WO2004010073A1

WO2004010073A1 - Tranquilliser dart

Info

Publication number: WO2004010073A1
Application number: PCT/GB2003/003267
Authority: WO
Inventors: Richard Ian Brydges-Price
Original assignee: Richard Ian Brydges-Price
Priority date: 2002-07-23
Filing date: 2003-07-23
Publication date: 2004-01-29
Also published as: GB0317231D0; GB0217064D0; AU2003246971A1; GB2393236B; GB2393236A

Abstract

A gun fired tranquilliser dart for safely delivering a drug to an animal provides greater accuracy and uses higher velocities with a flatter trajectory. A thin walled cylinder (1) forms the projectile body and defines a cavity housing a plunger (4). The cylinder has a flat, or blunt, front surface (1a). The front chamber (2) of the cavity includes the drug and the rear chamber (5) is pressurised by the firing gases through one-way valve (5a, 6). Injecting needle (7) projects forward with a displaceable sheath (8) covering discharge ports (9). A cuff (10) forms a retention barb. On target penetration the sheath is moved back to open ports (9) and the dose is delivered by the pressure gases in chamber (5).The dart is fired with a high spin rate which, in conjunction with the blunt front end gives stability and accuracy.

Description

Title:

TRANQUILLISER DART

This invention relates to a tranquilliser dart primarily for delivering a dosage of a drug or other substance to an animal from a distance using a gun or other launching device. In order that greater accuracy can be provided using a flatter trajectory launching at higher velocities is required. However the energy dissipated over a defined area at impact must not exceed certain levels. Impact energy is a function of velocity and mass. The energy to be dissipated is not simply kinetic energy but also relates to inertia. This can be explained by the perceived difference between a large heavy bullet fired at low velocity and a small lighter bullet fired at higher velocity, whilst the calculated kinetic energy may be the same the effect at a target is demonstrably different and relates to the inertia involved and the target material.

It is a primary object of this invention to provide for greater accuracy with a flatter trajectory using higher velocities with a projectile having reduced mass and a larger frontal surface area.

In accordance with a first aspect of this invention there is provided a projectile, primarily for delivering a substance into a target, the projectile comprising:

a) a hollow cylindrical body with a substantially planar front end surface, as hereinafter defined, and a rear end surface defining a cavity, b) the said front end surface having a forwardly projecting target penetrating needle with a discharge aperture adjacent the tip thereof communicating through a channel in the needle with the cavity, c) a plunger located within the cavity for longitudinal displacement with one side delimiting a forward chamber to receive the said substance, the chamber communicating through the channel in the needle with the tip aperture, d) the other side of the plunger delimiting a rearward chamber to receive a pressure gas medium, and e) displaceable closure means over the needle discharge aperture. The projectile is adapted for discharge from a gun or other launching device with the rear end surface of the body subject to a propulsive gas medium, impact with a target displacing the closure means over the needle aperture to release the substance through forward movement of the plunger effected by the pressure gas medium.

As used herein the term "planar" is intended to refer to not only a true flat front surface of the cylindrical body but also to surfaces which may have a small forward projection and those which present a blunt frontal surface, this being in contrast to known projectiles which hitherto have been designed with a streamlined or ogival front nose

Advantageously the propulsive firing gases are utilised to pressurise the rearward chamber during the firing operation. A valve means may be incorporated into the rear end surface of the cylinder to permit passage of the firing gases for storage within the rearward chamber.

A feature of this construction is the planar front end surface of the cylinder which has been found through test firings, and most surprisingly, to provide enhanced stability. The projectile is preferably fired from a rifled barrel or launch tube to impart spin. One or more drive bands may be included around the periphery of the cylinder in order to impart spin. The spin imparted may be higher than that used in conventional projectiles. Conventional projectiles are spun at about one turn in sixty centimetres whereas in this invention the preferred spin is one turn in twenty centimetres. The length to diameter ratio of the cylinder is about 2 : 1 (L = 2D). The cylinder is characterised by a thin walled construction providing lightness of weight. The substance to be delivered may be in a gel-like form.

The rear end of the cylinder may also be planar. The calibre of the projectile may be of "twelve bore" being 18.3 mm diameter In accordance with this invention there is also provided a projectile, primarily for delivering a substance into a target, comprising: a) a hollow cylindrical body with a forward facing substantially planar front end surface defining a cavity, b) the said front end surface having a forwardly projecting target

penetrating needle with a discharge aperture adjacent the tip

thereof, communicating through a channel in the needle with the

cavity, c) a plunger located within the body and delimiting a forward chamber to receive the said substance and communicating through the channel in the needle with the tip aperture, d) a rearward end of the body connected with one end of a hollow shaft having reduced diameter relative to the said body, e) the other end of the shaft connecting with a tail having a diameter substantially the same as the body, f) an opening in the tail communicating with the interior of the hollow shaft through a one way valve,

g) displaceable closure means over the needle discharge aperture; The projectile is adapted for discharge from a launching device with the tail subject to a propulsive gas medium which pressurises the rear side of the plunger through the valve and the shaft, impact with a target displacing the closure means over the needle aperture to release the substance through forward movement of the plunger.

