GB2272962A - Projectile warhead - Google Patents

Abstract

A projectile warhead comprises an airframe including separate primary (1) and secondary (2) explosive charges which are arranged one behind the other on opposite sides of a barrier (4) and which, in use, are detonated sequentially. The charges (1) and (2) are movable away from one another into a position remote from one another before detonation to prevent detonation of the primary charge (1) interfering unduly with that of the secondary charge (2). The warhead also includes means (6, 12) to cause the relative movement between the charges (1) and (2) after launch of the projectile (3) and before detonation of the warhead. <IMAGE>

Description

Projectile Warhead A very effective warhead consists of an airframe containing two Munroe effect explosive charges located one behind the other on opposite sides of a barrier. The charges are detonated sequentially as a projectile carrying the warhead approaches a target and the cumulative effect of the two charges is able to penetrate and destroy the target.

The efficient operation of the rearmost or secondary charge requires that it be protected from the disruptive effects of the detonation of the leading, or primary charge during its formative sequence. In the past this has been achieved by the introduction of a barrier having the form of a mass located adjacent the primary charge and spaced from the secondary charge. The mass is accelerated towards the secondary charge under the influence of the blast from the primary charge and the free space provided between the mass and the secondary charge is of such a dimension that full formation of the penetrative ability of the second charge has time to develop before the mass reaches the secondary charge.

Typically the longitudinal dimension of the free space provided between the mass and the secondary charge is typically 1 to 1.5 body diameters of the airframe of the projectile. In modern weapon systems there is a strong pressure towards higher packing density and thus the inclusion of such a relatively large empty space within the body of a weapon is undesirable.

An earlier proposal described in GB-A-2141809 describes an armour piercing projectile which, after launch separates into two separate parts each of which contains a Munroe effect explosive charge. The two parts fly independently and arrive at the target one after the other. However the different flight characteristics of the two parts mean that they often do not engage the same part of the target and hence their cummulative effect is lost.

According to this invention a projectile warhead comprises an airframe including separate primary and secondary explosive charges which are arranged one behind the other on opposite sides of a barrier, which, in use, are detonated sequentially and which are movable away from one another into a position remote from one another whilst still constrained by the airframe before detonation to prevent detonation of the primary charge interfering unduly with that of the secondary charge, the warhead also including means to cause the relative movement between the charges after launch of the projectile and before detonation of the warhead.

The means to cause the relative movement between the charges may be achieved by the deployment of a drogue parachute coupled to the secondary charge and thus arranged to pull it away from the primary charge during the flight of the projectile. Alternatively the means to cause the relatively movement between the charges may have the form of some stored energy device such as a spring or a gas charge arranged to drive the two charges apart into their position in which they are remote from one another. It is preferred the drogue parachute or the stored energy device is triggered only as the projectile is nearing the completion of any ballistic flight or as it approaches its target.

The secondary charge may simply move rearwards relative to the remainder of the projectile and warhead or, alternatively, the primary charge and barrier may be arranged to move forwards relative to the secondary charge and elements of the warhead or projectile. In this way the separation of the barrier and the primary charge is constant and it is the separation between the barrier and the secondary charge which increases as the charges move apart.

The projectile may be a shell or a missile and preferably the projectile includes a direction control system. When the projectile includes a forward direction control system using, for example, canards or thrusters located towards the front of the projectile the secondary charge is preferably arranged to move rearwards with respect to the remainder of the projectile. In this way with the secondary charge in its foremost position, the position at the launch of the projectile, the projectile has the greatest aerodynamic stability. However, when the secondary charge moves rearwards this shifts the centre of gravity of the projectile rearwards and moves it closer to the centre of pressure of the projectile so making the projectile more manoeuvrable and increasing the control moment of the forward control system.When the projectile includes a tail control system it is preferred that the primary charge and barrier move forwards with respect to the secondary charge and the tail control system of the missile. This leads to the forward movement of both the centre of gravity and centre of pressure and again results in stability being reduced as the charges are moved apart when the projectile approaches its target so making the projectile more maneouvrable.

The movement apart of the two charges may be triggered by, or used to trigger, an arming system for the warhead and, in this case, is triggered just prior to impact. It may be triggered by the application of a signal pulse to some form of latching system to release a constraint on the movement apart of the two charges.

Alternatively the movement apart of the two charges may be used to trigger an arming system and, in this case, the triggering of the movement apart of the charges occurs at a predetermined time after launch and the completion of movement apart of the charges causes the arming system to assume its active state.

