Abstract:
A drag inducing armor includes a projectile hindering layer and a pliant layer operably associated with the projectile hindering layer to envelop a projectile that has passed through the projectile hindering layer. A drag inducing armor includes a forward face sheet, a projectile hindering layer disposed adjacent the forward face sheet, a rear face sheet, and a pliant layer disposed between the projectile hindering layer and the rear face sheet. A method for using a drag inducing armor includes providing a projectile hindering layer and a pliant layer disposed behind the projectile hindering layer, hindering a projectile with the projectile hindering layer, and enveloping the projectile after the projectile passes through the projectile hindering layer.

Description:
BACKGROUND  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to armor for inhibiting the effectiveness of ballistic projectiles. In particular, the present invention relates to a drag inducing armor and a method of using the armor.  
         [0003]     2. Description of Related Art  
         [0004]     It is often desirable to protect vehicles, such as tanks, personnel carriers, and the like, from serious damage caused by ballistic projectiles. Accordingly, these types of vehicles are known to have armor to reduce the likelihood that such projectiles will penetrate the vehicle. If the projectiles penetrate the vehicle, the occupants of the vehicle may be injured or the vehicle&#39;s ability to operate may be impaired.  
         [0005]      FIG. 1A  illustrates one particular example of a conventional anti-ballistic armor  101  with an approaching ballistic round or projectile  103 . In the illustrated example, armor  101  includes a ceramic layer  105  and a ballistic fabric layer  107  captured between a forward face sheet  109  and a rear face sheet  111 . Ballistic fabric layer  107  is made up of a woven fabric of aramid or other high tensile strength yarns, fixedly held between ceramic layer  105  and rear face sheet  111 . Typically, ballistic fabric layer  107  is continuously, adhesively bonded to substantially an entire rear surface  113  of ceramic layer  105  and/or to substantially an entire front surface  115  of rear face sheet  111 . Face sheets  109 ,  111  typically protect ceramic layer  105  and ballistic fabric layer  107  from inadvertent damage and environmental effects, in addition to face sheet  111  holding ballistic fabric layer  107  in a fixed position. In some conventional armors, forward face sheet  109  provides additional ballistic protection.  
         [0006]      FIG. 1B  illustrates ballistic projectile  103  impacting armor  101 . The impact of ballistic projectile  103  on ceramic layer  105  shatters at least a portion of ceramic layer  105 . The reactive force produced by the impact of ballistic projectile  103  and ceramic layer  105  breaks apart, tips, and/or otherwise damages projectile  103 , as shown in  FIG. 1C . Ballistic fabric layer  107  captures and retains broken or tipped ballistic projectile  103  within armor  101 . Ballistic fabric layer  107  also captures and retains spall  117  from forward face sheet  109  and spall  119  from ceramic layer  105 . Accordingly, armor  101  relies upon ballistic fabric layer  107  to remain attached to ceramic layer  105  and/or rear face sheet  111 . Armor  101  completely halts the progression of ballistic projectile  103 , such that the residual velocity of ballistic projectile  103  is essentially zero.  
         [0007]     It should be noted that the thicknesses of ceramic layer  105  and ballistic fabric layer  107  are sized based upon, for example, the maximum mass and maximum velocity of an expected ballistic projectile  103 . Generally, the thicknesses of ceramic layer  105  and ballistic fabric layer  107  are proportional to the mass and velocity of ballistic projectile  103 . In other words, a ballistic projectile  103  having a greater mass and/or velocity will require a thicker ceramic layer  105  and/or ballistic fabric layer  107  to be halted, as compared to a ballistic projectile  103  having a lesser mass and/or velocity. Greater thicknesses of ceramic layer  105  and/or ballistic fabric layer  107  result in greater overall weight and size of armor  101 .  