Preferably the junction between the body and the shaft is of reduced diameter with a waist portion. The diameter of the body and the tail will conform to the calibre of the weapon although a sub-calibre construction may be adopted using a discarding sabot.

Further features of this invention will be described an illustrated by way of examples and illustrated in the accompanying drawings, wherein: Fig. 1 shows a diagrammatic cross-section of a dart forming a first embodiment of this invention, Fig. 1 a is a modification of the embodiment of Fig. 1 ,

Fig. 2 shows a diagrammatic cross-section of a dart forming a second embodiment of this invention, Fig. 3 shows the embodiment of Fig. 2 after impact,

Fig. 3a shows the modification Fig 1a including features of the embodiment shown in Figs. 2 and 3, and Fig. 4 shows a further embodiment in side view and the dissembled components thereof.

Referring to Fig. 1 and 1a of the drawings the principle behind the improved tranquilliser dart is to offer greater accuracy and a flatter trajectory. This requires the projectile to be launched at a higher velocity, but in doing so the energy per unit area at the target must not exceed values achieved with currently used darts. Impact kinetic energy and inertia must therefore be minimised and thus the impact area must therefore be maximised.

Impact energy is a function of impact velocity and projectile mass. Because it is necessary to maximise dart velocity to achieve higher accuracy and flatter trajectory it is therefore necessary to minimise projectile mass, Minimum mass is achieved by optimising the projectile length and diameter and by making the dart from strong lightweight materials, such as plastics or light metals such as aluminium or their alloys. Thus the dimensions of the body of the dart (1) are selected to give the correct length to diameter to give the minimum mass for a given payload. In a typical embodiment the ratio of length to diameter is 2 : 1.

A feature of the construction according to this invention is the flat or blunt front surface 1a of the body 1. Conventionally such a surface would be thought to have poor ballistic characteristics leading to disruptive instability particularly in the present application. However it has been found that this construction produces excellent and unexpected results especially where high rates of spin are used and gives good stability and accuracy at longer ranges than know darts. Energy is also dissipated in a more favourable way following impact. To achieve further aerodynamic stability of the dart the tail (3) ensures that the centre of pressure is behind the centre of gravity. This is effected in Fig. 1 by providing a flat tail end surface which has been found to give the required stability with a spin stabilised projectile. The tail part (3) may be joined to the body (1) by a shaft (5b) as shown in Fig. 1a. Upon impact with the target the payload is injected by means of a plunger (4). This is forced forwards by high gas pressure in the reservoir (5). The reservoir (5) is pressurised by the propellant gases through a valve (6) located in a rear aperture (5a) in the body (5), as in Fig. 1 , or in the shaft portion (5b), as in Fig. 1a, as the dart is passing down the barrel of the gun from which it is fired. The one way valve (6) allows gas into the reservoir during firing and maintains the pressure. To seal the payload cavity (2) a side ported forward projecting hollow injecting needle (7) is used of which the port or ports (9) are closed using tight fitting displaceable slide tube (8). Upon striking the target the needle penetrates into it and the tube (8) is pushed rearwards or detaches from the needle to uncover the side ports (9) to allow the payload to be injected. A cuff on the needle (10) provides resistance to prevent the dart falling from the target. The cuff (10) may be formed from a soluble material, such as gelatine, which will dissolve or soften to allow the projectile to detach from the target. To aid loading and for checking complete injection of the payload (2) the dart body (1) can be made from transparent material or a window may be provided. If required, to release the pressure in the reservoir (5) the one way valve (6) can be pushed forward to release any stored propellant gas.

In the embodiment shown in Figs. 2 and 3 to seal the payload cavity (2) a side ported needle (7) is used which is sealed with tight fitting tube (8) extending forwardly beyond a deformable squash head (11). The head is designed to have a generally large and almost flat or blunt frontal surface. Upon striking the target the needle penetrates into it and the tube is pushed rearwards to uncover the side ports (9) to allow the payload to be injected. The squash head collapses and expands sideways absorbing impact energy and increasing the impact area. A cuff on the needle (10) provides resistance to prevent the dart falling from the target. The squash head may comprise a deformable plastics material, being either resilient or capable of being squashed into a more flattened form increasing the frontal area. The arrangement shown in Fig. 3a is similar to that of Figs 2 and 3 but includes the tail of the Fig. 1a embodiment.

A feature of this invention is the large generally flat frontal area and the cylindrical body shape dimensioned and arranged to give stability. The construction described has proved to achieve the objects of this invention as regards accuracy of the trajectory and stability providing greater effective

range.

In the embodiment of Fig. 4 the tail (3) is joined through the shaft (5a) to the body (5) and the junctions (5c) are tapered with the angle of the taper of the front junction being typically 45 degrees and arranged to smooth air flow and reduce turbulence. An opposed reaction force thus compensates yaw tendency. The angle of the rear taper junction is less than that of the front being typically 30 degrees to the longitudinal axis. The differing tapers have been found to assist ballistic stability The body, the shaft and the tail may be of one-piece construction with the valve (6) being incorporated into a separate insert (6a) which locates within the tail 5a. A drive band may seat in a forward groove (5d).

