GB2187825A - Munitions with submunitions for zonal attack - Google Patents

Abstract

A munition comprises submunitions 32 with gliding trajectories, each submunition being provided with a parachute 50 whose apex is attached to the body of the charge of the submunition, and whose skirt is equipped with ballast 54 around its periphery. Overbinding cords 58 are lacquered around the folded parachute and unwind under the effect of centrifugal force to ensure the progressive unfurling of said parachute at a controlled speed and duration under very high spin speeds. Radial shutters 56 sloping at, e.g., 3 DEG enable gliding and supplement lift. The parachute and charge axes are aligned art angle beta , e.g. 20 DEG , for effective scanning. <IMAGE>

Description

SPECIFICATION Improvements to munitions with submunitions for zonal attack The present invention relates to improvements in munitions with submunitions for zonal attack.

The concept of modern warfare envisages, inter alia, the disabling, at long distances of up to approximately 20-25 km, of large concentrations of tanks spread over large areas of terrain (10-20 hectares).

During the last World War, and since then, the great nations of the world have concerned themselves with this problem.

Various means of solving this problem have been devised, or have been previously or are currently envisaged. These comprise, on the one hand, multiple rocket launchers, such as the "Stalin organ" (USSR), the SYRA (France), and the MLRS (USA) and, on the other hand, artillery projectiles of large calibre-i 50 mm, 175 mm, 203 mm, for example which are currently undergoing an important evolution.

All these recommended solutions have as their aim the attainment of optimum probable destruction, in restrained conditions of combat, by improving target detection and the distribution over the terrain of the munitions and their submunitions, and by improving the terminal effects, especially by the use of "smart" heads, reputed only to make direct hits thanks to their having their own means of detection and even of manoeuvre.

The present invention aims to improve, by relatively simple means, one or other of the areas with a view to increasing the probability of destroying the targets.

Consequently, the invention provides a munition comprising a plurality of submunitions having gliding trajectories, each submunition being provided with a parachute whose apex is attached to the body of the submunition charge and whose skirt is equipped with ballast around its periphery, and overbinding means for ensuring the progressive unfurling of said parachute at a controlled speed and at a controlled duration under very high spin speeds.

Thus, a plurality of such submunitions equipped, for example, with a charge of the deformable plate or self forging fragment (SFF) type and a target detector is delivered above the target zone.

Preferably the submunitions are of the same calibre as the munition itself (shell or rocket body etc.), so as to improve their efficacy. The containers thereof, if possible prepared for fragmentation, may themselves constitute the wall of the munition. It is capable of withstanding the stresses of departure and flight.

At a fixed altitude recognized by an altimetric laser-diode fuze, the submunitions are separated pyrotechnically.

According to another characteristic of the invention, the ballasted skirt of each parachute, whose apex is attached to the body of the submunition charge, has radial shutters.

When unfurling of its ballasted parachute is completed, each submunition descends at a substantially fixed rate, with a vertical speed of the order of several m/s (for example 5 m/s) and a high spin speed (for example 30 rev/s) around an axis approximating to that of the parachute and with which the axis of the charge forms an angle ss (of the order of 20 ).

The submunition remains for a prolonged amount of time (8 seconds, for example) at a low altitude (for example, from 70 to 20 m), above the targets, which substantially improves target detection, resistance to interference and the terminal effects of the charges, while at the same time remaining free from the obstacles of the terrain.

The effect of side wind, at high altitude, combined with that of predetermined dissymetries, gives the submunition a lateral speed of the order of several m/s (approximately 10 m/s, for example).

For each submunition analysis of the terrain and the search for targets is effected over a reduced area, of the order of approximately 0.5 hectares or more, for example by infrared detection of "temperature jumps" with a scanning step of the order of less than 0.50 m.

The various characteristics and advantages of the invention will become evident from a reading of the description given below with reference to the accompanying drawings, which show an exemplary embodiment.

It should be emphasized that the following description deals merely with examples, and that all other embodiments, shapes, proportions and arrangements of munitions such as rockets, artillery shells, mortars etc., can also be used without going beyond the context of the invention.

In the drawings: - Figure 1 is a longitudinal section through an exemplary embodiment of a munition according to the invention, comprising three submunitions; - Figure 2 is a section similar to that of Fig. 1, showing, in a larger scale partial view, one of the submunitions; - Figures 3 and 4 show external views of the submunition after release, with its parachute respectively folded and unfurled; - Figure 5 is a section along the line 5-5' of Fig. 4 showing the canopy of the parachute at the level of its shutters; - Figures 6 to 9 show, in perspective, the different stages involved in putting the parachute in position in the submunition; and Figure 10 is a diagram illustrating the overall functioning sequence of a munition according to the invention.

