US3913917A

US3913917A - Stabilisers

Info

Publication number: US3913917A
Application number: US491800A
Authority: US
Inventors: Philip Coxon
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-07-25
Filing date: 1974-07-25
Publication date: 1975-10-21
Anticipated expiration: 1992-10-21

Abstract

A flight for a missile such as a dart comprising a shaft having a number of vanes extending radially therefrom, each vane comprising a number of vane components which extend in a plane transverse to the longitudinal axis of the shaft. The flight may be formed in a plurality of vane carrying parts, each part having at least one vane and a formation whereby it may be secured to a shaft or a portion of a shaft.

Description

United States Patent [191 Coxon Oct. 21, 1975 1 1 STABILISERS {76] Inventor: Philip Coxon, 4 York Road, Kings Heath, Birmingham, England, B14 7R2 [22] Filed: July 25, 1974 [21] Appl. No.: 491,800

{52] US. Cl 273/1065 C [51] Int. Cl. A63B 65/02 [58] Field of Search 273/1065 C, 1065 R [56] References Cited FOREIGN PATENTS OR APPLICATIONS 590,842 7/1947 United Kingdom 273/1065 C 272,658 6/1927 United Kingdom 273/1065 R 556,805 10/1943 United Kingdom 273/1065 C 4/1940 United Kingdom 273/1065 C 10/1939 United Kingdom 273/1065 R Primary Examiner-Paul E. Shapiro Attorney, Agent, or Firm-Miller, Frailey & Prestia [57] ABSTRACT A flight for a missile such as a dart comprising a shaft having a number of vanes extending radially therefrom, each vane comprising a number of vane components which extend in a plane transverse to the longitudinalaxis of the shaft. The flight may be formed in a plurality of vane carrying parts, each part having at least one vane and a formation whereby it may be secured to a shaft or a portion of a shaft.

6 Claims, 5 Drawing Figures U.S. Patent 0(121. 1975 3,913,917

STABILISERS Conventionally, dart flights comprise radially extend- 7 ing vanes of natural feather flumes bonded to a wooden shaft which includes a spigot portion to be received in a socket of a threaded intermediate member. Such flights are favoured by darts players but they are expensive due to the use of natural materials and the relatively time consuming fabrication techniques used in their production. They are also fragile and have a limited useful life. Furthermore, supplies of natural feathers are limited thus limiting the supply of such flights.

Attempts have been made to replace the natural feather dart flights with synthetic plastics materials but these have not gained acceptance with more discerning darts players despite being generally tougher and easier to manufacture.

One example of a synthetic dart flight comprises an integral shaft, vanes and threaded member injection moulded from a plastics material such as polyethylene. Other examples include stems of wood, plastics or fibre-glass" having slots therein to receive separate vane members of paper; sheet plastics, such as polyester film; and sheet fibre-glass." Such dart flights have not, however, proved as satisfactory as those made from natural feathers.

According to one aspect of the present invention a flight for a missile such as a dart comprises a shaft having a number of vanes extending radially therefrom, each vane comprising a plurality of vane components which extend in a plane transverse to the longitudinal axis of the shaft.

Conveniently, the flight comprises four radially distributed vanes.

Adjacent vane components may be connected together by a web extending over all or a portion of their radial length but it is preferred that the vane components are spaced apart and attached to the shaft only. This enables the vane components to be readily deflected by another dart striking the vane components.

The vane components are desirably angled so that the leading edges thereof lie at an obtuse angle relative to the longitudinal axis of the shaft.

Advantageously, the flight is formed in a plurality of vane carrying parts, each part comprising at least one vane and a formation whereby it may be secured to a shaft or a portion of a shaft. In a preferred embodiment the flight is moulded in two parts, each part comprising a pair of vanes, which, advantageously, are diametrically opposed vanes.

One part of the flight may include a slot into which a cooperating portion on a second part can be retained. The slot and co-operating portion may be an interference fit and/or may have features which increase friction therebetween or which provide a measure of interlocking to prevent accidental longitudinal displacement of the assembly.

In addition to the friction inducing or interlocking features, if provided, it is preferred that at least one longitudinally extending bearing surface is provided in order to prevent displacement transverse to the longitudinal axis of the shaft.

If desired, of course, the mechanical securement of the parts of the flight can be supplemented or replaced entirely by the use of a suitable adhesive.

In one form of the invention the shaft is moulded with two diametrically opposed vanes, the shaft having a longitudinally extending slot which is closed at one end. The other part of the flight comprises two diametrically opposed vanes connected by a web which is adapted to be received in the slot by sliding it therein from the open end. Suitable bearing surfaces may be provided to prevent transverse displacement of the web from the slot and, if desired, friction inducing or interlocking features may also be provided.

The slot may be open at the front or rear of the shaft. Where the slot is open at the front, after assembly, it may be closed by an intermediate portion which enables the flight to be secured to the body of a dart of, the intermediate portion may be integral and the slot closed by the body of the dart. Where the slot is open at the rear it may be, if desired, closed by an end cap.

The invention is hereinafter more particularly described with reference to the accompanying drawings, in which:

FIG. 1 is a schematic side elevation of a dart flight according to the invention;

FIG. 2 is a schematic end elevation of the dart flight shown in FIG. 1;

FIG. 3 is a cross-section on the line 33 in FIG. I on an enlarged scale;

FIG. 4 is a cross section of a portion of the length of the dart flight showing an arrangement of; and

FIG. 5 is a cross section on an enlarged scale of a blade of the flight shown in FIG. I.

