Abstract:
A technique for launching a missile 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 the missile clear of the launch platform—with sufficient velocity to attain aerodynamic flight—before the missile&#39;s engine is ignited.

Description:
FIELD OF THE INVENTION 
     The present invention relates to missilery in general, and, more particularly, to missile launchers. 
     BACKGROUND OF THE INVENTION 
     A missile is propelled by fuel and a chemical-propulsion engine. A chemical-propulsion engine propels a missile by the reaction that results from the rearward discharge of gases that are liberated when the fuel is burned. For the purposes of this specification, a “missile” is defined as a projectile whose trajectory is not necessarily ballistic and can be altered during flight (as by a target-seeking radar device and control elements). 
     When a missile is launched, the discharge of the hot gases causes several problems. First, the hot gases heat the launch platform, which renders the launch platform more visible to enemy infrared sensors and, therefore, more vulnerable to attack. Second, the hot gases can obscure the ability of personnel in the area of the launch platform to see, which might impair their ability to perform routine tasks, such as detecting enemy threats. Third, the brightness of the flame exiting the engine can—especially at night—temporarily blind the personnel in the area of the launch platform. Fourth, the missile&#39;s fuel often comprises an aluminized compound that is dispersed in the atmosphere surrounding the launch platform, which can impair the operation of radar systems near the launch platform. And fifth, as modern missiles become larger, their gases become hotter and more voluminous, and, therefore, cannot be adequately vented within the launching platform using current technology. 
     Therefore, the need exists for a technique for launching a missile that avoids or mitigates some or all of these problems. 
     SUMMARY OF THE INVENTION 
     The present invention provides a technique for launching a missile 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 the missile clear of the launch platform—with sufficient velocity to attain aerodynamic flight—before the missile&#39;s engine is ignited. This mitigates some of the problems associated with launching missiles in the prior art. 
     The illustrative embodiment comprises: a missile; a sled; a guide for substantially constraining the motion of the sled to a line; a first coil that is substantially immovable with respect to the guide; and a second coil that is substantially immovable with respect to the sled; wherein the flow of electric current in the first coil and the second coil induces the sled to move with respect to the guide and to throw the missile. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a representational diagram of a ship-borne multi-cell electromagnetic launch system in accordance with the illustrative embodiment. 
         FIG. 2  depicts a schematic diagram of multi-cell electromagnetic launch system  102 . 
         FIG. 3  depicts a schematic diagram of power system  210  in accordance with the illustrative embodiment. 
         FIG. 4  depicts a representational diagram of multi-cell electromagnetic launcher  204  in accordance with the illustrative embodiment. 
         FIG. 5  depicts a cross-sectional view of launch cell  426 -i at the beginning of a representative launch sequence (as described with respect to  FIG. 10 ), in accordance with the illustrative embodiment. 
         FIG. 6  depicts a cross-sectional view of the same electromagnetic launch cell  426 -i depicted in  FIG. 5 , but wherein sled  532 -i is shown near the end of its travel at the end of the representative launch sequence. 
         FIG. 7  depicts an alternative embodiment of the present invention prior to a launch a representative launch sequence (such as that described with respect to  FIG. 10 ), respectively. 
         FIG. 8  depict an alternative embodiment of the present invention at the end of a representative launch sequence (such as that described with respect to  FIG. 10 ), respectively. 
         FIG. 9A  depicts a cross-sectional view of sled  532 -i in accordance with the illustrative embodiment of the current invention. 
         FIG. 9B  depicts a cross-sectional view of missile  428 -i in accordance with the illustrative embodiment of the current invention. 
         FIG. 10  depicts a representative launch sequence according to the illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts a representational diagram of a naval launch system in accordance with the illustrative embodiment. Although launch system  102  is mounted on the deck of a warship, it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which launch system  102  is terrestrially-based or is mounted on another type of vehicle (e.g., a truck, a railroad car, a submarine, a space vehicle, a satellite, etc.) 
       FIG. 2  depicts a schematic diagram of the salient components of launch system  102 . Launch system  102  comprises multi-cell electro-magnetic launcher  204 , weapons control system  206 , launch controller  208 , power system  210 , return power bus  211 , propulsion current bus  212 , signal line  213 , and data bus  214 . 
     Launcher  204  is a system that has the capability to house and expel one or more missiles upon command. The system expels each missile from its cell using an electromagnetic catapult and without the aid of the missile&#39;s chemical-propulsion engines. This is advantageous because it enables the missile to clear the launch platform before it ignites its engine, which mitigates the deleterious effects of the engine&#39;s ignition near the launch platform. 