         [0008]     While protecting the vehicle and its occupants is generally of primary importance, other factors may play a role in the design of armor for the vehicle. It is typically desirable for the vehicle to be as lightweight as possible. Generally, fuel consumption by the vehicle increases as its weight increases. A heavier vehicle usually requires a heavier drive train than a lighter vehicle, which further increases weight. Increased weight may also reduce the mobility of the vehicle and, thus, reduce the utility of the vehicle in evasive situations. As the weight of the vehicle&#39;s armor can contribute to the overall weight of the vehicle, it is desirable for the vehicle&#39;s armor to be as lightweight as possible. Many known armor systems, while protecting the vehicle from ballistic damage, add significant weight to the vehicle and provide little or no additional structural strength to the vehicle.  
         [0009]     It is also not desirable for the vehicle&#39;s armor to greatly increase the overall size of the vehicle (e.g., the vehicle&#39;s height, width, length, volume, and the like). It is desirable for existing transportation equipment (e.g., trucks, trailers, aircraft, and the like) to be capable of transporting the vehicle. If the size of the vehicle is increased over previous vehicles, the existing transportation equipment may not be capable of transporting the vehicle, or the existing transportation equipment may be limited to carrying fewer vehicles per load. Moreover, if the vehicle&#39;s size is increased over previous vehicles, the vehicle may not be able to pass through existing roadway or railway tunnels.  
         [0010]     The overall size of the vehicle may also be a factor in combat situations. Generally, smaller targets (i.e., smaller vehicles) are more difficult to hit with artillery, such as rockets, mortars, missiles, ballistic rounds, and the like. Thus, it may be desirable for the vehicle&#39;s overall size to be smaller, rather than larger, to reduce the likelihood of an artillery hit.  
         [0011]     Cost is also typically a consideration when designing or choosing vehicle armor. Armor that uses exotic materials may be quite effective in defeating or limiting the damaging effect of ballistic projectiles but may be unaffordable.  
         [0012]     While there are many types of armor well known in the art, considerable room for improvement remains.  
       SUMMARY OF THE INVENTION  
       [0013]     There is a need for an improved apparatus and method for hindering a projectile.  
         [0014]     In one aspect of the present invention, a drag inducing armor is provided. The drag inducing armor includes a projectile hindering layer and a pliant layer operably associated with the projectile hindering layer to envelop a projectile that has passed through the projectile hindering layer.  
         [0015]     In another aspect of the present invention, a drag inducing armor is provided. The drag inducing armor includes a forward face sheet, a projectile hindering layer disposed adjacent the forward face sheet, a rear face sheet, and a pliant layer disposed between the projectile hindering layer and the rear face sheet.  
         [0016]     In yet another aspect of the present invention, a method for using a drag inducing armor is provided. The method includes providing a projectile hindering layer and a pliant layer disposed behind the projectile hindering layer, hindering a projectile with the projectile hindering layer, and enveloping the projectile after the projectile passes through the projectile hindering layer.  
         [0017]     The present invention provides significant advantages, including: (1) providing an armor having less areal density than conventional armor; and (2) providing improved protection for projectile impacts at joints between armor tiles.  
         [0018]     Additional objectives, features and advantages will be apparent in the written description which follows.  
