Abstract:
A munitions disabling device is disposed in a storage container proximate the muzzle of a single-use weapon. A projectile having a fused warhead is loaded in the weapon prior to storing the weapon. If an unplanned stimulus launches the projectile while the weapon is in the storage container, the projectile will impact or strike the disabling device. The disabling device prevents detonation or explosion of the warhead.

Description:
STATEMENT OF GOVERNMENT INTEREST 
     The inventions described herein may be manufactured, used and licensed by or for the United States Government. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates in general to munitions, and in particular to compliance with Insensitive Munitions (IM) standards. 
     IM standards require that, to the extent practicable, munitions are safe when subjected to unplanned stimuli. Shoulder-launched single-use weapons are problematic because the weapon is packaged and stored with the projectile (and warhead) already loaded in the weapon. When exposed to unplanned external stimuli, single-use shoulder-launched munitions may fail IM requirements. For example, an unplanned stimulus may ignite the propellant in the single-use shoulder-launched weapon, thereby launching the projectile and activating the arming sequence of the warhead. If the warhead arms, it may detonate on impact (IM Type I detonation reaction). An IM Type V burning reaction is required to pass most IM requirements, but can be very difficult to achieve. Thus, an improvement from a Type I detonation to a Type IV deflagration reaction is desirable if it may be easily achieved. 
     Known munition cans or containers have several forms, including boxes and tubes. Some of these cans have IM features that: 1) provide for the venting of gases; 2) provide ballistic protection; or 3) provide insulation to delay the reaction time so other IM features may be utilized. Ballistic protection against fragment impact is often costly in terms of both packaging cost and logistical cost (weight, volume). Venting and insulation alone are often not sufficient, and additional IM features must be built into the weapon. The additional IM features may not be feasible due to cost and technical difficulty. While there are known methods to contain exploding ammunition, none of the known methods can contain a projectile with an exploding warhead after it is launched from a weapon. 
     A need exists for an apparatus and method for achieving at least a Type IV deflagration reaction when a projectile is launched from a weapon by unplanned stimuli. The solution must be relatively low in cost and have minimal logistical impact. 
     SUMMARY OF INVENTION 
     One aspect of the invention is an apparatus including a single-use weapon having a barrel, a muzzle, and a projectile with a fused warhead loaded in the weapon. The barrel defines a bore with a central longitudinal axis and a bore cross-sectional area. The apparatus includes a storage container of a size for storing no more than one of the single-use weapon. The storage container has a central longitudinal axis. The single-use weapon is disposed in the storage container with the central longitudinal axis of the bore of the weapon generally parallel to the central longitudinal axis of the storage container. 
     The storage container includes first and second closed ends joined by a closed body. A projectile disabling device is disposed inside the storage container proximate the first closed end and proximate the muzzle of the weapon such that the projectile strikes the disabling device when the projectile is launched from the weapon. 
     In one embodiment, the disabling device is a metal plate having a planar surface that is angled with respect to the central longitudinal axis of the bore and that faces the muzzle. In another embodiment, the disabling device is a curved pipe with a bore. The disabling device may also be a metal plate positioned parallel to the bore axis of the weapon such that the metal plate intersects a projection of the bore cross-sectional area along the bore axis. In a further embodiment, the disabling device is a metal spike positioned generally parallel to the bore axis and transversely offset from the bore axis. 
     The disabling device may be a pivoting frame. The pivoting frame includes a pair of parallel sides spaced apart a width greater than a width of the projectile, a striking panel that connects the pair of sides at one end of the pivoting frame, and a rear panel that connects the pair of sides at the other end of the pivoting frame. 
     Another aspect of the invention is a method of disabling a projectile launched from a single-use weapon. The projectile includes a fused warhead. The method includes launching the projectile from the single-use weapon while the single-use weapon is in a storage container. Then, the fused warhead is disabled using a disabling device disposed in the storage container proximate a muzzle of the single-use weapon. Disabling the warhead may produce a Type IV Insensitive Munitions reaction. 
