Abstract:
A self-propelled and constant-acceleration rocket for use in triggering an avalanche includes a hollow cylindrical body member having an interior volume, an open top end, and an open bottom end whose exterior surface includes a plurality of flight guidance fins. A partition wall divides the interior volume into an upper volume and a lower volume. An explosive payload is mounted within the upper volume, and a nose cone having a circular and planar tip closes the open top end of the body member. A rocket motor is mounted within the lower volume. The rocket has a center of gravity and a center of pressure that are both located on the rocket&#39;s central axis and within the lower volume. The center of gravity is located closer to the open top end than is the center of pressure. A collapsible launch stand holds the rocket in a launch tube for launching of the rocket. Adjustment of a pair of launch tube support members provides for adjustment of the rocket&#39;s launch angle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of co-pending U.S. Provisional Patent Application Ser. No. 60/214,869, filed Jun. 28, 2000 and entitled SELF-PROPELLED AVALANCHE/MUDSLIDE CONTROL APPARATUS. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to the control of snow avalanches and mudslides. More specifically, this invention provides a self-propelled rocket and a collapsible launch stand that can be easily transported to a desired location in order to produce snow avalanches or mudslides in a controlled manner.  
           [0004]    2. Description of the Related Art  
           [0005]    As used herein, the term avalanche is intended to mean a large mass of snow, ice, earth, mud, rock, or the like, that swiftly moves down an incline such as a mountain side or over a precipice.  
           [0006]    In attempting to prevent dangerous avalanches, explosive devices are conventionally propelled into a mountainside in order to controllably initiate or trigger an avalanche, thus reducing the risk of a naturally occurring, dangerous and uncontrolled avalanche.  
           [0007]    Conventionally, a variety of mechanisms have been used to attempt to trigger an avalanche in a controlled manner. For example, hand charges are lit and then manually thrown into the desired hillside. This method can subject personnel to risks of injury.  
           [0008]    U.S. Pat. No. 5,872,326 discloses an apparatus for triggering an avalanche or the like. In the device of this patent, an explosive charge is made up of an explosive, a detonator, and a lighting mechanism for triggering the detonator. The explosive charge is placed in a tube with a propelling charge. A pulling element operates to trigger the lighting mechanism after the explosive charge has been propelled out of the tube.  
           [0009]    Guns can be used to trigger an avalanche, an example of which is an avalanche launch gun, such as the “Avalauncher.” The Avalauncher operates like a gun in that a charge is shot into the air by way of an initial force, whereupon the charge travels a distance which is, at least in part, a function of the initial force that is applied to the charge.  
           [0010]    What is needed is a self-propelled rocket, a collapsible launch stand, and method for triggering an avalanche wherein the rocket is self-propelled at a substantially constant acceleration to travel in a substantially line of sight path to a point of impact. It is against this background that various embodiments of the present invention were developed.  
         SUMMARY OF THE INVENTION  
         [0011]    This invention provides a self-propelled rocket and collapsible launch stand that are easily transported by way of a snowmobile, backpack, or the like to a site whereat naturally occurring avalanches are known to occur. Upon setting up of the launch stand at an appropriate angle and the placement of a launch tube thereon, the self-propelled rocket is placed into the launch tube, a rocket motor within the rocket is ignited, and the rocket proceeds to a somewhat distant hillside to then explode and induce an avalanche thereon in a controlled manner.  
           [0012]    As a feature of the invention, a second or redundant rocket motor may be provided such that, after a time delay that is indicative of failure of the first rocket motor to ignite, the second rocket motor ignites whereupon the rocket proceeds to a somewhat distant hillside to then explode and induce an avalanche in a controlled manner.  
           [0013]    The self-propelled rocket moves at a constant acceleration rocket. The rocket includes a hollow cylindrical body member having an interior volume, an open top end, and an open bottom end whose exterior surface includes a plurality of flight guidance fins.  
           [0014]    The inner volume of the hollow cylindrical body provides an upper volume and a lower volume. As a feature of the invention, a partition wall is provided to divide this interior volume into an upper volume and a lower volume.  
           [0015]    An explosive payload is mounted within the upper volume, and a nose cone having a circular and planar tip closes the open top end of the body member. A rocket motor is mounted within the lower volume. The rocket has a center of gravity and a center of pressure that are both located on the rocket central axis and within the lower volume. The center of gravity is located closer to the open top end than is the center of pressure.  