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0019]     The novel features believed characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as, a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, in which the leftmost significant digit(s) in the reference numerals denote(s) the first figure in which the respective reference numerals appear, wherein:  
         [0020]      FIG. 1A  is a stylized, partial cross-sectional view illustrating an exemplary, conventional armor and a ballistic projectile approaching the tile;  
         [0021]      FIG. 1B  is a stylized, partial cross-sectional view illustrating the ballistic projectile impacting the conventional armor, all of  FIG. 1A ;  
         [0022]      FIG. 1C  is a stylized, partial cross-sectional view illustrating the conventional armor capturing the ballistic projectile, all of  FIG. 1A ;  
         [0023]      FIG. 2  is a stylized, perspective view of an illustrative embodiment of a drag inducing armor according to the present invention;  
         [0024]      FIG. 3  is a stylized, cross-sectional view of the drag inducing armor of  FIG. 2  taken along the line  3 - 3  in  FIG. 2  illustrating various particular ways of attaching a pliant layer to adjacent layers in the drag inducing armor;  
         [0025]      FIG. 4  is a stylized, cross-sectional view of the drag inducing armor of  FIG. 2  taken along the line  4 - 4  in  FIG. 2  illustrating an alternative way of attaching the pliant layer to adjacent layers in the drag inducing armor;  
         [0026]      FIG. 5A  is a stylized, cross-sectional view of the drag inducing armor of  FIG. 2  taken along the line  5 - 5  of  FIG. 2 , illustrating a ballistic projectile approaching the drag inducing armor;  
         [0027]      FIG. 5B  is a stylized, cross-sectional view of the drag inducing armor of  FIG. 2  taken along the line  5 - 5  of  FIG. 2 , illustrating the ballistic projectile impacting the drag inducing armor;  
         [0028]      FIG. 5C  is a stylized, cross-sectional view of the drag inducing armor of  FIG. 2  taken along the line  5 - 5  of  FIG. 2 , illustrating the ballistic projectile traveling into the drag inducing armor;  
         [0029]      FIGS. 5D-5F  are stylized, cross-sectional views of the drag inducing armor of  FIG. 2  taken along the line  5 - 5  of  FIG. 2 , illustrating the ballistic projectile urging the pliant layer of the drag inducing armor through a rear face sheet of the drag inducing armor;  
         [0030]      FIG. 6  is a stylized, perspective view of a portion of an alternative, illustrative embodiment of a drag inducing armor according to the present invention, illustrating a one particular illustrative embodiment of a pliant layer disposed behind a plurality of ceramic tiles; and  
         [0031]      FIG. 7  is a stylized perspective view of a portion of an alternative, illustrative embodiment of a drag inducing armor according to the present invention, illustrating an alternative, illustrative embodiment of a pliant layer disposed behind a plurality of ceramic tiles. 
     
    
       [0032]     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0033]     Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer&#39;s specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.  
         [0034]     The present invention represents a drag inducing armor and a method of making the armor. Generally, the drag inducing armor of the present invention provides a pliant layer that, when contacted by a projectile, envelops the projectile. As used herein, the term “pliant” means “easily bent, flexed, or twisted without breaking.” The projectile, spall fragments, and the pliant layer, urged by the projectile, exit the rear face of the drag inducing armor at a much reduced velocity, as will be discussed in greater detail below. The pliant layer and the projectile have a very large aerodynamic drag, since the pliant layer has a very large surface area as compared to the projectile. Accordingly, the velocity of the projectile is greatly reduced. Moreover, the leading surface of the pliant layer enveloping the projectile (or projectile fragments if the projectile has fragmented) is more blunt than the leading edge of the projectile or projectile fragments alone. For at least these reasons, the drag inducing armor of the present invention lessens, or in some cases eliminates, the behind-armor damage caused by the projectile.  
         [0035]      FIG. 2  depicts an illustrative embodiment of a drag inducing armor  201  according to the present invention. In the illustrated embodiment, drag inducing armor  201  comprises a forward face sheet  203 , a projectile hindering layer  205  disposed adjacent forward face sheet  203 , a rear face sheet  207 , and a pliant layer  209  disposed between projectile hindering layer  205  and rear face sheet  207 .  
         [0036]     Face sheets  203 ,  207  house projectile hindering layer  205  and pliant layer  209 . In some embodiments, face sheets  203 ,  207  comprise a material such as a polymeric composite, steel, aluminum, or the like. In other embodiments, forward face sheet  203  provides additional protection from ballistic projectiles. In these embodiments, forward face sheet  203  comprises a material such as steel, tungsten, or other such protective or projectile hindering material. It should be noted that face sheets  203 ,  207  may comprise elements of another device or apparatus. For example, if drag inducing armor  201  is implemented on or in a vehicle, face sheets  203 ,  207  may comprise elements of the vehicle. In one particular implementation, rear face sheet  207  may comprise a vehicle panel, such a body panel.  