     Weapons control system  206  provides targeting and flight information and firing authority to launch controller  208  prior to and during a launch sequence. It will be clear to those skilled in the art, after reading this disclosure, how to make and use weapons control system  206 . 
     Launch controller  208  provides the targeting and flight information to a missile prior to launch and the directive to launch to power system  210 . 
     Power system  210  comprises circuitry that conditions and manages the storage and delivery of power to, and the recover of power from, launcher  204  in response to signals from launch controller  208 . Power system  210  controls power generation, scavenging, storage, and delivery prior to, during, and after each launch. Power system  210  is described in detail below and with respect to  FIG. 3 . 
     Propulsion current bus  212  carries power from power system  210  to each launch cell within launcher  204 . Return power bus  211  carries scavenged power from each launch cell within launcher  204  to power system  210 . 
     Signal line  213  connects launch controller  208  to power system  210  and carries the commands that direct power system  210  to initiate and control the launch of a missile. Data bus  214  carries the targeting information from launch controller  208  to the missiles and sled position information from sled-position sensor  560  (shown in  FIG. 5 ) to launch controller  208 . 
       FIG. 3  depicts a schematic diagram of the salient components of power system  210  in accordance with the illustrative embodiment. Power system  210  comprises electrical system  316 , energy storage device  318 , current controller  322 , launch cell power controller  324 , and return power conditioner  320 . 
     Launch cell power controller  324  comprises circuitry for delivering electricity to the appropriate launch cell of launcher  204  under the direction of current controller  322 . 
     Current controller  322  comprises circuitry for conditioning and controlling delivery of electric current from energy storage device  318  to launch cell power controller  324 . In response to firing signals from launch controller  208 , delivered on signal line  213 , current controller  322 , together with launch cell power controller  324 , delivers electric current to the launch cells of launcher  204  on propulsion current bus  212 . 
     Energy storage device  318  is an electrical capacitor system that is capable of transferring high voltage/amperage electrical current to the launch cells of launcher  204 . It will be clear to those skilled in the art how to make and use energy storage device  318 . Although energy storage device  318  is an electrical capacitor system, it will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the present invention in which energy storage device  318  is a rotational mass power storage system, or any other power storage system capable of transferring high voltage/amperage electrical current. 
     Electrical system  316  comprises an electrical generator and power conditioning circuitry that charges energy storage device  318  in well-known fashion to supply electricity to launcher  204 . It will be clear to those skilled in the art how to make and use electrical system  316 . 
     Return power conditioner  320  comprises electrical circuitry, in well-known fashion, that recharges energy storage device  318  with the electrical energy on return power bus  211 . 
     In general, current controller  322  and energy storage device  318  deliver electrical energy to launch cell power controller  324 , upon receipt of a firing command from launch controller  208 , via signal line  213 . Launch cell power controller  324  then delivers the electrical energy to the appropriate cell of launcher  204  via propulsion current bus  212 . Return power bus  211  carries energy scavenged during a launch (as will be described below in detail and with regard to  FIGS. 5 through 8 ) to return power conditioner  320 , which conditions the energy and delivers it to energy storage device  318 . 
       FIG. 4  depicts a representational diagram of launcher  204  in accordance with the illustrative embodiment. Launcher  204  comprises eight (8) launch cells  426 - 1  through  426 - 8 , data bus  214 , propulsion current bus  212 , return power bus  211 , and missile  428 -i wherein i is a positive integer in the set {1, . . . 8}. 
     Data bus  214  comprises eight (8) data lines  430 - 1  through  430 - 8 , and each of the data lines feeds one of the launch cells. Propulsion current bus  212  comprises eight (8) propulsion current lines  432 - 1  through  432 - 8 , and each of the data lines feeds one of the launch cells. Return power bus  211  comprises eight (8) return power lines  434 - 1  through  434 - 8 , and each of the data lines feeds one of the launch cells. Although the illustrative embodiment comprises 8 launch cells, it will be clear to those skilled in the art, after reading this disclosure, how to make and use embodiments of the present invention that comprise any number of launch cells. 
       FIG. 5  depicts a cross-sectional view of launch cell  426 -i at the beginning of a representative launch sequence (as described with respect to  FIG. 10 ), in accordance with the illustrative embodiment. Launch cell  426 -i comprises: canister  530 -i, missile  428 -i, sled  532 -i, sled restraint bolt  539 , missile restraint bolts  533 -i, sled coil  534 -i, canister to sled current conductors  535 -i, guide  538 -i, first coil  536 - 1 -i, second coil  536 - 2 -i, third coil  542 -i, canister-to-sled umbilical  546 -i, sled-to-missile umbilical  544 -i, and fly-through cover  548 -i, sled-position sensor  560 -i, and reflector  561 -i. Each launch cell in launcher  204  is identical and operates independently of the other launch cells. 
