Patent Application
20130199395
The technical field is explosive devices for breaching doors, and more particularly stand-off breaching devices that may be thrown or shot from a launcher.
Currently, dismounted troops have the capability to effectively breach medium weight steel doors using rifle-launched stand-off breaching devices such as the SIMON device and a similar U.S. Army derivative the GREM. Attempts are currently underway to develop a similar stand-off breaching capability which may be fired from a 40 mm grenade launcher. The 40 mm grenade is known as the Hell Hound. Both of these platforms have their advantages and disadvantages.
The SIMON is effective, but is not a compact device.
The 40 mm grenade (Hell Hound) is compact, but its effectiveness is limited by its maximum payload and by the fact that it explodes on impact. A typical Hell Hound grenade has the following characteristics:
What is needed is a stand-off breaching device that combines the breaching effectiveness of the SIMON device and GREM with the compactness of the Hell Hound. To be effective, such a stand-off breaching device should produce minimal fragmentation and minimal blast hazards for the operator.
Embodiments described herein have numerous advantages, including overcoming the defects of the prior art described above. These advantages may be achieved by a stand-off breaching device for breaching a target, such as a door. The stand-off breaching device includes a nose at a front end of the stand-off breaching device that is a rounded cone shape, the nose configured to cause the stand-off breaching device to rebound from a target after the nose impacts the target, and a body connected to the nose and extending to a back-end of the stand-off breaching device. The body includes a main explosive fill, in which the main explosive fill is detonated and explodes to provide an explosive breaching force, and a delay detonator that initiates the main explosive fill and that is triggered when the nose impacts a target. The delay detonator is configured to delay the detonation of the main explosive fill until the stand-off breaching device has rebounded to a determined stand-off distance chosen to cause effective breaching of the target. The nose and body, and components of each, are fabricated from material that will be substantially consumed by the explosion of the main explosive fill, minimizing any resultant fragments.
These advantages may also be achieved by a stand-off breaching device for breaching a target, the stand-off breaching device including means for activating means for delayed detonating of the stand-off breaching device, in which said activating means activates said delayed detonating means and causes the stand-off breaching device to rebound from the target upon impact with a target, a main explosive fill, in which the main explosive fill, when detonated, explodes and provides a explosive load on a target, and said delay detonating means, connected to said activating means, in which said delay detonating means detonates the main explosive fill after a delay designed to allow the stand-off breaching device to rebound to a desired stand-off distance from a target. Said activating means and said delay detonating means are substantially consumed by the explosion of the main explosive fill, minimizing any resultant fragments.
The detailed description may refer to the following drawings, wherein like numerals refer to like elements, and wherein:
Described herein are embodiments of a stand-off door breaching device and method. In an embodiment, the stand-off breaching device is a stand-off breaching grenade (“SOBG”) that may be accurately hand-thrown or launched by a grenade or similar launcher. Embodiments are designed with a delay detonator that is triggered by impact of the stand-off breaching device with a target (e.g., a door to be breached). The stand-off breaching device is also designed to rebound away from the target after impacting the target. In such embodiments, upon impact with the target, the delay detonator is initiated, the stand-off breaching device rebounds away from the target and, after a delay, the stand-off breaching device detonates. Embodiments are designed, and the delay detonator set, so that the stand-off breaching device detonates at some predetermined stand-off distance from the target. The delay-time of the delay detonator, and the speed with which the stand-off breaching device rebounds away from the door, determines the stand-off distance at which the stand-off breaching device detonates. Embodiments are also designed so that substantially all of the stand-off breaching device is consumed by the explosion, minimizing fragmentation and blast hazards.
The embodiments described herein, and indeed most door-breaching explosive devices, are found to most effectively breach a door when the device explodes at a “stand-off” distance away from the door. The desired stand-off distance is the distance at which the explosive loading on the door (the pressure on the door caused by the explosion) is sufficient to force open/breach the door. If the explosion occurs to close to the door, the explosive loading will tend to simply punch a hole in through the door rather than opening the door. If the explosion occurs to far from the door, the explosive loading will not be sufficient to open the door. The embodiments described here are designed to rebound to the effective, desired stand-off distance and explode, explosively loading the door with sufficient force to force the door open. The detonation delay for such embodiments may range from 75 to 100 ms. The stand-off distance for such embodiments may range from 8-14 inches.
The embodiments described herein are also designed to provide the effectiveness of the SIMON and GREM devices with the compactness of the 40 mm Hell Hound. Consequently, embodiments may have a similar amount of explosive fill as the SIMON 120 or even the standard SIMON. The amount of explosive fill used in embodiments of the stand-off breaching device may vary, as discussed in detail below, depending on the intended applications and effectiveness needed. For example, the explosive fill needed for breaching heavy-weight steel doors will necessarily be greater than that needed to breach medium-weight steel doors.
