Abstract:
According to an embodiment, a method for controlling the shape and direction of an explosion may include sensing the direction of an incoming threat, calculating an intercept vector for the threat, and triggering an explosive device in a manner that may generate an intercepting force directed along the intercept vector. According to one embodiment, a system may include a sensor configured to detect the direction of an incoming threat, an explosive device including an explosive and a plurality of embedded detonators, and a firing sequence calculator connected to receive information from the sensor regarding the direction of the threat and to trigger the detonators sequentially to produce an explosion having a selected shape, direction and intensity to create a counteracting force in response to the incoming threat.

Description:
FIELD 
       [0001]    The present disclosure relates to methods and systems for controlling the shape and direction of an explosion, and more particularly, methods and systems for controlling the shape and direction of an explosion in order to refract and diminish an approaching shock wave. 
       BACKGROUND 
       [0002]    A common feature of explosive ordnance is that it includes an explosive charge encased within a warhead. The warhead may be self-propelled, as the payload of a missile or rocket-propelled grenade (RPG), or it may be ballistic, as the payload of a mortar round, shell or air-to-ground bomb. Such explosive ordnance creates destruction and injury in two principal ways. 
         [0003]    First, when detonated, the explosive charge creates a heated volume of gas and plasma that expands rapidly and disintegrates the warhead in which it is contained. Pieces of the disintegrated warhead create high-velocity shrapnel that may impact and damage surrounding structures, including vehicles, and personnel. Stationary structures may be hardened to protect against the damage caused by shrapnel. Protective armor may be applied to vehicles to lessen the damage caused by shrapnel, but such armor adds to the weight of the vehicle, which may negatively affect its performance. Body armor may be worn by individuals, but is less effective because such armor typically leaves portions of the individual, such as the head, arms and legs, unprotected. 
         [0004]    Second, detonation of the explosive charge creates an expanding volume of hot gases and heated plasma caused by rapid combustion of the explosive charge. The outer boundary of the expanding volume of hot gases and plasma forms a pressure shock wave. Depending upon the energy released by the detonation of the explosive charge of the warhead, this shock wave may contain sufficient energy to severely damage adjacent structures, including vehicles, and cause injury or death to personnel it impacts. Stationary structures may be hardened to withstand the energy imparted by such shock waves. Adding armor to vehicles is less effective, especially with respect to lighter vehicles, which cannot carry heavy armor. Personnel may be particularly vulnerable to high-energy shock waves caused by exploding ordnance. For example, a shock wave from an explosion may at a minimum damage a person&#39;s ear drums, and at higher energy levels, can cause a concussion resulting from a person&#39;s brain impacting his skull, or death. 
         [0005]    Accordingly, there is a need to develop a countermeasure that can lessen the destructive effect of shock waves caused by exploding ordnance. Such countermeasures preferably should be capable of deployment on the order of milliseconds once explosive ordnance has detonated. 
       SUMMARY 
       [0006]    The present disclosure is directed to a method and system for controlling the shape and direction of an explosion. In one particular aspect, the method and system may be used to counteract the force of a shock wave created by detonation of an explosive associated with an incoming threat. By shaping and directing a counteractive explosion toward the explosion resulting from an incoming threat, the disclosed method and system may create an expanding volume of heated gas that may be directed toward the shock wave from the incoming threat. 
         [0007]    The volume of heated gas created by the explosion of the disclosed method and system may change the refractive index at the boundary between ambient air and the outer boundary of the shock wave from the counteractive explosion of the disclosed method and apparatus, thus deflecting the shock wave from the incoming threat away from the intended target. The volume of heated gas may act as a lens to “steer” the shock wave and hot gases from the incoming threat away from the intended target. The shock wave from the incoming threat also may be dispersed and diminished in intensity from the maximum force that otherwise would impact the intended target. 
         [0008]    According to one embodiment, a method may include sensing the direction and velocity of an incoming threat, calculating an intercept vector for the threat, and activating an explosive detonation grid within an explosive charge to detonate the charge in a manner that generates an explosion having an intercepting force directed along the intercept vector. In one aspect, activating the explosive detonation grid may include activating a plurality of discrete detonators in a pre-set sequence in order to create an intercepting explosive force of a desired shape. 
