GB2215015A

GB2215015A - Explosive projectile arming system

Info

Publication number: GB2215015A
Application number: GB8804187A
Authority: GB
Inventors: Charles Anthony Howard Knight
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-02-23
Filing date: 1988-02-23
Publication date: 1989-09-13
Anticipated expiration: 2008-02-23
Also published as: GB2215015B; GB8804187D0

Abstract

An arming system for a projectile (1) fired from a barrel of a gun comprises at least one port (6) in a side of the projectile (1). A collar (4) is attached at a muzzle end of the barrel to extend therefrom by a predetermined distance and provides a passageway for high pressure gas from the barrel to bypass the projectile as it exits from said barrel and act at the or one of the ports (6). Each port (6) is connected to a detonator of the projectile by delay means. The delay means may comprise a pyrotechnic fuse that is exposed to the gases by the set-back of a shutter on firing the projectile. Bore-riding pins close a flash-tube that connects the fuse to the detonator. The delay means may, alternatively, comprise a pair of parallel switches connected between a power source and the detonator, the first switch being closed in response to the gas pressure and the other being closed by time or distance delay means. A third, electro-mechanical, delay means, comprises a flywheel that is released by the application of gas pressure through the port(s) and rotates relative to the projectile to close a switch. The flywheel comprises steel balls impregnated with plastics and adapted to burst into fragments upon detonation of the projectile. <IMAGE>

Description

EXPLOSIVE PROJECTILE ARMING SYSTEM The present invention relates to an arming system for an explosive projectile, and more particularly, an arming system actuated by high pressure gas from the barrel of the gun being applied to the projectile as it leaves the gun. It is often desirable that a projectile fired from a gun is safe whilst in the gun and beforehand, but is armed after leaving the gun to detonate after a predetermined time interval or after a predetermined distance travelled.

It is an object of the present invention to provide an arming system of this type utilising the propulsion gases from the gun.

According to the present invention there is provided an arming system for a projectile fired from a barrel of a gun comprising at least one port in a side of the projectile, a collar attached at a muzzle end of the barrel to extend therefrom by a predetermined distance and providing a passageway for high pressure gas from the barrel to bypass the projectile as it exits from said barrel and act at the or one or more of said at least one port, the or each port being connected to a detonator of the projectile by delay means.

Preferably the projectile is provided with a plurality of ports spaced axially one from the next along at least a portion of its length.

In this case, each of said plurality of ports may be connected to said detonator by delay means of a different time period.

The collar may have an internal diameter generally greater than that of the barrel but may have a portion of substantially identical internal diameter to that of the barrel. In this case, said portion may be at an end of the collar remote from the muzzle.

Alternatively the collar may have a passageway within its thickness having an annular butlet towards a forward end thereof.

In either of these cases, the collar may be so attached to the barrel that said predetermined distance may be changed, thereby allowing the high pressure gas to act on a different one or more of said ports.

The collar may be attached to the barrel by means of a screw thread to permit changing said predetermined distance by turning the collar or barrel one relative to the other.

The delay means may be pyrotechnic, in which case there is preferably provided a fuse means extending along the length of the projectile in communication with each of said ports and adapted to be ignited by gas acting on a port.

The fuse may extend from the rear of the projectile to the forward end thereof and thence to the detonator, so that the delay is set by the port furthest remote from the muzzle accessible to said passageway.

The fuse preferably extends helically around the body of the projectile.

A shutter mechanism may be provided to cover the fuse until removed by inertial forces during firing.

The fuse may connect with the detonator by means of a flash tube which can be closed, e.g. by bore riding pins, on actuation of a disarming mechanism.

In an alternative embodiment, the delay means may be electrical, where a plurality of pairs of normally open switches are provided, each pair being in parallel, the pairs being connected in series between an electrical power source and the detonator, one of each pair being closable by gas acting on a respective port, and the other of each pair being closable by time elapsed or distance travelled related means.

In this case, the more switches that are closed by the high pressure gas, the less that must be closed by the time or distance related means before detonation occurs.

