HDRM device

Abstract

A high density reactive material (HDRM) munition 22 comprises a tail unit 12, a main body 15 which comprises a payload cavity 24 for receiving a high explosive payload apparatus which comprises a high

Description

The invention relates to high density reactive materials, preferably materials with a high density and exothermic output for and a liner for the effective takeover of HDRM, particularly for the defeat of soft targets, especially UAS / drones. High Density reactive materials (HDRM) are a new emerging class of materials http: / / en.wikipedia.org / wiki / Reactive_materials, which have higher densities than conventional reactive materials such that they may provide enhanced performance with mechanical properties suitable for application in a broad range of weapon systems. This includes potential for effective transfer of Kinetic Energy in impact penetrators, fragments and other systems, whilst offering an additional advantage of providing a further exothermic output under explosive loading or following High Velocity impact. According to a first aspect of the invention there is provided a high density reactive material (HDRM) munition comprising a tail unit, a main body which comprises a payload cavity for receiving a high explosive payload apparatus which comprises a high explosive, a fuze, an ogive portion located between said main body and the fuze, and an explosive train operably connected to said fuze and high explosive, wherein the main body or the explosive payload apparatus comprises an HDRM material, wherein a liner comprising a plurality of apertures is located between the high explosive and HDRM material, such as to allow an explosive output from the high explosive to be more effectively transferred to initiate the HDRM material reaction. Preferably the high explosive is a non-ideal or metallised explosive. The liner comprising the apertures may be made from any material, preferably the liner material is selected from a metal, metal alloy or composites. The metal may be a lightweight metal such as, for example aluminium or titanium. The strong polymer may be a polymer or a fibre-reinforced polymer composite, the polymer may be such as, for example, CA-30 Peek and Polyamide-lmide (PAI). The liner may have any wall thickness, however if the material is too thick it will reduce the volume of high explosive, or may reduce the thickness of the HDRM material, preferably the liner thickness may be less than 10% of the charge diameter. The use of a liner in HE rounds, is typically required to either improve the adhesion of the high explosive to the main body, ie to prevent differential movement of the shell and the high explosive especially under high spin. Alternatively, liners are used to provide a means of reversibly loading a high explosive material into a payload cavity. The use of a plurality of apertures in the liner allows the explosive output ie detonative output, to more readily transfer to the HDRM material in order to initiate the secondary reactive material chemical reaction. This secondary reaction may be overly delayed if the explosive output has to first penetrate a solid unitary liner. For a standard HE shell, the main body of the shell provide containment and is simply fragmented and does not take part in the detonative or chemically in any secondary reaction. The apertures in the liner may be of any size, dimension and shape, such as, for example they may be elongate, circular, grid, or polygonal. The shape and area is selected to ensure that sufficient detonative output from the high explosive passes through the liner, without delay to start the secondary HDRM chemical reaction. The total area of all of the apertures may be greater than 1%, more preferably 5% of the surface area of the liner. The area of each aperture is selected to allow sufficient detonative wave to pass quickly therethrough. During the filling of the liner, the perforations may be temporarily covered, or the liner may have removable portions to provide the apertures. The HDRM material may have any wall thickness, dependent on the material selected, and the type of munition, those that experience high g on launch may require larger wall thickness, the order of a few mm may provide sufficient structural integrity and allow optimisation of the payload. According to a further aspect of the invention there is provided a method of defeating an unmanned aerial system(UAS) comprising the step of detonating an HDRM munition as defined herein. The HDRM may be selected from any known composition, preferably selected from a composition comprising, A) at least two separate group 4 metals, present in the range of from 40 to 90%wt B) at least one oxidiser or alloying element, present in the range of from 5 to 55%wt wherein said reagents and optional pressing aids are present in substantially 100%wt. Preferably wherein B) is at least one oxidiser, carbon or boron. The reagent A) group 4 metals are group 4, d-block (transition metals) such as titanium, zirconium, and hafnium. These metals offer high densities, and the specific selection of two different group 4 options offers a chance to target specific density ranges for the final composition whilst retaining similar reactivity. For the defeat of small UAS targets and especially swarms of targets, it is desirable to subject a large area to a very long time period of intense overpressure and heat. The longer