Abstract:
A method and apparatus for trapping projectiles so that the projectiles are not damaged is disclosed. An elongated trough is typically filled with alternating layers of a foam substance and a fibrous substance. Alternatively, the trough can be filled with just a foam or fibrous substance. A projectile launcher such as a gun is connected to the trough and a projectile is shot into the filling substance substantially parallel a longitudinal axis of the trough. The trough can be opened and the projectile can be recovered from the filling substance.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    I. Field of the Invention.  
           [0002]    The present invention relates generally to the field of ballistics, and more particularly to a method and apparatus for trapping bullets for ballistics testing. II. Description of the Related Art.  
           [0003]    In many areas of law enforcement, ballistics and forensics, it is often necessary to use projectile research apparatuses such as tanks of water and tanks of ballistics gelatin into which projectiles are fired for research. The goal is to recover the projectile in as near perfect condition to carry out the studies. However, often times the projectile is damaged from the testing itself rendering the tests with inaccuracies. One problem is that the testing medium, for example, the water or the ballistics gelatin, is nearly incompressible. Therefore, when the projectile is shot into the medium, although the medium provides a path for the projectile, the projectile can be damaged from the medium due to the incompressibility. Therefore, markings left on the projectile from the barrel of the gun from which the projectile was shot are also deformed, making it difficult to analyze the projectile.  
         SUMMARY OF THE INVENTION  
         [0004]    In accordance with the present invention and the contemplated problems which have and continue to exist in this field, the invention features a method and apparatus for recovering a projectile with minimal damage to the projectile.  
           [0005]    In general, in one aspect, the invention features a projectile recovery apparatus including an elongated trough having a first end, a second end, a longitudinal axis and a substantially hollow interior and a filling material positioned in the entire interior of the trough and oriented about the longitudinal axis, wherein one of the first and second ends is open, exposing the interior filled with the material, and the other end is closed.  
           [0006]    In an implementation, the apparatus of claim  1  includes a gun mount connected to the trough at the open end.  
           [0007]    In another implementation, the closed end can be removed to expose the interior of the trough.  
           [0008]    In another implementation the filling material is a foam substance such as polyurethane or a fibrous material such as cotton.  
           [0009]    In another implementation, the apparatus includes a series of openable hatches that can expose the filling material at various locations along the longitudinal axis.  
           [0010]    In another aspect, the invention features a projectile recovery apparatus, including an elongated trough having a first end, a second end, a longitudinal axis and a substantially hollow interior, at least one fibrous layer and at least one foam layer, wherein the fibrous layer and the foam layer are configured along the longitudinal axis, and filling the interior, wherein one of the first and second ends in open, exposing the interior.  
           [0011]    In an implementation, the apparatus also includes a gun mount connected to the trough at the open end.  
           [0012]    In another implementation, the closed can be removed to expose the interior of the trough.  
           [0013]    In another implementation, the apparatus includes a series of openable hatches that can expose the filling material at various locations along the longitudinal axis.  
           [0014]    In another implementation, the apparatus includes at least one additional foam layer and at least one additional fibrous layer, wherein the foam layers and fibrous layers are alternately configured along the longitudinal axis.  
           [0015]    In another implementation, the foam layers and the fibrous layers are substantially perpendicular to the longitudinal axis and substantially parallel with respect to each other.  
           [0016]    In still another implementation, the foam layers and the fibrous layers are angled with respect to the longitudinal axis and substantially parallel with respect to each other.  
           [0017]    In an implementation, the foam substance is polyurethane and the fibrous substance is cotton.  
           [0018]    In another aspect, the invention features a method of recovering a projectile, including providing a projectile recovery system, having an elongated trough having a first end, a second end, a longitudinal axis and a substantially hollow interior, and a filling material positioned in the entire interior of the trough and oriented about the longitudinal axis, wherein one of the first and second ends is open, exposing the interior filled with the material, and the other end is closed, shooting a projectile into the projectile recovery system substantially parallel to the longitudinal axis, wherein the projectile is aimed at the filling material searching through the filling material of the projectile recovery system for the projectile and recovering the projectile from the projectile recovery system.  
           [0019]    In an implementation, the filling material is a foam substance, a fibrous substance or alternating layers of fibrous material and foam material.  
           [0020]    One advantage of the apparatus is that a projectile to be studied can be shot into the projectile-capturing medium of the system and can be recovered with minimal to no damage to the projectile for ballistics and forensics research.  