           [0016]    A collapsible launch stand holds the rocket in the launch tube for launching of the rocket. Adjustment of a pair of launch tube support members provides for adjustment of the rocket launch angle.  
           [0017]    The rocket center of gravity is located closer to the cone end of the rocket than is the rocket center of pressure, and the tip of the cone is a flat plane that extends generally perpendicular to the rocket central axis; i.e., generally perpendicular to the rocket direction of flight. With these characteristics, and as a result of the rocket fins and the rocket velocity at the time that motor burnout occurs, it is ensured that upon rocket motor burn out occurring, the rocket drops in a declining trajectory downward and into the hillside.  
           [0018]    These and other features and advantages of the invention will be apparent to those of skill in the art upon reference to the following detailed description which description makes reference to the drawing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0019]    [0019]FIG. 1 is a side view of a self-propelled rocket in accordance with the invention, the rocket internally having an explosive payload that is adapted to detonate upon impact with a slope having a propensity to naturally generate an avalanche.  
         [0020]    [0020]FIG. 2 is a side view of a manually-lightable igniter, or fuse, that operates to ignite a rocket motor that is within the FIG. 1 rocket.  
         [0021]    [0021]FIG. 3 is a side view of a mobile launch stand for use in positioning the FIG. 1 rocket prior to launch of the rocker, the launch stand being shown in its collapsed position.  
         [0022]    [0022]FIG. 4 is a top view of the FIG. 3 collapsed launch stand.  
         [0023]    [0023]FIG. 5 illustrates the FIG. 1 rocket within a launch tube that is positioned on the FIG. 3 launch stand, the launch stand now being in its opened or upright position, and the launch tube loosely resting against a pair of vertically extending support members that are a portion of the launch stand. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    The following embodiments and examples of the present invention are illustrative of the invention, and are not restrictive of the spirit and scope of the invention. Modifications that come within the meaning and range of present and after developed equivalence are to be included within the spirit and scope of the invention. While the invention will be shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention.  
         [0025]    Referring to FIG. 1, rocket  10  in accordance with the present invention includes a nose cone  11 , a body tube  12  that is adapted to internally hold an explosive payload  13 , a rocket motor  14 , and a plurality of external flight guidance fins  15  that are mounted on body tube  12  at the opposite end from nose cone  11 .  
         [0026]    The rocket nose cone  11  is positioned at the top end  16  of rocket  10 , while rocket motor  14  is positioned generally at the bottom end  17  of rocket  10 . As will be explained below, explosive payload  13  is positioned toward the top end  16  of rocket  10 . When rocket  10  hits snow/mud/ground, explosive payload  13  detonates to start an avalanche in a controlled manner.  
         [0027]    As shown in FIG. 1, nose cone  11  is generally conically-shaped and extends from an interface end  18  that is adapted to connect to body tube  12  to a top end  19  that comprises a generally flat plane that extends perpendicular the central axis  20  of rocket  10 .  
         [0028]    The flat top end  19  of nose cone  11  is provided so that when rocket  10  physically contacts or engages the snow, mud or the ground, nose cone  11  provides a larger contact area  19  against the snow/mud/ground when compared to a non-flat top cone end, such as a conventional pointed end that terminates at a sharp tip. In one example, nose cone  11  of the present invention was about 2.75-inches long (see dimension  24 ), had a 1.5-inch diameter area at its flat top end  19 , and was formed from molded plastic.  
         [0029]    The top end  21  of the rocket body tube  12  is mechanically coupled to the interface end  18  of nose cone  11 . Body tube  12  provides a two-part internal volume, or area  22 , for the storage of explosive payload  13 , provides a bottom end external and cylindrical surface region  23  for the attachment of a plurality of flight guidance fins  15 , and provides a lower internal volume or area  25  for housing rocket motor  14 .  