A particular example of a projectile in accordance with this invention will now be described and contrasted with a conventional projectile with reference to the accompanying drawings, in which: Figure 1 is a diagram of the warhead; Figure 2 is a sketch of a conventional projectile; Figures 3A and 3B are diagrams of a tandem warhead in accordance with this invention, with Figure 3A showing the projectile before it is deployed and Figure 3B showing the projectile after deployment when it is about to engage a target; Figures 4A and 4B are diagrams similar to those of Figure 3 to illustrate the enhancement of the control that occurs with the present invention; and, Figures 5A and 5B are diagrams of a second example in accordance with the invention which also illustrates the enhancement of the control.

Figure 1 illustrates the principle of a warhead in accordance with this invention and illustrates that the warhead includes a primary charge 1 located in front of a secondary charge 2 when considered in relation to the direction of flight of the warhead and, consequently, its direction of attack. Figure 2 shows a typical conventional tandem warhead layout with the primary charge 1 located at the front of the airframe of a projectile 3 and a secondary charge 2 located towards the rear of the airframe of the projectile 3. A barrier formed by a mass 4 is located adjacent the primary charge 1 and a free space 5 is provided between the mass 4 and the secondary charge 2.

In the first example of this invention shown in Figure 3, Figure 3A shows the projectile in its predeployment state and in this state the secondary charge 2 is located adjacent the mass 4. This first example also includes a drogue parachute 6 packed into the tail of the projectile 3 and connected to the secondary charge 2. During the flight of the projectile and as it approaches its target the drogue parachute 6 is deployed and as this is connected to the secondary charge 2 it retards it causing it to move rearwards with respect to the barrier 4 and the airframe to provide the free space 5 between the barrier 4 and the secondary charge 2.

Figure 4 shows the projectile illustrated in Figure 3 but also illustrates its centre of gravity 7 and centre of pressure 8. The figures illustrate how the centre of gravity and centre of pressure move closer together after the secondary charge 2 has moved rearwards with respect of the remainder of the projectile 3 so reducing the static margin SM and increasing the control arm CA which is the distance between the point at which the control force from thrusters or canards located towards the nose of the projectile 3 act and the centre of gravity 7.

Figure 5 shows the different configuration of projectile including tail control surfaces 9. The body 3 of the projectile comprises a nose portion 10 containing the primary charge 1 and barrier 4 and a tail section 11 carrying the control surfaces 9 and containing the secondary charge 2. The nose portion 10 and tail section 11 of the airframe telescope together. Before deployment the two parts of the airframe are telescoped together to their maximum extent with the secondary charge 2 lying adjacent the barrier 4 and this is the condition of the projectile when it is launched. As the projectile approaches its target the nose portion 10 and tail section 11 are moved apart, either by deployment of a drogue attached to the tail section or by means 12 such as release of a spring or inflation of a gas bag acting between the two to drive the nose portion 10 away from the tail section 11 into the position shown in Figure 5B.

This provides the free space 5 between the mass 4 and the secondary charge 2. Movement of the nose portion 10 moves the centre of gravity 7 forwards to a greater extent than the centre of pressure 8 and accordingly again reduces the static margin SM and increases the control arm CA.

Claims (8)

1. A projectile warhead comprising an airframe including separate primary and secondary explosive charges which are arranged one behind the other on opposite sides of a barrier, which, in use, are detonated sequentially and which are movable away from one another into a position remote from one another whilst still constrained by the airframe before detonation to prevent detonation of the primary charge interfering unduly with that of the secondary charge, the warhead also including means to cause the relative movement between the charges after launch of the projectile and before detonation of the warhead.

2. A projectile according to claim 1, in which the means to cause relative movement between the charges comprise a drogue parachute coupled to the secondary charge and arranged, in use, to pull it away from the primary charge during the flight of the projectile.

3. A projectile according to claim 1, in which the means to cause relative movement between the charges has the form of a stored energy device arranged to drive the two charges apart into their position in which they are remote from one another.

4. A projectile according to any one of the preceding claims, in which the secondary charge moves rearwards relative to the airframe of the projectile.

5. A projectile according to claim 4, which also includes a forwardly located direction control system.

6. A projectile according to any one of claims 1 to 3, in which the primary charge and barrier are arranged to move forwards relative to the secondary charge.

7. A projectile according to claim 6, which also includes a rearwardly located direction control system.

8. A projectile substantially as described with reference to any of Figures 3 to 5.