         [0009]    According to another embodiment, a system for controlling the shape and direction of an explosion may include a sensor configured to detect the direction and velocity of an incoming threat, an explosive device including a detonator grid, the detonator grid being configured to selectively detonate the explosive device to produce a shaped explosion in a selected direction and having a selected intensity, and a firing sequence calculator configured to activate the detonator grid to produce the shaped explosion and create a counteracting force in response to the incoming threat. In one aspect, the explosive device may include a reinforcement or hardened substrate, such as a steel plate, to which explosive material is attached. The explosive device may be oriented such that the substrate is between the explosive material and the item to be protected to ensure that when the explosive is detonated by the detonator grid, the explosive force is directed away from the item to be protected and toward the incoming threat. 
         [0010]    According to yet another embodiment, a vehicle may include a system for controlling the shape and direction of an explosion having a sensor configured to detect the direction and velocity of an incoming threat, an explosive device including a detonator grid, the detonator grid being configured to selectively detonate the explosive device to produce a shaped explosion in a selected direction and having a selected intensity, and a firing sequence calculator configured to activate the detonator grid to produce the shaped explosion and create a counteracting force in response to the incoming threat. In one aspect, at least the explosive device may be mounted on a door of the vehicle and may include a reinforcement or hardened substrate, such as a steel plate, to which explosive material is attached. The explosive device may be oriented such that the substrate is between the explosive material and the vehicle to ensure that when the explosive is detonated by the detonator grid, the explosive force is directed away from the item to be protected and toward the incoming threat. In one aspect, the sensor also may be mounted on the vehicle door. The vehicle may include a cover to protect the explosive device. 
         [0011]    In one aspect, the sensor is selected to detect an explosion caused by an incoming threat before the resultant shock wave reaches the item the system is to protect. The sensor may be selected to detect electromagnetic radiation created by detonation of an explosive associated with the incoming threat, because such radiation travels at light speed and will reach the sensor before the shock wave. The electromagnetic radiation may include microwave bursts, and flashes of radiation in one or more of the x-ray, infrared, visible light and ultraviolet portions of the electromagnetic spectrum. 
         [0012]    In one aspect, the detonator grid may include a plurality of discrete detonators arranged in a pattern embedded in the explosive material, and in a further aspect, the pattern may be in the shape of a regular grid. In other aspects, the detonators may be arranged in rings, concentric circles or a radial pattern. The explosive material may be formed in the shape of a plate, a cylinder, a sphere, a cone, a truncated pyramid or other regular geometric shape. The selected shape of the explosive material may be determined by the surface or structure on which it is to be mounted, and by the desired shaped explosion. The pattern of detonators in the explosive material may be selected depending on the shape of the explosive material and by the desired shaped explosion. 
         [0013]    In one aspect, each detonator may be individually connected to the firing sequence calculator so that the firing sequence calculator may create a desired sequence of detonator activation. In another aspect, groups of detonators may be connected to the firing sequence calculator so that the groups of detonators may be triggered sequentially to create a desired shaped explosion. 
         [0014]    Other objects and advantages of the disclosed method and system will be apparent from the following description, the accompanying drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a schematic drawing of an exemplary embodiment of the disclosed system for electronically shaping detonated charges; 
           [0016]      FIG. 2  is a schematic drawing of the explosive device of  FIG. 1  showing details of exemplary detonator grid; 
           [0017]      FIG. 3  is a schematic drawing of an exemplary embodiment the explosive device of  FIG. 2 , shown mounted on a door of a vehicle; 
           [0018]      FIGS. 4A ,  4 B and  4 C show perspective, plan and elevational views, respectively, of an aspect of the disclosed explosive device in the form of a cylinder with an arrangement of detonators; 
           [0019]      FIG. 5  shows an elevational view of an aspect of the disclosed explosive device in the form of a sphere with an arrangement of detonators; 
           [0020]      FIGS. 6A ,  6 B and  6 C show perspective, mid-sectional and bottom views, respectively, of an aspect of the disclosed explosive device in the form of a cone with an arrangement of detonators; and 
           [0021]      FIGS. 7A ,  7 B and  7 C show elevational, plan and bottom views, respectively, of an aspect of the disclosed explosive device in the form of a trapezoid or truncated pyramid with an arrangement of detonators. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    As shown in  FIG. 1 , the disclosed system for electronically shaping detonated charges, generally designated  10 , may include a sensor  12 , a firing sequence calculator  14  connected to the sensor, and an explosive device  16 . The explosive device  16  may include an explosive  18  in which are inserted a plurality of discrete detonators  20 . Each of the detonators  20  may be connected to the firing sequence calculator  14  so that it may be individually detonated in a pre-set or predetermined sequence. 