         [0030]    Body tube  12  has a top end  21  and a bottom end  23 , and in one example, body tube  12  was a generally circular cylinder having a centrally-located axis  20 , and having a hollow interior  22  that extended therethrough. In one example, body tube  12  was 14-inches in axial length, and was made of fiber wound plastic, or like material. The bottom end  23  of body tube  12  further includes has a plurality of slots (not shown) that are adapted to receive rocket guidance fins  15  (for example, four slots for four fins  15 ). These slots extend parallel to axis  20  and are cut into the bottom end  23  of body tube  12 , each slot being, for example, {fraction (1/16)} of an inch in width. These slots can be equally spaced about the periphery of the body tube, for example at 90-degree intervals.  
         [0031]    Furthermore, body tube  12  is adapted to house rocket motor  14  at its bottom end  23  and within lower volume  25 . In one example, body tube  12  had an outer diameter of 2.2-inches and an inner diameter of 2.1-inches, thus providing a wall thickness of 0.1-inch.  
         [0032]    In one example, rocket motor  14  was positioned and held within the interior  22  of body tube  12  through the use of O-rings or like structures (not shown), which non-movably secure rocket motor  14  within body tube  12 .  
         [0033]    Further, fins  15  (in one example comprising four fins made of molded plastic) are secured within the slots formed within body tube  12  through the use of an adhesive substance such as glue, or rivets or other securement means.  
         [0034]    In order to position explosive payload  13  within body tube  12 , a rigid partition or bulkhead  30  may be positioned within the interior  22  of body tube  12  at a desired location along axis  20 . Bulkhead  30  divides volume  22  into a lower volume  25  and an upper volume  26 . Partition  30  comprises a flat and rigid disk whose plane extends generally perpendicular to axis  20 . In one example, partition  30  was a solid disk-shaped member that was positioned within body tube  12  at a desired location, and then secured within body tube  12  using, for example, rivets or an adhesive substance, such as glue.  
         [0035]    The axial position of partition  30  is dependent upon the size of explosive payload  13 , and this positioning of partition  30  affects how rocket  10  travels after rocket motor  14  has burned out. Preferably, partition  30  is positioned between motor  14  and explosive payload  13 , and generally towards the top end  21  of body tube  12 .  
         [0036]    Rocket motor  14  provides a means to propel rocket  10  during flight, preferably at a substantially constant acceleration with increasing velocity, in order to deliver explosive payload  13  to a desired location. In one example, rocket motor  14  was an H45W rocket motor by Aerotech Consumer Aerospace of Las Vegas this rocket motor having a 15 to 18 pound initial thrust (preferably an 18 pound initial thrust) and preferably this rocket motor operates for 7.1 seconds until burnout, with an average thrust of approximately ten pounds being distributed over the 7.1 seconds of operation.  
         [0037]    In one example, a rocket  10  with such a rocket motor  14  traveled a distance of one mile, in an approximately line of sight flight path, when fired at a 35-degree angle relative to a horizontal plane. In one example, rocket motor  14  had an axial length of 7-inches and an outer diameter of 1.5-inches. By way of example, rocket  10  had a dimension  27  of 17.5-inches and a dimension  28  of 16.75-inches.  
         [0038]    In order to reduce the amount of travel of rocket  10  after burnout of motor  14  occurs, and in accordance with one embodiment of the present invention, it was desirable to use fins  15  of a small size, and it was desirable to position explosive payload  13  within body tube  12  in a forward position. By reducing the amount of travel of rocket  10  after engine burnout occurs, the risk that rocket  10  will travel a substantial distance after burnout, and thereby possibly miss the desired target, is reduced. Preferably, rocket  10  travels a distance that is a function, in part, of the size of rocket motor  14 , the burn time of motor  14 , and the particular dimensions and configurations of rocket  10 .  
         [0039]    In one example, four equally-spaced fins  15  were provided to assist rocket  10  in flying in a stable manner and in a relative straight line. Each fin  15  had an approximate thickness of {fraction (1/16)}-inch, a width of 1.365-inches (measured perpendicular to axis  20 ), and a length of 6-inches (measured parallel to axis  20 ). Each fin  15  had a slanted leading edge  31  approximately 2-inches long and a 2-inch long slanted trailing edge  32  that axially-extended approximately 1-inch beyond the bottom end  23  of body tube  12  and rocket motor  14 . This form of a slanted trailing edge  32  has been found to improve the flight stability of rocket  10 , and the slanted trailing edges  32  have been found to reduce deterioration of fins  15  due to heat generated by rocket motor  14 .  
