GB2444311A

GB2444311A - Reactive ballistic protection device

Info

Publication number: GB2444311A
Application number: GB8825036A
Authority: GB
Inventors: Gunter Weihrauch; Erich Wollman; Klaus Sterzelmeier
Original assignee: Institut Franco Allemand de Recherches de Saint Louis ISL
Current assignee: Institut Franco Allemand de Recherches de Saint Louis ISL
Priority date: 1987-10-26
Filing date: 1988-10-26
Publication date: 2008-06-04
Anticipated expiration: 2008-10-26
Also published as: GB2444311B; DE3736106B3; GB8823054D0; FR2911182A1; GB8825036D0

Abstract

A device for protection against either guided or unguided projectiles comprises an electromagnetic launcher consisting of primary and secondary coil assemblies for the acceleration of a missile towards an attacking projectile. The primary and secondary coil assemblies J, K are rotationally offset by an angle a such that the accelerating force produced comprises not only a component causing translational movement, but also a circumferential component, rotating the misssile so that it is spin-stabilized, which results in a longer range and higher accuracy of the missile, effects that may be improved further by the attachment of aerodynamic elements, e. g. propeller wings, to the missile. The missile may be attached to either of the coil assemblies, or may be formed by either one of the coil assemblies alone. The primary coil assembly J may comprise six individual triangular coils and the current flows through adjacent coils in opposite directions. The secondary coil assembly K differs from assembly J in that it is a single continuous body without any gap between adjacent coils.

Description

DEVICE FOR NEUTRALIZING PROJECTILES AS WELL AS INITIATING

OR DEFLECTING GUIDED MUNITION WARHEADS

The present invention concerns a device for neutralizing projectiles in accordance with the preamble of claim 1 and as described in U.K. Patent Application No. 8808294.6.

Such devices are known from the earlier U.K. Patent Applications Nos. 8808294.6, 8808296.1 and 8820779.0. They comprise an electromagnetic projecting device for a missile which is accelerated towards any approaching projectile, reducing the effect of that projectile to such an extent that it is no longer able to penetrate the armor protected by the device described.

The electromagnetic projecting device comprises a primary coil assembly and a coaxial secondary coil assembly with the so-called missile, which may also be formed by one of the coil assemblies proper.

A very high current supplied by, eg., a bank of capacitors, to the primary coil assembly, induces a strong axial magnetic field therein.

The current in the primary coil assembly induces a current in the secondary coil assembly, mounted on top of the primary coil assembly, with a strong magnetic field being produced in the secondary coil assembly, too. The two magnetic fields are oriented in such a way that the primary and secondary coil assemblies are separated. The enormously high current which can be reproduced with great accuracy, though, allows for the missile being accelerated accurately over a distance of' a few meters to that point of collision with the attacking projectile predetermined by a computer.

The missile may be attached to the primary coil or the secondary coil assembly and also be formed by either one of the coil assemblies.

The first configuration even allows for the simultaneous acceleration of several missiles at short intervals or independently of each other.

Thus, more than one missile may be hurled towards a particularly heavy KE projectile, tandem projectiles may be engaged by two missiles shortly following each other, without leaving the respective area of the armor unprotected after the acceleration of one missile, for the capability of projecting further missiles will be retained.

The configuration of the mffle as a grid with each of the meshes being faced by a mating primary coil, and with opposing flow directions of current in adjacent coili appears to be particularly useful.

In another possible embodiment, the axes of the primary and secondary coils are inclined towards each other or offset, or there are several offset primary coils, which can be triggered separately or in a group, as desired. In any case, the missile is not accelerated in a direction perpendicular to the plane of the coils; but in a direction which is inclined towards that plane. Thus it is possible, by appropriate triggering, to protect a particularly large area.

Triggering of the electromagnetic device selected is always done automatically, i. e. controlled by a sensing probe that determines the velocity, direction of flight, and type, as applicable, of an approaching projectile, ard actuates a suitable electromagnetic projecting device at the appropriate time. The type of actuation may vary with the type of projectile determined.