         [0023]    As shown in  FIGS. 1 and 2 , the explosive  18  may be regularly shaped. As shown in the drawing figure the explosive may be formed in the shape of a flat, oblong plate. In one aspect, the explosive  18  may be made of known material, for example a plastic explosive such as C4, PE4, or Semtex, or an explosive such as trinitrotoluene (TNT). A plastic explosive may be preferable because of its stability and moldability. In one aspect, the explosive  18  may be mounted on a substrate  22 , which may be a plate of material, such as steel or Kevlar, of sufficient strength and thickness to direct the force of the explosion  24  created by detonation of the explosive  18  away from the protected region  26 . In some applications, the structure or mount supporting substrate  22  also may need to be specially reinforced. The substrate  22  is shown in  FIG. 2  as a substantially flat plate, but it is within the scope of the disclosure to form the substrate to have a three-dimensional shape, such as a concave shape. The explosive  18  may be attached to the concave side of such a plate so that the hot gas  28  generated by the explosion  24  may act as a counteracting force that may be focused toward the shock wave  30  from an explosion  32  resulting from the detonation of a warhead of an incoming threat  34 . 
         [0024]    The protected region  26  may be located behind the explosive device  16  and may include a vehicle  36  (see  FIG. 3 ) or personnel (not shown). If the explosive device  16  includes a substrate  22 , the protected region  26  may be on a side of the substrate opposite the explosive  18 . 
         [0025]    The detonators  20  may be arranged in the explosive  18  in a regular grid pattern; that is, the detonators may be arranged in substantially evenly spaced and aligned rows and columns in the explosive so that they may be dispersed substantially evenly throughout the explosive. Although the detonators  20  are shown arranged in substantially a single plane in the explosive  18 , it is to be understood that the detonators may be arranged in a three-dimensional pattern in the explosive such that the detonators may form a three-dimensional prism shape within the explosive, and not depart from the scope of the disclosed system  10 . It is also to be understood that the arrangement of detonators  20  may take a different pattern in the explosive  18 , depending upon the desired shape of the shock wave to be created by detonating the explosive. 
         [0026]    The sensor  12  may be selected to detect the explosion  32  from the incoming threat  34 , which may include a mortar round, artillery shell, guided missile, RPG or air-to-ground bomb, as well as detonation of a stationary explosive device such as an improved explosive device (IED) or a land mine. In each case, the sensor  12  preferably is selected to detect detonation of the incoming threat  34  before the resultant shock wave  30  reaches the protected region  26 . In one aspect, the sensor may be selected to detect electromagnetic radiation  38  emitted by the explosion  32  because it travels much faster than the shock wave  30 . 
         [0027]    The sensor  12  may be selected to detect any subset of the electromagnetic spectrum emitted by the explosion  32 , such as microwave bursts; flashes of infrared, visible and ultraviolet light; and x-ray bursts. For example, it has been found that IEDs may emit x-rays during detonation. Such an x-ray signature may be detected by the sensor  12  in advance of the shock wave  30  so that the system  10  would have time to deploy. In one aspect, a sensor  12  may be selected to detect two or more different types of electromagnetic radiation  38  to minimize deployment of the system  10  in response to false positives. In another aspect, the system  10  may include a sensor  12  selected to detect bursts of electromagnetic radiation  38  in the form of gamma rays or neutrons, in addition to or instead of x-rays or microwaves, such that the system may deploy in response to an incoming shock wave from a nuclear detonation. 
         [0028]    In one aspect, the sensor  12  not only may detect the explosion  32 , but also estimate one or more of the magnitude, distance, elevation angle and azimuthal position. These estimates may prevent the sensor  12  from signaling the firing sequence calculator  14  to detonate the explosive  18  when the explosion is too small or distant to be a threat to the protected region  26 . When the location of the explosion  32  is determined to be sufficiently close to present a threat to the protected region  26 , the sensor  12  may send a signal over cable  40  to the firing sequence calculator  14 , which may send instructions over cable  42  to the detonators  20  of the explosive device  16 . 
         [0029]    As shown in  FIG. 2 , the explosive device  16  may include detonators  20  arranged in a grid pattern  44  in the explosive  18 . In one aspect, the arrangement may be in the form of a grid pattern, which, for purposes of illustration is labeled A-J on the Y-axis and  1 - 10  on the X-axis. Each of the detonators  20  is connected to the firing sequence calculator  14  (see  FIG. 1 ) by a discrete cable  40 . As illustrated in  FIG. 2 , detonators  20 A and  20 B, located at grid co-ordinates  1 A and  2 A, may be connected by cables  40 A,  40 B, respectively, to firing sequence calculator  14 . Although not shown for clarity, each of the other detonators  20  also may be connected by its own cable to the firing sequence calculator  14 . 