In a further alternative embodiment, the delay means may be electromechanical, in which a slowly rotating wheel, set for rotation during firing, optionally by means of a flywheel remaining substantially stationary during rifled firing of the projectile, may contact one of a plurality of pins, each pin being movable into the path of said wheel under the influence of gas applied at a respective port, detonation occurring when said wheel contacts a first moved one of said pins.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: FIGURE 1 is a schematic view of a muzzle end of a barrel of a gun with a projectile leaving the muzzle; FIGURE 2 is a diagrammatic view, in separated condition, of a pyrotechnic delay means; FIGURES 3 and 4 show diagrammatically an electromechanical delay means; and FIGURE 5 is a circuit diagram of an electrical delay means.

Referring now to the drawings, Figure 1 shows schematically a projectile 1 at the point of leaving the muzzle of a gun. Surrounding the muzzle of the gun is an external screw-thread 2 which cooperates with an internal screw-thread 3 of a collar 4 which projects beyond the muzzle of the gun. The internal diameter of the collar 4 is greater than that of the barrel of the gun, but at an end remote from the muzzle, the collar is restricted by flange 5 to be of a substantially identical diameter.

As indicated by arrows in Figure 1, as soon as the projectile 1 leaves the barrel, the high pressure gas causing its propulsion escapes around the projectile through the collar 4 and is diverted back towards the projectile by flange 5.

The projectile 1 is provided with a plurality of ports in its periphery, one of which is shown in Figure 1 but a number of which are shown in Figure 2. The gas entering through the port 6 initiates a delay mechanism for causing detonation of the projectile. As can be appreciated, with the arrangement described, the high pressure gas exiting from the barrel will act on all ports rearward of flange 5 at the moment the projectile leaves the muzzle. In such cases the delay system is arranged to be actuated by the forward most port acted on by the high pressure gas.

It is of course possible for collar 4 to be provided with an internal passageway exiting at one specific annulus so that only one port is actuated.

The delay system incorporated in the projectile may operate in a number of different ways. One is shown diagrammatically in Figure 2 where the high pressure gas entering through a port ignites a pyrotechnic fuse 7 which extends helically from the rear to the front of the projectile, and thence through a flashtube 11 to a detonator 8. Each port 6 connects with a portion of the fuse 7 so that the forward-most port 6 acted on by the gas ignites the fuse to give a shorter burning time.

The collar 4 can be adjusted to extend further from or nearer to the muzzle of the barrel by screw adjustment between screw-threads 2 and 3. By this means, the high pressure gas can act on a port further from or nearer to the rear of the projectile. Thus the time delay between the projectile leaving the muzzle and its detonating is preset by the position of the collar. If necessary, this can be calibrated.

For the pyrotechnic delay fuse, a shutter 9 may be provided to obscure the ports from the fuse 7 until the shutter is dislodged by the inertial forces of firing. A shear pin 10 may be provided to hold the shutter to the body until the moment of firing. The flashtube 11 leading from the fuse 7 to the detonator 8 may be blocked by bore riding pins for safety purposes, should the projectile go off course.

An alternative delay means is shown in Figures 3 and 4. Each port is connected to a respective contact pin 12, the pins being held in a base 13 in a rearward disposition. The action of the gas pushes the pin connected to the port in question forwardly through the base. The forward most port is connected to the upper of the pins shown in Figure 3. A flywheel 14 is provided and, once released by a setback on firing is free to be kept relatively static by inertia whilst the projectile spins.

A wheel 15 is journalled for rotation about an axis offset from that of the flywheel 14 and rotates slowly hy means of gearing from the flywheel. As seen in Figure 4, the wheel 15 rotates in a clockwise direction. As the wheel rotates, it will eventually contact a first of the pins 12 which has been moved forward by action of gas. On contact, a firing circuit is closed and the projectile will detonate.

For optimum efficiency, this electromechanical delay system is adapted to fragment into sub-particles on detonation. The base 13 is pre-fragmented while the flywheel 14 comprises steel balls impregnated with a plastics material.

An electrical delay system is shown in Figure 5.

The detonator 16 is connected to a battery 17 through a number of pairs of parallel switches, each pair being arranged in series. The lower (as seen in Figure 5) switches 18 are each connected to a respective port. As seen in this Figure, the right-hand switch is connected to a rearmost port while the left-hand switch is connected to a foremost port. In fact, for safety reasons, it may be preferable to have at least one of switches 18 not connected to a port to prevent detonation until the projectile is clear of the collar. Upper (as seen in Figure 5) switches 19 are connected to a lanyard extending between the launch site and the rear of the projectile. As the lanyard is paid out, certain points on the lanyard are connected to upper switches 19 to cause closure thereof.