           [0021]    Another advantage is that the projectile-capturing medium minimally interferes with the projectile itself.  
           [0022]    Another advantage is that as a result of the non-interference of the projectile capturing medium, the projectile includes markings representative of being shot from a unique barrel.  
           [0023]    Other objects, advantages and capabilities of the invention will become apparent from the following description taken in conjunction with the accompanying drawings showing the preferred embodiment of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    [0024]FIG. 1 illustrates a perspective view of an embodiment of a projectile recovery apparatus;  
         [0025]    [0025]FIG. 2 illustrates a top view of an embodiment of a projectile recovery apparatus;  
         [0026]    [0026]FIG. 3 illustrates a side view of an embodiment of a projectile recovery apparatus;  
         [0027]    FIGS.  4 A- 4 F illustrate a view of a projectile as it passes through an embodiment of a projectile recovery apparatus; and  
         [0028]    [0028]FIG. 5 illustrates a flow chart of an implementation of a method  500  of projectile recovery. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]    Referring to the drawings wherein like reference numerals designate corresponding parts throughout the several figures, reference is made first to a projectile recovery apparatus wherein FIG. 1 illustrates a perspective view of an embodiment of a projectile recovery apparatus  100  having a gun  105  connected to the apparatus  100 . The apparatus  100  typically includes an elongated trough  110 . The cross section of the trough can be any variety of shapes. FIG. 1 illustrates the trough  110  having a square cross section. The trough can be any length. Typically, as described in more detail below, it is useful to have the length of the trough be on the order of eight feet. It is understood that any other length can be used. Furthermore, the ends of the trough  110  can be adapted to receive the ends of additional troughs so that a longer overall projectile recovery apparatus can be created by attaching additional troughs.  
         [0030]    The trough  110  includes a series of hatches  115  to expose the interior of the trough  110 . The hatches  115  are connected to the trough by a mechanism such as a hinge  120 . The hatches  115  can be securely closed by lock  125 . The hatches generally make up the entire top surface of the trough  110 . The tough has a gun receiving end  116  that typically is open exposing the interior of the trough  110 . The opposite end  117  is typically a closed end. In an embodiment, the closed end can be adapted to be opened so that an additional trough can be attached to the trough  110 .  
         [0031]    The trough  110  is constructed of a sturdy material that can prevent a projectile from exiting a surface of the trough  110 . In an embodiment, the trough is constructed entirely of a metallic substance.  
         [0032]    The trough  110  also includes a gun mount  130 . The gun mount  130  is used to support the gun  105  to provide a predictable trajectory of a bullet by preventing the gun from uncontrollably kicking back. The gun mount  130  can have a variety of forms. As shown in FIG. 1 the gun mount  130  includes two vertical support bars  135  and a vertical adjustment cross bar  140 . The vertical adjustment bar  140  can be set and secured along the vertical support bars  135 . A horizontal adjustment  145  is used to support the barrel of the gun  105  as well as to set and secure the gun horizontally. The horizontal adjustment can also be pivoted about the cross bar  140  providing an angle to the trajectory of the bullet with respect to a longitudinal axis  150  of the trough  110 . In general, the user of the projectile recovery apparatus  100  does not adjust the angle of trajectory as described below with respect to operation of the apparatus  100 .  
         [0033]    The apparatus  100  also includes several alternating layers of fibrous material  155  and foamy material  160 . The alternating layers perform as a projectile-capturing medium. Typically, the first layer in the trough  110  is a fibrous layer  155  followed by the foamy material  160  and so forth. The layers are generally perpendicular to the longitudinal axis  150  of the trough  110 . The fibrous material  155  can be used through the entire length of the trough  110 . The foamy material  160  can also be used throughout the entire length of the trough. However, the alternating layers of the fibrous material  155  and the foamy material  160  have been determined to be an efficient configuration for projectile recovery with minimal to no damage to the projectile.  
         [0034]    During operation of the apparatus  100  a projectile generally travels in a trajectory that is generally parallel to the longitudinal axis  150  of the apparatus  100 , and perpendicular to the layers  155 ,  160 .  
         [0035]    [0035]FIG. 2 illustrates a top view of an embodiment of a projectile recovery apparatus  200 . A gun barrel  205  is shown aimed into the interior of the trough  210 . The hatches  215  are shown in the closed position and securely fastened by lock  225 . Each of the hatches  215  can be opened by having hinges  220 . A broken view on two of the hatches  215  shows the alternating fibrous material  255  and foamy material  260  through which a projectile can travel in a substantially perpendicular trajectory with respect to the layers  255 ,  260 . The trough is shown to be length A.  