         [0037]     Projectile hindering layer  205  comprises a material suitable for breaking, blunting, fragmenting, deforming, tipping, or otherwise hindering a ballistic projectile, as will be discussed in greater detail below. In preferred embodiments, projectile hindering layer  205  comprises at least one of a ceramic material, such as silicon carbide or silicon nitride; steel; titanium; a metal-matrix composite; a ceramic-matrix composite; or the like.  
         [0038]     Still referring to the embodiment illustrated in  FIG. 2 , pliant layer  209  comprises one or more plies of woven fabric disposed between projectile hindering layer  205  and/or rear face sheet  207  such that, when a ballistic projectile encounters pliant layer  209 , the ballistic projectile is enveloped by pliant layer  209 . The force produced by the ballistic projectile carries the ballistic projectile and the pliant layer through rear face sheet  207  and out of drag inducing armor  201 , as will be discussed in greater detail below. Generally, in one embodiment, pliant layer  209  comprises high tensile strength yarns woven into a fabric. Pliant layer  209  comprises one or more plies (e.g.,  8 - 10  plies) of such fabric. It should be noted that the scope of the present invention encompasses pliant layer  209  comprising any number of plies. In various embodiments, pliant layer  209  comprises aramid fibers, such as Kevlar®, produced by E. I. du Pont de Nemours of Richmond, Va.; high molecular weight polyethylene fibers, such as Spectra®, produced by Honeywell Specialty Materials of Morris Township, N.J.; and/or p-phenylene-2,6-benzobisoxazole (PBO) fibers, such as Zylon®, produced by Toyobo Co., Ltd. of Osaka, Japan. Pliant layer  209 , however, may take on other forms that are encompassed by the present invention.  
         [0039]     As discussed above, pliant layer  209  is incorporated into drag inducing armor  201  such that a ballistic projectile can be enveloped by pliant layer  209  and pliant layer  209  can be urged from drag inducing armor  201  by the ballistic projectile. Accordingly, pliant layer  209  is removably disposed between projectile hindering layer  205  and rear face sheet  207 . Pliant layer  209  is held in place between projectile hindering layer  205  and rear face sheet  207  prior to the ballistic projectile impacting drag inducing armor  201 . As will be more fully described below, pliant layer  209  is adapted to envelop the ballistic projectile and be urged from drag inducing armor  201  by the ballistic projectile.  
         [0040]     In one embodiment, pliant layer  209  is compressively held within drag inducing armor  201  without the use of any adhesive. For example, pliant layer  209  may be compressively held in place between projectile hindering layer  205  and rear face sheet  207 . Other ways of retaining pliant layer  209  in a removable configuration within drag inducing armor  201 , such that a projectile may be enveloped by pliant layer  209  and may urge the projectile and pliant layer  209  from drag inducing armor  201 , are within the scope of the present invention. For example, as shown in  FIG. 3  pliant layer  209  is adhesively attached at discrete locations to projectile hindering layer  205  and/or rear face sheet  207 . In one implementation, pliant layer  209  is adhesively attached to both projectile hindering layer  205  and rear face sheet  207  by adhesive portion  301 . In this implementation, adhesive portion  301  extends through the thickness of pliant layer  209  and is adhesively bonded to a rear face  303  of projectile hindering layer  205  and to a forward face  305  of rear face sheet  207 .  
         [0041]     Alternatively, pliant layer  209  is adhesively bonded to rear face  303  of projectile hindering layer  205  via an adhesive portion  309  and/or a rear portion  311  of pliant layer  209  is adhesively bonded to a forward face  305  of rear face sheet  207  via an adhesive portion  313 . In either implementation illustrated in  FIG. 3 , forces applied by a projectile to pliant layer  209  readily detaches pliant layer  209  from projectile hindering layer  205  and/or rear face sheet  207 . Note that, in one drag inducing armor  201 , pliant layer  209  may be attached to projectile hindering layer  205  and/or rear face sheet  207  by one or more adhesive portions  301 ,  309 ,  313  or by a combination of adhesive portions  301 ,  309 ,  313 . As presented above, pliant layer  209  may be retained between projectile hindering layer  205  and rear face sheet  207  omitting adhesive portions  301 ,  309 ,  313 .  
