Patent Publication Number: US-7895931-B2

Title: Electro magnetic countermeasure launcher

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The underlying concepts, but not necessarily the language, of the following cases are incorporated by reference:
         (1) U.S. patent application Ser. No. 10/899,234, filed 26 Jul. 2004;   (2) U.S. patent application Ser. No. 11/278,988, filed 7 Apr. 2006;   (3) U.S. patent application Ser. No. 11/428,697 filed 5 Jul. 2006.
 
If there are any contradictions or inconsistencies in language between this application and one or more of the cases that have been incorporated by reference that might affect the interpretation of the claims in this case, the claims in this case should be interpreted to be consistent with the language in this case.
       

     FIELD OF THE INVENTION 
     The present invention relates to weaponry in general, and, more particularly, to countermeasures. 
     BACKGROUND OF THE INVENTION 
     Countermeasure systems are employed by military vessels to confuse or otherwise frustrate the targeting systems of an approaching missile or similar threat. Countermeasure devices, such as flares, chaff, acoustic emitters, IR emitters, and the like, are deployed to present a false image (i.e., decoy) of the vessel to these targeting systems. The false image is presented so as to draw the threat toward the false image and, therefore, away from the actual vessel. The false image manifests sufficiently far from the actual vessel so that damage caused by the threat when it strikes the decoy is mitigated or avoided all together. 
     Modern missiles incorporate sophisticated sensor platforms in their targeting systems. Many of these sensor platforms are capable of sensing target signature information across a spectrum of signal types (e.g., radar, acoustic, thermal, etc.). In addition, many of these sensor platforms incorporate counter-countermeasure systems that can discriminate many countermeasure devices from an actual vessel based on the dynamic behavior of the signals it senses. It is necessary, therefore, for countermeasure systems to closely mimic the multispectral signature, shape, and behavior of an actual vessel. 
     Conventional countermeasure systems utilize arrays of missiles. Each missile in the array has a warhead that incorporates countermeasure devices. These systems have certain drawbacks that limit their effectiveness against relatively sophisticated sensor platforms. 
     One drawback relates to the limited flexibility of such systems. Specifically, the missiles in these conventional systems have a fixed position and launch angle. Furthermore, the propulsive force from the chemical propellant of each missile is not controllable. As a consequence, effective decoy placement requires that a vessel (e.g., warship, etc.) undergo complicated maneuvers prior to and after launch of the missiles. 
     A second drawback relates to missile signature. When the missiles launch from the countermeasure system, each chemical-propellant engine emits a characteristic signature that has thermal, aural, and visual aspects. In particular, the signature includes a thermal bloom, a cloud of smoke, noise, a thermal trail and a smoke trail. In most cases, the thermal bloom heats the area immediate to the launch area, which results in a residual local thermal signature. 
     A third drawback relates to countermeasure system downtime. In particular, after launch, the countermeasure launcher must be cleaned and reloaded, which renders the vessel relatively more vulnerable to attack. 
     Finally, in order to provide a convincing decoy, numerous countermeasure devices, including multiple device types, are required. Of course, as the complement of missiles increases, the size of the countermeasure system grows and contributes significantly to deck clutter, as well as increasing the complexity and cost of the countermeasure system. 
     There exists a need, therefore, for a countermeasure system that avoids or mitigates some or all of these problems. 
     SUMMARY OF THE INVENTION 
     The present invention provides a system for launching a countermeasure device that avoids some of the costs and disadvantages for doing so in the prior art. In particular, the illustrative embodiment of the present invention uses an electromagnetic catapult to throw a countermeasure device with controlled force and direction, without generating a substantial launch signature. 
     In the illustrative embodiment, the countermeasure system comprises an electromagnetic launch tube, which can propel a series of countermeasure payloads; a payload magazine, which can provide a plurality of payload types; and a breech loader for conveying a payload from the magazine and loading it into the launch tube. 
     Embodiments of the present invention comprise a countermeasure launcher that utilizes non-explosive force to precisely place multiple countermeasure devices at specific coordinates at specific times. This enables the inventive countermeasure system to generate a relatively more convincing decoy; one that is geometrically and dynamically similar to an actual vessel. 
     In addition to providing a more convincing decoy, the system does not generate a tell-tale launch signature that would otherwise betray the illusion created by the system. In other words, unlike conventional countermeasure systems, the present system does not generate any significant thermal, aural, or visual signature during launch. 