The effective range of the missile for neutralizing an approaching projectile is relatively short, so that the known devices still require the protection of armor in crder to prevent parts of the projectile interfered with from causing damage.

The use of the known devices is less practical when the probable attackers are very effective warheads and/or when only light or no armor can be used, e. g.

when ships or helicopters are to be protected against guided missiles.

The devices described in the earlier patent applications would be able, on principle, to project a missile at such a long range that warheads of the type described could be rendered ineffective at a relatively safe distance, but the accuracy with which the trajectory of the missile can be reproduced would be too small in this case, i. e. the missile tumbles after too short a time, turns over and is unable then to achieve full effectiveness.

Therefore, the invention is based on the problem of developing the known devices described in the beginning in such a way that the effective range of the missile and thus the operational range of the device is increased.

This problem is solved by the features as claimed in claith 1. The primary and Sqri1 o/,ds secondary coil assemblies as claimed there are not merely -rotating boie but comprise at least one sector each, that does not extend in the circumferential direction. According to the invention, the primary and secondary coil assemblies are not stacked exactly one above the other but are offset by a predetermined small angle, so that the force generated upon triggering of th. primary coil assembly does not only accelerate the missile axially, but also comprises a circumferential component, so that the missile will be rotated. The extent of the rotational component of missile acceleration can be determined by selecting the angle and the coil geometry, so that spin is 1nrted to the missile o a degree that is just sufficient for keeping the missile on a stable trajectory with respect to the linear direction of acceleration. Thus it is possible to reliably hit an approaching projectile with a flat missile with the extension perpendicular to its linear direction of acceleration much larger than its depth in this direction, a missile that retains a stable position even at long ranges of several tens of meters, and to hit the projectile even at such ranges, as the earlier occurrences of unreliability, such as the tendency of the missile to turn over uncontrollably after having traveled a certain distance, have been eliminated by the invention.

The device according to the frivention can thus be used for the protection of such objects that are unarmored or only lightly armored, since interference with n approaching projectile takes place at a great distance from the object to be protected, so that the risk of this object being substantially damaged by residual fragments is very much decreased. Surface-to-surface missiles, in particular, which have been used very successfully up to now for the engagement of small and medium vessels, and which have a very high warhead yield, can be destroyed by the device according to the invention at such a distance from the vessel, that the residual effect of the missile at least no longer endangers the overall safety of the vessel.

The device according to the invention has a high accuracy of projection, and therefore it is no longer necessary to attach this device directly to the protecting armor, e. g. when used on board of a ship. On principle, such a device can be mounted on a flexible turret instead, providing for perimetric protection over a minimum angle of 180 degrees. This configuration also allows for the use of substantially higher currents, from the projection of the missile will be absorbed by the foundation of such a flexible turret without any difficulty.

Moreover, since a guided missile attacking a ship can be detected several seconds before impact, one or more of the devices according to the invention may be activated any time during the approach of the guided missile and used to success-fully enge the missile with the use of an automatic target acquisition system that controls the devices according to the invention arid triggers them at the appropriate time (and with the appropriate current, as required), allowing for any maneuver of the vessel without degrading the effectiveness of the device according to the invention.

By proper selection of the coil geometry and of the offset angle of the primary and secondary coils, spin can be imparted to the missile to such a rate that even Speeds the high wind fói-cc-o often prevailing at sea do not affect the in-flight stability of the missile.

On principle, the offset angle can be adjusted, as required, prior to projection of the missile taking into consideration the desired missile range and the oeed disturbances to be expected, such as wind f'or:c, velocity of the vehicle equipped with the device etc., in order to ensure a maximum portion of the electrical.

energy input being used for the linear acceleration of the missile, and of only such a portion being used for imparting spin to the missile as is required for achieving in-flight stability.

Assuming a suitable design of the missile, it may be advisable, though, to impart a higher spin rate to the missile than needed for maintaining in-flight stability, since the rotation of the missile nay, in additicn to the translational velocity, help to interfere with the in-flight stability of a KE projectile, particularly that of an elonted KE projectile of the type fired from modern smooth-bore weapons. In such an application of the device according to the invention, a very substantial portion of the electrical energy input is used to rotate the missile.