         [0036]    [0036]FIG. 3 illustrates a side view of an embodiment of a projectile recovery apparatus  300 . A gun barrel  305  is shown aimed into the interior of the trough  310 . The hatches  315  are shown in the closed position and securely fastened by lock  325 . Each of the hatches  315  can be opened by having hinges  320 . A broken view of the side of the trough  310  shows the alternating layers of fibrous material  355  and foamy material  360  through which a projectile can travel in a substantially perpendicular trajectory with respect to the layers  355 ,  360 .  
         [0037]    As described above, the materials used for the alternating layers in the projectile recovery apparatus have been described as fibrous and foamy. In one embodiment, cotton can be used for the fibrous layer. In various experiments, it has been determined that for the fibrous material, cotton can be used for efficient projectile recovery. The cotton can be in the form of loose fluffed cotton, cotton balls and cotton batting. It has been experimentally determined that using the different types of cotton does not result in any noticeable change in recovered projectiles.  
         [0038]    A variety of other fibrous materials can be used for the fibrous layers so long as the fibrous layer does not interfere with the projectile. Some fibrous materials can stick to the projectile when the projectile is hot. For example, although synthetic cotton can be used in an embodiment, the synthetic cotton doesn&#39;t offer as great resistance as natural cotton, taking too long for the projectile to stop. In addition, the fibers do not tend to gather as well on the projectile (as described below with respect to operation of the apparatus). Finally, the heat from the fired projectile causes the synthetic cotton to fuse to the projectile, making it difficult to remove from the projectile, thereby interfering with ballistics testing.  
         [0039]    In one embodiment, the foamy layers can be expanded polyurethane foam, which is typically a make-up of calcium carbonate and malomine. In various experiments, it has been determined that soft, medium or high density foam can be used for the foamy layers for efficient projectile recovery. It is understood that various other foamy materials can be used for the foamy layers. The expanded polyurethane foam has been experimentally determined to stop the projectile quickly with minimal to no damage to the projectile. The expanded polyurethane foam has the following typical characteristics:  
         [0040]    [0040] Light : Density of 1 lb. per cubic foot with a compression of 20 to 25.  
         [0041]    [0041] Medium : Density of 2 lb. per cubic foot, with a compression of 28 to 33.  
         [0042]    [0042] Heavy : Density of 3 lb. per cubic foot, with a compression of 40 to 45.  
         [0043]    Typically the compression of foam is determined by placing ga 5 inch steel weight of approximately 20 lbs on foam using an arbitrary scale to measure.  
         [0044]    It has been experimentally determined that medium density foam provides the optimum results. Soft foam does not stop the projectile as quickly as desired causing longer stopping distances. Heavy foam tends to cause “pitting” on the projectile as described further below. Other types of foam are also contemplated. Such foamy material may also include rubber or latex foam.  
       Projectile Recovery Method  
       [0045]    The projectile recovery apparatus described above with respect to FIGS.  1 - 3  can be used to fire a projectile into the interior of the trough through the alternating layers. The apparatus can typically be used for ballistics testing, leaving the projectile in a condition with minimal to no damage from the alternating layers. The travel of the projectile through the alternating layers is now described with respect to FIGS.  4 A- 4 F which illustrate a projectile at various points in a projectile recovery apparatus.  
         [0046]    [0046]FIG. 4A illustrates a side view of a projectile recovery apparatus  400  at a point in which a projectile  405  is initially shot into the apparatus  400 . The projectile  405  first enters the fibrous layer I. As the projectile moves through the layer I, the projectile  405  quickly gathers fibers from the layer around the projectile  405 . As the fiber gathers it creates a first fiber covering  410  around the projectile  405 . It has been determined that minimal to no damage is caused to the projectile from the fibrous layer I. By passing through the layer I the projectile also loses some of its kinetic energy, momentum and velocity due to friction from the surrounding layer I and increasing fiber covering  410 .  
         [0047]    [0047]FIG. 4B illustrates a side view of the projectile apparatus of FIG. 4A at a point in which a projectile is traveling through the apparatus. After leaving layer I, the projectile then enters layer II, which is typically a foamy layer. The projectile also travels with the fiber covering  410  as it travels through the foamy layer II. Friction between the fibers covering  410  and the foam layer II removes more kinetic energy momentum and velocity from the projectile  405 . The fiber cover  410  also provides protection for the projectile  405  as it travels through the foamy layer II that is relatively rougher than the fibrous layer I.  
