GB2211430A

GB2211430A - Dart flights

Info

Publication number: GB2211430A
Application number: GB8708888A
Authority: GB
Inventors: John Francis Harris; Colin John Harris; Ronald William Woodhead
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-04-14
Filing date: 1987-04-14
Publication date: 1989-07-05
Anticipated expiration: 2007-04-14
Also published as: GB2211430B; GB8708888D0

Abstract

A plastics dart flight is embossed with both elongate formations (e.g. V-shaped formations 5 and 6) and non-elongate formations (e.g. circular or polygonal formations 4). <IMAGE>

Description

"Improvements in Dart Flights" This invention relates to an improved dart flight and is especially directed to dart flights formed from a thin sheet of plastics material which is folded, with adjacent sides thereafter being brought together and adhered so as to form a flight having a cruciform cross-section.

In GB 2166059A there is described and claimed a dart flight formed from a thin plastics material wherein a surface of the flight is embossed, the embossing comprising a plurality of discrete small areas. Preferably the discrete areas are circular or polygonal in plan form and this construction has certain advantages, being improved rigidity and better aerodynamic properties than prior constructions.

It is also known from GB 628041 and 514085 to produce moulded dart flights having corrugations for the purposes of imparting greater rigidity. Such corrugations, however, do not impart any advantages to aerodynamic properties and can have the effect of increasing drag to the point where the flight becomes useless in practical terms.

According to this invention there is provided a dart flight formed from a thin plastics material and wherein the surface of the flight is embossed, the embossing on a flight surface

comprising in part a plurality of discrete small areas and

impart corrugations.

In a preferred construction the outboard portions of a wing of the flight are embossed with the aforsesaid plurality of discrete small areas comprising dimples and/or protuberances preferably being of circular or polygonal plan form0 The inboard areas of a wing of the flight are embossed with corrugations which form an angle relative to the longitudinal axis of the flight of 45 degress or less.

Surprisingly, it has been found that a combination of discrete areas and corrugations produces a flight having significantly improved aerodynamic properties and this is believed to be due to the effect of the discrete areas on the outboard portions of the wing imparting better characteristics to the flight and the corrugations on the inboard portions of the wing

serving to stabilize air flow and thustemBancing the aerodynamic properties.

The discrete areas to the outboard sides of the fin may comprise protuberances or recesses in accordance with 2166059A, and the corrugations on the inboard sections of the wing may be of V-shape with the apex of the V extending towards the leading edge of the flight. Preferably two or more V-shaped corrugations may be provided nested one within the other. The inboard corrugation may extend parallel to the longitudinal axis of the flight with the other limb of the V-shaped corrugation extending at some 30 degrees, preferably between 10 and 45 degrees.

The invention will be further described in conjunction with a preferred embodiment shown by way of an example only in the accompanying drawing.

The drawing shows a cruciform cross-section dart flight in side view with two opposed wings 1 and 2 shown in plan and a third wing 3 in edge view. As shown, each of the wings includes a series of discrete areas 4 comprising cylindrical protuberances extending to each side of the wing and provided on the outboard sections.

On the inboard side of the wing there is provided a series of corrugations,in the example shown there are two sets of Vshaped corrugations 5 and 6. The apexes of these V-shaped corrugations are indicated by 7 and 8 respectively. The inboard parts of the V-shaped corrugations extend parallel to the longitudinal axis of the flight.

This arrangement of using the cylindrical protuberances on the outboard sections of each fin and the corrugations on the inboard section have been found to provide distinct advantages.

The invention also provides a method of making a dart flight in which the flight after manufacture is deformed by passing same between co-operating male and female

dtes so as to simultaneously produce the discrete areas 4 and the corrugations 5 and 6.

In the construction described the ribbed V-shape corrugations provide strength and the protuberances and recesses in the outboard sides of the wings provide improved air flow.

Claims

1. A dart flight formed from a thin plastics material and wherein the surface of the flight is embossed, the embossing on a flight surface comprising in part a plurality of discrete small areas and in part corrugations.

2. A dart flight in accordance with Claim 1, wherein the outboard portions of a wing of the flight are embossed with said plurality of discrete small areas comprising dimples and/or protuberances preferably being of a circular or polygonal plan form.

3. A dart flight in accordance with Claim 1 or 2, wherein the inboard areas of a wing of the flight are embossed with corrugations which form an angle relative to the longitudinal axis of the flight of 45 degrees or less.

4. A dart flight in accordance with Claim 2 or 3, wherein the discrete areas on the outboard areas of the wing may comprise protuberances or recesses in accordance with Patent 2166059, and the corrugations on the inboard sections of the wing may be of V-shape with the apex of the V extending towards the leading edge of the flight.

5. A dart flight in accordance with Claim'4, wherein two or more V-shaped corrugations are provided nested one within the other.

6. A dart flight in accordance with Claim 5, wherein the inboard limb of the corrugation extends parallel to the longitudinal axis of the flight with the other limb of the V-shaped corrugation extending at some 30 degrees, preferably between 10 and 45 degrees.

7 A dart flight as described herein with reference to the drawings or as shown in the drawings.

8. A method of forming a dart flight according to any preceding claim in which the flight after manufacture is deformed by passing same between co-operating male and female dies so as to simultaneously produce the discrete areas and the corrugations.