EP1329684B1 - Deployable decoy and ammunition for scattering said decoy - Google Patents

Abstract

The decoy (1) comprises a reflector (15) made of a flexible, electrically conducting material. This is attached to spring-loaded elements designed to deploy the reflector after firing, presenting a large surface which is detectable with millimetric waves. The automatically deployable decoy (1) comprises at least one reflector (15). This reflector is made of a flexible, electrically conducting material connected by a link to a deployment system (2,3). The deployment system is formed from two arches (2,3) which are hinged together. These include a steel wire with a spring which is intended to be folded in order to form at least two loops which store elastic potential energy. The wire ensures the deployment of the decoy. The decoy itself may be integrated within a decoy munition.

Description

The technical sector of the present invention is that of target sensor decoy devices operating in the millimeter wavelength range, for example radar detectors.

It is well known to interpose between a target and a detector integrated in a projectile or an observation system a lure consisting of deployable reflectors, which allows to deflect the attacking projectile to this lure.

Thus, patent US4503101 describes a lure of this type composed of deployable elements comprising two or more reflective panels articulated together and whose spacing from each other is caused by a spring. The disadvantage of this lure lies in the fact that the joint is an integral part of the contiguous part of the panels and that the spring is connected directly to at least two panels. Therefore, the strength of the panels must be provided to ensure this articulation and withstand the tensile force of the spring both on the hinge itself and on the panel.

JP63033906 discloses a radio lure using a shape memory alloy.

EP148635 also discloses a deployable lure in the form of an inflatable bladder.

US Patent 3671965 which is the basis of claim 1 discloses a reflector integral with two elastic hoops which are compressed radially so as to be introduced into a launch tube. Such a lure is bulky, in fact the radial compression of the arches causes their longitudinal elongation.

The object of the present invention is to provide a lure whose deployment is simplified and whose dimensions in the folded state are reduced. The invention also relates to a launching munition of said decoys and a method of folding said decoys.

The invention therefore relates to a self-deployable lure comprising at least one reflector made of an electrically conductive flexible material connected by a connection means to a deployment system, lure characterized in that the deployment system comprises at least two hoops substantially circular hinged together, and which consist of a spring steel wire capable of being folded to form at least two loops by storing elastic potential energy, wire whose trigger ensures the deployment of said lure.

Each arch may be formed of two strands interconnected at their ends.

The connecting means between the reflector and the deployment system may be constituted by tabs or son.

The tabs or the son may be metallic or made of a material identical to that of the reflector.

The tongues or the son may be made of an elastically deformable material.

Each arch is advantageously provided with two diametrically opposed plates, the plates of each arch being joined in pairs by an articulated connection.

The reflector may be constituted by eight rectangular trihedrons assembled by their vertices and formed of sheets of conductive flexible material or carrying a conductive coating.

The invention also relates to a decoy ammunition incorporating such self-deployable decoys, ammunition characterized in that it comprises at least two lures stacked in a cylindrical case disposed in a launcher tube.

The lures can be separated by washers. Alternatively each lure may be disposed in a thin envelope may tear during the deployment of the lure.

The cylindrical case may consist of two half-shells. The launcher tube may be provided with an ejection means capable of pushing a piston pushing itself the cylindrical case.

The invention also relates to a method of folding a self-expanding decoy as defined above, the method comprising the following steps: one folds a bow of the lure on the other bow of the lure by rotating it around the joints of so as to place the two arches substantially in the same plane, is applied to the two arches at least one torsion movement relative to a diametral axis so as to form at least three superposed loops.

A first advantage of the lure according to the invention lies in the fact that the deployment energy is in the form of an elastic potential energy.

Another advantage lies in the fact that the system of Deployment ensures the tensioning of the sheets constituting the reflector.

Another advantage is that the decoys can be stacked stably while providing instant deployment upon release.