the energetic event occurs, the more chance there is of defeating, immobilising or damaging the UAS targets or at least more of the targets. The use of HDRM substantially increases the bare charge equivalence, ie an increased energetic event is caused, without increasing the amount of high explosive content. The formulations as defined herein have provided at least a 20% increase in overpressure duration (impulse) and peak overpressure compared to the use of a standard steel encasement. The energetic event has been even further increased when paired with a non-ideal, blast enhancing base explosive, when compared to a standard high explosive. The use non-ideal explosive or aluminised high explosives offer further enhancement of TNT equivalence and their use increased the duration further. The increase in the duration of the overpressure allows the blast to do more work on the UAS targets. Blast waves, can, if they have a long time duration may go around corners and act on all surfaces of a target and not just the one it is facing. A slower acting, non-ideal explosive(an explosive that releases some of its energy after the shock front) when paired with HDRM will create afterburn which goes on long after the detonation event, thereby overpressure duration. This means that the explosive event may potentially last between milliseconds and seconds rather than the microseconds, compared to that of a standard explosive which would be 1000 to 1 million time faster, ie much shorter duration. The use of a non- ideal explosive with HDRM provided substantially no loss in peak pressure. Typically for explosive events, when you increase impulse you lose peak overpressure but with the formulations according to the invention no loss in peak pressure and a gain in impulse was observed over standard explosives with steel cases. Preferably the munition comprising the HDRM, may comprise a proximity fuze. The problem of the prior art fragmenting systems is that the fragmenting system has a narrow window for frag dispersion, meaning that you would have to have exact timings to take out any other drones apart from the one that you had “proximity on”. A large scale, enhanced blast, as caused by the munition according to the invention, will fill a significantly larger volume / region in the air, due to the longer duration of the energetic event, and the increased amounts of overpressure and heat. The blast cloud formed using the HDRM is constantly burning so there will be very intense heat as well as burning metallic particles that can get stuck into the UAS materials. An enhanced blast wave, with afterburn would increase the effective blast radius dramatically, compared to a high shock standard blast which decays quickly, so it might get the closest drone and then just knock a few others off course, briefly. The proximate to a UAS target may be achieved by the use of a proximity fuze, which detects when the fuze is at a set distance from a target. Alternatively the fuze may be caused to activate after a period of time, upon contact with a UAS target or caused to detonate at a set altitude. In a preferred arrangement at least one of the group 4 metals is hafnium. Preferably the hafnium is present in the range of from 20 to 79%wt or more preferably in the range of 20 to 35%wt. The specific inclusion of Hafnium, provides a significant increase to the overall effective density of the consolidated composition, for a relatively minor volumetric inclusion. The group 4 metals may offer a range of morphologies - comprising nano, sub micron, or micron sized particulates. The at least two group 4 metals may be selected to maximise mixing capability to promote uniformity of distribution (these may be substantially the same size, or targeted different size ranges to achieve a specific multimodal distribution, such as a bimodal distribution. Preferably B) is at least one oxidiser. The at least one oxidiser may preferably present in the range of from 35 to 55%wt. The at least one oxidiser may be a metal salt, such as, for example, oxides, nitrates, perchlorates, permanganates, peroxides, chlorates. Preferably a high density metal salt, such as for example, metal oxides, for example CuO. The reagent B) when selected from an alloying element may be selected from any non-group 4 metal, metalloid, that undergoes an exothermic alloying reaction with group 4 metals, preferably carbon or boron. The boron may be present in an amount 5 to 20%wt, preferably 10%wt. The reagent B may be selected from nano, sub micron, or micron sized particulates, such that upon intimate mixing with group 4 metals, may support / provide a homogenous mixture. The particulate size of the group 4 metals and reagent B materials may be selected to provide multimodal distributions. In one arrangement there is a reagent C) a binder in the range of 1-10%wt. The reagent C) binder may be selected from any polymer binder, or fluoropolymer binder, preferably at least one fluoroelastomer binder. The fluoroelastomer binder may be selected from a range of materials such as for example hexafluoropropylene, vinylidene fluoride, terpolymers of tetrafluoroethylene, vinylidene fluoride and hexafluoropropylene (HFP), perfluoromethylvinylether, THV 220, and PTFE, preferably a Viton, more preferably Viton A. The reagent C) binder may preferably be present in the in the range of from 3 to 7%wt, preferably 5%wt. The at least two group 4 metals may be encapsulated