Thereby, the objective according to the invention is achieved in the end, namely to protect an object sufficiently by countering an approaching projectile outside of the object to be protected, even if unarmored or cily very llitly anrxred. A missile rotating very fast is not thly able to affect the in-fliit stability of an apprchirig KG projectile, so that it impacts the surface of the object to be protected with its side, but also to deflect this projectile in such a way that it misses the object.

For this purpose, it is advisable to further modify the coordinating system that is connected to sensing probes in such a way, that the triggering point of the device according to the invention is selected such, that the missile hits the attacking KE projectile with its rim and at such a high rotation velocity, that the projectile is deflected from the object to be protected. In addition, a device for the control of the projecting direction may be used and triggered by the coordinating system and a computer, respectively, as described in U.K. Patent Application No. 8808294.6, the contents of which is integrated fully in this application by referring to it.

In order to achieve a particularly stable flight of the missile, the axis with respect to which the primary and secondary coils are offset, according to an embodiment of the invention, is selected such that it passes through the centre of gravity of the missile and that of the missile with its supporting coil assembly, respectively.

According to a preferred embodiment of the invention, the primary and secondary coil assemblies each are designed as similarly shaped grids as disclosed in U.K. Patent Application No. 8808296.1, the contents of which is integrated fully in the disclosure of this application by referring to it.

The same applies to U.K. Patent Application No. 8808294.6, which includes the disclosure, in addition, of the design of a vaporizing element for further acceleration of the missile. This vaporizing element, in turn, may be designed in such a way that it imparts spin to the missile or increases the spin imparted.

When high currents are used, it is likely that, in particular with the secondary coil generally designed as a metal ring or disk only, the secondary and/or primary coils are fragmented because of the high magnetic and thermal loads. These fragments are accelerated towards the approaching projectile. It is to particular advantage, therefore, to place a separate missile on the electromagnetic projecting device. This missile is then accelerated by the above-mentioned fragments and projected towards the approaching projectile. The missile should prefer-ably be made of a nonconductive material or one of low conductivity, so that the thermal load due to the induction of eddy currents on the missile is small enough for it to remain undamaged during discharge of the power supply. Such a missile is preferably made of ceramic material, which because of its extreme hardness is particularly suited for deflecting a KE projectile.

As mentioned earlier, waste heat is generated in the primary and secondary coils in the projection process. This waste heat can be used in accordance with further embodiments of the invention. These provide for a vaporizing element or layer, which is evaporated by the above-mentioned waste heat; an exactly defined amount of vapor is generated that, due to its compression, sustains the acceleration of the missile substantially.

This allows for a number of embodiments, too. The secondary coil can be designed as a vaporizing element by using metal with a low melting point. Or the armor equipped with the launcher can be used as a secondary coil, and the primary coil potted with a highly evaporative compound. In this embodiment, the missile is mainly accelerated by the vapor pressure of the evaporating potting compound.

A further preferred embodiment of the invention is the offset and inclined arrangement of the primary and secondary coil assemblies for adjusting the direction of linear acceleration of the missile, as mentioned above.

As mentioned above, the missile may be designed as a rectangular grid, for instance, but preferably, it should be of a rotationally symmetrical shape as nearly as possible, in order to minimize the decelerating effect of the ambient air. A grid assembly with meshes radially symmetric with respect to a common axis and with edges forming a polygon approximating a circle is of particular advantage here.

According to a further preferred embodiment of the invention, aerodynamic guidance, stabilization and/or lift elements, eg. propeller-like wings, may be attached to the missile or form part of it, so that sustained hovering or gliding of the missile in the air is possible.

Such aerodynamic elements do not only allow for improvement of the range and of the accuracy of the missile course, but also for a reduction of the requirements the coordinating system has to meet. This system is necessary for the adjustment of the triggering of the device according to the invention to the predetermined trajectory of the attacking projectile in such a way that the missile travels along the trajectory with reduced velocity or remains stationary by unfolding its aerodynamic elements after having travelled a certain distance, so that unpredict-able trajectory deviations of the attacking projectile or computational errors with regard to its trajectory do not result in the missile missing the projectile.

