Abstract:
A method of manufacturing a non-lethal impact projectile having a nose composed of a frangible, rigid, polymer foam material such that the nose crushes upon impact with a target to disperse energy, thereby reducing the kinetic energy transferred to the target. The projectile is provided with a cavity to retain a payload, such as marker agents, lacrimators, irritants, inflammatory agents, odorants or inert powders, such that the payload is laterally dispersed upon impact to further dissipate energy transferred to the target.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to the field of non-lethal projectiles or impact munitions and more particularly relates to the field of such projectiles capable of delivering a gas, powder or liquid payload. Even more particularly, the invention relates to such projectiles having a rigid, frangible nose. 
         [0002]    It is often desirable to provide for law enforcement, corrections or military users a relatively low-impact, non-lethal projectile for use with firearms or launchers, where the projectile is capable of imparting blunt trauma without deadly force and is also capable of delivering a payload for dispersion upon impact, the payload comprising a gas, liquid or powder having certain desired properties. Such munitions are used for example in crowd control and other special operations, where it is desirable to deter certain activity without utilizing lethal force. The payload may comprise for example marker agents, lacrimators, irritants, inflammatory agents, odorants and the like. 
         [0003]    Since the projectile is designed to be direct-fired at the human target, it is necessary to insure that the impact force is sufficient to deliver enough pain to the target for compliance, but without causing serious injury. This is accomplished through the structural design of the projectile as well as by limiting the projectile velocity. Reducing the velocity of the projectile also reduces the accuracy of the trajectory, so a minimum acceptable velocity must be retained. By producing an energy absorbing projectile, sufficient velocity may be maintained for accuracy. 
         [0004]    In order to achieve the desired results, projectiles have been developed where the entire projectile or at least the nose of the projectile is formed of a compliant, resilient material that compresses upon impact. The compliant material may take the form of a sphere. Alternatively, the nose of the projectile may be formed of a rubber, sponge or compliant foam material that dissipates impact energy due to compressive elastic deformation. Examples of such projectiles are shown in U.S. Pat. No. 3,714,896 to Young and U.S. Pat. No. 6,041,712 to Lyon. A problem can occur with the use of compliant nose materials in that the resilience of the material is detrimental to projectile accuracy due to adverse aerodynamic effects on the non-rigid nose. In addition, the use of compliant or soft materials to retain gas, liquid or powder payloads creates problems in handling and storage, since the projectiles are readily subject to accidental failure, resulting in unwanted dispersal of the payload. Likewise, environmental degradation will more rapidly affect the resilient material containing the payload. 
         [0005]    It is also known to produce low-impact, non-lethal projectiles adapted to carry payloads for dispersal on impact where the projectile or the nose of the projectile is made of a frangible material that breaks upon impact as a result of compressive plastic deformation. For example, U.S. Pat. No. 6,145,411 to Woddall et al. shows a payload carrying spherical projectile formed of a rigid plastic material and provided with dimples and score lines to create localized stress points that fracture upon impact. The dimples and score lines also create a more accurate spherical projectile through aerodynamic effects. Another example is shown in U.S. Pat. No. 5,035,183 to Luxton, where a projectile having the typical bullet-shape is provided, the projectile being composed of a rigid plastic material. Score lines are provided on the projectile such that it will rupture on impact. While the projectile accuracy is more readily maintained in these designs, the energy dissipation at impact is relatively small and remains concentrated, and the material of construction is more likely to result in injury to the human target since breaking of the projectile results in jagged or sharp edges of relatively non-compliant material. In addition, these projectiles are more likely to deliver serious injury if utilized at short range. 
         [0006]    It is an object of this invention to provide a non-lethal, low-impact projectile capable of delivering blunt trauma of sufficient amount to induce compliance as well as to deliver a payload of a gas, liquid or powder substance having desired effects on the human target. It is a further object to provide such a projectile that overcomes the drawbacks inherent in the known systems. These and other objects that will become apparent from the disclosure to follow are accomplished by providing a projectile having a nose formed in an aerodynamically preferred configuration and composed of a frangible, rigid foam material, such that impact energy is dissipated through plastic deformation of the nose, which first compresses and then breaks to disperse the payload. The projectile is capable of being mounted onto known projectile delivery systems for use in known firearms, launchers or the like. 
       SUMMARY OF THE INVENTION 
       [0007]    The invention comprises in general a non-lethal impact munition or projectile adapted to be discharged from a firearm or other launcher device and directed at a human target, wherein the impact energy of the projectile is below the threshold where serious injury or death would result from the impact, yet is of sufficient force such that blunt trauma is delivered for the purpose of pain compliance. The design and structure of the projectile is such that aerodynamic properties and projectile velocity are not excessively adversely affected in order to maintain the accuracy of delivery. 
