Lightweight armour against firearm projectiles

Abstract: A lightweight armor assembly resistant against the penetration of firearm projectiles. The armor assembly has at least one front body of a lightweight material slanted relative the expected trajectory of an oncoming firearm projectile, and a rear body. The assembly may be transparent or opaque.

Description: FIELD OF THE INVENTION The present invention is in the field of armor against regular and armor piercing firearm projectiles and their fragments, and aims at providing lightweight armor suitable for a variety of purposes such as, for example, for making protective garments, for fitting enclosures with opaque or transparent armored wall portions and the like. More specifically, the present invention is directed to a lightweight armor assembly as defined in the preamble of the appended claim 1. Such assemblies are known e.g. from US-A-3 389 406 and US-A-2 318 301, and are based on the observation that if a slanting body is put in the path of a firearm projectile, the latter is subjected to asymmetric forces which cause the projectile to be diverted from its trajectory in the direction of the obtuse angle formed between the trajectory and the body. In addition, the projectile may also be broken up, and all this has the result that the projectile can easily be stopped either by the said body or by rear body. The slanting front body of these assemblies is made of high modulus material, such as glass or ceramics in US-A-3 380 406, and metals in US-A-2 318 301. BACKGROUND OF THE INVENTION There is a widespread need for protected enclosures with firearm projectile resistant transparent wall portions, typical examples being shop windows in riot prone areas, armored car windows, fighter plane domes, helicopter windows, domes for a tank commander post, etc. According to the prior art it is customary to use for such purposes laminated glass panels, e.g. 11 to 40 mm thick or even more, which by the effect of their mechanical properties are resistant against the penetration of various types of firearms. However, such panels are very heavy, weighing about 3 to 4 times more than an opaque armor, and also costly and therefore impractical for many purposes. There is thus an ever increasing need for lightweight transparent armor material. There is also a widespread need for firearm projectile resistant pliable material, e.g. for making protective garments, bullet resistant tarpaulins and the like. There is furthermore a need for hardened lightweight opaque armor against firearms. It is the object of the invention to satisfy all these needs. GENERAL DESCRIPTION THE INVENTION Thus, in accordance with the invention there is provided a lightweight armor assembly resistant against the penetration of firearm projectiles, as defined in the appended claim 1. The expressions "front body" and "rear body" nerely refer to the relative positions of the two bodies, and do not exclude an additionnal, non-slanted front panel as shown in figure 4. If desired, the armor assembly according to the invention may comprise two or more front bodies. The low modulus, brittle, lightweight material used in accordance with the present invention may be transparent or opaque and be either soft or hard. Where out of the two complementary angles formed between the trajectory of the firearm projectile and the surface of said at least one front body the upper angle is obtuse and the lower one is acute, the impinging firearm projectile is deflected upward. In contrast, where the lower angle is obtuse and the upper one is acute, an impinging firearm projectile is deflected downward. In case of a transparent front body the rear body is preferably also transparent. A transparent front body may be made of PMMA (perspex), various synthetic materials such as polycarbonates, epoxy resins, PVC and the like. An opaque front body may be made of a heavy duty cloth material such as of Kevlar™, Spectra™, and various epoxy materials and the like. Such materials may be used in soft pliable form or in composite hardened form, e.g. by being soaked with a suitable polymeric material which hardens upon curing. The front body in the lightweight armor assembly according to the invention may be a monoblock, i.e. be made of a single material. Alternatively, it may be laminated and made of two or more layers of the same material or be composite and be made of two or more layers of different materials. In either case adjacent layers are suitably glued or cemented to each other. If desired, in a laminated or composite block forming the front body in a lightweight armor assembly according to the invention, the individual layers may be slanted relative to the expected trajectory of an oncoming firearm projectile. In operation an oncoming firearm projectile penetrates across the said at least one front body and when it emerges therefrom, either intact or broken up, it is deflected either upwards or downwards depending on the slant of the front body relative to the trajectory, and does not penetrate across the rear body. In case of a thick front body the projectile may be deflected without hitting at all the rear body. It is thus seen that in accordance with the invention the required impact resistance of the rear body is much less than in the prior art. For example, where the rear body is a transparent wall or pane, its weight per unit area may be about half of that of a prior art body which has to be resistant to the full impact of an oncoming firearm projectile. BRIEF DESCRIPTION OF THE DRAWINGS For better understanding the invention will now be described with reference to the next drawings in which: Fig. 1 is a schematic illustration showing the manner in which the invention operates in case of one single slanted lightweight material front body; Fig. 2 is a similar illustration for two successive slanted lightweight material front bodies; Fig. 3 is a schematic illustration similar to the one of Fig. 1, with the front body being a composite body; and Fig. 4 is a schematic illustration of another embodiment of the invention. DESCRIPTION OF SPECIFIC EMBODIMENT Turning first to Fig. 1, there is shown schematically an assembly comprising a slanted lightweight front panel 1 and a vertical rear panel 2 . Arrow 3 stands for an oncoming firearm projectile and as can easily be concluded from the figure, the trajectory of the projectile 3 is essentially normal to the vertical rear panel and of the two angles formed at the intersection of the trajectory of projectile 3 with panel 1, the upper angle is obtuse. In consequence, once the projectile 3 has penetrated across panel 1 it is diverted upwards as shown at 4, either as a whole or broken up, and it either does not at all hit the vertical rear panel 2, or else is readily intercepted by it without passing across. In the embodiment shown schematically in Fig. 2, in which similar components are marked by similar numerals, there are provided two differently slanted transparent front panels 1 and 5. In this arrangement the oncoming firearm projectile 3 is deflected by panel 1 in the manner shown at 6 at which it is still in a position to penetrate across the second panel 5 where it is again deflected into the direction shown at 7, the end result being similar as in Fig 1. In the embodiment of the invention schematically shown in Fig. 3, which is essentially similar to that in Fig. 1 with similar components again being marked by the same numerals, panel 1 is sheathed by sheets 8 and 9 of a different lightweight material. Basically this embodiment operates in a similar way as the embodiment of Fig. 1. The embodiment shown schematically in Fig. 4 comprises a front panel 10 , a lightweight material block 11 composed of a plurality of slanting plates 12 glued or cemented together, and a vertical rear panel 13. In its passage across block 11 the firearm projectile 3 is diverted by any of the plates 12 which it hits on its way, and it accordingly does not penetrate the rear panel 13. In any of the above embodiments the lightweight front and rear panels may be transparent or opaque, according to requirements.