In this case, the earliest connection point of the lanyard is adapted to close the left-hand switch (as seen in Figure 5) and so on rightwardly.

If for example the collar is set so that gas enters two ports, the projectile must travel a sufficient distance for the lanyard to close the first three switches.

Detonation will then occur since the circuit is complete.

The more switches that are closed by high pressure gas action, the less distance the projectile must travel before the lanyard operated switches complete the circuit and cause detonation. The number of pairs of switches can of course be varied as desired. The number shown in Figure 5 is merely one example.

As can be seen, the pyrotechnic delay of Figure 2 and the electromechanical delay of Figures 3 and 4 are adapted to initiate detonation a predetermined time, set by the position of the collar, after firing. The electrical circuit of Figure 5 initiates detonation a predetermined distance from the barrel, again set by the position of the collar. However, it would be possible to arrange the upper switches 19 to be closed sequentially by time delay means.

Claims

CLAIMS:

1. An arming system for a projectile fired from a barrel of a gun comprising at least one port in a side of the projectile, a collar attached at a muzzle end of the barrel to extend therefrom by a predetermined distance and providing a passageway for high pressure gas from the barrel to bypass the projectile as it exits from said barrel and act at the or one or more of said at least one port, the or each port being connected to a detonator of the projectile by delay means.

2. An arming system as claimed in claim 1, wherein the projectile is provided with a plurality of ports spaced axially one from the next along at least a portion of its length.

3. An arming systems as claimed in claim 2, wherein each of said plurality of ports is connected to said detonator by delay means of a different time period.

4. An arming system as claimed in any one of the preceding claims, where the collar has an internal diameter generally greater than that of the barrel but has a portion of substantially identical internal diameter to that of the barrel.

5. An arming system as claimed in any one of claims 1 to 3, wherein the collar has a passageway within its thickness having an annular outlet towards a forward end thereof.

6. An arming system as claimed in any one of claims 2 to 5, wherein the collar is so attached to the barrel that said predetermined distance may be changed, thereby allowing the high pressure gas to act on a different one or more of said ports.

7. An arming system as claimed in any one of the preceding claims, wherein the collar is attached to the barrel by means of a screw thread to permit changing said predetermined distance by turning the collar or barrel one relative to the other.

8. An arming system as claimed in any one of the preceding claims, wherein the delay means is pyrotechnic, and there is provided a fuse means extending along the length of the projectile in communication with the or each of said ports and adapted to be ignited by gas acting on a port.

9. An arming system as claimed in claim 8, wherein the fuse means extends from the rear of the projectile to the forward end thereof and thence to the detonator, so that the delay is set by the port furthest remote from the muzzle accessible to said passageway.

10. An arming system as claimed in either claim 8 or claim 9, wherein the fuse means extends helically around the body of the projectile.

11. An arming system as claimed in any one of claims 8 to10, wherein a shutter mechanism is provided to cover the fuse means until removed by inertial forces during firing.

12. An arming system as claimed in any one of claims 8 to 11, wherein the fuse means connects with the detonator by means of a flash tube which can be closed, e.g. by bore riding pins, on actuation of a disarming mechanism.

13. An arming system as claimed in any one of claims 1 to 7, wherein the delay means is electrical, where a or a plurality of pairs of normally open switches are provided, each pair being in parallel, the pair being connected in series between an electrical power source and the detonator, one of the or each pair being closable by gas acting on the or a respective port, and the other of the or each pair being closable by time elapsed or distance travelled related means.

14. An arming system as claimed in claim 13, wherein there are provided a plurality of pairs of switches and the more switches that are closed by the high pressure gas, the less that must be closed by the time or distance related means before detonation occurs.

15. An arming system as claimed in any one of claims 2 to 7, wherein the delay means may be electromechanical, in which a slowly rotating wheel, set for rotation during firing by means of a flywheel remaining substantially stationary during rifled firing of the projectile, contacts one of a plurality of pins, each pin being movable into the path of said wheel under the influence of gas applied at a respective port, detonation occurring when said wheel contacts a first moved one of said pins.

16. An arming system for a projectile fired from a barrel of a gun and substantially as described herein with reference to the Figures of the accompanying drawings.