     Canister  530 -i, together with fly-through cover  548 -i, encloses sled  532 -i, sled restraint bolt  539 , missile restraint bolts  533 -i, sled coil  534 -i, missile  428 -i, guide  538 -i, canister to sled umbilical  546 -i, sled to weapon umbilical  544 -i, first coil  536 - 1 -i, second coil  536 - 2 -i, and third coil  542 -i to provide a substantially air-tight environment, in well-known fashion. 
     Missile  428 -i comprises an explosive warhead, a chemical-propellant engine, and an accelerometer. Missile  428 -i is described in detail below and with respect to  FIG. 9B . It will be clear to those skilled in the art, after reading this disclosure, how to make and use missile  428 -i. 
     Sled  532 -i comprises a rigid platform of suitable size for holding missile  428 -i, and comprises bearings  954 -i. Prior to a launch, sled  532 -i is rigidly attached to canister  530 -i by sled restraint bolt  539 , and missile  428 -i is attached to sled  532 -iby missile restraint bolts  533 -i. 
     Sled restraint bolt  539  is commonly and colloquially called a “dog bone.” Sled restraint bolt  539  is designed to break when subjected to a tensile force above a specific and pre-determine threshold. It will be clear to those skilled in the art, after reading this disclosure, how to make and use sled restraint bolt  539 . 
     Missile restraint bolts  533 -i are actuatable (e.g., explosive, electromagnetic, etc.) in order to proactively unfasten missile  428 -i from sled  532 -i at the proper instant. It will be clear to those skilled in the art, after reading this disclosure, how to make and use missile restraint bolts  533 -i. 
     Bearings  954 -i and position sensor  561 -i (which are depicted in  FIG. 9A ) are also enclosed by canister  530 -i but are omitted from  FIGS. 5 through 8  for clarity. Sled  532 -i holds sled coil  534 -i such that sled coil  534 -i has a helical shape and is substantially immovable with respect to sled  532 -i. Sled  532 -i is described in detail below and with respect to  FIG. 9A . It will be clear to those skilled in the art, after reading this disclosure, how to make and use sled  532 -i. 
     Sled coil  534 -i comprises a helical coil of electrical conductor, capable of carrying sufficiently high voltage/amperage to enable sufficient launch power, and sled coil  534 -i is substantially immovable with respect to sled  532 -i. Sled coil  534 -i generates an electromagnetic force along axis  540 -i when energized with electric current. The direction of electromagnetic force generated by sled coil  534 -i along axis  540 -i depends on the direction of current flow in sled coil  534 -i. 
     Canister-to-sled current conductors  535 -i comprise electrical conductors of sufficient length to span the length of travel of sled  532 -i during a launch. Canister-to-sled current conductors  535 -i provide electrical connection of sled  532 -i to power system  210  throughout the entire launch. 
     Guide  538 -i comprises four vertical members that provide structural support for canister  530 -i and first coil  536 - 1 -i, second coil  536 - 2 -i, and third coil  542 -i which are affixed to guide  538 -i in a substantially-immovable manner. Guide  538 -i also provides straight, smooth tracks against which bearings  954 -i ride during a launch. Although the illustrative embodiment comprises four (4) vertical structural members, it will be clear to those in skilled in the art, after reading this disclosure, how to make and use embodiments of the present invention that comprise any number of vertical structural members. 
     First coil  536 - 1 -i and second coil  536 - 2 -i each comprise a helix of electrical conductor, wherein each helix has an inner diameter larger than the outer diameter of sled coil  534 -i, and wherein the electrical conductor is capable of carrying sufficiently high voltage/amperage to enable sufficient launch power. First coil  536 - 1 -i and second coil  536 - 2 -i each generate electromagnetic force along axis  540 -i when energized with electric current. The direction of electromagnetic force generated along axis  540 -i by each of first coil  536 - 1 -i and second coil  536 - 2 -i depends on the direction of current flow in that coil. It will be clear to those skilled in the art, after reading this disclosure, how to make and use first coil  536 - 1 -i and second coil  536 - 2 -i. 
     Third coil  542 -i comprises a helix of electrical conductor, wherein the helix has an inner diameter larger than the outer diameter of sled coil  534 -i and third coil  542 -i is substantially immovable with respect to guide  538 -i. During a launch, third coil  542 -i is used to recover some of the kinetic energy of moving sled  532 -i as electric current and return the recovered power to energy storage device  318  through return power bus  211  and return power conditioner  320  as is described in detail below and with respect to  FIG. 6 . It will be clear to those skilled in the art, after reading this disclosure, how to make and use third coil  542 -i. 