in a binder. In a preferred arrangement, the composition further comprises tungsten metal, in the range of 10 to 50 wt%. The tungsten provides a high density material. The presence of tungsten metal into the composition adds a large amount of mass for a small volume, due to its high density. It is not a reactive substance in the formulation, but the high density provides reactive fragments, with increase mass, and thereby cause more damage to the UAS, when they are ejected during the energetic event. The HDRM fragments also reduce collateral damage, because they are burning whilst travelling, reducing their mass and size whilst decelerating through drag. There is provided a method of defeating an unmanned aerial system(UAS) comprising the step of detonating a high explosive munition comprising a blast enhancement device proximate to the UAS, wherein the blast enhancement device comprises an HDRM material located on said high explosive. Preferably the high explosive is a non-ideal explosive or a metallised explosive, such as, for example aluminium metal. Preferably the fuze is a proximity fuze. The munition may be any munition that undergoes a detonative or deflagration reaction, such as, for example a shell, mortar, bomb or grenade. Preferably the high explosive is a non-ideal explosive or a metallised explosive, such as, for example aluminium metal. Preferably the fuze is a proximity fuze. The munition may comprise a portion of consolidated composition as defined herein. The portion of the munition may comprise all, substantially all or part of a munition. The munition may such as for example be a direct fire or indirect fire munition. The munition may be kinetic energy or chemical energy munition or a combination thereof, such as, for example a projectile, shell, casing, shaped charge liner, preformed fragments, grenade or mortar. The HDRM may be provided as a collar around the high explosive. The HDRM may preferably be the munition case or main body. The munition may be a gun launched shell, such as for example, 105mm 155mm or any other typically used calibre, wherein part, substantially all or all of the shell casing is a composition as defined herein. The composition may be prepared to form pre formed fragments which are further consolidated to form a shell casing. In a munition subjected to a high set back force, such as a gun launched munition, preferably there is a higher percentage weight of binder. The particulates of the composition may not be consolidated and may be available as agglomerates / clumps, and may be ignited as such, and undergo ignition and continue to burn in flight. This may offer enhancement to blast and after burn or Kinetic Energy transfer to targets at range. The HDRM composition either solid or agglomerates may be ejected, or projected , in such a manner to retain physical form / mass and associated Kinetic Energy allowing reaction on impact with targets at a specific thresh-hold impact velocity causing shock reaction and ignition of the material on the surface or within the target structure. There is provided a method of preparing a high density reactive material as defined herein, such as for example, dead load pressing, isostatic pressing, hot sintering, to provide a composition which may be consolidated to form a structural casing or projectile. There is provided a high density reactive material composition comprising, at least two group 4 metals, present in the range of from 45 to 90%wt tungsten in the range of from 40 to 70%. wherein said reagents and optional pressing aids are present in substantially 100%wt. Preferably wherein said consolidated composition provides an effective density by weight fraction of greater than 10. Ingredient 1 Ingredient 2 Ingredient 3 Ingredient 4 Overall Ref Name Wt% Name Wt% Name Wt% Name Wt% Effective Density by Wt fraction 1a Zirconium 25% CuO 50% Viton A 5% Hafnium 20% 6.27 21a Titanium 35% Boron 10% Viton A 5% Hafnium 50% 5.46 23a Hafnium 51% Boron 10% Viton A 5% Zirconium 34% 6.28 25a Titanium 25% CuO 45% Viton A 5% Hafnium 25% 5.79 26a Hafnium 20% CuO 45% Viton A 5% Zirconium 30% 6.28 28a Zirconium 45% THV220 10% Tungsten 45% 5.71 29a Hafnium 79% THV220 10% Zirconium 11% 6.29 U1 Zirconium 45% Zinc 40% Tungsten 15% 7.53 4a Zirconium 15% Hafnium 20% CuO 15% Tungsten 50% 11.39 5a Hafnium 35% Titanium 10% Tungsten 50% Boron 5% 10.38 6a Zirconium 20% Hafnium 30% Tungsten 50% 12.59 Table 1 Table 1 provides a number of examples where the composition comprises a group 4 metal present in the range of from 45 to 95%wt. the materials are sintered, preferably using both elevated temperatures and pressure with the a binder and optional pressing aids to facilitate consolidation. Reagent A Reagent B Reagent C Reagent A Overall Ref Name Wt% Name Wt% Name Wt% Name Wt% Effective Density by Wt fraction 4a Zirconium 15% Hafnium 20% CuO 15% Tungsten 50% 11.39 5a Hafnium 35% Titanium 10% Tungste n 50% Boron 5% 10.38 6a Zirconium 20% Hafnium 30% Tungsten 50% 12.59 Table 2 Table 2 above, provides preferred examples of compositions, wherein there is further provided tungsten metal and at least two different group 4 metals are selected. The group 4 metals may be encapsulated or a passivation layer, or sacrificial layer to prevent reaction with air, moisture or unwanted reactions with the other reagents, until activated in the designed mode of use. The group 4 metals may be encapsulated with at least one inert