This invention is thus provides a gun fired tranquilliser dart for safely delivering a drug to an animal which provides greater accuracy and uses higher velocities with a flatter trajectory. A thin walled cylinder 1 forms the projectile body and defines a cavity housing a plunger 4. The cylinder has a flat, or blunt, front surface 1a. The front chamber 2 of the cavity includes the drug and the rear chamber 5 is pressurised by the firing gases through one-way valve 5a, 6. Injecting needle 7 projects forward with a displaceable sheath 8 covering discharge ports 9. A cuff 10 forms a retention barb. On target penetration the sheath is moved back to open ports 9 and the dose is delivered by the pressure gases in chamber 5. The dart is fired with a high spin rate which, in conjunction with the blunt front end gives stability and accuracy.

Claims

CLAIMS:

1. A projectile, primarily for delivering a substance into a target, the projectile comprising: a) a hollow cylindrical body with a substantially planar front end 5 surface and a rear end surface defining a cavity, b) the said front end surface having a forwardly projecting target penetrating needle with a discharge aperture adjacent the tip thereof communicating through a channel in the needle with the cavity, o c) a plunger located within the cavity for longitudinal displacement with one side delimiting a forward chamber to receive the said substance, the chamber communicating through the channel in the needle with the tip aperture, d) the other side of the plunger delimiting a rearward chamber to s receive a pressure gas medium, and

e) displaceable closure means over the needle discharge aperture.

2. A projectile in accordance with claim 1 , for discharge from a gun or other launching device with the rear end surface subject to a propulsive gas medium, impact with a target displacing the closure means over the needle aperture to o release the substance through forward movement of the plunger effected by the pressure gas medium.

3. A projectile, primarily for delivering a substance into a target, comprising: a) a hollow cylindrical body with a forward facing substantially planar front end surface defining a cavity, b) the said front end surface having a forwardly projecting target penetrating needle with a discharge aperture adjacent the tip thereof, communicating through a channel in the needle with the

5 cavity, c) a plunger located within the body and delimiting a forward chamber to receive the said substance and communicating through the channel in the needle with the tip aperture, d) the other side of the plunger delimiting a rearward chamber to o receive a pressure gas medium, e) a rearward end of the body connected with one end of a hollow shaft having reduced diameter relative to the said body, f) the other end of the shaft connecting with a tail having a diameter substantially the same as the body, and s g) displaceable closure means over the needle discharge aperture.

4. A projectile in accordance with claim 3, wherein the projectile is adapted for discharge from a launching device with the tail subject to a propulsive gas medium, impact with a target displacing the closure means over the needle aperture to release the substance through forward movement of the plunger. o

5. A projectile in accordance with any preceding claim, wherein the propulsive firing gases are utilised to pressurise the rearward chamber during the firing operation.

6. A projectile in accordance with claim 5, wherein a valve means is incorporated into the rear end surface of the cylinder or a tail connected therewith to permit passage of the firing gases for storage within the rearward chamber.

7. A projectile in accordance with any preceding claim and adapted to be fired from a rifled barrel or launch tube to impart spin, wherein one or more

5 drive bands are provided around the periphery of the cylinder in order to impart spin.

8. A projectile in accordance with claim 7, wherein the spin imparted is between one turn in sixty centimetres and one turn in twenty centimetres.

9. A projectile in accordance with any preceding claim, wherein the length o to diameter ratio of the cylinder is about 2 : 1 (L = 2D).

10. A projectile in accordance with any preceding claim, wherein the cylinder is characterised by a thin walled construction.

11. A projectile in accordance with any preceding claim, wherein the substance to be delivered is in a gel-like form. s

12. A projectile in accordance with any preceding claim, wherein the rear end of the cylinder is planar.

13. A projectile in accordance with any preceding claim, wherein the calibre of the projectile is of "twelve bore" being 18.3 mm diameter.

14. A projectile in accordance with any preceding claim, wherein the o cylindrical body is connected to a tail through a shaft of reduced diameter

forming a waist portion.

15. A projectile in accordance with claim 14, wherein the junctions between the body and the shaft and the shaft and the tail are conically tapered.

16. A projectile in accordance with claim 15, wherein the degree of conical taper of the junction between body and shaft is greater than that between shaft and tail relative to the longitudinal axis.

17. A projectile in accordance with claim 16, wherein the angles of taper are respectively 45 degrees and 30 degrees.

18. A projectile in accordance with any preceding claim and a firing device for the projectile, the projectile incorporating a peripheral drive band or bands and the firing device including a rifled bore.

19. A projectile and a firing device for the projectile in accordance with claim 16, wherein the rifling pitch is less than one turn in sixty centimetres and is preferably one turn in twenty centimetres.

20. A projectile as described herein with reference to, and as shown by, Fig. 1, or Fig. 1a, or Figs. 2 and 3, or Fig. 3a, or Fig. 4 of the drawings.