the case of the feathered shuttlecocks, and further may comprise a set of main stems arranged in similar manner to the stems of the feathers and adapted to perform the same function, namely to support and strengthen the vane part of the skirt. In an alternative construction the skirt may be of uniform thickness, for example of sheet material having holes formed in it.

The plastic must be of a resilient nature in order to avoid cracking or breakage during use and further, due to the relatively high density of the plastic compared with that of the feathers, the skirt is preferably of delicate lattice construction if the flight of a feathered shuttlecock is to be closely simulated.

As a result, the plastic skirt may not be so rigid as a feather skirt and though this may have certain advantages it can give rise to a serious disadvantage, namely a tendency for the skirt to turn inside out as a result of the sudden reversal of movement at the moment of impact with the racquet. This tendency is disadvantageous since it affects the flight of the shuttlecock from the racquet and, on occasion, the skirt may even remain in the inside out position.

It has now been found that this tendency for a plastic shuttlecock skirt to turn inside out can be substantially reduced if the skirt is constructed so as to be unbalanced with respect to the effect of torsional forces acting on it. Accordingly the present invention provides a shuttlecock skirt of resilient plastic material having a greater resistance to twisting in one direction about its axis than in the other.

The difference in resistance to twisting according to direction may be produced by a spiral arrangement of strengthening ribs or stems or of holes.

In a preferred embodiment of the invention a shuttlecock skirt of resilient plastic material comprises a set of main stems which spiral in one direction round the skirt.

As a result of this torsional asymmetry, the skirt is structurally unbalanced in the sense that if it is compressed axially, as happens when its motion is suddenly reversed on being struck by a racquet, the skirt tends to twist and crumple in the direction in which it is torsionally weaker. This is in contrast with the reaction of previously proposed skirts of symmetrical and structurally balanced design. These skirts, being equally resistant to torsional forces in either direction, have no inclination to twist and the forces which are applied to the skirt when the shuttlecock is struck mainfest themselves in a tendency for the skirt to turn inside out.

Where it comprises a set of spirally arranged main stems, the skirt is preferably of a lattice construction formed by inter-connection of the main stems by secondary stems or ribs.

atent The two types of members forming this lattice are preferably arranged substantially at right angles to each other and if the lead at which the main stems spiral is very coarse this condition is approximately satisfied if the secondary stems or ribs are in the form of rings or if they also are spirally arranged, but with a very fine lead, either in the opposite or even in the same direction as the main stems.

Preferably the spirally arranged main stems are formed in relief on the outer surface of the skirt so that when the shuttlecock is in flight the effect of the air flow over the stems is to cause the shuttlecock to spin.

In the accompanying drawings Figures 1 and 2 show a shuttlecock having a skirt of lattice structure comprising a set of spirally arranged main stems interconnected by closely spaced ring-like and spirally arranged ribs respectively.

In the figures the shuttlecock comprises generally a skirt 1 which is attached to cap 2 of the shuttlecock by means of a collar 3 formed at the narrow end of the skirt.

In each of the embodiments shown in Figures 1 and 2 the skirt comprises a lattice structure constituted by a set of main stems 4 which spring from the collar and spiral in one direction around the skirt. The lead of the main stems is very coarse and in tr e embodiments illustrated in Figures 1 and 2 the stems spiral approximately one-ninth of the way round the cone. In each of the Figures 1 and 2 embodiments, the main stems 4 are intersected and connected by ribs 5 (Figure l) or 6 (Figure 2) which extend around the skirt without the lead of the main stems 4, that is, more nearly in planes perpendicular to the longitudinal axis of the skirt than the main stems 4.

In Figure l the main stems 4 are interconnected by closely spaced circular rib 5 of lighter construction than the main stems to form a lattice. These ribs which lie at right angles to the air flow provide the main aerofoil effect of the skirt.

In Figure 2 the main stems are interconnected by spirally arranged ribs 6 which again are of lighter construction than the stems 4. The lead and pitch of the ribs is very fine, the ribs spiralling approximately 2%, times round the cone.

In both constructions illustrated in Figures '1 and 2 the stems and ribs interconnect approximately at right angles, the net effect being that the stems provide the main support for the skirt whilst the ribs provide the aerofoils in simulation of feathers. With this construction, the skirt is more easily twisted in the direction in which the stems spiral than in the opposite direction.