         [0042]     Alternatively, as shown in  FIG. 4 , one or more adhesive portions  401 ,  403  extend across pliant layer  209  alone or in conjunction with adhesive portions  301 ,  309  and/or  311 . As specifically illustrated in  FIG. 4 , adhesive portions  401 ,  403  extend partially around a periphery of pliant layer  209 . The scope of the present invention, however, encompasses a single adhesive portion  401 ,  403  extending around a periphery of pliant layer  209 . Other particular configurations of releasable adhesive attachment are within the scope of the present invention, such as minimally spot gluing pliant layer  209  to projectile hindering layer  205  and/or rear face sheet  207 . It should be noted, however, that if pliant layer  209  is adhesively retained between projectile hindering layer  205  and rear face sheet  207 , a projectile encountering pliant layer  209  will fail adhesive portions  301 ,  309 ,  313 ,  401 , and/or  403  prior to pliant layer tearing, such that the projectile can be enveloped by pliant layer  209 .  
         [0043]      FIGS. 5A-5F  depict drag inducing armor  201  in one particular use at certain time intervals. In each of  FIGS. 5A-5F , pliant layer  209  is depicted as being adhesively bonded to projectile hindering layer  205  via adhesive portions  309  and to rear face sheet  207  via adhesive portions  313 . As discussed above, however, the present invention is not so limited. Rather, other ways of releasably retaining pliant layer  209  are within the scope of the present invention.  
         [0044]      FIG. 5A  illustrates a projectile  501  approaching drag inducing armor  201 . Upon impact with drag inducing armor  201 , as shown in  FIG. 5B , projectile  501  encounters forward face sheet  203  and projectile hindering layer  205 . In the illustrated embodiment, projectile hindering layer  205  comprises a hard, brittle, high compressive strength material, such as a ceramic. The impact of projectile  501  shatters or cracks projectile hindering layer  205 . The collision between projectile  501  and projectile hindering layer  205  blunts, breaks, fragments, and/or tips projectile  501 , as shown in  FIG. 5C .  
         [0045]     Still referring to  FIG. 5C , the collision between projectile  501  and projectile hindering layer  205  also reduces the velocity of the projectile  501 , whether intact or fragmented. Projectile  501 , however, still exhibits considerable velocity and, thus, momentum. Projectile  501  continues to travel into drag inducing armor  201 , encountering pliant layer  209 . Pliant layer  209  is deformed, as is rear face sheet  207 .  
         [0046]     Referring now to  FIG. 5D , projectile  501  applies sufficient force to pliant layer  209  to break through rear face sheet  207 , creating an opening  502 , and to urge pliant layer  209  through rear face sheet  207 . Note that, if pliant layer  209  is originally attached to projectile hindering layer  205  and/or rear face sheet  207 , pliant layer  209  becomes detached from projectile hindering layer  205  and/or rear face sheet  207 . Pliant layer  209  is constrained by rear face sheet  207  as projectile  501  urges pliant layer  209  through opening  502 , reducing the velocity of projectile  501 . Moreover, friction between pliant layer  209  and projectile hindering layer  205  and between pliant layer  209  and rear face sheet  207  resist the movement of pliant layer  209  through opening  502 , further reducing the velocity of projectile  501 .  