In the embodiment shown in FIG. 1, the flight consists of a shaft 10 having a plurality of spaced parallel angled blades 11 arranged in four radially spaced

sets forming vanes

12a and 12b. The blades 11 have a cross section and are arranged as shown in FIG. 4.

The shaft 10 is formed in two coaxial parts; the first part includes an axially extending transverse slot having a central ridge portion 14; the second part comprises an axially extending transverse web 10b which is an interference fit in the slot of part 100. The slot is closed at 15.

The first part 100 of the shaft carries the blades which form vanes 12a and the second part 10b carries the blades which form vanes 12b. Each part and its associated blades are moulded as an integral unit and the two parts assembled by sliding the shaft part 10b into the slot of shaft part 10a. The central ridge portion 14 prevents lateral relative movement of the two parts and the integral end portion 15 forms an end stop.

The shaft portion or spigot 10a has a screw threaded portion 17 which can be screwed into a conventional dart body. In this position the two

parts

10a and 10b of the shaft are held together. To facilitate screwing the flight into a dart body there are provided radially extending

flanges

18a and 18b.

In an alternative embodiment the end of the shaft 10 is a plain cylinder for insertion into a conventional intermediate member having a socket to receive the cylindrical end of shaft 10 and a screw-threaded portion for engagement with a dart body. The shaft is a tight interference fit in the socket and thus the flight is maintained in its assembled state.

In a further alternative embodiment the end stop for the slot is located at the leading end of the shaft and the slot communicates with the other end to permit assembly of the two parts. The assembly is maintained by the interference fit but if the materials do not provide sufficient friction then friction-inducing means and/or interlocking means may be provided.

Alternatively, or in addition, a cap which fits over the end of the shaft may be provided; the cap may have a formation which interlocks with a formation on the shaft.

FIG. 5 shows an alternative cross section of a blade.

It will be apparent that the embodiments described above may be modified within the scope of the invention. For example, alternative means may be provided to prevent relative transverse movement of the shaft parts. Furthermore any suitable number of vanes may be used although four is preferred. The end of the shaft or the intermediate member, when used, may have an interference fit spigot instead of a screw-threaded spigot for insertion and engagement with a dart body.

The flights may be moulded from a suitable plastics material, e.g. polyethylene, polypropylene, ABS or nylon. The material may be pigmented and, if desired the two parts may be of different colours.

What we claim is:

l. A flight for a dart comprising a shaft having a number of vanes extending radially therefrom, said shaft comprising a first shaft part and a second shaft part, the first shaft part having a longitudinally extending slot with an open end and the second shaft part having a formation for locating in said slot with spaced surfaces disposed externally of the slot, said shaft parts having cooperating formations whereby the shaft parts are located against transverse movement, each shaft part bearing at least one radially extending vane comprising a plurality of vane components, and the shaft having a spigot portion at the end of the shaft adjacent the open end of the slot, said spigot portion having securing means whereby it may be secured to a dart body.

2. A flight as defined in claim 1 in which the spigot portion has a screw thread whereby it may be secured to a dart body.

3. A flight as defined in claim 1 in which each shaft part carries a pair of diametrically opposed vanes.

4. A flight as defined in claim I in which the cooperating formations for locating the shaft parts against transverse movement comprise a ridge on one of said shaft parts and a corresponding recess on the other shaft part.

5. A flight as defined in claim 1 in which the slot is formed transversely of the first shaft part and the external surfaces of the second shaft part are spaced diametrically of the shaft.

6. A flight as defined in claim 1 in which a. the slot is formed transversely of the first shaft part,

b. the two shaft parts are coaxial,

c. the external surfaces of the second shaft part are spaced diametrically of the shaft,

d. each shaft part carries a pair of diametrically opposed vanes, and

e. the cooperating formations of the shaft parts comprise a ridge on one shaft part and a corresponding recess on the other shaft part to lock the two parts against transverse movement.

i t l

Claims

1. A flight for a dart comprising a shaft having a number of vanes extending radially therefrom, said shaft comprising a first shaft part and a second shaft part, the first shaft part having a longitudinally extending slot with an open end and the second shaft part having a formation for locating in said slot with spaced surfaces disposed externally of the slot, said shaft parts having cooperating formations whereby the shaft parts are located against transverse movement, each shaft part bearing at least one radially extending vane comprising a plurality of vane components, and the shaft having a spigot portion at the end of the shaft adjacent the open end of the slot, said spigot portion having securing means whereby it may be secured to a dart body.

4. A flight as defined in claim 1 in which the cooperating formations for locating the shaft parts against transverse movement comprise a ridge on one of said shaft parts and a corresponding recess on the other shaft part.

6. A flight as defined in claim 1 in which a. the slot is formed transversely of the first shaft part, b. the two shaft parts are coaxial, c. the external surfaces of the second shaft part are spaced diametrically of the shaft, d. each shaft part carries a pair of diametrically opposed vanes, and e. the cooperating formations of the shaft parts comprise a ridge on one shaft part and a corresponding recess on the other shaft part to lock the two parts against transverse movement.