On principle, additional signal and deflecting devices can be attached to the missile, eg. an incendiary composition with an infrared spectrum corresponding with that produced by the engine/propulsion unit of the object to be protected. Thus, when an approaching guided missile has been acquired, it is possible, eg., to trigger the device according to the invention from a helicopter, tank or vessel early enough to ensure that the missile is at a safe distance from the object to be protected when it intercepts the approaching infrared-guided warhead.

The warhead will be diverted and initiated by the protection device missile. Here, the aerodynamic elements attached to the missile are of particular advantage, since they increase its time of flight, so that it can be projected for interference with a guided missile not at the very last moment, but early enough.

In this case, the device according to the invention may be triggered either automatically or manually, as desired.

Furthermore, such a missile may be projected in the direction of a supposed guided weapon emplacement, and thus be used for the initiation of enemy guided munitions.

The missile may, eg., also be used to disperse a light-metal powder that generates a radar jamming signal.

The device according to the invention as developed for the inter-ference with warheads, may, on principle, still be used to neutralize unguided projectiles, ie. the device according to the invention can form a universally usable protection and defence system. The electronics, which may be attached to the device according to the invention, may be designed in such a way that it identifies the type of approaching attacker and then takes the suitable measures for countering the attack automatically.

In a multiple array of missiles as described in U.K. Patent Application No. 8808294.6, the uppermost missile can be designed in such a way, that it is suited for the deflection of guided missiles, and the lower missiles in such a way, that they, in turn, are suited for jamming such a guided missile to a very large extent, even when the uppermost missile should not have been able to deflect it.

The subject of the invention is illustrated further by the examples shown in the accompanying schematic diagrams as follows: Fig. 1 shows an oblique view of the device according to the invention; Fig. 2 shows the top view of the primary coil assembly of the device according to the invention; Fig. 3 is a schematic drawing of one element in a further device according to the invention.

The primary coil assembly shown in Figure 2 is composed of six individual coils J, each in the shape of an equilateral triangle with flattened vertices.

Six of the individual coils J are combined, leaving minimum gaps, to form a primary coil assembly with the outside contour approximating a regular hexagon.

As shown in Figure 2, upon triggering of the assembly a current I flows through each of the individual coils in the direction indicated -11 -by the arrow. Current flow is in the same direction each in adjacent coil sides. Thus, in each individual primary coil there is a magnetic flux B, which is antiparalle]. in adjacent coils, as indicated by the front and rear views of the vector arrows in Figure 2.

The secondary coil assembly K is a grid made from a material of good conductivity. The contour of this grid is largely similar to that of the primary coil assembly, with the exception of the secondary coil assembly K being a single continuous body without the gaps found between adjacent primary coils. This body may be made of ceramic material, that has been coated with a material of good conductivity.

As shown in Figure 1, the primary coil assembly formed by the individual coils J and the secondary coil assembly K, the contours of which are largely similar, are offset by an angle a, but otherwise coaxial. The magnetic fields induced by the current flow through the coil, as shown in Figure 2, are offset circumferentially from those fields produced by the current induced in the secondary coil assembly.

Therefore, acceleration of the secondary coil assembly K, which also forms the missile, does not only mean linear acceleration of the missile along the above-mentioned axis, but also a circumferential component, which imparts a stabilizing spin to the missile.

The radial branches of the secondary coil assembly K may be designed as propeller wings. Material and diameter of the components of the secondary coil assembly K may be selected such, that these components heat up to such an extent due to the current flow at missile projection, that they produce an infrared spectrum capable of influencing a warhead.

-12 -Figure 3 shows the secondary coil assembly (1) designed as a solid, level cassette-type grid made of aluminum or copper with nearly square meshes. The grid shown has webs of relatively small thickness, but of large height. The web size, as compared to the web thickness, is also large.