     The invention will be better understood, and further objects, features and advantages of the invention will become more apparent from the following description, taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, which are not necessarily to scale, like or corresponding parts are denoted by like or corresponding reference numerals. 
         FIG. 1  is a schematic drawing of one embodiment of a shoulder-launched single-use weapon. 
         FIG. 2  is a schematic drawing of the muzzle end of the weapon of  FIG. 1 . 
         FIG. 3  is a schematic cutaway drawing of one embodiment of a projectile for use in the weapon of  FIG. 1 . 
         FIG. 4  is a schematic cutaway drawing of a storage container for a shoulder-launched single-use weapon. 
         FIG. 5  is a schematic top view of one embodiment of a storage container having a disabling device in the form of a plate. The top portion of the container is cutaway. 
         FIG. 6  is a schematic perspective view of the plate of  FIG. 5  showing the projection of the bore cross-sectional area onto the plate. 
         FIG. 7  is a schematic top view showing deflection of a projectile as it strikes a disabling plate. 
         FIG. 8  is a cutaway top view of a curved metal pipe or tube. 
         FIG. 9  is a schematic top view showing deflection of a projectile as it strikes a curved metal pipe. 
         FIG. 10  is a schematic top view of another embodiment of a storage container having a disabling device in the form of a plate. The top portion of the container is cutaway. 
         FIG. 11  is a schematic top view showing penetration of a projectile by the plate of  FIG. 10 . 
         FIG. 12  is a schematic top view showing penetration of a projectile by a metal spike. 
         FIG. 13  is a schematic top view of another embodiment of a storage container having a disabling device in the form of a pivoting frame. 
         FIG. 14  is a side view of one embodiment of a pivoting frame. 
         FIG. 15  is a bottom perspective view of the pivoting frame of  FIG. 14 . 
         FIG. 16  is a schematic side view showing the impact of a projectile with the pivoting frame of  FIG. 14 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a schematic view of one embodiment of a shoulder-launched single-use weapon  10  having a barrel or tube  12  with a muzzle end  14 . Weapon  10  may be, for example, the U.S. Army M136 AT4 recoilless rifle. As seen in  FIG. 2 , barrel  12  has a bore  18  having a diameter or caliber D and a central longitudinal axis A.  FIG. 3  is a schematic cutaway drawing of one embodiment of a projectile  18  that is loaded in tube  12  and launched by weapon  10 . 
     Projectile  18  includes a warhead  20  containing an explosive composition  22 . A fuze  24  is used to ignite or detonate explosive composition  22 . Explosive composition  22  may fill only a portion of the interior of projectile  18  or substantially all of the interior of projectile  18 . Warhead  20  may be, for example, in the form of a shaped charge with a liner  26  and a void or empty space  28  forward of liner  26 . Fuse  24  may be located behind explosive composition  22 . In some embodiments of projectile  18 , fuse  24  may be located at the nose  30  of projectile  18  or at some other location. Projectile  18  may include a fin assembly  32  enclosed in a rear portion  31  of the external casing of projectile  18 . Fuse  24  will not arm warhead  20  until sufficient time has elapsed for projectile  18  to travel a safe distance from weapon  10  and the weapon user. Prior to arming warhead  20 , it is possible to disable warhead  20  and/or fuse  24 . 
     Weapon  10  is stored in a storage container  34 , shown schematically in  FIG. 4 . Projectile  18  with warhead  20  is loaded in weapon  10  prior to storage in container  34 . Container  34  stores only a single weapon  10  and is sized for only a single weapon  10 . Container  34  has a central longitudinal axis B. Weapon  10  is disposed in container  34  with bore axis A of weapon  10  generally parallel to axis B of container  34 . Storage container  34  includes first and second closed ends  36 ,  38  joined by a closed body  39 . Container  34  may be made of, for example, metal or wood. If wood is used, metal framing for container  34  may be required. The metal frame may be required to enable container  34  to maintain enough structural integrity during the fast cook-off test. Container  34  with loaded weapon  10  disposed therein is stored in a horizontal position, that is, bore axis A and container axis B are horizontal in the stored position. Multiple containers  34  with respective loaded weapons  10  therein may be stacked or palletized with axes A and B horizontal. 
