GB2337576A

GB2337576A - Tandem warhead

Info

Publication number: GB2337576A
Application number: GB8820046A
Authority: GB
Inventors: Phillip Daryoush Djali
Original assignee: Royal Ordnance PLC
Current assignee: BAE Systems Global Combat Systems Munitions Ltd
Priority date: 1988-08-24
Filing date: 1988-08-24
Publication date: 1999-11-24
Anticipated expiration: 2008-08-24
Also published as: GB2337576B; GB8820046D0

Abstract

A tandem warhead device comprises a front shaped charge warhead (1) and a rear shaped charge warhead (2), a target sensor (16), means (18) for detonating the front warhead at an appropriate standoff from the target, and means (18) for detonating the rear warhead at a predetermined delay time after detonation of the front warhead, wherein the front warhead is provided with a liner (10) of a polymeric material. The polymeric material may be polythylene, polyvinylchloride or polytetrafluroethylene and the liner of the front warhead may also comprise a layer of metal. The liner of the front warhead can be of generally part-spherical from or of Misznay-Schardin form.

Description

Tandem Warhead 2337576 This invention relates to tandem warheads, and in

particular to a form of such warhead which is especially suitable for the attack of a target which is protected by an outer layer of explosive reactive armour.

Explosive reactive armour (ERA) has been developed for providing additional protection to a conventionally armoured vehicle or installation, such as a main battle tank. ERA comprises a layer of explosive sandwiched between metal plates, and can be applied externally to the armoured hull of a main battle tank in the form of discrete "tiles", to provide greatly enhanced protection against a conventional shaped charge. On attack by a shaped charge jet, the explosive layer of the ERA tiles in the attack area is detonated, and the metal plates fly outwards into and across the path of the jet to disrupt the jet and attenuate its effect.

The defeat of such a target protected by ERA poses considerable difficulty to the weapon designer. In order to counter the defence offered by ERA, a conventional tandem warhead has been developed, which comprises two axially aligned shaped charges of a standard type (front and rear), with a protective barrier between the two. On approaching a target, the front warhead detonates causing perforation of the ERA and detonation of the. explosive ERA layer. The ERA plates fly apart and consume the front warhead jet. Meanwhile the rear warhead is protected by the intermediate barrier from the blast effects of the front warhead. After a preghlected and critical time, the rear warhead detonates and can attack the underlying conventional armour directly, through the path cleared by the front warhead.

A number of difficulties are inherent in the design of a conventional tandem warhead as described. The detonation of the ERA by the front warhead gives rise to flying metal plates which can have a disruptive effect, for example by physically damaging the rear charge before it can attack the main armour structure.

1 Also, a significant delay time, of the order of several hundred microseconds is required between the detonation of front and rear warheads in order to allow time for clearance of the flying metal plates, and of the jet from the front shaped charge, both of which might otherwise interfere with the action of the rear shaped charge jet. Such a long delay cannot be provided by a single electronic safety and arming unit (SAU), hence separate SAUs interconnected for example by a sufficient length of miniature detonating card, must be provided, adding to cost and complexity. A long time delay also magnifies the problem of protecting the rear warhead against the effects of detonating the front warhead.

The present invention seeks to provide a tandem warhead device for the attack of targets protected by ERA being a device in which some or all of the aforesaid disadvantages associated with conventional tandem warheads are eliminated or at least mitigated. The invention also makes possible a significant saving in mass as compared to a conventional tandem warhead of similar calibre.

Accordingly the present invention provides a tandem warhead device comprising a front shaped charge warhead and a rear shaped charge warhead, a target sensor, means for detonating the front warhead at an appropriate standoff from the target, and means for detonating the rear warhead at a predetermined delay time after detonation of the front warhead, wherein the front warhead is provided with a liner of a polymeric material.

Examples of suitable polymeric materials are polyethylene, polyvinylchloride, and polytetrafluoroethylene. In general the polymeric material should be a relatively low density material, normally less than 3gm/ce and one which deforms plastically under stress.

The liner of the front warhead may additionally comprise a layer of metal, such as aluminium, behind the polymeric material.

The liner of the front warhead is preferably of a rounded shape such as for example a Misznay-Schardin form, or generally of a part-spherical form.

The front and rear warheads may be supported in a casing having a nose extending forwardly of the front warhead.

The nose may incorporate a target sensor in the form of a crush switch, for initiating the warhead device with the front warhead at a appropriate stand-off from the target.

Alternatively, the warhead device may be provided with a different from of target sensor, for example a proximity fuze.

The said delay time is preferably of the order of tens of microseconds, for example 80 microseconds or less.

Very conveniently the warhead device incorporates a single safety and arming unit including means for initiating detonation of the front warhead on receipt of a signal from the target sensor and means for initiating detonation of the rear warhead after the said delay time.

The said delay time may be controlled by electronic means forming part of the safety and arming unit.

The invention will now be described by way of example only with reference to the accompanying drawing, which is a sectional diagrammatic view of a tandem warhead device in accordance with the invention.

As shown in the drawing, a tandem warhead device in accordance with the invention comprises a front warhead 1, and behind and axially aligned therewith, a rear warhead 2. The front and rear warheads 1 and 2 are supported in a cylindrical casing 3 which includes a nose portion 4 of ogival form. The casing and nose portion can be of fibre reinforced plastics material.

The front warhead 1 is of a smaller diameter than the casing 3, and is supported therein by means of a retaining collar 5 at its forward end, and an elongate cylindrical support member 6 at its rearward end. The support member 6 is secured in the casing 3 by means of screws 7.

The rear warhead 2 is of slightly smaller diameter than the casing 3, and is supported therein by retaining collars 8 and 9.

