Patent Application
20060011057
The present invention is concerned with elements for making a protective reactive armor to be fitted on the outside of an enclosure liable to be exposed to attack by shaped-charge warheads and other threats, such as kinetic energy projectiles and fragments, to thereby enhance survivability of the enclosure and its contents. The invention is further concerned with a non-explosive energetic material useful for such reactive armor elements.
Examples of enclosures protectable by a reactive armor element made of elements according to the invention are land vehicles such as battle tanks, armored personnel carriers, armored fighting vehicles, helicopters, armored self-propelled guns; armored static structures such as buildings, above-ground portions of bunkers, container tanks for the storage of fuel and chemicals; etc.
Warheads with shaped-charge munitions, also known as hollow charge munition, are known to pierce armors and thereby destroy the protected object from within and, its contents. This capacity of a shaped charge results from the fact that upon detonation there forms an energy-rich jet also known as “thorn” or “spike” which advances at very high speed of several thousands of meters per second and is thereby capable of piercing even relatively thick armor walls.
Several arrangements have become available in recent years to afford protection against the penetrating effect of an exploding shaped charge, wherein a structure holding at least one reactive armor element, wherein reactive armor element comprises an array of layers comprising one or more plate layers and at least one layer of explosive or any other energetic material (‘energetic material’—a material releasing energy during activation/excitement), tightly bearing against at least one of the plate layers. The plate layers are made, for example, of metal or a composite material.
A basic reactive armor element comprises two metal plates sandwiching between them the layer of energetic material. Such prior art reactive armor elements are based on the mass and energy consuming effects of moving plates and their functioning is conditional on the existence of an acute angle between the jet of an oncoming hollow charge threat and the armor itself.
In general, a reactive armor element is a multi-layer body in which each layer tightly bears against each contiguous layer, wherein the multi-layer body includes an outer cover plate, at least one layer of energetic material, at least one intermediary inert body juxtaposed to each of the at least one energetic material layer. Upon activation/excitement of the energetic material (e.g. upon striking by shaped-charge warhead) the jet energizes the armor, where a vast energy discharge occurs so that within microseconds the discharged gases accelerate the metal plates and displaces them away from one another thus disrupting/defeating the jet, thereby loosing its energy to penetrate the protected enclosure.
Whilst efficiency and survivability of the armor are important, the overall performance of an armor is determined by comparing its efficiency versus its survivability. One criteria of an armor, having significant importance, is the ratio of weight per area unit of the armor element. An other criteria of importance is sensitivity of the energetic material. Whilst sensitivity may be an advantage for improving efficiency of the armor, it may reduce survivability of the armor and it may be problematic as far as complying with various transportation requirements.
There are known four principal groups of intermediate materials for armors, disclosed hereinafter in order of their energetic catachrestic:
A. Explosive Reactive Armor (ERA):
Explosive Reactive Armor is the most effective technology to defeat hollow charges, kinetic projectiles, small arms, shrapnel etc. Advanced ERA concepts are considered leap-ahead technology against emerging anti-armor threats. The major challenges of applying ERA to ground combat vehicles are the use of an explosive material as an intermediate layer of the sandwich element, reducing survivability of the armor.
B. Self-Limiting Explosive Reactive Armor (SLERA):
Self-Limiting ERA provides reasonable performance, substantially better than NERA (see below), though less than ERA, with reduced effects on vehicle structures, as compared to ERA. The energetic material layer in SLERA has the potential of being classified as a passive material (NATO specification). SLERA can provide good multiple-hit capability in modular configuration. Thus, while the energetic material used in SLERA is not as effective as fully detonable explosives, this type of reactive armor may provide a more practical option than ERA owing to its survivability characteristics.
C. Non-Explosive Reactive Armor (NxRA):
Non-Explosive Reactive Armor provides a comparable efficiency to SLERA, comparable survivability to NERA (see below), and excellent multiple-hit capability against hollow charge warheads. NxRA's advantages over other reactive armor technologies are that it is totally passive and has substantially better efficiency than NERA.Energetic materials for NxRA are disclosed for example in DE 3132008C1 and in U.S. Pat. No. 4,881,448.
D. Non-Energetic Reactive Armor (NERA):
Non-Energetic Reactive Armor has limited efficiency against hollow charges. NERA's advantage is that it is totally passive and thus provides excellent survivability and maximal multiple-hit capability, comparable to NxRA.
It is an object of the present invention to provide a non-explosive energetic material suitable for NxRA which does not contain explosive material and fulfills its protective function (high efficiency and high survivability of the armor), whilst the non-explosive energetic material lowers the requirements of transportation and logistics according to various standards e.g. UN regulations as appearing in the Recommendations on the Transport of Dangerous Goods.
It is a further object of the present invention to provide an armor element fitted for such an energetic material and where the armor is of comparable efficiency to SLERA and of comparable survivability to NERA.
The above and other objects are achieved by using a non-explosive energetic material being a gas generator, comprising oxidizers and fuels, whereby exciting the material upon striking by a jet of a hollow charge results in vast generation of gas which accelerates/bulges the armor plates of the reactive armor. This however requires that the gas be discharged rapidly, i.e. not more than a few μsec (microseconds), to thereby ensure disruption/defeating of the jet, and to minimize the penetration into the protected environment.
For that purpose, a group of oxidizers was selected and a group of fuels, which together with suitable catalyst/s and binder/s provide the resultant non-explosive energetic material to constitute a gas generator. According to one particular embodiment, the non-explosive energetic material comprises an oxidizer selected from the group of families comprising, among others, nitrates, nitrites, chromates, dichromates, perchlorates, chlorates, etc. and fuels of any type of carbon containing material, and a suitable binder which may also serve as a fuel.