Reference is made firstly to Figs. 1 and 2, which show respectively the whole munition 10 (a shell in the non-limiting example shown) and a submunition. The submunition 10 comprises, from back to front: a base assembly for ensuring setting into spinning motion and tightness vis-a-vis the propellant gases and comprising a bottom 12 of a high-strength alloy (titanium, for example), a body 14, a driving band 16 conformed to the internal arrangements of the gun, a gasket 18 and a support brace.

The ogive 20 of the munition comprises: -an altimetric laser-diode fuze 22, which supplies an electrical signal to initiate the submunition release sequence at an altitude of the order of 150 to 200 m, for example; and -a thermal cell 26, which serves to supply the preceding sub-assemblies and to ignite the separating detonator fuses 28, 28', 28" and 30.

The munition 10 is provided with a plurality of submunitions (three in this non-limiting example), and each submunition 32, 32', 32" comprises, respectively: -a steel body 34, 34', 34", which constitues the wall of the shell and contains a military explosive charge 36, 36', 36" of the deformable plate type 38, 38', 38", or the "Self forging fragment" type (SFF), and a submunitions priming unit 40, 40', 40"; -a pyrotechnic priming fuse 42, 42', 42", comprising mechanical and electric safety devices; -a target detector 44, 44', 44", whose operation is based on the reading of "temperature jumps"; an unfolding mirror 46, 46', 46", which reflects onto the detector the radiation emitted in parallel to the axis of the charge, and especially by the target;; a thermal cell and the processing electronics 48, 48', 48"; and a ballasted parachute 50, 50', 50", whose canopy is fastened directly to the bottom of the charge.

Referring to the drawings, it can be seen that each submunition 32, 32', 32" is composed of the following units: the military charge, which has a calibre across the body of D mm and a calibre across the explosive of d or d' mm, and a large container (structural walls) prepared for fragmentation for example by grooving or by electron beams (FFE).

Each charge comprises: a casing of copper or tantalum for example, resting on the explosive under compression (octocire) or of octolite, 36, 36', 36" respectively and immobilized against spin by serrations or knurlings (not shown) situated opposite those on the blocking ring: -a compressed explosive and its priming unit, respectively 40, 40', 40", the compression ratio of the explosive being such that, under the effect of the starting acceleration, there is no movement of the casing; -a casing blocking ring, respectively 52, 52' and 20 (ejectable ogive), with its face directed towards the casing and with serration or knurlings (not shown).

The pyrotechnic fuse 42, 42', 42" respectively is of conventional design and comprises substantially a pyrotechnic chain-interrupting shutter with respect to the priming of the separating detonator fuse and the priming of the military charge. This shutter (not shown in the drawings) has two positions, and it thus allows the possibilities successively of fuse and then charge initiation to be established.

Each target detector 44, 44' and 44", whose operation is based on the reading of "temperature jumps", comprises a group of infrared cells (Se-Pb) and a processing logic circuit.

From a limited altitude (A in Fig. 10) corresponding to the terminal effect, very close to that obtained at point blank range, that is 70 m, by way of example, activation of the detector 44, 44' and 44" is obtained by electronic or pyrotechnic delay, not shown on the drawing, the start of which is controlled by the altimetric fuze 22 of the shell 10.

Said fuze is always set for the same altitude; activation of the detector is thus obtained for a substantially constant altitude A (75 m for example).

The ballasted parachute 50 is shown in Fig. 3 in the folded state in position on a submunition 32, and, in Fig. 4, in the completely unfurled state above the submunition.

In this unfurled state, the shape of the parachute is substantially that of a truncated cone whose small base b is fixed to the charge 32 (or 32', 32"), and whose large base B is situated behind the charge. The periphery of the large base B is ballasted to keep the canopy open under the effect of the centrifugal forces. The canopy of the parachute 50 is typically made of a "Kevlar" fabric, i.e. of thin carbon (for example from 1 to 2/10 mm).

The parachute ballast 54 is of heavy material, lead for example, and is distributed around the whole periphery of the parachute.

To secure for the unfurled parachute 50 the maintenance of a kinetic moment and to increase its lift and thus enable it to glide, the parachute radial has shutters 56.

The Y-Y' axis of the charge and the small bass b of the surface of the unfurled canopy form an angle ss (20 for example) with the axis X-X' of this canopy 50, so as to permit scanning of the target zone.