As noted above, embodiments are designed to be accurately and effectively hand-thrown. Such embodiments may have an effective range similar to that of the SIMON and GREM devices. However, the lack of a stand-off rod (which makes the device heavier and less compact and) and the more aerodynamic design of embodiments described here suggests that embodiments of the stand-off breaching device will have a greater effective thrown range than the SIMON and GREM devices. Embodiments of the stand-off breaching device may also be designed to be launched from a grenade launcher or similar device; such embodiments would likely have a similar effectiveness to the Hell Hound grenade.
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Safety pin 112 prevents SOBG 100 from being accidentally armed and detonator triggered prior to throwing of SOBG 100 against target. Safety pin retainer 110 holds safety pin 112 inside safety pin extension 108 which connects safety pin 112 with bumper 106. Together with safety pin extension 108, safety pin 112 and safety pin retainer 110 form a safety pin assembly. Compression spring 114 connects safety pin 112 to firing pin assembly 118 and keeps safety pin 112 separated from firing pin assembly 118 and, therefore, keeps firing pin assembly 118 from triggering delay detonator, during normal handling of SOBG 100. Only when nose 102 impacts a target with sufficient force to move safety pin 112 with sufficient force to overcome inertia of compression spring 114 will compression spring 114 be compressed sufficiently to allow ball bearings 116 to disengage from housing 122 through the outside diameter contour of safety pin 112. With the ball bearings 116 disengaged from housing 122, the firing pin assembly 118 will be forced further into the body 104, impact the primer 126, and initiate the explosive train. Firing pin assembly 118 may include tip 120 (in affect, the firing pin) or other extension that impacts with primer to trigger detonation (see below).
It is noted that nose 102 may have different components than those shown and that the components shown may be shaped or configured differently. Such different components should cooperate and function in a manner consistent with the operation described above so that SOBG 100 does not detonate during routine handling, when thrown or shot at target, triggers delay detonator and bounces off of target upon impact with target, and detonates at ideal stand-off distance sufficient to force open target.
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In an embodiment, delay element 128 is a pyrotechnic delay element that burns. Time that delay element 128 takes to burn provides delay and is configured to delay sufficiently for SOBG 100 to rebound to ideal stand-off distance after impacting with target. Delay element 128, after burning, ignites delay detonator output/primary charge 130. Delay detonator comprises delay element 128 and primary charge 130. Primary charge 130 detonates explosive fill 134 (secondary charge or explosive). Explosive fill 134 then detonates, with explosive shockwave of explosive fill 134 traveling back towards nose 102 of SOBG 100 (and, therefore, towards target). Explosive fill 134 may be a COTS explosive or a specifically designed explosive. In embodiments, explosive is a safety-certified explosive such as PBXN-109. Back cap 136 seals back end of body 104. Back cap 136 shown is configured as flat circular disks that extend through entire circumference of interior (hollow space) of housing 122, although different shapes may be used.
To summarize the delay detonation chain, upon impact of the SOBG 100 with the target, nose 102 pushes firing pin 118 into percussion primer 126. Primer 126 sets off the delay element 128 in the time delay detonator, which bums and then sets off primary charge 130 of delay detonator. Primary chare 130 of delay detonator sets off booster 132, which in turn sets off main explosive fill 134. The time taken by the above-described detonation process provides the delayed detonation describe above. Accordingly, this process is configured by design and set-up to provide sufficient delay for an explosion of SOBG 100 at ideal stand-off distance from target. This configuration, therefore, takes into account amount of ‘bounce’ achieved by impact of nose bumper 106 on target under ordinary use (i.e., how far SOBG 10 will rebound from target in given amount of time—the rate, allowing for variations in speed of impact (e.g., as thrown by different persons at different speeds or launched by launchers), and ideal stand-off distance for given target type. In an embodiment the detonation delay may range from 75 to 100 ms, while the desired stand-off distance ranges from 8-14 inches. Accordingly, in such an embodiment, SOBG 100 may rebound from the target at about 0.08 to 0.19 inches per ms after impacting the target.
This rate of rebound and, therefore, the detonation delay, will vary depending on numerous factors including whether SOBG 10 is thrown or launched, how hard it is thrown, the weight of SOBG 10, aerodynamic variations, etc. Likewise, the desired stand-off distance may differ based on the target, the explosive used and other factors. Ideally, these factors are all taken into account when designing and calibrating an implementation of SOBG 10 or other stand-off breaching device according to the present invention.