Claims: A light weight armor assembly resistant against the penetration of firearm projectiles, comprising at least one front body (1;5) extending slanted relative to an expected trajectory of an oncoming firearm projectile (3), and a rear body (2) extending essentially normal to said expected trajectory, characterized in that said at least one front body (1;5) is made of a low modulus, brittle, lightweight material such as PMMA, polycarbonates, epoxy resins, PVC and the like. A lightweight armor assembly according to Claim 1, being transparent. An assembly according to Claim 2, wherein said at least one front body is made of a material selected from the group of organic materials. A lightweight armor assembly according to Claim 1, being opaque. An assembly according to Claim 4, wherein the low modulus, brittle, lightweight material is a heavy duty cloth material. A lightweight armor assembly according to any one of Claims 1 to 5, wherein the said at least one front body is a monoblock. An assembly according to Claim 6, wherein the said at least one front body is a composite. An assembly according to Claim 7, wherein the composite front body is made of a plurality of different low modulus, brittle, lightweight transparent materials. An assembly according to claim 8, wherein the composite front body is made of a plurality of different low modulus, brittle, lightweight opaque materials. An assembly according to Claim 7, wherein the composite front body is made of a heavy duty cloth material. An assembly according to Claim 9, wherein said heavy duty cloth is soaked with a suitable polymeric material that hardens upon curing. An assembly according to any one of Claims 1 to 5, wherein said at least one front body is in the form of a multilayer block in which the individual layers are slanted relative to the expected trajectory of an oncoming firearm projectile and in which adjacent layers are suitably glued or cemented to each other.

Inventors: YESHURUN YEHOSHUA, YESHURUN, YEHOSHUA
Applicants: RAFAEL ARMAMENT DEV AUTHORITY, RAFAEL ARMAMENT DEVELOPMENT AUTHORITY LTD.
Application year: 1999
Main classification: F41H5
IPC codes: F41H5