According to one particular embodiment, the non-explosive energetic material comprises sodium nitrate (NaNO3) as an oxidizer and a silicone binder as a fuel. It is also possible to combine several types of oxidizers and fuels so as to improve performance of the energetic material in the reactive armor element.
An example for a catalyst material suitable for use with the non-explosive energetic material in accordance with the present invention is a transition metal oxide, such as Fe2O3 (ferric oxide), which is usually used as a catalyst in energetic materials based on combinations of oxidizers and fuels.
In order to increase the reaction rate of the non-explosive energetic material, micro-balloons (i.e. hollow sphere elements) may be added to the formulation. It is appreciated that the micro-balloons increase the reaction rate upon striking of the armor by a jet of a hollow charge.
Accordingly, such a composition may be considered as a non-explosive material (, i.e. a non-class 1 material, as per definitions of the UN Regulations and the US Department Of Transportation (DOT).
The non-explosive energetic material according to the present invention may be a flexible sheet of material, pliable and it is easily cut, pierced, etc. whereby it is conveniently applied between the bearing plates of the armor element. According to one particular embodiment the material is rubber-like and is easily foldable.
According to the present invention there is provided a NxRA element with a non-explosive energetic material of the above type for protection against shaped-charge warheads, as well as against small arms, shrapnel, fragments and various types of kinetic projectiles, e.g. Armor Piercing Fin Stabilized Discarded Sabot (APFSDS).
The NxRA element comprises a module fitted with an outer cover plate and at least one sandwich element within the module. Said sandwich element comprising at least one pair of substantially flat inert plates with a non-explosive energetic material as disclosed herein above applied there between.
According to some embodiments, there may be several pairs of inert plates, e.g. made of metals (such as steel, aluminum, titanium), ceramics, composite materials and others, where the non-explosive energetic material is applied there between. Furthermore, the cover plate of the casing of the reactive armor, may constitute a front plate (or a top/bottom plate) of the at least one sandwich element.
A reactive armor according to the present invention may be of any shape and size as known in the art, suited for applying to different enclosures, and may be of various configurations.
A reactive element according to the invention (NxRA) is efficient against shaped charge war-heads, giving as an example RPG7, as well as against various types of kinetic projectiles, e.g. APFSDS, small arms (e.g. 14.5 mm), shrapnel and fragments. A NxRA element according to the present invention provides comparable efficiency to SLERA as discussed hereinabove, as well as comparable survivability to NERA. The NxRA element is advantageous over other reactive armor technologies as it is totally passive, as NERA, and it offers improved survivability to the protected enclosure, to neighbouring reactive elements and further provides excellent multiple-hit capability against hollow-charge warheads, small arms and kinetic projectiles and eliminates fragmentation hazards.
According to the present invention there is provided a non-explosive energetic material being a gas generator, comprising oxidizers and fuels, whereby exciting the material upon striking by a jet of a hollow charge results in vast generation of gas which accelerates/bulges the armor plates of the reactive armor.
This however requires that the gas be discharged rapidly, i.e. not more than a few μsec (microseconds), to thereby ensure disruption/defeating of the jet, and to minimize the penetration into a protected environment.
For that purpose, a group of oxidizers is selected and a group of fuels, which together with suitable catalyst/s and binder/s to provide the resultant non-explosive energetic material to constitute a gas generator.
According to one particular embodiment, the non-explosive energetic material comprises an oxidizer selected from the group of families comprising, among others, nitrates, nitrites, chromates, dichromates, perchlorates, chlorates, etc. and fuels of any type of carbon containing material, and a binder which may also serve as a fuel.
According to one particular embodiment, the non-explosive energetic material comprises sodium nitrate (NaNO3) as an oxidizer and a silicone binder as a fuel. It is also possible to combine several types of oxidizers and fuels so as to improve performance of the energetic material in the reactive armor element.
An example for a catalyst material suitable for use with the non-explosive energetic material in accordance with the present invention is a transition metal oxide, such as Fe2O3 (ferric oxide), which is usually used as a catalyst in energetic materials based on combinations of oxides and fuels.
In order to increase the reaction rate of the non-explosive energetic material, micro-balloons (i.e. hollow spheric elements) may be added to the formulation. It is appreciated that the micro-balloons increase the reaction rate upon striking of the armor by a jet of a hollow charge.
Such spheric elements may be made for example of glass, plastic material, metallic or ceramic materials. The diameter of such spheres may be about 40 μm, though other dimensions may be also suitable.
The non-explosive energetic material according to the present invention is a flexible sheet of material, pliable and it is easily cut, pierced, etc. whereby it is conveniently applied between the bearing plates of the armor element. According to one particular embodiment the material is rubber-like and is easily foldable.
The energetic material qualifies as a non-class 1 material as defined by UN Regulations and the US Department Of Transportation (DOT), and is thus a non-explosive energetic material.
The non-explosive energetic material is suitable for manufacturing a NxRA element for protection of enclosures against shaped-charge warheads, small arms, shrapnel, fragments and kinetic projectiles. Such a reactive armor element comprises a casing attached to the enclosure and fitted with an outer cover plate, and at least one sandwich element extending behind the plate; said sandwich element comprising at least one pair of substantially flat plates with the non-explosive energetic material applied there between.
It is appreciated that the above descriptions are intended only to serve as examples and that many other embodiments are possible, all of which fall within the spirit and the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 161586 | Apr 2004 | IL | national |