• les figures 1 et 2 montrent en perspective deux variantes du leurre selon l'invention,
• la figure 3 est une coupe montrant la liaison d'un arceau sur la plaquette,
• la figure 4 est une coupe montrant la liaison des deux arceaux,
• la figure 5 montre la liaison d'un arceau avec une feuille du réflecteur,
• la figure 6 est une vue externe d'une articulation assemblée,
• les figures 7 à 9 montrent le mode de pliage d'un arceau,
• la figure 10 est une coupe d'une munition incorporant des leurres selon l'invention.

Other features, details and advantages of the invention will emerge more clearly from the description given below as an indication in relation to the appended drawings in which:

• Figures 1 and 2 show in perspective two variants of the lure according to the invention,
• FIG. 3 is a section showing the connection of an arch on the wafer,
• FIG. 4 is a section showing the connection of the two arches,
• FIG. 5 shows the connection of a hoop with a sheet of the reflector,
• FIG. 6 is an external view of an assembled articulation,
• Figures 7 to 9 show the folding mode of an arch,
• Figure 10 is a section of an ammunition incorporating decoys according to the invention.

A lure according to the invention is used to decoy the detectors operating in millimeter wavelengths.

A first embodiment of such a decoy is shown in the extended position in FIG. 1. It comprises a reflector 15 made of an electrically conductive flexible material (or carrying a conductive coating) which is connected by a connecting means a deployment system which comprises two substantially circular arches (2,3) articulated to each other at joints 7.

The reflector 15 consists of eight trihedrons 16 connected by their apex. A trihedron 16 is formed by three sheets cut into right triangles and welded together. The sheets forming the trihedrons 16 are for example made of a polyethylene film coated with a thin layer of aluminum which allows to make it conductive of electricity. Any other flexible conductive material or not can be used. It is advantageous to use a polyethylene film tri-layer that is to say associating an aluminum layer between two layers of polyethylene. Such a film has the advantage of being heat-sealable.

If a non-conductive flexible material is used, a layer of paint or conductive lacquer will be applied to it without difficulty. For example, it is possible to use a cut and sewn synthetic fabric which will be coated with a conductive paint.

In the first embodiment shown in FIG. 1, the means ensuring the connection of the reflector 15 and the arches 2,3 is constituted by a thermal welding of the vertices of the trihedrons directly on the arches 2 and 3.

In the second embodiment of FIG. 2, the means ensuring the connection of the reflector 15 and the hoops 2,3 consists of tongues 11 and 13 and a ring 14 or 10.

The length of these tongues is provided in such a way that some tension is exerted by the arches 2 and 3 on the vertices of the reflector 15. This ensures a maintenance of each trihedron voltage which minimizes the structural defects and in particular flatness of the sheets forming each trihedron 16.

The tongues 11 and 13 may advantageously be made of the same material as that used to manufacture the reflector. The tension provided by the tabs causes deformation of the arches which is not detrimental to the bending of the lure.

The structures of the hoops and means of connection of the reflector 15 with the hoops 2 and 3 are more particularly visible in Figures 3 to 6. The deployment system 1 of the lure thus comprises two hoops 2 and 3 which are in the form of metal wires or tongues. These arches are for example made of spring steel and they can be folded so as to store them a potential elastic energy as it will be explained below.

Each arch 2 or 3 may be in the form of two strands 2a and 2b (respectively 3a and 3b) of the same length, each strand covering half of the arch considered (see also Figures 1 and 2).

As is more particularly visible in Figures 3, 4 and 6, each end of a strand is connected to one end of another strand by means of a wafer 4 welded. Two strands 2a and 2b are thus connected to one another by two plates 4 to form a closed loop close to a circle. Each plate 4 is provided with a transverse hole 5.

The arch 3 is also formed of two strands 3a, 3b which are connected to each other by two plates 6 welded and also pierced. The two arches 2 and 3 are joined together at the platelets 4 and 6 in two diametrically opposed points by a hinge. Each joint (FIGS. 4 and 6) is constituted by a bolt 7 which comprises a screw 9 and a nut 8 and which passes through the holes 5 of the plates 4 and 6. This bolt ensures freedom of rotation of the two plates 4 and 6. one relative to the other, therefore allows the pivoting of one arch relative to the other around a diametrical axis 12 materialized by the two joints (Figures 1 and 2). Pivoting is between a folded position in which the two arches 2 and 3 are substantially in the same plane and an extended position (that of Figures 1 and 2) in which the two arches are in orthogonal planes.