     Due to the ability to provide a more realistic decoy and a reduced launch signature compared to the prior art, embodiments of a countermeasure system disclosed herein provide an improved ability to confuse the multi-spectral sensor platforms of approaching threats. This ultimately reduces the effectiveness of the threats and improves the likelihood of survivability of the actual vessel. 
     The ability of the present system to control the direction, elevation, and propulsive force of the countermeasures reduces or eliminates the need for complex maneuvering by the vessel in order to develop an effective decoy. Finally, the launch of countermeasures without using explosive force eliminates the post-firing maintenance that is required by conventional hot-launch countermeasure systems. This also reduces vulnerability and improves survivability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a schematic diagram of a warship deploying countermeasure payloads in accordance with an illustrative embodiment of the present invention. 
         FIG. 2  depicts a schematic drawing of a prior-art countermeasure launcher. 
         FIG. 3  depicts a schematic diagram of a countermeasure launch system in accordance with the illustrative embodiment of the present invention. 
         FIG. 4  depicts a schematic diagram of a countermeasure launcher in accordance with the illustrative embodiment of the present invention. 
         FIG. 5  depicts a schematic diagram of a launch tube in accordance with the illustrative embodiment of the present invention. 
         FIG. 6  describes a representative countermeasure deployment in accordance with the illustrative embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts a schematic diagram of a warship deploying countermeasure payloads in accordance with an illustrative embodiment of the present invention. Warship  100  carries radar tracking system  102  and countermeasure launch system  104 . 
     Radar tracking system  102  is a system that detects and tracks potential threats and provides an estimate of their velocity and path, as is well-known in the art. 
     Countermeasure launch system  104  will be described in detail below and with respect to  FIGS. 3 through 5 . 
     In response to the detection of an approaching threat by radar tracking system  102 , countermeasure launch system  104  launches a series of countermeasure payloads,  106 - 1 ,  106 - 2 , and  106 - 3  (referred to collectively as “payloads  106 ”). Countermeasure payloads  106  are devices that provide an indication of the presence of a vessel to the sensors of an approaching threat by passively reflecting a signal (e.g., chaff that reflects radar signals, etc.) or actively producing a signal (e.g., flares that emit light and heat, explosives that emit acoustic and thermal energy, etc.). For the purposes of this specification, including the appended claims, the phrase “provide a signal” means either passively reflecting or actively producing a signal. 
     Countermeasure launch system  104  launches countermeasure payloads  106 - 1 ,  106 - 2 , and  106 - 3  on paths  108 - 1 ,  108 - 2 , and  108 - 3 , respectively, so as to coordinate the timing of their deployment at a distance from warship  100 . In some cases, it is desirable to have payloads  106  deploy simultaneously at the position of decoy  110 . In some embodiments, the deployment of payloads  106  is based upon the type and path of the incoming threat. 
     Countermeasure launch system  104  deploys payloads  106  to their intended coordinates, each at a specific time, so that they collectively provide an image of decoy  110  to the sensors of an approaching threat. In some embodiments of the present invention, countermeasure payloads,  106 - 1 ,  106 - 2 , and  106 - 3  provide signals of different types in order to frustrate and/or confuse a multi-spectral sensor capability of an incoming threat. Although the illustrative embodiment comprises three types of countermeasure payloads, it will be clear to those skilled in the art, how to make and use alternative embodiments of the present invention that comprise any number of countermeasure payload types. In various embodiments, countermeasure payloads,  106 - 1 ,  106 - 2 , and  106 - 3  comprise, for example, countermeasure devices that are:
         i. thermal devices; or   ii. acoustic devices; or   iii. infrared-emitting devices; or   iv. chaff; or   v. explosives; or   vi. radar reflecting; or   vii. flash-bang devices; or   viii. any combination of i through vii.       

       FIG. 2  depicts a schematic diagram of prior-art countermeasure launcher  200 . Launcher  200  comprises launch tubes  202 - 1 ,  202 - 2 ,  202 - 3 , and  202 - 4  and platform  204 . 
     Launch tubes  202 - 1 ,  202 - 2 ,  202 - 3 , and  202 - 4  (referred to collectively as “launch tubes  202 ”) are conventional countermeasure launch tubes, suitable for launching countermeasure payloads using a chemical-propellant, such as black-powder explosives. Typically, launch tubes  202  accept pre-loaded countermeasure canisters and locate them in a pre-arranged configuration. 
     Platform  204  is a substantially rigid structure for holding launch tubes  202 . Typically, platform  204  is attached to the deck of warship  100  using means such as bolts, welding joints, etc. Typically, launch tubes  202  are rigidly held in platform  204 . 