material, to prevent reaction with moisture or air. Preferably by premixing the group 4 metal with reagent C) a binder, preferably a fluoroelastomer. The coating / microencapsulation of the group 4 metal may prevent combustion in air during the sintering process. According to a further aspect of the invention there is provided a UAS defeat system comprising a platform, at least one gun barrel and at least one munition defined herein, and operated according to a method defined hereinbefore. The platform may be a vehicle, vessel, craft or land based. The platform may have a combat system, radar and other means for detecting, and setting the fuze on the munition, and firing the munition to engage with a plurality of UAS devices. For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic Figures in which: Figure 1 schematically depicts a vessel firing at a plurality UAS devices; Figure 2 schematically depicts a shell comprising an HDRM case; Figure 3 shows the assembly of Figure 2 with an HDRM liner, inside the main body of a shell; Figures 4a and 4b show an empty perforated liner and high explosive filled liner; Figures 4c and 4d show the perforated liner located in an HDRM payload apparatus; As seen in Figure 1 there is a UAS defeat system 1, a battleship 2 is located on a body of water 4, and comprises a gun 6 having a gun barrel 7. Other examples may not include a particular vehicle, and could simply comprise a gun, e.g. on static land or water-based platform. In order to engage and defeat a UAS system 9 a munition 5 is launched into the air from the gun barrel 7. The munition is a shell and comprises an HDRM liner. This allows the battleship 2 to deploy the shell 5 at significant range, and accuracy. The shell when proximate to the UAS 9 will be cause to detonate, and the HDRM material will cause a large overpressure in the vicinity of the UAS and for an increase duration, which will be able to defeat a plurality UAS 9 systems. It will be recognised by the person skilled in the art that other platforms or vessels aside from the example battleship 2 could be employed by the present invention, including but not limited to: land-based vehicles; land platforms; or aircraft. Figure 2 shows a high explosive shell 22, with a unitary main body 15 formed from an HDRM material, with a driving band 14 located thereupon. A tail unit 12 is located at the aft of the main body 15. The tail unit 12 is made from aluminium and contains a male threaded portion, which engages with a reciprocal female threaded portion located at the aft of the main body 15. The tail unit 12 may be a boat tail or base bleed unit. The payload 23 which may be a high explosive, or aluminised high explosive 20 is located in the payload cavity 24. The payload is a removable liner 21 which is pre-filled with the high explosive 20. The removable liner 21 and high explosive 20 are loaded into the payload cavity 24 in a single step. The ogive element receives the explosive train 18 and fuze 19. Upon operation of the fuze 19, the explosive train 18 provides a greater detonative event sufficient to detonate the high explosive 20. The fuze may be a proximity fuze, timed fuze, or point detonating fuze. Figure 3 shows an empty shell 25 made from steel, with a fuze 29, located at the forward end. The removable liner 31 is an HDRM material, which contains the high explosive fill (not shown) which can be inserted from the rear of the shell 25. The tail unit 32 may then be secured to the shell 25 to provide the complete shell. The tail unit 32 may be secured to the main body 25 by a cooperative thread, shearable cooperative thread, or shear pins. Figures 4a and 4b show a liner 40, formed from a lightweight body 41 which comprises a plurality of perforations 42 located therein. The body 41 may typically be cylindrical in shape to conform to the inside of a munition, but the liner 40 may be of any external shape to fit the required payload cavity. The liner 40 has a high explosive fill 44 located inside the body 41. The high explosive 44 (shown partially inserted in Fig 4b) may be a preformed pellet inserted into the liner 41, or the high explosive may be filled directly into the liner body 41, ensuring that the perforations are temporarily covered up during the filling process to prevent leakage. The liner body has a threaded portion 43, to allow it to be secured to an end cap(shown in figures 4c and 4d. Figure 4c shows the payload arrangement 50, with the liner body 41 (filled with the high explosive 44), being partially located in the HDRM payload body 51. The perforations 42 will allow uninhibited and direct transfer of the detonation wave from the high explosive to impinge on the HDRM material 51, to allow the secondary reaction to commence without any delay. Whilst the detonation reaction is a sub-microsecond event, the linerwithout perforations will add a small but significant delay to the initiation of the HDRM reactions. It is desirable for the HDRM reaction to start at or near the peak of the detonative peak pressure. The end cap 52 is this arrangement may be threaded onto thread 43. The end cap, may be part of a test vehicle, or part of an explosive train, or part of the munition that the payload arrangement 50 is affixed to. It may be desirable to not provide machined threads or connectors in the HDRM material due to the physical properties of the material, and expense of wasting highly a engineered material.

