GB2219219A - Flights for projectiles, e.g. darts - Google Patents

Abstract

A dart flight comprises a plurality of vanes which have been formed into a helical shape by the application of heated formers (Figures 9-12). The dart flight is rigidly fixed to the dart barrel, such that the forward movement of the dart generates the required air flow to cause the flight and hence the rigidly connected inertial mass of the dart to rotate and thereby improving its stability. <IMAGE>

Description

SS I!PkOVED PROJECTILE FLIGHT AND A METHOD OF MANUFACTURING SAME This invention relates to an improved projectile flight more particulary but not exclusively a flight for a dart, and a method of manufacturing same.

UK Patent Number 589,208 teaches that to arrange the vanes of dart flights at an angle to their longitudinal axis will cause the dart flight to rotate. This has its limitations because the mass of the projectile is not rotating and hence will not contribute to its own stability. Also the vanes of the flights are individually manufactured and fitted.

An object of the present invention is to provide an improved flight which when fitted to a projectile such as a dart rotates the mass of the projectile thus increasing its stability during flight and enables a more accurate aim to be achieved.

According to one aspect of the present invention there is provided an improved flight for a projectile, comprising a plurality of radially projecting vanes which are curved so that they follow a helical path.

According to another aspect of the present invention there is provided an improved flight for a projectile, comprising a plurality of radially projecting vanes which are bent so that they form a helical angle. Preferably, the projectile is a dart.

According to another aspect of the invention there is provided a method of manufacturing a flight for a projectile, comprising a heart shaped construction of layers of laminated plastic material, flattening the layers by spreading them away from each other and placing them between the shaped faces of a pair of formers, closing the formers and applying heat to the or each former to set the laminated layers into the curved or bent shape.

The heat to the formers to effect a thermosetting or thermoforming process is conveniently supplied by hot water, steam, hot air or electrically heated.

In one arrangement the pair of formers have an 'S' shaped face.

In an alternative arrangement the pair of formers have an shaped face.

Embodiments of the projectile flight and embodiments of a method of manufacturing a projectile flight according to the invention, will now be described by way of example only, with reference to the accompanying drawings, in which: Fig 1 is the side elevation of a projectile comprising curved flights that rotates in a clockwise direction.

Fig 2 is the side elevation of a projectile comprising curved flights that rotates in an anti-clockwise direction.

Fig 3 is a side elevation of a flight with bent helical angles.

Fig 4 is a plan view of the flight shown in fig 3.

Fig 5 is an auxiliary view of the flight shown in fig 3.

Fig 6 is a front elevation of a flight according to the invention.

Fig 7 is a plan view of the flight shown in fig 6.

Fig 8 is a plan view of the flight in a folded position prior to the shaping step.

Fig 9 is a diagrammatic view -of a pair of shaping formers with the flight of figure 8 placed between them.

Fig 10 is a plan view of the lower former shown in fig 9.

Fig 11 is an exploded perspective view of an alternative pair of formers to those shown in figs 9 and 10 and Fig 12 is a vertical section through the formers shown in fig 11 with the flight between them.

Referring first to figure 1 a dart is shown having a body 1, shaft 3 and flight 5 connected to shaft 3 by cross slots 7. The flight 5 contains in this instance 4 vanes curved in a right hand spiral.

As the dart progresses, air hitting the curved vanes 5 will cause a perpendicular force to be set up on the surface of the vanes 5 thus causing the projectile body 1 to rotate in the direction of the perpendicular force in proportion to the curvature of the vanes. Arrows on the vanes indicate curvature.

Figure 2 shows a similar arrangement to figure 1 but opposite in as much as the flight 9 is curved in a left hand spiral thus causing anti-clockwise rotation of the projectile.

Referring now to figures 3, 4 and 5 the projectile flight comprises in this example four radially projecting vanes 11 bent at a helical angle (P) to the axis 13 of the flight and the amount of bend depicted by the angle (e). The peripheral shape of vane A is denoted by the thick black line 15. The angle (ç) may be bent in the opposite direction to make the flight rotate in the opposite direction.

As the flight progresses, air hitting the bent portion 17 of the vane 11 will cause a perpendicular force to be set up on the surface of the vane 1 thus causing the flight to rotate (and hence the projectile) the amount of rotation being in proportion to the angles (P) and ().

Referring now to fig 6 onwards, the projectile flight comprises four radially projecting vanes 19 which are formed from shaped laminated sheets of a plastic material such as polyester. The shaped sheets of plastics material are bent into right angles and secured to adjacent sheets by an adhesive. The radially projecting vanes 19 are then folded in the direction of the arrows "C", as shown in Figure 7, so that they become a flat layer of four laminated sheets, as shown in Figure 8. The flattened flight is then placed between a pair of formers 23 and 25 see Figure 9, having an undulating shaped face 27 in the form of an 'S' to provide a right hand helical curve to the vanes 19.

One or both of the formers 23 and 25 are heated to shape the laminated flight into a permanent curve.

Figure 10 shows a plan view of the lower former 25 which is shaped with curved surfaces 37 arranged at an angle (F) to the longitudinal axis 39 of the flight to produce the helical curve to the flight vanes.

The shaped flight is removed from the heated formers and the vanes 19 opened into a radial formation such that they follow a helical path.

An alternative embodiment of the formers shown in Figures 9 and 10 is illustrated in Figures 11 and 12. This embodiment comprises an upper former 29 having four quadrants 31 which mate with a lower former 33 shaped with four scalloped quadrants 35.

The radially projecting vanes are not folded as in the first embodiment but are each slotted into one of the four quadrants 31 of the upper former 29. The two halves of the former are mated with the curved edges of the flight being sandwiched between the upper and lower formers, as shown in Figure 12. Heat is applied to the formers, which may be supplied by hot water, steam, hot air or electrically heated to carry out a thermosetting or thermoforming operation on the plastic laminated vanes 19 of the flight. The foregoing method of manufacturing would be the same for flights that have helical angles formed by bent flaps as shown in figures 3, 4 and 5 except the formers of whichever embodiment would be shaped to suit.

In addition to the rotational orientation imported to a dart, fitted with the flight of the present invention, during it's flight path, the curved ends of the vanes provide a resilient surface if struck by a following dart which, with conventional dart flights often cause the following dart to rebound and fall to the ground without scoring. The resilience of the curved vanes of the improved flight deflects the path of the following dart to permit it to continue and strike the dartboard, this will also enable close grouping of two or more of the darts. Although the two methods of manufacturing the flight hereinbefore described are by heating and shaping laminated sheets of plastics material using formers, it will of course be possible to mould the flights from a plastics material by an injection moulding process.

Claims (5)

1. AN IMPROVED PROJECTILE FLIGHT

   AND A METHOD OF MANUFACTURING SAME CLAIMS What we claim is: 1. A one piece flight containing a plurality of vanes which have been formed into a helical shape.
2. 2. A flight as in claim 1 which when attached to a projectile such as a dart will cause the dart and its inherent inertial mass to rotate.
3. 3. A flight as in claim 2 which has been manufactured by the application of heated formers.
4. 4. A dart having a helical flight substantially as herein described and illustrated.
5. 5. A flight constructed substantially as herein described with reference to the accompanying drawings.