         [0008]    The projectile comprises a projectile nose mounted onto a projectile base, wherein the nose is composed of a frangible, rigid, polymer foam material, such as polyurethane. The nose has a rounded forward end and a cylindrical wall, and the base has a generally flat forward wall and a cylindrical rear wall, adapted to be separably joined to a propulsion shell or casing to form a munition or cartridge capable of being discharged from a firearm or launcher by propulsion means within the propulsion shell, the projectile having a typical bullet shape for aerodynamic purposes. The polymer foam material composing the nose is sufficiently rigid so as to maintain its structural configuration during discharge and flight, but which is crushed and broken upon impact with a human target such that the impact energy is dissipated or reduced. Preferably, the forward end of the nose is thicker than the cylindrical wall of the nose, such that the compression and fracture occurs mainly in the cylindrical wall. The nose may further comprise a rear plug wall that is directly joined to the forward wall of the projectile base, with the rear plug wall being preferably composed of a resilient, compliant polymer or rubber material. 
         [0009]    The projectile nose further comprises a cavity adapted to receive a payload to be dispersed upon impact with the human target. The payload is chosen for a particular purpose and may consist of marker agents, lacrimators, irritants, inflammatory agents, odorants, inert powders or other materials. The crushing and fracture of the projectile nose upon impact laterally expels or disperses the payload, which further reduces the impact energy delivered to the target. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is an external view of the invention. 
           [0011]      FIG. 2  is a cross-sectional view of the invention taken along line II-II of  FIG. 1 . 
           [0012]      FIG. 3  is a view of the projectile at impact showing dispersal of a payload. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    With reference to the drawings, the invention will now be described with regard for the best mode and the preferred embodiment, but with the understanding that the scope of the patent is not limited to such and that other variations and embodiments are covered by the language of the claims. In a most general sense, the invention is a projectile, or the projectile in combination with a casing or shell to define an impact munition, to be discharged or propelled from a firearm or similar launcher device such that the projectile is accurately delivered to impact a target, and in particular such that the projectile can strike a human target without inflicting death or serious bodily injury, yet will have sufficient impact force to deliver blunt trauma in an amount designed to inflict sufficient pain so as to cause compliance by the target. In addition, the projectile is designed to be capable of delivering and dispersing upon impact a payload material, such as a liquid, gas or solid, the energy required for payload dispersal acting to further reduce the impact force. To accomplish these purposes, at least a portion of the projectile is designed to crush and fracture upon impact such that some of the impact energy is dissipated. 
         [0014]    The structure of the invention must take into account several conflicting and competing requirements for effective operation. The pain inflicted by the projectile at impact must be sufficient enough to force compliance, yet the impact energy delivered to the target must be low enough to prevent serious energy. Projectile accuracy must be maintained through the aerodynamic design of the projectile as well as by maintaining sufficient projectile velocity upon discharge. 
         [0015]      FIGS. 1 and 2  show an external view and a cross-sectional view of the complete impact munition or cartridge of the invention, which is defined to comprise in combination a propulsion casing or shell  10  and a projectile comprising a projectile base  20  and a projectile nose  30 . The impact munition is constructed so as to be useable in firearms or launchers of known type, especially those firearms or launchers having rifled barrels, such as for example a 40 mm rifled-barrel gas gun or an M203 rifled grenade launcher. The dimensions of the cartridge may vary to accommodate launchers of different caliber (37 mm, 66 mm, etc.), as well as shotguns of varying gauges. The propulsion shell  10  may be of known type, and is shown to comprise an annular forward wall  14  having a forward shell rim  16  and joined to a shell base  11  having a rear wall  17 . A co-axially oriented propulsion cavity  12  is disposed in the shell base  11  and retains propulsion means  13  of known type, preferably a smokeless system. The annular forward wall  14  defines a shell cavity  15  to receive the expanding gases produced by the propulsion means  13  at discharge. 
         [0016]    Mounted in separable manner onto the front of the propulsion shell  10  is a projectile comprised of a projectile base  20  joined to a projectile nose  30 . The projectile base  20 , preferably composed of a polycarbonate material, comprises a domed forward end  21  joined to a cylindrical wall  22  such that the combination defines a projectile cavity  23 . The exterior of the cylindrical wall  22  is provided with an undercut  24  that defines a rearward extending annular insertion flange  25 . The insertion flange  25  is received within the shell rim  16  and shell forward wall  14  in a male-female coupling, such that the projectile cavity  23  and the shell cavity  15  combine to form a single larger cavity. 
