GB2221521A

GB2221521A - Tandem warheads

Info

Publication number: GB2221521A
Application number: GB8912338A
Authority: GB
Inventors: Norman Williams
Original assignee: Hunting Engineering Ltd
Current assignee: Lockheed Martin UK Ampthill Ltd
Priority date: 1988-06-07
Filing date: 1989-05-30
Publication date: 1990-02-07
Anticipated expiration: 2009-05-30
Also published as: GB8912338D0; GB2221521B; GB8813374D0

Abstract

In a system for controlling the detonation of a tandem warhead constituted by an electrical or electronic circuit, energy from capacitor 7 is upon closure of switch 5 due to impact or proximity diverted firstly into the primary winding of transformer 20 to fire a first detonator 2, and then via the transformer to activate a RC time delay 13, 14 and eventually to fire a second detonator is fired by a thyristor 16 or field effect transistor (19) discharging capacitor 12 which has been charged via inductor 10. <IMAGE>

Description

INITIATION SYSTEM FOR THE DETONATION OF MULTIPLE PYROTECHNIC CHARGES This invention relates to a system for controlling the initiation of detonation of multiple pyrotechnic charges, and particularly to a system for controlling the initiation of detonation of multiple pyrotechnic charges in tandem warheads.

Detonation of the main pyrotechnic charge in the warhead of a weapon is commonly initiated by means of a detonator placed in physical contact with it, or otherwise connected to it. Such detonators are often electrically activated, and the components and techniques which are used to ensure a normally 'safe' system, that is, one essentially free from the risks of inadvertent initiation, are closely integrated with the source of electrical energy from which the detonator itself is activated. Such safety and arming systems, as they are known, are normally developed in accordance with well-tried principles, one preferred aspect of which is that of minimal complexity.

The need to control the initiation of the detonation of multiple pyrotechnic charges has arisen especially in the context of tandem warheads for projectiles and the like. A tandem warhead is one in which detonation of a first warhead charge is initiated for an attack on a target area, and detonation of a second charge is initiated some microseconds later. Detonation of the first warhead induces considerable mechanical shock in the remaining portions of the system associated with the second warhead, as well as unavoidably destroying some components associated with the first warhead. It is known to employ a pyrotechnic delay to control detonation of the second warhead, but this tends to be vulnerable to physical damage arising from the earlier shockwave, and to some system inaccuracies arising from chemical, thermal or other physical or environmental changes.

In order to obtain a practical, effective and dependable safety and arming system for use with tandem warheads, therefore, it is desirable to employ an electrical or electronic means to fire a detonator and so initiate detonation of the second warhead charge. It is also desirable to integrate this second initiation means with that for the primary warhead, so as to exploit established principles and optimise the overall reliability and safety characteristics of the system. Furthermore, where a proven design already exists for a weapon, such that a tandem warhead is to be introduced as an improvement, it is desirable to use an initiation system of known reliability.

According to the present invention there is provided a system for controlling the initiation of detonation of a tandem warhead constituted by an electrical or electronic circuit comprising means for storing energy, means for coupling a portion of the energy into a first initiation sub-system to initiate detonation of a first warhead, means for sensing the coupling of the energy to first warhead, and means responsive to said sensing means for coupling a further portion of the energy into a second initiation sub-system to initiate detonation of a second warhead after a time delay.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a simple block diagram which schematically illustrates the invention inits simplest form; Figure 2 is a circuit diagram showing one possible circuit configuration utilizing a thyristor switch; Figure 3 is an alternative circuit configuration utilizing a field effect transistor switch; Figure 4 is a more complete circuit implementation of the circuit shown in Figure 2; and Figure 5 is a more complete circuit implementation of the circuit shown in Figure 3.

Referring firstly to Figure 1, the system comprises a charge reservoir 1 from which part of the stored energy is enabled to pass directly to initiate a first detonator 2 and hence a first warhead, whilst a further portion of the energy is enabled to pass by way of a time delay element 3 to a second detonator 4 to initiate detonation of a second warhead.

Energy is allowed to pass into both paths by closure of a switch 5 in response to a controlling means 6, which might operate directly, for example as an impact sensing switch, or which might respond to some other electrical signal such as a proximity sensor, or which might be implicit in the charge reservoir circuit itself.