         [0048]    [0048]FIG. 4C illustrates a side view of the projectile apparatus of FIGS. 4A and 4B at a point in which a projectile is traveling through the apparatus  400 . After leaving layer II the projectile then enters layer II that is typically a fibrous layer. The projectile still includes the fiber covering  410 . As the projectile  405  travels through the layer III along with the cover 410 , the cover 410  begins to become covered with another fiber layer  415 . The friction of the cover  410  with the surrounding layer and the increasing cover  415  further decreases the kinetic energy, momentum and velocity of the projectile  405 .  
         [0049]    [0049]FIG. 4D illustrates a side view of the projectile apparatus of FIGS.  4 A- 4 C at a point in which a projectile is traveling through the apparatus  400 . After leaving layer III, the projectile then enters layer IV, which is typically a foamy layer. The projectile  405  also travels with the fiber coverings  410 ,  415  as it travels through the foamy layer IV. Friction between the fiber covering  415  and the foam layer IV removes more kinetic energy momentum and velocity from the projectile  405 . The covers  410 ,  415  also provide protection for the projectile  405  from the rough foam layer IV.  
         [0050]    [0050]FIG. 4E illustrates a side view of the projectile apparatus of FIGS. 4A and 4D at a point in which a projectile is traveling through the apparatus  400 . After leaving layer IV the projectile then enters layer V that is typically a fibrous layer. The projectile still includes the fiber covers  410 ,  415 . As the projectile  405  travels through the layer V along with the covers  410 ,  415 , the cover  415  begins to become covered with another fiber layer  420 . The friction of the cover  415  with the surrounding layer V and the increasing cover  420  further decreases the kinetic energy, momentum and velocity of the projectile  405 .  
         [0051]    [0051]FIG. 4F illustrates a side view of the projectile apparatus of FIGS.  4 A- 4 E at a point in which a projectile is traveling through the apparatus  400 . After leaving layer V, the projectile then enters layer VI, which is typically a foamy layer. The projectile  405  also travels with the fiber coverings  410 ,  415 ,  420  as it travels through the foamy layer VI. Friction between the fiber covering  420  and the foam layer VI removes more kinetic energy momentum and velocity from the projectile  405 . The covers  410 ,  415 ,  420  also provide protection for the projectile  405  from the rough foam layer VI. In an implementation, depending on the muzzle velocity of the projectile, the projectile  405  finally loses all of its velocity and ceases moving in layer VI. When the projectile  405  comes to a stop, the fiber covers  410 ,  415 ,  420  typically leave a tail portion as shown in layers IV, V.  
         [0052]    [0052]FIG. 5 illustrates a flow chart of an implementation of a method  500  of projectile recovery using the apparatus described above. The user of the apparatus chooses a gun to be tested. The gun is mounted on the apparatus on the gun mount described above. The projectile is then fired  505  into the recovery apparatus. This process of firing a projectile apparatus can be repeated as many times as desired. Typically, the user repositions the gun so that the subsequent projectile does not travel the same trajectory as the previous projectile. It is desirable not to fire too many projectiles into the apparatus without changing the layers. Too many projectiles fired into the layers typically causes the foam to weaken which results in greater stopping distances. New foam offers more resistance to the projectile and fiber covers resulting in substantially short stopping times and shorter stopping distances.  
         [0053]    Once the desired number of projectiles are fired into the apparatus, the user opens  510  the hinges of the apparatus to search for the projectile. Typically, the user searches  515  the alternating layers and separates the layers to search for the fiber trail caused by the accumulation of fiber covers as discussed above. The user typically discovers an accumulated ball of fiber. The user recovers  520  the fiber covers containing the projectile. The user then removes  525  the projectile from the fibers layers for subsequent testing.  
         [0054]    The user can then optionally realign  530  the layers to prepare the apparatus to receive subsequent projectiles. The user may have to replace the foam and cotton as described above.  