The front warhead comprise a mass of high explosive 9 within a light casing 9A. The forward face of the explosive 9 has a recess of partsphercial form, and is provided with a liner comprising a thin layer 11 of aluminium in contact with the explosive 9 and a thicker layer 10 of polypropylene forward thereof. The front warhead 1 is also provided with a detonator and initiating means 12.

The rear warhead 2 is a more conventional form of shaped charge, comprising a mass of high explosive 13, having a conical shaped charged recess in its forward face lined with a conventional liner 14 of a metal such as copper. A detonator and associated initiating means 15 is provided at the rear of the warhead 2.

A crush switch 16 is provided in the nose portion of the casing 3 which closes an electrical circuit when the nose deforms on impact with a target. An electrical connector 17 connects the switch 16 with a safety and arming unit (SAU) 18 located to the rear of the rear warhead 2. The SAU has the conventional function of preventing initiation of the warhead device until it has sensed an environment which confirms the warhead device has been deployed as intended, for example by launch from a rocket launcher. Once this environment has been sensed, the SAU is activated. The SAU has an electrical output connection 19 to the detonator means 12 of the front warhead 1, and a second electrical output directly to the detonator means 15 of the rear warhead. The SAU also includes an electronic time delay (not shown) and the arrangement is such that on closure of the crush switch 16, as by impact with a target, following activation of the SAU, the SAU immediately sends an electrical pulse via connection 19 to the detonator 1 means 12, and the front warhead 1 is thereby detonated at an appropriate standoff dictated by the length of the nose 4.

After a time which is predetermined by its electronic time delay, for example between 30 and 70us the same SAU sends a further electrical pulse to the detonator means 15 of the rear warhead, which is thereby detonated after the said predetermined delay.

The operation of the warhead device on impact with a target protected by ERA is as follows. The front warhead is initiated at the appropriate standoff as already described, and the composite liner 10, 11 is formed into a two-part projectile.

The shape of the liner 10, 11 is selected such as to produce a projectile of moderate aspect ratio, significantly less elongated than the jet produced by a conical liner, but less compact than the more extreme form of slug which can be produced by certain designs of liner. Part-spherical or other rounded shapes such as Misznay-Schardin type may be suitable.

The projectile formed by the composite liner comprises a front section of polypropylene, and it has been found surprisingly, that this or other suitable polymeric projectiles of appropriate form can penetrate an ERA plate without detonating the explosive layer thereof. An opening is thus produced through the ERA, through which succeeding projectiles can pass without disruption by the ERA.

The layer 11 of aluminium provided in the present embodiment is optional, but provides the added benefit of a further projectile following immediately behind and through the opening already created from the layer 10. This projectile of aluminium possess higher penetrating capability than the polymeric projectile, and can effect a useful initial attack on the underlying armour layers.

Because the ERA has not been detonated, the time delay between detonation of front and rear warheads can be relatively short, for example of the order of about 50 microseconds, hence the rear warhead is detonated before it can be disrupted by rearward blast from the front warhead, and it is thus found that the baffle required in conventional tandem warheads between front and rear charges can be dispensed with. This leads to simpler construction and significant weight saving. A further advantage of the reduced time delay is that a single SAU with electronic time delay can be used. Conventional tandem warhead designs require longer delays, involving the use of miniature detonating card or other pyrotechnic delay means, and hence two separate SAUls are needed with a corresponding penalty in terms of mass, complexity and cost.

A beneficial factor arises from the fact that the polymeric liner is found to be effectively consumed by penetration of the ERA, thus avoiding interference with the penetrator formed by the rear warhead, although where provided there may be minor interference from the metal layer 11.

The lighter polymeric material of the liner 10 also of itself gives rise to a significant weight saving as compared to conventional tandem warheads.

Claims

Claims

A tandem warhead device comprising a front shaped charge warhead and a rear shaped charge warhead, a target sensor, means for detonating the front warhead at an appropriate standoff from the target, and means for detonating the rear warhead at a predetermined delay time after detonation of the front warhead wherein the front warhead is provided with a liner of a polymeric material.
2. A tandem warhead according to claim 1 wherein the polymeric material is polyethylene, polyvinylchlorlde or polytetrafluoroethylene.
3. A tandem warhead according to claim 1 or claim 2 wherein the polymeric material has a density less then 3gmIcc.
4. A tandem warhead according to any one of claim 1 to 3 wherein the liner of the front warhead also comprises a layer of metal.
5. A tandem warhead according to claim 4 wherein the metal is aluminium.
6. A tandem warhead according to any one preceding claim wherein the liner of the front warhead is of a rounded shape.
7. A tandem warhead according to claim 6 wherein the liner of the front warhead is of generally part-spherical from or of Misznay-Schardin form.
8. A tandem warhead according to any one preceding claim wherein the front and rear warheads are supported in a casing having a nose extending forwardly of the front warhead.
9. A tandem warhead according to claim 8 wherein the nose incorporates the target sensor.
10. A tandem warhead according to claim 9 wherein the target sensor is a crush switch.
11. A tandem warhead according to any one preceding claim wherein the said delay time is of the order of tens of microseconds.
12. A tandem warhead according to any one preceding claim wherein the said delay time is less than 80 microseconds.
13. A tandem warhead device according to any once preceding claim incorporating a single safety and arming device including means for initiating detonation of the front warhead on receipt of a signal from the target sensor and means for initiating detonation of the rear warhead after the said delay time.
14. A tandem warhead device according to claim 13 wherein the said delay time is controlled by electronic means forming part of the safety and arming unit.
15. A tandem warhead device substantially as hereinbefore described with reference to the accompanying drawing.