         [0030]    In one aspect, the grid pattern  44  may be in the shape of a rectangular prism. However, it is within the scope of the disclosure to provide grid patterns  44  in different shapes, for example as a radial grid. In one aspect, the grid pattern  44  is two dimensional. However, it is within the scope of the disclosure to provide detonators  20  in a three-dimensional pattern. In such an embodiment, as shown in  FIG. 2 , detonators  20 A and  20 B would be located at  1 Aα and  2 Aα, respectively. Other detonators (not shown) may be located at grid  44  co-ordinates  1 Aβ and  2 Aβ, for example, on a Z axis. It is also within the scope of the disclosure to provide detonators  20  in a one-dimensional pattern. In such an embodiment, for example, detonators may be arranged in a single row F, column  5 , or along the Z axis at co-ordinate F 5 , or along a skewed line relative to grid  44 . 
         [0031]    The firing sequence calculator  14  ( FIG. 1 ) may determine an optimum sequential firing pattern for the detonators  20 , such as a pattern corresponding to a phased array transmitter of acoustic energy, so that the system  10  may direct the vector of the explosion  24 , and resultant volume of hot gas  28 , in a desired direction, which may be toward explosion  32  and shock wave  30 . The firing sequence calculator  14  may include an onboard chip or circuit board that may compute, via a code sequence received from the sensor  12 , a desired detonator  20  firing sequence. In the alternative, the firing sequence calculator  14  may select a firing sequence from among a plurality of stored firing sequences in response to the code sequence received from sensor  12 . That firing sequence may be transmitted to the grid  44  of detonators  20 . 
         [0032]    In one aspect, the system may operate as follows, as illustrated in  FIG. 1 . Incoming threat  34 , which may be a bomb dropped from an aircraft, a howitzer shell, a mortar shell, land mine or IED, detonates to form explosion  32 . The explosion  32  also may transmit radiation  38 , which may include subatomic particles such as neutrons, that is detected by sensor  12 . The sensor  12  is programmed to sense the radiation  38  and from it may determine the magnitude and location of the explosion  32 . From this information (i.e., from one or more of the magnitude, direction and type of radiation) the sensor  12  may determine that the explosion  32  presents a threat to the protected region  26 . It is within the scope of the disclosure to provide the system  10  with multiple sensors  12  (not shown) that may provide a triangulation feature. 
         [0033]    The sensor  12  transmits information over cable  40  to the firing sequence calculator  14 , which uses location information to create an appropriate firing sequence for the detonators  20  in the grid  44  (see  FIG. 2 ). The firing sequences—and corresponding electrical pulses—may then be sent to the detonators  20 , which will then fire in the prescribed order, indicated at  46  in  FIGS. 1 and 2  to create explosion  24 . The firing sequence of the detonators  20  directs the volume of hot gas  28  toward the shock wave  30  from the explosion  34 . 
         [0034]    In one aspect, the explosive  18  may be shaped to fit a surface on which it is mounted, rather than be shaped to effect a desired explosion  24  and directed volume of hot gas  28 . For example, in  FIG. 3  the explosive  18  is formed in the shape of a plate that is mounted on a substantially vertical surface behind a plate (not shown) inside the door  48  of a vehicle  36 . However, by triggering the detonators  20 , arranged in a grid array  44 , in a pre-set order, the resulting explosion  24  ( FIG. 1 ) may be shaped as desired to direct a resultant hot gas  28  toward the shock wave  30  of explosion  32  from an incoming threat  34 . 
         [0035]    In the embodiment of  FIG. 3 , the sensor  12  may also be positioned within the door  48 , of a vehicle  36 , which in one aspect may be an armored vehicle. In this embodiment, it is preferable to provide the explosive  18  with a substrate  22  (see  FIG. 2 ) that provides reinforcement to protect the vehicle and its occupants from the explosion  24 . In some applications, the structure or mount supporting substrate  22  may also need to be specially reinforced. In one aspect, the substrate  22  may be made of steel/titanium, and/or be parabolic in shape. In one aspect, the substrate  22  also may protect the occupants of the vehicle  36  in the event that the explosive  18  is detonated maliciously, as by being shot at by a gun. 
         [0036]    In one aspect, the sensor  12  of the system  10  may be selected to detect an incoming threat  34  in the form of an RPG, then signal the firing sequence calculator  14  that in turn triggers detonators  20  embedded in explosive  18 . The direction of the incoming threat  34  would be fed to the firing sequence calculator  14  that would trigger detonators  20  in a pattern that would create a shaped explosion  24  that would deflect or destroy the threat. 