Figure 2 is a circuit diagram of one implementation of the invention, in which energy is developed by a means not shown, and stored as an electrical charge on capacitor 7 corresponding to charge reservoir 1 in Figure 1.

When switch 5 is closed, for example in response to a proximity sensor, current is allowed to flow in the primary circuit 8 of transformer 20 and in a first detonator 2.

Current also begins to flow in the inductor 10 and increases with time. The load in the secondary circuit 9 of transformer 20, comprised mainly by diode 11 and capacitor 12, represents a short circuit so that all energy flowing initially after the closure of switch 5 is dissipated effectively in the first detonator 2 which is consequently fired to initiate detonation of the first warhead.

It is usual for detonators in warhead applications to be destroyed in the firing process to create an open circuit.

They may become a short circuit. The function of inductor 10 is to provide an alternative by-pass path for current to flow other than through the detonator, so allowing capacitor 12 to charge via diode 11.

Corresponding to the time delay element 3 in Figure 1, resistor 13 and capacitor 14 in Figure 2 provide an RC delay time constant in conjunction with breakdown diode 15, to enable thyristor 16 to switch on following the time delay, and so discharge capacitor 12 into a second detonator 4 thus initiating detonation of a second warhead. By this means, energy from the charge reservoir is dissipated firstly to fire the first detonator, then diverted via the transformer to activate a time delay and eventually to fire the second detonator. This detonator, like the first, may be fired on reception of a specified charge within a specified (short) time.

Figure 3 is an alternative circuit configuration employing a field effect transistor 19 to provide switching. The additional secondary winding 21 of transformer 20 together with diode 18 provide a negative level at capacitor 14 to hold the field effect transistor 19 non-conducting for a period of time dependent on the voltage at capacitor 12, the delay time constant being provided by resistor 13 and capacitor 22.

Figures 4 and 5 represent more complete circuit implementations of the circuits shown in figures 2 and 3 respectively, and show various components and constraints required in a practical design.

Both the first and second detonators 2 and 4 are protected by switches 23 and 24 respectively, while capacitors 12 and 14 are protected by resistors 25 and 26 respectively. A further additional resistor 27 is provided in the circuit of Figure 4 across the breakdown diode 15 and capacitor 14, as a protection for the thyristor 16.

Claims

1. A system for controlling the initition of detonation of a tandem warhead constituted by an electrical or electronic circuit, comprising means for storing energy, means for coupling a portion of the energy into a first initiation sub-system to initiate detonation of a first warhead, means for sensing the coupling of the energy to the first warhead, and means responsive to said sensing means for coupling a further portion of the energy into a second initiation sub-system to initiate detonation of a second warhead after a time delay.

2. A system for controlling the initiation of detonation of a tandem warhead according to claim 1 wherein the energy storing means comprises a capacitor.

3. A system for controlling the initiation of detonation of a tandem warhead according to claim 1 or claim 2, wherein the energy is enabled to flow into the circuit to initiate detonation by means of a switch.

4. A system for controlling the initiation of detonation of a tandem warhead according to claim 3, wherein said switch comprises an impact sensing switch.

5. A system for controlling the initiation of detonation of a tandem warhead according to claim 3, wherein said switch is operated in response to a proximity sensor.

6. A system for controlling the initiation of detonation of a tandem warhead according to any of the preceding claims, wherein the first initiation sub-system constitutes the primary circuit of a transformer, and the second initiation sub-system constitutes the secondary circuit of the said transformer.

7. A system for controlling the initiation of detonation of a tandem warhead according to any of the preceding claims, wherein the first initiation sub-system comprises a electrically operable detonator by-passed by an inductor.

8. A system for controlling the initiation of detonation of a tandem warhead according to any of the preceding claims, wherein the second initiation sub-system includes an RC delay circuit.

9. A system for controlling the initiation of detonation of a tandem warhead according to claim 8, wherein the second initiation sub-system includes an additional capacitor and a breakdown diode which enables a thyristor to switch on and thus discharge the additional capacitor into a second detonator.

10. A system for controlling the initiation of detonation of a tandem warhead according to claim 8, wherein the second initiation sub-system includes an additional capacitor and a diode, which control a field effect transistor and, dependent on the voltage at a further capacitor, allow the further capacitor to discharge into a second detonator.