         [0047]     As shown in  FIG. 5E , the momentum of projectile  501  continues to urge pliant layer  209  through opening  502 , until projectile  501  and pliant layer  209  are free of rear face sheet  207 , as shown in  FIG. 5F . Pliant layer  209  envelops projectile  501 . While projectile  501  and pliant layer  207  are still moving after exiting rear face sheet  207 , projectile  501  enveloped by pliant layer  209  exhibits an increased aerodynamic drag than projectile  501  alone, further reducing the velocity of projectile  501 . Moreover, the velocity of projectile  501  and pliant layer  207  is generally insufficient to cause serious harm to personnel and/or equipment behind drag inducing armor  201 . It should be noted that, in implementations wherein drag inducing armor  201  is disposed outside of a vehicle or the like, structural elements disposed behind drag inducing armor  201  may be of sufficient strength to completely halt projectile  501 .  
         [0048]     As shown in  FIG. 6 , it should be noted that drag inducing armor  201  may include a plurality of tiles  601 , disposed edge-to-edge, comprising projectile hindering layer  205 . Moreover, pliant layer  209  may comprise a plurality of plies  603 ,  605  of woven fabric, such as the woven fabric described above. In one embodiment, at least one of plurality of plies  603 ,  605  extends across joints  607  between tiles  601 . In the illustrated embodiment, at least one of plurality of plies  603 ,  605  comprises a plurality of sheet portions  609  of woven fabric, such as the woven fabric described above, separated by perforations  611 . Perforations  611  reduce the tensile strength of plies  603 ,  605  in portions between sheet portions  609 . Thus, when a projectile encounters a particular sheet portion  609  of plies  603 ,  605 , perforations  611  defining the particular sheet portion  609  allow the particular sheet portion  609  to be broken away from the rest of ply  603 ,  605 , so that the projectile can be enveloped by sheet portion  609 . Alternatively, one or more of plies  603 ,  605  may comprise a woven fabric that incorporates, as part of the weave, reduced tensile strength portions corresponding to perforations  611 .  
         [0049]     If, for example, plies  603 ,  605  each comprise separate sheet portions  609  of woven fabric, ply  603  may be positioned such that perforations  611  between sheets  609  of ply  603  are not aligned with perforations  613  between sheets  609  of ply  605 . In other words, sheets  609  of ply  603  extend across at least some of perforations  613  between sheets  609  of ply  605 . Such a configuration provides additional protection from projectile impacts occurring at joints  607  between tiles  601 . Preferably, at least two plies, such as plies  603 ,  605 , are used when a plurality of tiles  601  are incorporated in drag inducing armor  201 .  
         [0050]     Alternatively, as shown in  FIG. 7 , at least one of plurality of plies  701 ,  703  may also comprise a plurality of separate sheet portions  705  of woven fabric, such as the woven fabric described above, disposed edge-to-edge. If, for example, plies  701 ,  703  each comprise separate sheet portions  705  of woven fabric, ply  701  may be positioned such that joints  707  between sheet portions  705  of ply  701  are not aligned with joints  709  between sheet portions  705  of ply  703 . In other words, sheet portions  705  of ply  701  extend across at least some of joints  709  between sheet portions  705  of ply  703 . Such a configuration provides additional protection from projectile impacts occurring at joints  607  between tiles  601 .  
         [0051]     Generally, in either of the embodiments of FIGS.  6  or  7 , it is generally desirable for a projectile to encounter as many sheet portions  609 ,  705  as possible to decrease the projectile&#39;s velocity. Moreover, it is preferable, in embodiments wherein tiles  601  comprise projectile hindering layer  205 , to include at least two plies  603 ,  605 ,  701 ,  703  adjacent tiles  601 . It should also be noted that, while sheet portions  609 ,  705  are illustrated herein as being rectangular, the present invention is not so limited. Rather, sheet portions  609 ,  705  may take on any shape, such as triangular.  
         [0052]     The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention. Accordingly, the protection sought herein is as set forth in the claims below. It is apparent that an invention with significant advantages has been described and illustrated. Although the present invention is shown in a limited number of forms, it is not limited to just these forms, but is amenable to various changes and modifications without departing from the spirit thereof.