         [0037]    In one aspect, the system  10  may be used as an offensive weapon against an incoming threat. In one exemplary embodiment, the sensor  12  may detect an incoming threat in the form of, for example, hostile personnel or vehicle. The sensed signature may include, for example infrared radiation from body heat of the hostile personnel or hostile vehicle, movement of hostile personnel or vehicle, or the flash of electromagnetic radiation from a weapon held by hostile personnel, such as a rifle or machine gun, or mounted on the hostile vehicle. The sensor  12  may detect the location of the hostile personnel relative to the protected area  26  or vehicle  36  and send a signal containing distance, elevation and azimuthal information to firing sequence calculator  14 . Firing sequence calculator  14  may then trigger detonators  20  in a pre-set sequence determined by information received from sensor  12 . The resultant explosion  24  may be shaped and directed by firing sequence calculator  14  toward the incoming threat to neutralize, destroy or deter the threat. 
         [0038]    As shown in  FIGS. 4A-4C , the explosive  18 A may be formed in regular shapes other than in a plate shape—in this embodiment it may take the form of a cylinder. The detonators  20  may be arranged in a grid  44 A or pattern that may be in the form of a column of concentric rings of detonators extending through the volume of the explosive. The pattern may have linear, cylindrical, or spherical symmetry. For the sake of clarity, only the concentric ring appearing on the top surface of the explosive  18 A in  FIG. 4A  is shown in full. It is to be understood that rings  201 ,  202 ,  203  and  204  may have the same number of detonators  20  in substantially the same arrangement as concentric rings  205 . It is also within the scope of the disclosure to provide spacing and arrangement of detonators  20  that varies among rings  201 - 205 , or to provide fewer or greater numbers of rings. 
         [0039]    In one aspect, as shown in  FIG. 4A , if the rings of detonators  20  are detonated in a series such that ring  201  is detonated first, followed sequentially separated by microsecond time delays by rings  202 ,  203 ,  204  and  205 , an explosive force may be strongly projected upward from the explosive  18 A, as shown in the drawing figure. In another aspect, shown in  FIGS. 4B and 4C , if only detonators  206  are fired with microsecond delays, the resultant explosion would be concentrated in a wide vertical line generally to the left in  FIG. 4B . 
         [0040]    As shown in  FIG. 5 , the explosive  18 B may be formed generally in the shape of a sphere. The detonators  20  may be arranged in concentric rings or radii expanding outward from the center of the sphere. With this shape of explosive  18 B, it may be possible to fire the detonators from the outside in, thereby minimizing the explosive force, or from the inside out, thereby maximizing the force of the concussion wave  28  ( FIG. 1 ), or patterned to create a conical or directed force of a pre-set trajectory. 
         [0041]    As shown in  FIGS. 6A-6C , the explosive  18 C may be formed in the shape of a cone. Detonators may be arranged in concentric rings through the volume of the cone. The explosion  24  may be shaped as desired by sequencing the firing of successive rings of the detonators  20 . 
         [0042]    As shown in  FIGS. 7A-7C , the explosive  18 D may be formed in the shape of a pyramidal frustum. Detonators  20  may be placed in stacked grids through the elevation of the frustum. Again, for clarity only grid arrangements on the top ( FIG. 7B ) and bottom ( FIG. 7C ) of explosive  18 D are shown in full, it being understood that this embodiment may contain several grid arrangements of detonators through its height, or may contain only what is actually shown. In one aspect, by triggering the detonators  207  a parabolic explosion projecting outward through the top of the explosive  18 D; that is, outward from the plane of the drawing of  FIG. 7B , may be created. 
         [0043]    These particular embodiments are shown to illustrate the general principle of embedding detonators in a pattern within an explosive having a particular shape, then initiating the detonators in a sequence to produce an explosion of a desired, pre-set shape that may be directed toward an incoming hostile threat. Other explosive shapes and detonator patterns are included within the scope of this disclosure. 
         [0044]    The system  10  described herein may be used both offensively and defensively in response to a threat to create an explosion having a pre-set shape by selectively triggering a plurality of detonators embedded in an explosive and project a volume of hot gas toward the threat. While the methods and forms of apparatus described herein may constitute preferred aspects of the disclosed method and apparatus, it is to be understood that the invention is not limited to these precise aspects, and that changes may be made therein without departing from the scope of the invention.