         [0040]    Further, in one example, explosive payload  13  was positioned relatively forward within body tube  12 , as is shown in FIG. 1, in order to reduce an amount of travel of rocket  10  after burnout of rocket motor  14  has been completed. The axial position of explosive payload  13  within body tube  12  is governed, in part, by the position of the above-mentioned partition/bulkhead  30  by the axial length of explosive payload  13 , and by the weight of explosive payload  13 .  
         [0041]    In one example, a 8 ounce explosive payload  13  was 1⅝-inches in diameter and 4¾ inches long; and for this explosive payload  13  partition  30  was positioned 5½-inches from the top end  21  of body tube  21 , resulting in a distance traveled of 1.25 miles by rocket  10 .  
         [0042]    In another example, a 10 ounce explosive payload  13  was 2-inches in diameter and 4¾-inches long; and partition  30  was positioned 5⅘-inches from the top end  21  of body tube  12 , to thereby produce travel distance of 1.00 miles by rocket  10 .  
         [0043]    In another example, a 12 ounce explosive payload  13  was 2¼-inches in diameter and 4¾-inches long, partition  30  was positioned 6 inches from the top end  21  of body tube  12 , to produce a travel distance of 0.85 miles by rocket  10 .  
         [0044]    In another example, for an explosive payload  13  of 8, 10, or 12 ounce, partition  30  was positioned at from 5¾-inch to 6¾-inch from the top end  21  of body tube  12 .  
         [0045]    It is understood that the dimensions provided herein are by way of example only, and that the particular structure and positioning of each of the elements of rocket  10  for triggering an avalanche is a matter of choice depending upon the particular implementation.  
         [0046]    Furthermore, the flight stability and distance that rocket  10  travels after rocket motor  14  has burned out is also governed by the relative positions of the center of pressure  34  and the center of gravity  35  of rocket  10 . Preferably, the center of pressure  34  is located on axis  20 , within lower volume  25 , and toward the bottom end  17  of rocket  10 , whereas the center of gravity  35  is located on axis  20 , within lower volume  25 , and toward the top end  16  of rocket  10 . That is, the center of pressure  34  is below the center of gravity  35 .  
         [0047]    The axial position of the center of pressure  34  is controlled, in part, by the size of fins  15  and by the position of fins  15  along the axial length  20  of body tube  12 , by the diameter of body tube  12 , and by the shape of nose cone  11 . In one example, the rocket center of pressure  34  was 7-inches above the bottom end  23  of body tube  12 .  
         [0048]    The position of the rocket center of gravity  35  depends, in part, on the position of explosive payload  13  within body tube  12 . Preferably, center of gravity  35  is above center of pressure  34  by a distance that is approximately equivalent to the outer diameter of body tube  12 . In one example, body tube  12  had an outer diameter of 2.2-inches.  
         [0049]    By positioning the center of gravity  35  above the center of pressure  34 , rocket  10  of the present invention is “nose heavy.” Thus, upon burnout of motor  14  occurring, rocket  10  quickly falls to the ground, with nose cone  11  striking the ground/avalanche/mud with an acceleration that is approximately equal to the acceleration of rocket  10  before motor burn out occurred, thereby detonating explosive payload  13 .  
         [0050]    Explosive payload  13 , in one example of the present invention, comprised a main charge  40  and a cap detonator  41 . Main charge  40  was a booster explosive having an ultra high explosive rating with a detonation velocity of approximately 26,000 feet per second. Main charge  40 , when detonated, was responsible for initiating an avalanche.  
         [0051]    Cap detonator  41  was positioned proximate to main charge  40 , and was preferably secured to the top end of main charge  40 , as is shown in FIG. 1, toward the top end  21  of body tube  12 . Cap detonator  41  is a high explosive that ignites with as much force as is required to detonate main charge  40 .  
         [0052]    In operation, and after rocket motor  14  has burned out, rocket  10  decelerates downward and into the ground/snow/mud, with nose cone  11  pointing down, and with nose cone  11  being the first element of rocker  10  to contact the ground/snow/mud. Because of the positioning of cap detonator  41  toward the top end  16  of rocket  10 , with main charge  40  being positioned behind cap detonator  41 , upon impact, main charge  40  (which weighs more than cap detonator  41 ) slides forward within body tube  12  and crushes cap detonator  41 . Cap detonator  41  then ignites and causes main charge  40  to detonate, which then initiates an avalanche. A small primer is associated with cap detonator  41 . This primer explodes cap detonator  41 , whereupon main charge  40  explodes. In other words, the explosion sequence comprises an impact, detonation of the primer, detonation of cap detonator  41 , and detonation of main charge  40 .  