The main stems are triangular in section and are formed in relief on the outer surface of the skirt so that the effect of air flowing over the skirt is to cause the shuttlecock to spin. This spinning characteristic tends to improve the flight qualities of the shuttlecock.

Although in Figures 1 and 2 the skirt is uniformly of lattice structure, in other embodiments of the invention the ribs may be absent in the narrow end of the cone commencing only part way down towards the wider end of the cone.

The skirts of the present invention may be conveniently made by an injection moulding process using such materials as polythene, nylon or polyvinyl chloride.

In such a process the skirt may be formed in one piece with a cap which is subsequently covered with leather or a layer of rubber-like material to provide a surface suitable for impact with a racquet.

Shuttlecocks formed in accordance with the invention will include a skirt made up of a set of stem members 4 and a set of rib members 5 or 6, at least one of the sets of members, as shown in Figure 1, having its roots connected to the collar of the cap. In the Figure 1 construction, the rib members 5 are grown from the stem members 4 and start at a point above the collar or cap, but in the Figure 2 construction both the stem and rib members start in and are grown from the collar or cap.

The stem members 4 preferably are superimposed on the rib members 5 and 6 as shown, and may taper in width from their start ends. The stem members 4 preferably are formed with two facets 8 and 9, the facet 8 lying on the inside of the spiral and being set at an angle such that when in flight it acts as a guide to exert the maximum spin effect.

What is claimed is:

1. A shuttlecock skirt wider at one end than at its other end and having a collar at its narrower end, said skirt comprising a lattice structure constituted by a set of main stems extending from the collar to the wider end of the skirt and ribs intersecting the main stems, said main stems extending spirally in one direction around the longitudinal axis of the skirt and said ribs extending around said skirt more nearly in planes perpendicular to the longitudinal axis of the skirt than said main stems, said skirt being torsionally weaker in said one direction than in the opposite direction.

2. A shuttlecock skirt wider at one end than at its other end and having a collar at its narrower end, said skirt comprising a lattice structure constituted by a pinrality of ribs extending from the collar in a series of closely spaced spirals and main stems superimposed on and being connected by the ribs, said main stems commencing at the narrower end of said skirt and continuing to the wider end of the skirt in spirals opposite to the rib spirals and having a coarser pitch than the pitch of the rib spirals, said skirt being torsionally weaker in the direction in which said main stems extend spirally.

3. A shuttlecock skirt wider at one end than at its other end and having a collar at its narrower end, said skirt comprising a set of main stems with roots in the collar and extending in a spiral in one direction to the wider end of the skirt and each having at least one facet extending along the inside edge of the spiral, and ribs 4 intersecting and connecting the stems, said ribs being closely spaced to form with the stems a lattice structure, said ribs extending around said skirt more nearly in planes perpendicular to the longitudinal axis of said skirt than said main stems, said skirt being torsionally weaker in said one direction than in the opposite direction.

4. A shuttlecock skirt construction comprising a collar, a set of stem members, and a set of rib members, members of at least one of said sets of members having their starts end in the collar and extending from said collar in a spiral in one direction, and the members of the other of said sets extending around said skirt construction more nearly in planes perpendicular to the longitudinal axis of the skirt construction than the members of said one of said sets to intersect and connect the members of said one of said sets and form a substantially truncated cone shaped lattice structure torsionally Weaker in said one direction than in the opposite direction.

5. A construction as set forth in claim 4 in which each of the members of said other set of members is arranged in ring form.

6. A construction as set forth in claim 4 in which each of the members of the other set of members is arranged in spiral form.

7. A construction as set forth in claim 6 in which the members of said other set of members spiral in a direction opposite to the direction in which the members of said one set of members spiral.

8. A construction as set forth in claim 7 in which the members of said one set of members spiral at a coarser pitch than the members of the other set of members.

References Cited in the file of this patent UNITED STATES PATENTS D. 163,367 Carlton May 22, 1951 2,163,236 Collier June 20, 1939 2,626,806 Carlton Jan. 27, 1953 2,626,807 Carlton Jan. 27, 1953 2,632,647 Carlton Mar. 24, 1953 40 2,761,685 Lashley Sept. 4, 1956

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