Means are provided for preventing an entirely free unfurling of the parachute canopy under the effect of the centrifugal forces, which would entail a very rapid extraction of the canopy accompanied by a quasi discontinuity of the spin speeds, subjecting the parachute to unacceptable strains and the risk of tearing, or indeed of reclosure.

To this end, opening of the parachute 50 is braked so as to ensure that it happens in a safe and reproducible manner by gripping the parachute in an overbinding 58 during folding. After separation of the submunitions, the unwinding of this overbinding 58, under the effect of the centrifugal forces, ensures unfurling of the parachute 50 in a few tenths of a second, at the rate of the spin speed of the charge.

Figs. 6 to 9 show the placing in position of the parachute 50 in a submunition 32 (or 32', 32"), in several operations: attachment to the base of the charge; -tightening of the canopy generating lines of the length R,-R, AL Sin 0 -applying its n folds of the progressive width e:: 27rRo rev 2nR1 n n along a centering cylinder with a diameter of approximately 2 R the axis being inclined by ss in relation to that of the charge; overbinding of the surface of the parachute prepared in this way with m cords regularly staggered by the angle 27r/m, wound around the surface of the parachute at a pitch p; p=27rRo tga after deposition of a holding lacquer (cur= inclination of the overbinding); packing down around the centring cyclinder with a cylindrical tool, until the height Ho is reached, which is assigned to it in the submunition:: after alignment of the cylinder axis with that of the charge; then by the action of a tubular pushing device; polymerisation of the lacquer after packing.

Referring to Figs. 3, 4 and 5, the lifting and terrain scanning device is designed to fulfil the following conditions.

Beginning of unfurling: In the course of the successive and brief separation sequence (~ 0.3 secs) of the base, the submunitions 32, 32' and 32" and the head 20, these members spin at a speed of the order of 1000 rad/s, for example, and the centrifugal forces continue to be exerted on each parachute 50, 50', 50", while the walls of the shell are no longer there to oppose their radial expansion.

The cords, such as 58, overbound around each parachute 50, 50', 50" are then acted upon by these centrifugal forces, but the frictional (and lacquer-shearing) forces oppose loosening of the overbinding under the radial thrust of the parachute.

On the other hand, the overbinding cord 58 is free except for the lacquer, at its end. This end can therefore unwind tangentially to the diameter of the part of the parachute still held by the overbinding, of a diameter ds-2 R,.

The initiation and continuation of this unwinding, with a tangential speed of v=ogRO, can thus be facilitated by the ballast, such as 54, at the free ends of the overbinding cords.

The unwinding of these cords at the speed "frees the ends of the parachute generating lines of the length AL, at the speed: p (AL) =v~(uRO tg 2xRo Ultimately, the unfurling of the ballast occurs at a radial speed of: R'=U sind=RO tgaa) sinS, in which relationship represents the angle the canopy generating lines make with the axis of the parachute. In the simplest case one could say: R0 tga=K=Cte.

In fact unfurling does not start until after a length of overbinding has been unwound, it being possible to make the duration of unwinding correspond to the time between the separation of the members situated respectively situated behind and in front of the charge.

Continuation and completion of unfurling: Unfurling occurs rapidly, for example in less than 0.2 secs., from the initial radius R0 to the maximum radius, that is to say R1, corresponding to the perimeter of the unfurled parachute 2xR, tautened by the centrifugal forces with the tension T. The radii R0 and R, are functions of the calibre D of the shell 10; for example, for D=0.155 m. Rio=0 05 m, R1=0.40 m.

This movement takes place substantially perpendicularly to the axis of the charge in a line linked to the charge 67t/2. Thereafter, the unwinding of the apex canopy continues under the effect of the aerodynamic forces which push the ballast backwards, into a plane situated at AZ=AL CosO from the bottom of the charge.

It is at the conclusion of this movement that the dissymetry in the length of the canopy generating lines causes the charge to tip up an angle ss (20 approximately) in relation to the axis of the parachute. At this point a change in the pitch of the overbinding can give this tipping all the necessary progressiveness (limitation of constraints).

Gliding phase: The parachute 50 being completely unfurled and tautened by the centrifugal forces, the assembly charge+parachute behave like a solid.

The shutters, such as 56, arranged in each parachute 50, continue the action which they began to carry out during unfurling. They apply a torque Ct to the submunition, which maintains spinning by cancelling the effect of the opposing torque C, resulting from the forces of viscosity.

They slope at an angle , (for example 3 ), which is maintained by wedges 56'.