         [0053]    An ignition system for igniting rocket motor  14  is also disclosed herein. In one example (not shown), a conventional battery and an electric squib were used to ignite the rocket motor.  
         [0054]    As an alternative for use where allowed by government regulation, FIG. 2 shows a fuse assembly  45  in accordance with one embodiment of the invention for igniting rocket motor  14 . Preferably, fuse assembly  45  includes a fuse portion  46  and a portion  47  of heat-shrink material that surrounds a portion of fuse  46 . Fuse  46  is preferably a black powder fuse that is made of string-like material (i.e., candlewick cotton), approximately ⅛-inch in diameter and 11¼-inches long.  
         [0055]    The length of heat-shrink material  47  is preferably 6-inches long. A length  48  of fuse  46  is bent along the outer perimeter of heat-shrink material  47 . Because a portion of fuse  46  is contained inside of heat-shrink material  47 , once the end  59  fuse  46  is lit, fire within the lit fuse travels efficiently toward the top end  50  of fuse assembly  45 .  
         [0056]    Furthermore, fuse  46  preferably extends from the back portion  51  of heat-shrink material  47  by approximately 10-inches, which 10-inch extension provides an ignition delay period. Fuse  49  preferably burns at a rate of approximately 1-inch every 1.4 seconds.  
         [0057]    In one example, the top end  50  of fuse assembly  45  was dipped into a fire fluid to promote the rapid and instantaneous combustion of the top end  50  of fuse  49  proximate rocket motor  14 . It has been found that a more instantaneous and complete combustion of the top end  50  of fuse assembly  45 , proximate rocket motor  14 , promotes improved lighting and firing of rocket motor  14 . In one example, the fire fluid was an acetone-based solution generally described in “ The Chemistry of Pyrotechnics ” by John A. Conkling, 1985, the disclosure of which is expressly incorporated herein by reference.  
         [0058]    Preferably, after the top end  50  of the assembly  45  is immersed in the fire fluid, a thin line of the fire fluid is dripped along the outer perimeter of heat-shrink material  47 , approximately half way down its length. Fuse assembly  47  is then permitted to dry.  
         [0059]    Upon fuse assembly  45  being formed as above described, and after rocket  10  has been positioned on launch stand  55  (shown in FIGS.  3 - 5  and described below), the top end  50  of fuse assembly  45  is inserted into an opening (not shown) that is within rocket motor  14 , this opening being adapted to receive a fuse. Fuse assembly  45  can then be manually lit at the end  49  that is opposite to rocket motor  14 , in order to ignite rocket motor  14  and propel rocket  10  toward a desired target.  
         [0060]    Referring now to FIGS.  3 - 4 , a launch stand  55  in accordance with the present invention is shown. Launch stand  55  includes a pair of parallel-extending and rigid launch tube support members  56 , about 34-inches long, whose ends  57  are pivotally coupled to the ends  58  of a pair of parallel extending and rigid positioning members  59  that are about 34-inches long.  
         [0061]    Launch tube support members  56  are adapted to loosely support a launch tube  60  (see FIG. 5) having a rocket  10  positioned therein. In this position, the bottom end  36  of launch tube  60  rests against a pair of upright support members  37 .  
         [0062]    At one end  61 , launch tube support members  56  are rotatably connected to a flat base plate  62  by way of a dowel pin  63 . At the other end  57 , launch tube support members  56  are rotatably coupled to positioning members  59  by way of a dowel pine  64 .  
         [0063]    The ends  66  of positioning members  59  extend between a parallel set of rails  65  that are non-movably secured to base plate  62 . Rails  65  act as guide members on which the ends  66  of positioning members  59  can slide.  
         [0064]    In one example, a plurality of openings  67  were provided within rails  65  to securely and adjustably position the ends  66  of positioning members  59  relative to rails  65  and base plate  62 . Alternatively, positioning members  59  can be adjustably secured to rails  65  by the use of one or more clamps (not shown).  