         [0055]    When the projectile is recovered it is typically in virtually the same condition as it was before it was fired. The following tables illustrate empirical data on several different types of projectiles fired into the apparatus and the corresponding layer characteristics:  
                           TABLE 1                       Cotton/Foam                   Layering   Caliber   Stopping Distance   Projectile Condition                    1″ 1″   7.62 × 39   11′ 5″   Perfect        1″ 1″   45 ACP    2′ 8″   Perfect        2″ 2″   7.62 × 39   12′ 0″   Some Burning        2″ 2″   45 ACP    3′ 6″   Perfect        3″ 3″   7.62 × 39   13′ 3″   Some Burning        3″ 3″   45 ACP    3′ 9″   Perfect        4″ 4″   7.62 × 39   11′ 11″   Perfect        4″ 4″   45 ACP    4′ 6″   Perfect        4″ 4″   40    4′ 6″   Perfect        5″ 5″   7.62 × 39   10′ 6″   Perfect        5″ 5″   45 ACP    2′ 10″   Perfect        6″ 6″   7.62 × 39   11′ 0″   Perfect        6″ 6″   45 ACP    3′ 3″   Perfect        7″ 7″   7.62 × 39   10′ 10″   Perfect        7″ 7″   45 ACP    3′ 0″   Perfect        8″ 8″   7.62 × 39   10′ 9″   Perfect        8″ 8″   45 ACP    2′ 10″   Perfect        8″ 8″   40    4′ 0″   Perfect        9″ 9″   7.62 × 39   12′ 6″   Perfect        9″ 9″   45 ACP    4′ 0″   Perfect       10″ 10″   7.62 × 39   12′ 5″   Some Burning       10″ 10″   45 ACP    2′ 2″   Perfect       11″ 11″   7.62 × 39   10′ 5″   Some Burning       11″ 11″   45 ACP    2′ 2″   Perfect       12″ 12″   7.62 × 39   10′ 5″   Some Burning       12″ 12″   45 ACP    3′ 5″   Perfect       12″ 12″   40    3′ 9″   Perfect                  
 
         [0056]    [0056]                               TABLE 2                               Muzzle                       Velocity   Muzzle Energy   Stopping       Caliber   Weight   (FPS)   (Foot Pounds)   Distance                   22 Cal REM HP    36 Grains   1410    165    3′ 10″       7 mm REM MAG   150 Grains    310   3221   17′ 7″       223 SS109    62 Grains   3025   1260   11′ 10″       (AP)       40 S&amp;W   180 Grains   1150    499    4′ 6″       30 −30 WIN   150 Grains   2390   1900   10′ 4″       45 CAL HYDRA   230 Grains    850    370    4′ 0″       SHOCK       38 Special   158 Grains    760    200    3′ 7″       12 Gauge Slug    1 Ounce   1525   2260    7′ 0″       8 mm (AP)   154 Grains   2880   2837   13′ 7″       7.62 × 39   123 Grains   2365   1552   11′ 11″       9 mm Starfire   124 Grains   1175    364    3′ 4″                    
         [0057]    The data in Table 2 are results from tests in the projectile recovery apparatus using alternating layers of cotton fiber of  4 ″ and medium density foam layers of  4 ″.  
         [0058]    A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Several examples are now illustrated.  
         [0059]    As mentioned above all foam or all fiber layers can be used in the apparatus. In this embodiment, the bullet tends to be more difficult to locate. Using all foam does stop the projectile quickly but tends to cause pitting on the projectile. Using all fiber layers also stops the projectile quicker but does not always leave powder residue. In addition the projectile is difficult to find in all fiber layers. Finally the nose of the projectile tends to deform with all fiber layers.  
         [0060]    The following data are results for various tests of projectiles using all fiber or all foam layers:  
                           TABLE 3                       Caliber   Material   Stopping Distance   Projectile Condition                   7.62 × 39   All Foam   15′ 7″   Poor (Pitted)           All Fiber    7′ 8″   Poor (Burnt)       45 ACP Cast Lead   All Foam    1′ 6″   Good           All Fiber    1′ 10″   Good       45 ACP 230 gr HP   All Foam    7′ 2″   Fair                   (Nose Deformed)           All Fiber    2′ 2″   Good       7 mm REM MAG.   All Foam   20′ 0″   Good           All Fiber   13′ 7″   Fair       8 mm   All Foam   17′ 4″   Good           All Fiber   10′ 8″   Good       40 S &amp; W   All Foam   11′ 5″   Fair (Slight Pitting)           All Fiber    1′ 11″   Good                  
 
         [0061]    The embodiments described above have typically included projectiles in the of bullets. In another embodiment, the projectile recovery apparatus can be to test arrows BBs and other types of projectiles. It is understood that there limit to the types of projectiles that can be used in the apparatus.  
         [0062]    Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, various modifications may be made of the invention without departing from the scope thereof and it is desired, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and which are set forth in the appended claims.