     If an unplanned stimulus ignites the propellant (not shown in the Figures) in weapon  10 , projectile  18  may be launched from weapon  10 , even though weapon  10  is stored in container  34 . The kinetic energy of the launched projectile  18  may be used to disable warhead  20  and/or fuse  24 . A disabling device  40  may be stored in container  34  in front of muzzle  14  of weapon  10 . When an unplanned launch of projectile  18  occurs, projectile  18  will impact or strike disabling device  40  in container  34 . Disabling device  40  may be embodied in several forms. 
     Disabling device  40  may be a mass that damages projectile  18  or any of its components, for example, fuse  24  and/or warhead  20 . The mass may simply cause damage by impact with projectile  18  thereby damaging fuse  24  and/or warhead  20 . The mass may deflect or bend projectile  18  thereby deflecting, bending, shearing, or otherwise damaging fuze  24  or warhead  20 . The mass may cut apart projectile  18  thereby damaging fuse  24  or warhead  20 . The mass may puncture projectile  18 , thereby damaging fuse  24  and/or warhead  20 . The disabling device  40  may, in addition to other methods, use the force of impact to move, pivot or bend projectile  18  in a manner to damage fuse  24  located behind warhead  20 , or to damage warhead  20 , or to damage another fuse located behind a precursor warhead. 
       FIG. 5  is a schematic top view of one embodiment of storage container  34  for shoulder-launched single-use weapon  10 . The top portion of container  34  is cutaway. In  FIG. 5 , the disabling device is a metal plate  42  disposed inside container  34  proximate first closed end  36  and proximate muzzle  14  of weapon  10 .  FIG. 6  is a perspective view of plate  42 . Plate  42  is placed such that projectile  18  will strike plate  42  when projectile  18  is launched from weapon  10 . 
     Plate  42  may be made of metal, for example, low carbon steel. Plate  42  includes a planar surface  44  that forms an angle C ( FIG. 5 ) with respect to axis A of bore  16  and that faces muzzle  14 . Angle C may be, for example, in the range of 15 to 75 degrees, and, preferably, in the range of 40 to 50 degrees. Plate  42  may have a thickness E ( FIG. 6 ) in the range of about ⅛ inch to about 1.5 inches. The area of planar surface  44  is at least as large as the area H of the projection of the cross-sectional area of bore  16  ( FIG. 2 ) onto a plane parallel to planar surface  44 . 
     As shown in  FIG. 5 , which is a view from above container  34 , container  34  and weapon  10  are horizontal and plate  42  is preferably vertical. The preferred storage position is with container  34  and weapon  10  horizontal and with plate  42  vertical. In this position, components of deflected projectile  18  will travel in the general direction of arrow F and the deflected plate  42  will travel in the general direction of arrow G. Lateral deflection of projectile  18  and plate  42  is preferred rather than upward deflection of either projectile  18  or plate  42 . 
     Plate  42  must be positioned in container  34  securely enough to prevent movement of plate  42  during routine shipping and handling of container  34 . Of course, plate  42  will move after impact with projectile  18 . Various methods may be used to position plate  42  in container  34 . In one method, foam inserts may be disposed around plate  42  to maintain its position. If container  34  or a portion of container  34  is made of metal, another method of preventing unwanted movement of plate  42  is spot welding plate  42  at a few points to container  34  or its metal frame. There are numerous other methods to secure plate  42  in container  34  to prevent movement during routine shipping and handling. 
     Computer modeling and simulation tests were performed for a high energy projectile  18  fired from an M136 AT4 recoilless rifle and striking a one-half inch metal plate  42  at forty-five degrees. The simulation showed that the yield strength in the fuse and booster regions of projectile  18  was exceeded. 