     Launch tubes  202  are arrayed to deploy a plurality of countermeasure devices at some distance from a warship. In the prior-art, complicated maneuvering of warship  100  is typically required for the deployment of these countermeasures. Such maneuvers are required since prior-art countermeasure launchers do not have the capability for controlled launch trajectory and/or launch energy. 
     In addition, the use of a chemical-propellant to propel payloads from launch tubes  202  requires extensive maintenance, such as cleaning and reloading, after each use. Warship  100  is more vulnerable to attack during this maintenance period. A prior-art countermeasure system may have as many as twelve launch tubes, thus the period of increased vulnerability can be undesirably long. 
     The use of a chemical-propellant to propel countermeasure payloads also increases the visibility of warship  100  to an approaching threat. Explosives create a thermal signature, a visible signature (e.g., smoke, flash, etc.), and a thermal signature. Each of these signatures increases the likelihood that warship  100  will be successfully targeted by the incoming threat. In addition, the thermal signature from a chemical-propellant launch can provide a residual signal on which the approaching threat can register long after the countermeasure payload has been launched. 
       FIG. 3  depicts a schematic diagram of a countermeasure launch system in accordance with the illustrative embodiment of the present invention. Countermeasure launch system  104  is a system that has the capability to launch a payload upon command. The system expels the payload from a launch tube using an electromagnetic catapult and without the aid of explosive force. This is advantageous because the payload is launched without a substantial launch signature, thereby avoiding some of the problems discussed in the Background section. Advantageously, this enables a countermeasure payload to be deployed at desired coordinates at a desired time, and without an indication of the payload&#39;s origin. Countermeasure launch system  104  comprises controller  302 , countermeasure launcher  306 , and power system  308 . 
     Controller  302  is a general purpose controller for receiving signals and information from radar system  102  and providing targeting information and firing control signals to countermeasure launcher  306  and power system  308 . It will be clear to those skilled in the art, after reading this specification, how to make and use controller  302 . 
     Countermeasure launcher  306  is a countermeasure launcher which uses an electromagnetic force to propel countermeasure payloads. The propulsive force, azimuth, and elevation of countermeasure launcher  306  are controllable to enable it to propel a countermeasure payload to any desired point within its range. Although the illustrative embodiment comprises a countermeasure launcher that uses electromagnetic force to propel countermeasure payloads, it will be clear to those skilled in the art, after reading this specification, how to make and use alternative embodiments of the present invention that utilize other “cold-launch” (non-chemical-based) technologies to propel countermeasure payloads. 
     In some alternative embodiments, countermeasure launcher  306  comprises at least one launch tube that utilizes non-explosive propulsive force for launching countermeasure payloads and at least one launch tube that utilizes explosive propulsive force for launching countermeasure payloads. Countermeasure launcher  306  is described in more detail below and with respect to  FIGS. 4 and 5 . 
     Control cable  304  carries signals and control information from controller  302  to countermeasure launcher  306  and power system  308 . 
     Power system  308  comprises circuitry that conditions and manages the storage and delivery of power to countermeasure launcher  306  in response to signals from controller  302 . Power system  308  controls power generation, storage, and delivery prior to, during, and after each launch. Power system  308  provides an amount of power to countermeasure launcher  306  suitable to enable it to propel a countermeasure payload on its desired path (e.g., one of paths  108 - 1 ,  108 - 2 , or  108 - 3 ). It will be clear to those skilled in the art, after reading this specification, how to make and use power system  308 . 
     Current cable  310  carries power from power system  308  to countermeasure launcher  306 . In some embodiments of the present invention that comprise multiple electromagnetic launch tubes, current cable  310  is capable of carrying power to each electromagnetic launch tube independently from the other electromagnetic launch tubes. 
       FIG. 4  depicts a schematic diagram of a countermeasure launcher in accordance with the illustrative embodiment of the present invention. Countermeasure launcher  306  comprises electromagnetic launch tube  402 , magazine  404 , breech loader  406 , and alignment controller  408 . 
     Launch tube  402  is a countermeasure launch tube which uses an electromagnetic force to propel countermeasure payloads. Launch tube  402  will be described in more detail below and with respect to  FIG. 5 . 
     Magazine  404  is a countermeasure payload magazine that holds and contains a plurality of countermeasure payload types. It will be clear to those skilled in the art, after reading this specification, how to make and use magazine  404 . 