This shutter effect continues even at the end of the gliding phase, for very low values of the remaining speed V of the submunition.

In fact, owing to the high spin speed ((or110 rev/s, for example), the shutters 56 also supplement lift considerably, which allows the average speed of the charge to be reduced to approximately 5 m/s for 10 s, for example.

The unfurling phase and the gliding phase are fixed by applying mechanical and aerodynamic relationships to the model proposed, in the context of reasonable simplifying hypotheses: symmetry of the initial arrangement of the masses; -assimilation of the surface of the parachute 50 with the frusto-conical surface defined by the peripheral ballast (radius R) and by the attaching for overbinding perimeter (radius Ro~005 m, for example).

The type of parachute 50 allows the submunition 32, 32', 32", after separation, to be provided with a trajectory characterized by: -an unfurling phase (0.2 s for example) and rapid braking of the speed of descent (for example from 300 m/s to approximately 0 m/s in less than 1 second, with a loss of altitude of less than 50 m); -a phase of gliding flight, with an average speed of descent of the order of 5 m/s for almost 10 seconds, for example; during this gliding phase the shutters maintain the order of magnitude of the spin speed at from 40 to 20 rev/s, for example.

Furthermore, it is known that the wind provides the submunition, respectively 32, 32', 32", with an effective transverse speed of the order of 10 m/s, to which the dissymetry of the parachute contributes.

Of course, all the characteristic values are only indicated by way of example, and any other values are equally within the scope of the invention.

Fig. 10 shows the overall functioning sequence of the shell 10.

Over the trajectory of the shell 10 there is effected the separation of the three submunitions 32, 32', 32", staggered by a time At, and after the gliding of the submunitions the desired dispersal is obtained.

The separation S is obtained by the sequencer 24, which controls the ignition of the separating fuses, respectively 28, 28', 28" from back to front, and which is in turn controlled by the altimetric fuze 22 of the shell 10.

The activation of the detector is effected at a low altitude A, at a height of approximately 75 m, by a delay whose value is linked to the constant average altitude of the three separations.

From back to front, there are released successively: the first submunition 32, by the simultaneous functioning, at time t, of the two separating fuses surrounding it, 28, 28'; this is effected from the first and second pyrotechnic fuses 42 and 42'; -the second submunition 32', by the functioning, with a delay of At, of the separating fuse 28" situated immediately in front, effected from the third pyrotechnic fuse 42"; --the third submunition 32", by the functioning, with a delay of 2At, for example, of the last separating fuse; this is also effected from the third pyrotechnic fuse 42", but with the interposition of a pyrotechnic delay, for example of At.

Of course, it should be remembered that the invention is not restricted to the exemplary embodiments described and shown, but rather it embraces all variants.

Claims (10)

1. A munition which comprises a plurality of submunitions with gliding trajectories, each submunition being provided with a parachute whose apex is attached to the body of the submunition charge and whose skirt is provided with ballast around its periphery, and overbinding means for ensuring progressive unfurling of said parachute at a controlled speed and duration under very high spin speeds.

2. A munition according to Claim 1, wherein the skirts of said parachutes are provided with shutters for maintaining a high spin speed and for supplementing lift.

3. A munition according to Claim 1 or Claim 2, wherein the overbinding means and the shutters of said parachutes are designed to provide each submunition with a trajectory consisting of a phase of unfurling and of braking a rapid fall speed, followed by a long phase of gliding flight at a low speed of descent.

4. A munition according to any one of the preceding claims, wherein the submunitions are of the calibre of the whole munition the wall of which is formed by the walls of the submunition bodies.

5. A munition according to any one of the preceding claims, wherein each submunition includes a target detector functioning on the principle of reading temperature jumps and comprising a group of infrared cells and a processing logic circuit.

6. A munition according to any one of the preceding claims, further comprising an altimetric fuze for controlling the separation of the submunitions, and operating through a separation sequencer to ignite pyrotechnic separating fuses.

7. A munition according to Claim 6, wherein the altimetric fuze is set such that the gliding zone of each submunition's parachute is initiated at an altitude of the order of 70 m.

8. A munition according to any one of the preceding claims, wherein the parachute of each submunition is put in place, during assembly, by its being attached to the base of the charge, followed by its being folded around a centering cylinder, followed in turn by the operations of overbinding, lacquering and packing down.

9. A munition according to any one of Claims 1 to 8, wherein each submunition is provided with a charge of the deformable plate or self forging fragment (SFF).

10. A munition comprising a plurality of submunitions, substantially as hereinbefore described with reference to the accompanying drawings.