Claims

1. A high density reactive material (HDRM) munition comprising a tail unit, a main body which comprises a payload cavity for receiving a high explosive payload apparatus which comprises a high explosive, a fuze, an ogive portion located between said main body and the fuze, and an explosive train operably connected to said fuze and high explosive, wherein the main body or the explosive payload apparatus comprises an HDRM material, wherein a liner comprising a plurality of apertures is located between the high explosive and HDRM material, such as to allow an explosive output from the high explosive to be more effectively transferred to initiate the HDRM material reaction.

2. A munition according to claim 1, wherein the high explosive is a non-ideal or metallised explosive.

3. A munition according to claim 1 or claim 2, wherein the liner is a material selected from a metal, metal alloy or composites.

4. A munition according to claim 3, wherein the metal is aluminium or titanium.

5. A munition according to any one of the preceding claims wherein the liner has a wall thickness less than 10% of the charge diameter.

6. A munition according to any one of the preceding claims wherein the plurality of apertures are elongate, circular, grid, or polygonal.

7. A munition according to any one of the preceding claims wherein the total area of the plurality of apertures is greater than 5% of the surface area of the liner.

8. A munition according to any one of the preceding claims wherein the HDRM selected from a composition comprising,A) at least two separate group 4 metals, present in the range of from 40 to 90%wtB) at least one oxidiser or alloying element, present in the range of from 5 to 55%wtwherein said reagents and optional pressing aids are present in substantially 100%wt9. A munition according to claim 8, wherein B) is at least one oxidiser, carbon or boron.

10. A munition according to claim 8 or 9, wherein the at least one oxidiser is a metal oxide.

11. A munition according to any one claims 9 to 11, wherein at least one of the group 4 metals is hafnium.

12. A munition according to claim 11, wherein the hafnium is present in the range of from 20 to 79%wt.

13. A munition according to any one claims 9 to 12, wherein there is a reagent C) a binder in the range of 1-10%wt.

14. A munition according to any one of the preceding claims wherein the HDRM is selected from a composition comprising tungsten metal, in the range of 10 to 50%wt.

15. A UAS defeat system comprising a platform, at least one gun barrel and at least one munition according to any one of the preceding claims.

16. A method of defeating an unmanned aerial system(UAS) comprising the step of detonating a high explosive munition comprising an HDRM munition, as claimed in any one of the preceding claims, proximate to at least one UAS.

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