         [0065]    By moving the ends  66  of positioning members  59  relative to rails  65  changes the position of the pivot point at which launch tube support members  56  are connected to positioning members  59  (i.e., at dowel pin  64 ). In this way, this pivot point can be moved up or down to provide various angles for launch tube  60  relative to base plate  62 .  
         [0066]    A portion of launch tube support members  56  supports launch tube  60 , and a rocket  10  that is located therein, after launch stand  55  has been appropriately set and secured to achieve a desired angle for launch tube  60 , as shown in FIG. 5.  
         [0067]    Launch stand  55 , preferably in the collapsed position shown in FIGS. 3 and 4, is adapted to be towed behind a snowmobile, or to be mounted in or on a stretcher that is connected to a snowmobile, so that launch stand  55  is easily moveable to a location that is susceptible to avalanches. Launch stand  55  can also be adapted to be carried using shoulder straps (not shown), or by way of a backpack.  
         [0068]    In one example, base plate  62  of launch stand  55  was 5½ feet long and 2 feet wide.  
         [0069]    As shown in FIG. 5, launch tube  60  is preferably a hollow cylindrical tube having a closed bottom that can be made of similar materials as body tube  12  of rocket  10 . Preferably, launch tube  60  has a 4¾-inch inner diameter, and preferably the difference between the inner diameter of launch tube  60  and the outer dimensions of rocket  10  (including fins  15 ) is 0.015-inch.  
         [0070]    In overall operation, rocket  10  is formed and explosive payload  13  positioned at a desired location within body tube  12 . Launch stand  55  is placed and oriented in a proper position and at a proper angle for the firing of rocket  10 . Launch tube  60  is then placed on launch stand  55 , and rocket  10  is inserted within launch tube  60 . An ignition assembly  45  is then inserted into rocket engine  14  and the ignition assembly is activated; for example, a fuse is lit. After rocket motor  14  is ignited, rocket  10  travels, in one example, with substantially constant acceleration and in a substantially straight line of sight. When rocket motor  14  burns out, rocket immediately  10  falls and hits the ground/snow/mud. Due to the inertia that is created by the force of rocket motor  14 , main charge  40  now slides forward within body tube  12  and crushes cap detonator  41  and its primer, thus igniting cap detonator  41 , and thus detonating main charge  40 . The resulting explosion then triggers an avalanche.  
         [0071]    It is believed that the blast created by rocket  10  is directional and in the same direction as the flight of the rocket. If desired, main charge  40  may be constructed and arranged to provide a desired direction of blast upon impact.  
         [0072]    While the present invention has been described and shown in terms of a rocket  10  having particular dimensions and an explosive payload  13  having particular weights and dimensions, and a fuse assembly  45  and a launch stand  55  having particular characteristics, it is understood that these details are by way of example only and that changes in rocket  10 , explosive payload  13 , fuse assembly  45 , and/or launch stand  55  are a matter of choice within the spirit and scope of the invention.  
         [0073]    [0073]FIG. 6 is a partially sectioned view of the explosive payload  13  assembly. A percussion primer  41 A and a shock tube  41 B interact with the high-explosive main charge  40  as described.  
         [0074]    [0074]FIG. 7 is an end view of launch tube  60 A with a rocket  60 A in place. In this particular example, guide rails  81 - 84  run the length of tube  60 A and support the outer periphery of rocket  10 A during its outward travel although these rails are somewhat spaced from the rocket IOA outer surface. Supports members  81 - 84  are preferably offset from fins  15  as shown.  
         [0075]    If desired, a secondary or redundant explosive charge can be included within the body of rocket  10 . This charge could be located at the top end of the rocket motor and configured to explode a predetermined time period after impact or launch of the rocket. The rocket would then be buried in the snow, mud, etc. and produce the desired end result. Thus, if the explosive payload  13  should fail, the secondary charge would detonate after the time delay exploding both itself and the primary payload  13 . Conversely, the secondary charge could likewise be detonated by payload  13  when it successfully detonates.  
         [0076]    While the methods disclosed herein has been described and shown with reference to particular steps performed in a particular order, it will be understood that these steps may be combined, sub-divided, or re-ordered to form an equivalent method without departing from the teachings of the present invention. Accordingly, unless specifically indicated herein, the order and grouping of the steps is not a limitation of the present invention.