     Breech loader  406  is a system for conveying a countermeasure payload from magazine  404  to launch tube  402 . In response to commands from controller  302 , breech loader  406  works in concert with magazine  404  and launch tube  402  to select and provide a countermeasure payload to the launch tube. It will be clear to those skilled in the art, after reading this specification, how to make and use breech loader  406 . 
     Alignment controller  408  is a system for aligning launch tube  402  such that a countermeasure payload is propelled in a desired direction and at a desired launch angle. Alignment controller  408  aligns launch tube  402  in response to signals from controller  302 . It will be clear to those skilled in the art, after reading this specification, how to make and use alignment controller  408 . In some embodiments of the present invention, alignment controller controls only one of the azimuth and elevation of launch tube  402 . 
     Control of the azimuth and elevation of launch tube  402  for each payload, in addition to control of the force used to propel the payload enables the placement of multiple countermeasure payloads:
         i. at different coordinates at the same time; or   ii. at the same coordinates at the same time; or   iii. at the same coordinates at different times; or   iv. at different coordinates at different times; or   v. any combination of i, ii, iii, and iv.       

     As a result, embodiments of the present invention provide control over the configuration, position, and dynamics of decoy  110 . 
       FIG. 5  depicts a schematic diagram of a launch tube in accordance with the illustrative embodiment of the present invention. Launch tube  402  comprises tube  502 , propulsion coils  504 - 1  through  504 - 3 , and armature  506 . 
     Tube  502  is a cylindrical tube that has sufficient interior diameter to accommodate the largest countermeasure payload suitable for countermeasure launcher  306 . Tube  502  has sufficient strength to withstand the forces exerted on tube  502  during a countermeasure payload launch. 
     Each of propulsion coils  504 - 1  through  504 - 3  (referred to collectively as “coils  504 ”) is a length of electrical conductor that is suitable for carrying sufficient electric current to accelerate armature  506 . The propulsive force provided by each of coils  504  to armature  506  is a function of the number of turns it contains, the current it carries, and the separation between it and armature  506 . 
     Armature  506  is a rigid platform suitable for holding countermeasure payload  106 - i , wherein i is a positive integer in the set {1, . . . 3}, and developing a mutual inductance with a magnetic field generated by the flow of current in any of coils  504 . Armature  506  typically comprises a magnetic material such as iron, steel, Permalloy, etc. The magnitude of the force directed on armature  506  is a function of the mutual inductance between armature  506  and coils  504 . In some embodiments, armature  506  comprises a non-magnetic material and an armature coil, and the magnitude of the force directed on armature  506  is a function of the mutual inductance of this armature coil and coils  504 . It will be clear to those skilled in the art, after reading this specification, how to make and use armature  506 . 
       FIG. 6  describes a representative countermeasure deployment in accordance with the illustrative embodiment of the present invention. 
     Representative countermeasure deployment  600  begins at task  601 , wherein an approaching threat, an inbound missile in this example, is detected by radar system  102 . Radar system detects the inbound missile and estimates its path, and this information is provided to controller  302 . 
     At task  602 , controller  302  determines an appropriate location and time at which to form decoy  110 . 
     At task  603 , breech loader  406  conveys payload  106 - 1  from magazine  404  and loads payload  106 - 1  into launch tube  402 . 
     At task  604 , controller  302  determines the coordinates and time at which payload  106 - 1  should be deployed and provides them to alignment controller  408 . 
     At task  605 , alignment controller  408  sets the azimuth and elevation of launch tube  402 . 
     At task  606 , power system  308  sequences electric current to coils  504 - 1  through  504 - 3  to propel payload  106 - 1  with the appropriate force for deploying payload  106 - 1  at its specified coordinates at the specified time. 
     Countermeasure deployment  600  repeats tasks  603  through  606  for each of payloads  106 - 2  and  106 - 3 , thereby forming complete decoy  110 . 
     It is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. For example, in this Specification, numerous specific details are provided in order to provide a thorough description and understanding of the illustrative embodiments of the present invention. Those skilled in the art will recognize, however, that the invention can be practiced without one or more of those details, or with other methods, materials, components, etc. 
     Furthermore, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the illustrative embodiments. It is understood that the various embodiments shown in the Figures are illustrative, and are not necessarily drawn to scale. Reference throughout the specification to “one embodiment” or “an embodiment” or “some embodiments” means that a particular feature, structure, material, or characteristic described in connection with the embodiment(s) is included in at least one embodiment of the present invention, but not necessarily all embodiments. Consequently, the appearances of the phrase “in one embodiment,” “in an embodiment,” or “in some embodiments” in various places throughout the Specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.