FR2835049A1 - DEPLOYABLE LURE AND AMMUNITION ALLOWING THE DISPERSION OF SUCH A LURE - 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

a 40 mm gun.

1 2835049

  The technical sector of the present invention is that of devices for decoying 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 in a projectile or an observation system a lure consisting of deployable reflectors, which makes it possible to deflect the attacking projectile towards this lure. Thus, US-A-4,503,101 describes a lure of this type composed of playable elements comprising two or more reflective panels hinged together and of which

  the spacing of each other is caused by a spring.

  The drawback of this lure lies in the fact that the articulation 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 resistance of the panels must be provided to ensure this articulation and to support the tensile force of the spring both on the articulation.

itself and on the panel.

  Document JP63033906 describes a radio decoy using

a shape memory alloy.

  Patent EP-A-O 148 635 also describes a lure

  playable in the form of an inflatable bladder.

  The object of the present invention is to provide a lure whose deployment is simplified. The invention also relates to

  a launch ammunition for decoys.

  The subject of the invention is therefore a self-defeating lure comprising at least one reflector, characterized in that the reflector is made of a flexible electrically conductive material connected by a connection means to a deployment system. The deployment system will advantageously include at least two substantially circular hoops hinged together. The poles may consist of a spring steel wire capable of being folded back so as to form at least two loops by storing potential energy

2 2835049

  elastic, 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 system may be constituted by tabs or wires. 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 plates, the plates of each

  hoop being joined two by two by an articulated link.

  The reflector may consist of eight rectangular trihedra joined by their vertices and formed from sheets of flexible conductive material or carrying a conductive coating. Another subject of the invention is a decoy ammunition incorporating such self-deploying decoys, an ammunition characterized in that it comprises at least two decoys stacked in a cylindrical case disposed in a launcher tube.

  The lures can be separated by washers.

  Alternatively, each lure may be placed in a thin envelope capable of tearing during the

deployment of the lure.

  The cylindrical case may consist of two half

  shells. The launch tube may be provided with an ejection means capable of pushing a piston pushing itself

the cylindrical case.

  A very first advantage of the lure according to the invention lies in the fact that the deployment energy is under the

  form of an elastic potential energy.

  Another advantage is that the deployment system ensures the tensioning of the sheets

constituting the reflector.

  Another advantage is that the lures

3 2835049

  can be stacked stably while ensuring

  instant deployment upon release.

  Other features, details and benefits of

  the invention will emerge more clearly from the description

  given below as an indication in relation to the accompanying drawings in which: - Figures 1 and 2 show in perspective two variants of the lure according to the invention, - Figure 3 is a section showing the connection of a hoop on the plate, - Figure 4 is a section showing the connection of the two arches, - Figure 5 shows the connection of an arch with a sheet of the reflector, - Figure 6 is an external view of an assembled joint, - Figures 7 to 9 show the method of folding a hoop, - Figure 10 is a section of a munition incorporating

lures according to the invention.

  A lure according to the invention is used to lure detectors operating in millimeter wavelengths. A first embodiment of such a lure is shown in the deployed position in FIG. 1. It comprises a reflector 15 made of a flexible material which conducts electricity (or carries a conductive coating) which is connected by a connecting means. a deployment system which comprises two substantially circular arches (2,3) and

  articulated together at articulation level 7.

  The reflector 15 consists of eight trihedra 16 connected by their top. A trihedron 16 is formed by three sheets 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 possible to conduct electricity. Any other flexible material which may or may not be conductive may be used. It is advantageously possible to use a tri-polyethylene film

4 2835049

  layer ie associating a layer of aluminum between two layers of polyethylene. Such a film has the advantage

to be heat sealable.

  If a flexible non-conductive material is used, a layer of conductive paint or varnish will be applied to it without difficulty. We can for example 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 consists of a thermal weld of the

  vertices of the trihedrons directly on the arcs 2 and 3.

  In the second embodiment of FIG. 2, the means ensuring the connection of the reflector 15 and the arches 2,3 is constituted by tongues 11 and 13 and a ring 14 or 10. The length of these tongues is provided in such a way that a certain tension is exerted by the arcs 2 and 3 on the tops of the reflector 15. This thus ensures that each trihedron is kept in tension, which makes it possible to minimize structural damage 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 to manufacture the reflector. The tension provided by the tabs causes the deformation of the hoops which is not

  not detrimental to the folding of the lure.

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

explained below.

  Each hoop 2 or 3 can be in the form of two strands 2a and 2b (respectively 3a and 3b) similarly

2835049

  length, each strand covering half the arch

  considered (see also Figures 1 and 2).

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

transverse hole 5.

  The arccau 3 is also formed of two strands 3a, 3b which are connected to each other by two plates 6 welded and also drilled. The two arches 2 and 3 are joined together at the level of the plates 4 and 6 at two points diametrically opposed by an articulation. 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 with respect to the other, therefore authorizes the pivoting of a hoop with respect to the other about a diametrical axis 12 materialized by the two articulations (FIGS. 1 and 2). The pivoting takes place between a folded position in which the two arches 2 and 3 are substantially in the same plane and a deployed position (that of FIGS. 1 and 2) in which

  the two arches are in orEhogonal 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 the reflector 15 to be attached to the hoop. We can alternatively (variant of Figure 1) directly weld the top of a trihedron 16 on the ring 10. We can also pierce the head of the screw 9 transversely

  to insert the fixing ring or the tongue.

  For example, the arches 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 bolts 7, i.e.

  directly either through a tongue 11.

