EP1329684A2 - 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 decoy devices for target detectors operating in the millimeter wavelength range for example radar detectors.

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

Thus, patent US4503101 describes a lure of this type composed of deployable elements comprising two or more reflective panels hinged together and of which the spacing of each other is caused by a spring. The downside of this lure is that the joint is an integral part of the contiguous part panels and that the spring is connected directly to the minus two panels. Therefore, the resistance of the panels must be provided to ensure this articulation and support the tensile force of the spring both on the joint itself and on the panel.

Document JP63033906 describes a radio decoy using a shape memory alloy.

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

Patent US 3671965 describes a reflector integral with two elastic arches which are compressed radially by so that it can be introduced into a launch tube. A such a lure is bulky, in fact the radial compression hoops causes their longitudinal elongation.

The object of the present invention is to provide a lure whose deployment is simplified and whose dimensions to the collapsed state are reduced. The invention also relates to a ammunition for launching said lures.

The invention therefore relates to a self-deploying lure comprising at least one reflector made of a material flexible conductor of electricity connected by means of connection to a deployment system, lure characterized in the deployment system includes at least two roll bars substantially circular hinged together, and which are made of a spring steel wire capable of being folded so as to form at least two loops in storing elastic potential energy, wire whose trigger ensures the deployment of said lure.

Each hoop can be formed of two connected strands between them at their ends.

The connection means between the reflector and the deployment may consist of tabs or son.

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

The tabs or the wires can be made in one elastically deformable material.

Each hoop will advantageously be provided with two diametrically opposite pads, the pads of each hoop being joined two by two by an articulated link.

The reflector may consist of eight trihedrons rectangles joined by their vertices and formed of leaves of flexible conductive or coated material driver.

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

The lures can be separated by washers. Alternatively, each lure can be placed in a thin envelope likely to tear when deployment of the lure.

The cylindrical case may consist of two half-shells. The launch tube may be provided with a means ejection likely to push a piston pushing itself the cylindrical case.

A very first advantage of the lure according to the invention is that the deployment energy is under the form of an elastic potential energy.

Another advantage is that the deployment ensures the tensioning of the sheets constituting the reflector.

Another advantage is that the lures can be stacked stably while ensuring 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 characteristics, details and advantages of the invention will emerge more clearly from the description given below by way of indication in relation to the appended drawings in which:

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

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

A first embodiment of such a lure is shown in the deployed position in Figure 1. It includes a reflector 15 made of a flexible conductive material electricity (or with a conductive coating) which is linked by a connecting means to a deployment system which comprises two substantially circular arches (2,3) and articulated together at articulation level 7.

The reflector 15 consists of eight connected trihedra 16 by their summit. A trihedron 16 is formed by three leaves cut into right triangles and welded together. The sheets forming the trihedra 16 are for example made of a polyethylene film coated with a thin layer of aluminum which makes it conductive of electricity. Other flexible conductive material or not can be used. We can advantageously use a three-layer polyethylene film ie associating a layer of aluminum between two layers of polyethylene. Such a film has the advantage to be heat sealable.

If we use a flexible non-conductive material, we apply a coat of paint or varnish on it driver without difficulty. We could for example use a cut and sewn synthetic fabric which will be covered with conductive paint.

On the first embodiment represented in the figure 1, the means ensuring the connection of the reflector 15 and the hoops 2,3 is formed by thermal welding of the vertices of the trihedrons directly on arches 2 and 3.

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

The length of these tabs is provided in such a way a certain tension is exerted by hoops 2 and 3 on the tops of the reflector 15. This thus ensures maintenance of each trihedron in tension which minimizes the structural defects and in particular flatness of the sheets forming each trihedron 16.

The tongues 11 and 13 can advantageously be made of the same material as that used for make the reflector. The tension provided by tabs causes the deformation of the hoops which is not not detrimental to the folding of the lure.

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

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

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

The arch 3 is also formed by two strands 3a, 3b which are linked to each other by two welded plates 6 and also breakthroughs. The two arches 2 and 3 are joined between them at the pads 4 and 6 at two points diametrically opposed by a joint. Each articulation (figure 4 and 6) is constituted by a bolt 7 which includes a screw 9 and a nut 8 and which passes through the holes 5 in plates 4 and 6. This bolt provides freedom of rotation of the two plates 4 and 6, one relative to the other, therefore authorizes the pivoting of an arch relative to to the other around a diametrical axis 12 materialized by the two joints (Figures 1 and 2). The pivoting is done between a folded position in which the two arches 2 and 3 lie substantially in the same plane and a deployed 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 to the head of the screw 9 and which allows the fixing of the tongue 11 allowing to attach the reflector 15 to the hoop. We will be able to alternatively (variant of figure 1) weld directly the top of a trihedron 16 on the ring 10. We can also drill the head of screw 9 transversely to insert the fixing ring or the tab.

For example, the arches are made under 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 summits are linked to the joints formed by the bolts 7, i.e. directly either via a tongue 11. Each of the other four vertices is linked to an arch at level of a middle part of it. Two summits are linked to rollbar 2 two others to rollbar 3.

In Figure 5, there is shown the means ensuring this connection between a hoop 2 or 3 and the reflector. This means is consisting of a ring 14 brazed on the arch 2 or 3. The ring 14 allows the attachment of a tongue 13 which is connected to a vertex of the reflector 15. We can alternatively (variant of figure 1) weld directly the top of a trihedron 16 on the hoop or ring 14.

Figures 7 to 9 illustrate a method of folding a hoop. For clarity of the figure only one hoop 2 is shown with its rings 10 and 14 and the reflector 15 is also not shown. Concretely the second hoop 3, which is articulated on the first hoop 2 substantially at the level of the rings 10, is folded down before folding on hoop 2 so as to be in the same plane that this one. The flexibility of the reflector 15 allows such pivoting of the arches.