It is noted that the amount of main explosive fill 134 and the location of back cap 136 are not limited to what is shown in the accompanying drawings. More or less main explosive fill 134, for example, may be provided depending upon the intended target and use of SOBG 100. If greater explosive loading is needed, more explosive fill 134 may be used, and vice-versa. Furthermore, the affect of the amount and weight of main explosive fill 134 on the throwing balance of SOBG 100 may dictate that less or lighter main explosive fill 134 be used. For example, explosive fill 134 that extends to back cap 136 may cause the center of gravity of SOBG 100 to be to far to the back of SOBG 100, causing SOBG 100 to tumble in flight. In such circumstances, the amount of main explosive fill 134 may need to be reduced, lighter explosive fill may need to be used or counter-balances (e.g., heavier materials used or additional counter-balancing components added) included in the front of SOBG 100.
Accordingly, in an embodiment, main explosive fill 134 does not extend all the way to back cap 136. Such an embodiment may include an interior back cap that encloses main explosive fill 134 and creates an empty space between end of main explosive fill 134 and back cap 136. In such an embodiment, delay detonator may be shorter so that it does not extend beyond interior back cap and end of main explosive fill 134. Alternatively, if delay detonator extends to back cap 136 as shown, a booster that surrounds primary charge 130 of delay detonator may be provided. In such an embodiment, explosive booster acts as a bridge between delay detonator and explosive fill 134. Booster may wrap around primary charge 130 of delay detonator. Booster may be a COTS booster or specifically designed booster. In embodiments, the booster material is a safety-certified booster material. Booster is ignited by detonation of delay detonator primary charge 130, increasing explosive shockwave to degree sufficient to detonate main explosive fill 134.
Likewise, as noted, SOBG 100 may be designed to be hand-thrown or fired from a launcher. Accordingly, SOBG 100 be made built to a size comfortable for an average soldier to throw. The length, width and weight of such an embodiment of SOBG 100 should probably be on the same scale as an ordinary grenade, although perhaps a bit larger in all aspects since a SOBG 100 usually does not need to be thrown as far. In an embodiment, SOBG 100 is of a size and shape that is compact, so that it may be easily carried, and can be easily thrown by hand from a distance ranging from 5 to 10 meters. For such an embodiment, the expected safe usage distance of the SOBG 100 will be 5 to 10 meters. If designed to be fired, SOBG 100 may be larger in at least weight, although it will be restricted by launch capabilities of launcher. SOBG 100 may, therefore, be designed to fit within a launcher. Alternatively, an extension may be fitted to back-end of body 106 to fit inside launcher. In this manner, extension may extend out of back-end of body 106 into launcher when SOBG 100 is prepared for use. Back cap 136 may be configured to accept extension. As SOBG 100 may have its own launch tube attachment or system, SOBG 100 is not restricted to the 40 mm diameter or maximum length of the 40 mm grenade. Further, SOBG 100 weight may be increased because SOBG 100 will be launched at a much lower velocity than a standard 40 mm grenade because SOBG 100 needs to impact at a relatively low velocity to rebound (too fast a velocity and SOBG 100 will simply pass through some light-weight doors).
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As noted throughout, SOBG 100 shown and described herein is an embodiment. Many different variations on SOBG 100 are possible within the spirit of the invention. Variations based on payload, intended use (thrown or launched) or other conditions or factors may be taken into account when designing implementation of SOBG 100. Stand-off breaching devices according to the invention combine the breaching effectiveness of the SIMON device and GREM with the compactness of the Hell Hound while producing minimal fragmentation and minimal blast hazards for the operator. Such stand-off breaching devices accomplish this by bouncing off of target and delay detonating upon reaching ideal stand-off distance range. Such stand-off breaching devices accomplish this by being throw by hand or launched.
A typical SOBG 100, designed to be thrown, may weigh from 0.5 to 1.5 pounds and be approximately 2 to 6 inches in length and 1.5 to 3 inches in diameter. A typical SOBG 100, designed to be launched from a launcher, may weigh from 0.5 to 1.5 pounds and be approximately 2 to 6 inches in length and 1.5 to 3 inches in diameter. Variations of these ranges are possible and expected based on different types of launchers, different throwing conditions, etc.
Likewise, although shown is two separate components, nose 102 and body 104 may be formed as one continuous component. Additional features, such as fins, rifling, tapering of body, or other physical variations may be provided to improve or change performance and/or flight characteristics. Similar variations to the embodiments described herein, and components thereof, are apparent to those of ordinary skill in the art and may be implemented.
The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention as defined in the following claims, and their equivalents, in which all terms are to be understood in their broadest possible sense unless otherwise indicated.