  Each of the other four vertices is linked to an arch at the mAdiane part of it. Two summits are

  liAs the water 2 two others the arcau 3.

  In FIG. 5, the means ensuring this connection between a hoop 2 or 3 and the reflector has been shown. This means is

  constituted by a ring 14 arms on the arch 2 or 3.

  The ring 14 allows the fization of a tongue 13 which is connected to a somet of the reflecteu 15. We can alternatively (variant of Figure 1) weld directly

  the top of a tridre 16 on the arch or the ring 14.

  In FIGS. 7 9, a method of folding a steel is illustrated. For the clarity of the figure, only one arch 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 the hoop 2 so as to be in the same plane as this. The flexibility of the reflector 15 allows such

pivoting of accaux.

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

practically superposed.

  We start during a first phase (Figure 7) by twisting the arrow F1 manually the two arcs around the dAlimit axis by segment AB, both the point to which the torsion is applied and B the point fize. We

  then obtains two loops as shown in Figure 8.

  Then during a second phase (FIG. 8), a second twist in the opposite direction is carried out around point B (arrow F2), the point remaining fize, while bringing points A and B closer to each other ( arrows E3, E4). For this second phase we could alternatively (but less conveniently) J5 continue the torsional movement of point A by another half

turn, point B remaining fize.

  After a twist of a half-turn around each point A and B. and as a result the elasticity of the material of the arches,

7 2835049

  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 less than half that of the deployed arch. Thus, a hoop with an initial diameter of 36 cm has a final diameter of the order of 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 therefore that

of the reflector 15.

  Once the lure is folded, a wafer is obtained whose thickness is approximately that of the hoops, ie 3 mm for example for a diameter of the order of 150 mm. The reflector being made from a flexible material, it is fully compressible. The dimensions of the reflector 15 therefore of the entire lure are chosen by a person skilled in the art

  depending on the radar equivalent surface to be obtained.

  In Figure 10, there is shown in section a munition for launching the lures. This ammunition is intended to equip a machine (such as an armored vehicle, for example to provide protection of the roof) or a fixed structure (such as an autonomous portable area protection system, a building or a shelter). The launcher system is, for example, in accordance with that described in patent FR-A-2765869. The ammunition therefore conventionally comprises a tube 21 at the rear part of which is a base 22 screwed onto it and which carries a radial lug 23 allowing the ammunition to be fixed by a bayonet mount on a launcher not shown. 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 the contact 24 and on the other hand to the metal body of the base 22. The tube 21 contains a piston 28 on which is applied a cylindrical casing 29 containing a stack of lures 1. These lures are separated by washers 30 of cardboard or plastic. These washers avoid

8 2835049

  hooking between two lures when mounting the ammunition.

  Alternatively, each lure 1 could be placed in a thin paper or plastic envelope which 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 to it by a shearable radial pin.

  The operation is as follows. When it is desired to launch the lures after detection of a threat, the initiation of the igniter 27 of the charge 26 is controlled. The gas pressure is exerted on the piston 28 which pushes the cover 31 by means of the casing 29, shearing the connecting pin of the cover. The lures 1 are ejected from 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 jack suffered by the lures 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 composition generating gas internal to the lures is necessary for

  ensure the deployment of lures.

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

dispersing lures.

  Alternatively, it is also possible to replace the propellant ejection charge with a mechanical ejector, such as a banded spring pushing 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 cover.

9 2835049

Claims (14)

  1. Self-deploying lure (1) comprising at least one reflector (15), characterized in that the reflector (15) consists of a flexible electrically conductive material connected by a connecting means (11, 13) to a system of deployment (2, 3).   2. Self-deflecting lure (1) according to claim 1, characterized in that the deployment system comprises at least two hoops (2, 3) substantially circular articulated between them.   3. Self-deploying lure (1) according to claim 2, characterized in that the poles (2, 3) consist of a spring steel wire capable of being folded so as to form at least two loops by storing elastic potential energy, a wire whose trigger ensures deployment of said lure.   4. Self-playable lure (1) according to claim 2 or 3, characterized in that each arch (2, 3) is formed of   two strands connected together at their ends.   5. Self-defeating lure (1) according to one of   Claims 1 to 4, characterized in that the means for   connection is constituted by tabs or wires (11, 13). 6. Self-deploying lure (1) according to claim 5, characterized in that the tongues or the wires (11, 13) are metallic or made of a material identical to that of the reflector.   7. Self-deploying lure (1) according to claim 5, characterized in that the tongues or the wires (11, 13)   are made of an elastically deformable material.   8. Self-deploying lure (1) according to any one of   Claims 2 to 7, characterized in that each hoop is   provided with two diametrically opposed plates, the plates of each arch being joined two by two by a articulated connection.   9. Self-deploying lure (1) according to any one of   previous claims, characterized in that the   reflector (15) consists of eight rectangular trihedrons 2835049   joined by their vertices and formed from sheets of material   flexible conductive or carrying a conductive coating.   10. Decoy ammunition (20) incorporating decoys   self-deploying according to any of the claims   previous, characterized in that it comprises at least two lures (1) stacked in a cylindrical case (29), arranged in a launcher tube (21).   11. Decoy ammunition according to claim 10, characterized in that the decoys are separated by washers (30).   12. A decoy ammunition according to claim 10, characterized in that each decoy is placed in a thin envelope capable of tearing during the deployment of the lure.   13. Decoy ammunition according to one of claims 10   12, characterized in that the cylindrical case (29) is made up of two half-shells.   14. Ammunition according to one of claims 10 to 13,   characterized in that the launcher tube (21) is provided with an ejection means (26) capable of pushing a piston (28)