Facing the secondary coil (1) and angularly offset with respect to the secondary coil is a primary coil grid (2) consisting of individual primary coils, each shown simply as a loop. These primary coils are arranged in such a way that their inside widths correspond exactly with those of the meshes of the secondary coil grid.

The flow directions of current I in adjacent primary coils of the primary coil grid (2) are opposed, so that the corresponding magnetic

field vectors are antiparallel.

As can be seen from the drawing, a solid-metal secondary coil grid (1) has a substantially smaller mass as compared to that of eg. a solid plate of the same size, amounting to less than 1/10 per unit area. Due to the small mass of the secondary coil grid (1), the initial velocity achieved with the configuration shown in Figure 3 is three times higher than that obtained with a configuration with a solid secondary coil plate and a single primary coil.

Claims

Device for Neutralizing Projectiles as well as Initiating or Deflecting Guided Munition Warheads Patent Claims 1. Device for neutralizing projectiles as well as initiating or deflecting guided munition warheads, including - -a primary coil assembly which can be excited by way of an electric current, with at least one sector not extending in the circumferential direction with respect to the axis of the primary coil assembly, -a mating, shorted secondary coil assembly of preferably similar design, a1so with at least erie sector not extending in a circumferential direction with respect to the axis of the secondary coil assembly, -a missile preferably designed as a constructional unit with the primary and secondary coil assemblies, and to be accelerated by one of these assemblies, and -a triggering and actuating device, designed in such a way that the actuation of this device leads to the production of magnetic fields and thus of a force which jerks the primary and the secondary coil assnblies apart, roM/ioriQ//y Q19Sd c a r a c t e r i z e d by the primary and secondary coil assemblies (J, K) being FP. s4'i'Xd angle () with respect to the corresponding axis that the force which is generated upon operation the triggering and actuating device and which jerk the primary and the secondary coil assemblies apart comprises a component exter.ing in a circumferential direction with respect to the axis of the non-stati.rary coil assembly. -14 - 2. Device as claimed in claim 1, characterised by the primary and secondary coil assemblies (J, K) being designed as similarly shaped grids. 3. Device as claimed in any one of claims 1 or 2, characterised by the primary and secondary coil assemblies (J, K) being offset or inclined towards each other, too. 4. Device as claimed in any one of claims 1 to 3, characterised by aerodynamic guidance stabilization and/or lift elements. 5. Device for neutralizing projectiles, the device being constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.

1. Device for neutralizing projectiles as well as initiating or deflecting guided munition warheads, including -a primary coil assembly which can be excited by way of an electric current, with at least one sector not extending in the circumferential direction with respect to the axis of the primary coil assembly, -an associated, shorted secondary coil assembly also with at least one sector not extending in a circumferential direction with respect to the axis of the secondary coil assembly, -a missile comprising the primary coil assembly or the secondary coil assembly, and -a triggering and actuating device for supplying electric current to the primary coil assembly so that an electric current is induced in the secondary coil assembly and magnetic fields associated with these currents produce a force which jerks the primary and the secondary coil assemblies apart, characterised by each of the primary and secondary coil assemblies (J, K) being generally planar, the two assemblies being arranged in facing relationship, and at least one sector of one assembly being rotationally offset in its own plane relative to a corresponding sector of the other assembly by an angle (a), whereby the force which is generated upon operation of the triggering and actuating device and which jerks the primary and the secondary coil assemblies apart comprises a component extending in a circumferential direction with respect to the axis of the non-stationary coil assembly. Io

2. Device as claimed in Claim 1, characterised by the primary and secondary coil assemblies (J, K) being similarly shaped.

3. Device as claimed in claim 2, characterised by the primary and secondary coil assemblies (J, K) being designed as similarly shaped grids.

4. Device as claimed in any one of claims 1, 2 or 3, characterised by the primary and secondary coil assemblies (J, K) being offset or inclined towards each other, too.

5. Device as claimed in any one of claims 1 to 4, characterised by aerodynamic guidance stabilization and/or lift elements.

6. Device for neutralizing projectiles, the device being constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.