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

We start in a first phase (Figure 7) with twist following arrow F1 manually the two poles around the axis delimited by the segment AB, A being the point to which the torsion is applied and B the fixed point. We then obtains two loops as shown in FIG. 8.

Then during a second phase (Figure 8) we perform a second opposite twist around point B (arrow F2), point A remaining fixed, while bringing the points together A and B from each other (arrows F3, F4). For this second phase we could alternatively (but less conveniently) continue the twisting motion of point A by another half turn, point B remaining fixed.

After a twist of half a turn around each point A and B, and as a result of the elasticity of the material of the arches, we obtain an additional loop which is introduced into the other loops as shown in figure 9.

The final diameter of the loops is significantly smaller half that of the roll bar. So, a hoop of initial diameter of 36 cm has a final diameter of about 15 cm in the folded position. The flexibility of material forming the reflector allows such folding. The balance of hoops 2 and 3 thus folded is unstable and a simple shock is enough to cause their deployment so that of the reflector 15.

Once the lure is folded, we get a cake which the thickness is approximately that of the arches, i.e. 3 mm per example for a diameter of the order of 150 mm. The reflector 15 being made from a flexible material, it is fully compressible. The dimensions of the reflector 15 therefore of the whole lure are chosen by the skilled person depending on the radar equivalent surface to be obtained.

In Figure 10, there is shown in section a munition 20 allowing to launch the lures. This ammunition is intended to equip a machine (such as an armored vehicle, for provide roof protection) or a structure fixed (such as an autonomous portable zone protection system, a building or shelter). The launcher system is for example conforms to that described in patent FR-A-2765869. The ammunition therefore conventionally comprises a tube 21 to the part rear of which is a base 22 screwed thereon and which carries a radial lug 23 allowing the fixing of the ammunition by bayonet mounting on a non launcher represented. The base 22 carries an isolated axial contact 24 electrically 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 contact 24 and on the other part of the metal body of the base 22. The tube 21 contains a piston 28 to which an envelope is applied cylindrical 29 containing a stack of lures 1. These lures are separated by washers 30 of cardboard or plastic material. These washers avoid hooking between two lures when mounting the ammunition. We could alternatively place each lure 1 in a thin paper or plastic envelope that would be broken when fired. The envelope 29 is presented preferably in the form of two half-shells. The tube 21 is closed at its other end by a cover 31 connected to it by a shearable radial pin.

The operation is as follows. When we want launch the lures after detection of a threat, we order initiation of the igniter 27 of the charge 26. The pressure gas is exerted on the piston 28 which pushes the cover 31 through casing 29, shearing the pin cover connection. Lures 1 are thrown out of the tube 21 pushed by the piston. The half shells of the cylindrical casing 29 separate at the outlet of the tube allowing the release of the lures. The shock suffered by lures when ejected is sufficient to ensure their deployment outside the tube 21. The munition according to the invention is therefore of simple structure since no composition gas generator internal to the lures is not necessary for ensure the deployment of lures.

Depending on operational needs (number of surfaces reflective needed to simulate a given vehicle) we can define a whole range of ammunition including a number of different lures, possibly lures of different sizes and / or incorporating reflectors having materials of a different nature. We can thus foresee in a munition a number of lures between 3 and approximately 30. The ammunition will have different lengths in depending on the number of lures and the characteristics of the charge 26 of ejection will also be adapted to the number of dispersing lures.

We can also alternatively replace the load propellant of ejection by a mechanical ejector, such as a bandaged spring pushing the piston 28. In this case, the cover 31 will be provided with a remotely controllable lock and dispersion will be caused simply by opening the lid.

Claims (12)

Self-deploying lure (1) comprising at least one reflector (15) made of a flexible electrically conductive material connected by a connecting means (11,13) to a deployment system (2,3), characterized lure in that the deployment system comprises at least two substantially circular arches (2,3) articulated between them, and which consist of a spring steel wire capable of being folded back so as to form at least two loops by storing elastic potential energy, a wire whose trigger ensures the deployment of said lure. Self-deploying lure (1) according to claim 1, characterized in that each hoop (2,3) is formed by two strands connected together at their ends. Self-deploying lure (1) according to one of claims 1 or 2, characterized in that the connecting means is constituted by tongues or wires (11,13). Self-deploying lure (1) according to claim 3, characterized in that the tongues or the wires (11, 13) are metallic or made of a material identical to that of the reflector. Self-deploying lure (1) according to claim 3, characterized in that the tongues or the wires (11, 13) are made of an elastically deformable material. Self-deploying lure (1) according to any one of claims 1 to 5, characterized in that each hoop is provided with two diametrically opposed plates, the plates of each hoop being joined in pairs by an articulated connection. Self-deploying lure (1) according to any one of the preceding claims, characterized in that the reflector (15) consists of eight rectangular trihedra joined by their vertices and formed from sheets of flexible conductive material or carrying a conductive coating. Decoy ammunition (20) incorporating self-deploying decoys according to any one of the preceding claims, characterized in that it comprises at least two decoys (1) stacked in a cylindrical case (29), arranged in a launcher tube ( 21). Lure ammunition according to claim 8, characterized in that the lures are separated by washers (30). Lure ammunition according to claim 8, characterized in that each lure is placed in a thin envelope capable of tearing during deployment of the lure. Decoy ammunition according to one of Claims 8 to 10, characterized in that the cylindrical case (29) consists of two half-shells. Ammunition according to one of claims 8 to 11, characterized in that the launcher tube (21) is provided with an ejection means (26) capable of pushing a piston (28) pushing itself the cylindrical case (29) .

Images