     Actual tests were performed with a high energy projectile  18  striking low carbon steel plates with widths of ⅛, ¼, ⅜, ½, and one inch, respectively. When using either the one inch thick plate or the ½ inch thick plate: 1) fuse  24  separated from warhead  20 ; 2) the nose cone and half of shaped charge liner  26  shattered into 1 centimeter fragments; 3) shaped charge liner  26  was flattened; 4) explosive charge  22  pulverized into dust; and 5) fuse  24  did not arm. When using steel plates with ⅛, ¼, and ⅜ inch thicknesses, all plates successfully removed fuse  24  from warhead  20 . The ¼ and ⅜ inch thick plates also opened the warhead  20 . Damage to projectile  18  far exceeded expectations. The thickness of plate  42  needed to successfully de-arm projectile  18  was unexpectedly small. 
       FIG. 7  is a schematic top view showing deflection of projectile  18  as it strikes planar surface  44  of plate  42 . The fuse  24  has broken away from warhead  20 . 
       FIG. 8  is a schematic cutaway top view of a curved metal pipe or tube  46  having a bore  48  and a wall  50  with an interior surface  52 . Curved pipe  46  may be placed in container  34  in lieu of plate  42  such that projectile  18  strikes interior surface  52  of curved pipe  46  in a manner similar to that in which projectile  18  strikes plate  42 . Curved pipe  46  may be secured in container  34  against movement during routine shipping and handling in a manner similar to plate  42 .  FIG. 9  is a schematic top view showing deflection of projectile  18  as it strikes interior surface  52  of curved metal pipe  46 . The fuse  24  has broken away from warhead  20 . Curved pipe  46  may be especially useful if projectile  18  has dual or tandem warheads. Both warheads will strike or be disabled by curved pipe  46 . 
       FIG. 10  is a schematic top view of another embodiment of a storage container  34  having a disabling device in the form of an axially-situated metal plate  54 . The top portion of container  34  is cutaway. Metal plate  54  is positioned parallel to bore axis A such that metal plate  54  intersects a projection of the bore cross-sectional area along the bore axis A. As shown in  FIG. 10 , metal plate  54  is preferably offset transversely from bore axis A.  FIG. 11  is a schematic top view showing penetration of projectile  18  by plate  54 .  FIG. 12  is a schematic top view showing penetration of projectile  18  by a metal spike  58 . Spike  58  is positioned generally parallel to axis A and transversely offset from axis A. 
       FIG. 13  is a schematic top view of another embodiment of a storage container  34  having a disabling device in the form of a pivoting frame  60 .  FIG. 14  is a side view of pivoting frame  60  and  FIG. 15  is a bottom perspective view of pivoting frame  60 . Frame  60  may be made of metal, for example, steel. Frame  60  may include a pair of parallel sides  62 ,  64 . Sides  62 ,  64  are spaced apart a width J ( FIG. 13 ) that is greater than a width K ( FIG. 3 ) of projectile  18 . A striking panel  66  connects the pair of sides  62 ,  64  at one end of pivoting frame  60 . A rear panel  68  connects the pair of sides  62 ,  64  at the other end of pivoting frame  60 . In the embodiment shown in the Figures, rear panel  68  has the form of a wedge with the thickest portion  70  ( FIG. 13 ) at the top of frame  60 . A wedge shape may help rear panel  68  penetrate projectile  18 . 
     In the storage position of container  34  shown in  FIG. 13 , axis A of bore  16  and axis B of container  34  are horizontal and the pair of parallel sides  62 ,  64  of pivoting frame  60  are in vertical planes. In this position, the center of gravity L ( FIG. 14 ) of pivoting frame  60  is vertically above bore axis A. Pivoting frame  60  may be secured in container  34  against movement during routine shipping and handling in a manner similar to plate  42 . 
       FIG. 16  is a schematic side view showing projectile  18  impacting panel  66  of frame  60 . The force of impact of projectile  18  on striking panel  66  causes frame  60  to rotate clockwise such that rear panel  68  plunges into projectile  18 . Pivoting frame  60  may be especially useful if projectile  18  has dual or tandem warheads. Both warheads will strike or be disabled by pivoting frame  60 . 
     While the invention has been described with reference to certain embodiments, numerous changes, alterations and modifications to the described embodiments are possible without departing from the spirit and scope of the invention as defined in the appended claims, and equivalents thereof.