Such an arrangement makes it possible to fold the reflector. The bolt 7 carries a ring 10 which is brazed on the head of the screw 9 and which allows the fixing of the tongue 11 for attaching the reflector 15 to the arch. Alternatively (variant of Figure 1) can directly weld the top of a trihedron 16 on the ring 10. It will also be able to drill transversely the head of the screw 9 to introduce the fixing ring or the tongue.

For example, the hoops are made in the form of spring wire with a diameter of the order of mm or a thin blade 3 mm wide and 0.5 mm thick.

The reflector 15 has six vertices. Two vertices are linked to the joints formed by the bolts 7, either directly or via a tongue 11. Each of the other four vertices is linked to a bow at a middle portion thereof. Two vertices are linked to the hoop 2 two others to the hoop 3.

In Figure 5, there is shown the means providing this connection between a hoop 2 or 3 and the reflector. This means consists of a ring 14 brazed to the hoop 2 or 3. The ring 14 allows the attachment of a tongue 13 which is connected to an apex of the reflector 15. Alternatively (variant of Figure 1) solder directly the top of a trihedron 16 on the hoop or the ring 14.

In Figures 7 to 9, there is illustrated a method of folding a hoop. For clarity of the figure a single hoop 2 is shown with its rings 10 and 14 and the reflector 15 is not shown either. Concretely the second arch 3, which is articulated on the first hoop 2 substantially at the level of the rings 10, is folded before folding on the hoop 2 so as to be in the same plane as it ci. The flexibility of the reflector 15 allows such pivoting of the hoops.

The folding movement that will be described below therefore applies simultaneously to the two arches that are in the same plane and whose circular shapes are almost superimposed.

We begin in a first phase (Figure 7) by twisting along the arrow F1 manually the two arcs around the axis delimited by the segment AB, A being the point at which the twist is applied and B the fixed point. We then obtain two loops as shown in FIG.

Then, during a second phase (FIG. 8), a second reverse twist is performed around the point B (arrow F2), the point A remaining fixed while bringing the points A and B closer to each other. (arrows F3, F4). For this second phase one could alternatively (but less conveniently) continue the torsion movement of the point A of another half turn, the point B remaining fixed.

After twisting a half turn around each point A and B, and as a result of the elasticity of the material of the hoops, an additional loop is obtained which is introduced into the other loops as shown in FIG. 9.

The final diameter of the loops is substantially less than half that of the deployed arch. Thus, an arch of initial diameter of 36 cm has a final diameter of about 15 cm in the folded position. The flexibility of the material forming the reflector allows such folding. The balance of hoops 2 and 3 thus folded is unstable and a simple shock is sufficient to cause their deployment so that of the reflector 15.

Once the lure folded, one obtains a wafer whose thickness is about that of the arches is 3 mm for example for a diameter of about 150 mm. Reflector 15 being made from a flexible material, it is totally compressible. The dimensions of the reflector 15 therefore of the entire decoy are chosen by the skilled person according to the radar cross section to obtain.

In Figure 10, there is shown in section an ammunition 20 for launching the decoys. This ammunition is intended to equip a vehicle (such as an armored vehicle, to ensure for example a roof protection) or a fixed structure (such as a portable autonomous zone protection system, a building or shelter). The launcher system is for example in accordance with that described in FR-A-2765869. The ammunition therefore conventionally comprises a tube 21 at the rear part of which is a base 22 screwed on it and which carries a radial lug 23 for fixing the ammunition by a bayonet mounting on a launcher not shown. The base 22 carries an axial contact 24 electrically isolated from the base by an insulating cylinder 25.