         [0017]    The projectile nose  30  comprises a rounded forward end  31  combined with a cylindrical wall  32  and is composed of a substantially non-compliant, frangible, rigid, polymer foam material, most preferably a closed-cell polyurethane. The rigidity of the foam must be sufficient for it to retain its structural configuration upon discharge and during flight so as not to adversely affect accuracy, yet be below a rigidity threshold such that the foam is crushed and broken upon impact with soft tissue of a human target in order to dissipate the energy. In other words, the foam must undergo plastic deformation upon impact rather than elastic deformation. It has been found that a polyurethane foam having a density between approximately eight and 14 pounds per cubic foot used to form the forward end  31  and cylindrical wall  32  provides these desired characteristics. The thickness or radial dimension of the cylindrical wall  32  is preferably less than the thickness of the forward end. Through this construction, it is the cylindrical wall  32  that will deform, crush and break upon impact of the projectile with the target  99 . The precise shape of the rounded forward end  31  is determined by aerodynamic characteristics well known in the art. 
         [0018]    The combination of the forward end  31  and cylindrical wall  32  define a nose cavity  33  that may be empty or that may receive a payload  35  to be dispersed or expelled when the nose  30  is crushed and broken upon impact with the target  99 . The payload  35  may comprise a gas, liquid, solid or powder that possesses certain desirable properties when the payload  35  is exposed to the target  99 . For example, the payload  35  may comprise alone or in combination a marker agent, a lacrimator, an irritant, an inflammatory agent, an odorant or other material. Likewise, the payload  35  may consist entirely of or include an inert powder. The presence of a payload  35  is preferable since energy is required to laterally disperse the payload  35  upon impact, and this mass dispersion energy further reduces the momentum energy transferred from the projectile nose  30  to the target  99 . This allows the velocity to be increased slightly relative to an empty projectile nose  30  without increasing the kinetic energy transferred to the target  99 . 
         [0019]    Preferably, the nose  30  further comprises a rear plug wall  34  attached to the rearward end of the cylindrical wall  32  that seals cavity  33 . This allows the nose  30  to be manufactured by loading the payload  35  into the cavity  33  and then attaching plug wall  34 , by adhesives or other suitable means, prior to attachment to the projectile base  20 . Preferably, the rear plug wall  34  is composed of a resilient, compliant polymer or rubber material to further absorb impact energy and to prevent contact of the projectile base  20  with the target  99 . The rear plug wall  34  is joined to the face of the base forward wall  21  by adhesives or other suitable means. 
         [0020]    At discharge, the projectile base  20  and nose  30  separate from the shell  10  in known manner and travel such that the nose forward end  31  strikes the target  99 , as shown in  FIG. 3 . Upon impact the rigid foam forward end  31  is pushed to the rear toward the forward wall  21  of the projectile base  20 . The rigid foam cylindrical wall  32  of the nose  30 , being of thinner dimension than the forward end  31 , crushes and breaks such that openings or tears are created. This absorbs and dissipates energy that would normally be delivered to the target  99 . Any payload  35  retained within nose cavity  33  will be expelled laterally in multiple directions. 
         [0021]    The use of a closed-cell polyurethane foam or a polymer foam possessing similar characteristics to form the crushable components of the nose  30  has been found to be advantageous for several reasons. The density of the foam is easily controlled during the molding process, which can be performed by reaction injection molding. Specific shapes, contours and cavities are easily produced such that the external aerodynamic contour may be maximized for best accuracy. The polymer foam material is inert to most payloads and is suitable for retention of gas or liquid as well as a solid or powder. The rigid foam first deforms at impact through compression of air trapped within the cell walls and then breakage of the cell walls themselves, followed by rupture of the foam on a macro scale. The foam nose  30  is sufficiently structurally strong such that it is unlikely to break upon minor impacts that may occur during storage or handling. After deformation and discharge of the payload  35 , the crushed forward end  31  and cylindrical wall  32  form in combination with the resilient plug wall  34  a buffer or cushion between the projectile base  20  and the target  99 . This distributes the impact energy over the maximum surface area of the projectile, thereby minimizing the chance of penetration by the projectile base  20  into the target  99 . 
         [0022]    It is understood and contemplated that equivalents and substitutions for certain elements set forth above may be obvious to those skilled in the art, and therefore the true scope and definition of the invention is to be as set forth in the following claims.