The base contains a pyrotechnic ejection charge 26 (a propellant powder for example) and an igniter 27 which is electrically connected, on the one hand to the contact 24 and on the other hand to the metal body of the base 22. The tube 21 encloses a piston 28 on which is applied an envelope cylindrical 29 containing a stack of lures 1. These decoys are separated by washers 30 of cardboard or plastic. These washers make it possible to avoid a catch between two lures during assembly of the ammunition. Alternatively, each lure 1 could be placed in a thin paper or plastic envelope that would be broken when fired. The envelope 29 is preferably in the form of two half-shells. The tube 21 is closed at its other end by a cover 31 connected thereto by a shearable radial pin.

The operation is as follows. When it is desired to launch the decoys after detecting a threat, ignition of the igniter 27 of the charge 26 is commanded. The pressure of the gases is exerted on the piston 28 which pushes the cover 31 through the envelope 29, shearing the connecting pin of the lid. The lures 1 are ejected from the tube 21 pushed by the piston. The half-shells of the cylindrical envelope 29 separate at the outlet of the tube allowing the release of the lures. The shock suffered by the decoys during their ejection is sufficient to ensure their deployment out of the tube 21. The ammunition according to the invention is therefore of simple structure since no gas generating composition internal to the decoys is necessary to ensure the deployment of the decoys. .

Depending on the operational requirements (number of reflective surfaces necessary to simulate a given vehicle) we can define a range of ammunition including a number of different decoys, lures possibly different sizes and / or incorporating reflectors with different types of materials. It will thus be possible to provide in a munition a number of decoys of between 3 and about 30. The ammunition will have different lengths depending on the number of decoys and the characteristics of the ejection charge 26 will also be adapted to the number of decoys to be dispersed.

Alternatively, the propulsive ejection charge may be replaced by a mechanical ejector, such as a spring loaded to push the piston 28. In this case, the cover 31 will be provided with a remotely controllable lock and the dispersion will be caused simply by opening the lid.

Claims (13)

1. A self-deployable decoy (1) comprising at least one reflector (15) constituted by a flexible electrically-conductive material connected by linking means (11, 13) to a deployment system (2, 3) comprising at least two substantially circular hoops, decoy wherein said hoops are joined together and constituted by a wire of spring steel able to be folded so as to form at least two loops whilst storing elastic potential energy, a wire whose expansion ensures the deployment of said decoy.
2. A self-deployable decoy (1) according to Claim 1, wherein each hoop (2, 3) is formed of two strands connected together at their ends.
3. A self-deployable decoy (1) according to one of Claims 1 or 2, wherein the linking means are constituted by tabs or wires (11, 13).
4. A self-deployable decoy (1) according to Claim 3, wherein the tabs or wires (11, 13) are metallic or made of a material identical to that of the reflector.
5. A self-deployable decoy (1) according to Claim 3, wherein the tabs or wires (11, 13) are made of an elastically deformable material.
6. A self-deployable decoy (1) according to any one of Claims 1 to 5, wherein each hoop is provided with two diametrically opposed plates, the plates of each hoop being joined two by two by an articulated connection.
7. A self-deployable decoy (1) according to any one of the above Claims, wherein the reflector (15) is constituted by eight right-angled trihedra assembled by their vertexes and formed of sheets of flexible conductive material or material with a conductive coating.
8. A decoy ammunition (20) incorporating self-deployable decoys according to any of the above Claims, wherein it comprises at least two decoys (1) stacked in a cylindrical case (29) placed in a launch tube (21).
9. A decoy ammunition according to Claim 8, wherein the decoys are separated by washers (30).
10. A decoy ammunition according to Claim 8, wherein each decoy is placed in a thin envelope able to be torn when the decoy deploys.
11. A decoy ammunition according to one of Claims 8 to 10, wherein the cylindrical case (29) is constituted by two half-shells.
12. An ammunition according to one of Claims 8 to 11, wherein the launch tube (21) is provided with ejection means (26) able to push a piston (28) which in turn pushes the cylindrical case (29).
13. A folding process for the self-deployable decoy according to one of Claims 1 to 7, such process comprising the following steps: one decoy hoop is flipped over the other decoy hoop by making it pivot around the joins so as to place the two hoops substantially in the same plane, at least one twisting motion is applied to the two hoops with respect to a diametral axis so as to form three superimposed loops.

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