     Sled-position sensor  560 -i is an optical range-finding device on the bottom of canister  530 -i. Sled-position sensor  560 -i transmits an optical beam at reflector  561 -i, which is located on the bottom of sled  532 -i, and determines the position of sled  532 -i based on the time-of-travel of the reflected beam. The position of sled  532 -i is used by launch controller  208  to sequence current flow in first coil  536 - 1 -i and second coil  536 - 2 -i. It will be clear to those skilled in the art, after reading this disclosure, how to make and use sled-position sensor  560 -i and reflector  561 -i. 
     Prior to the launch, targeting information is passed from launch controller  208  to missile  428 -i via canister to sled umbilical  546 -i and sled to missile umbilical  544 -i. Canister-to-sled current conductors  535 -i connect power system  210  to sled  532 -i throughout a launch. 
     During the representative launch sequence, sled coil  534 -i and first coil  536 - 1 -i are energized with current supplied by power system  210 -i on propulsion current line  432 -i. Launch cell power controller  324 -i controls the flow of electric current in sled coil  534 -i, which is substantially immovable with respect to sled  532 -i. Launch cell power controller  324 -i also controls the flow of electric current in first coil  536 - 1 -i and second coil  536 - 2 . The current flow is controlled such that a first electromagnetic force is generated along axis  540 -i by sled coil  534 -i, and a second electromagnetic force is generated along axis  540  by first coil  536 - 1 -i. The direction of the forces is made so as to cause a propulsion force on sled  532 -i that is directed upward along axis  540 -i. When the magnitude of the propulsion force exceeds a pre-determined threshold, sled restraint bolt  539  releases, and sled  532 -i is allowed to travel upward along axis  540 -i. 
     As sled  532 -i travels along axis  540 -i, launch cell power controller  324  sequences the flow of current in first coil  536 - 1 -i and second coil  536 - 2 -i in order to substantially maximize propulsion of sled  532 -i. The illustrative embodiment comprises two propulsion coils, first coil  536 - 1 -i and a second coil  536 - 1 -i. It will be clear to those skilled in the art, however, after reading this specification, how to make and use alternative embodiments of the present invention that comprise any number of coils that are:
         i. continuous; or   ii. separate and on any suitable spacing; or   iii. inter-leaved along the length of guide  538 -i; or   iv. any combination of i, ii, and iii.       

       FIG. 6  depicts a cross-sectional view of the same electromagnetic launch cell  426 -i depicted in  FIG. 5 , but wherein sled  532 -i is shown near the end of its travel at the end of the representative launch sequence. Near the end of the representative launch sequence, missile  428 -i passes through fly-through cover  548 -i and sled-to-missile umbilical  544 -i detaches from missile  428 -i. Missile  428 -i is thrown from sled  532 -i (i.e., separation occurs) with velocity sufficient to achieve aerodynamic stability. 
     As sled  532 -i approaches the end of its travel along axis  540 -i, power system  210  institutes a change in current flow in sled coil  534 -i, first coil  536 - 1 -i, and second coil  536 - 2 -i to generate attractive electromagnetic force along axis  540 -i between sled coil  534 -i, first coil  536 - 1 -i, and second coil  536 - 2 -i to decelerate and stop sled  532 -i. Just prior to deceleration, missile restraint bolts  533 -i are actuated and missile  428 -i is released from sled  532 -i and missile  428 -i continues to exit the canister. Current flow is maintained in sled coil  534 -i as sled  532 -i decelerates and passes through third coil  542 -i. The sled&#39;s kinetic energy is absorbed by third coil  542 -i and returned to energy storage device  318  via return power current bus  211  and return power conditioner  320 . The energy scavenging process is analogous to the generation of electric power by rotor coils passing by fixed permanent magnets in a conventional electric generator. 
       FIGS. 7 and 8  depict an alternative embodiment of the present invention at times prior to a launch and at the end of a representative launch sequence (such as that described with respect to  FIG. 10 ), respectively. Referring to  FIG. 7 , launch cell  426 -i comprises: canister  750 -i, missile  428 -i, sled  532 -i, missile restraint bolts  533 -i, sled coil  534 -i, canister to sled current conductors  535 -i, guide  538 -i, first coil  536 - 1 -i, second coil  536 - 2 -i, third coil  542 -i, canister-to-sled umbilical  546 -i, sled-to-missile umbilical  544 -i, fly-through cover  548 -i, and launch structure  752 -i. Each launch cell in launcher  204  is identical and operates independently of the other launch cells. 
     Canister  750 -i, together with fly-through cover  548 -i, encloses sled  532 -i, sled coil  534 -i, missile  428 -i, missile restraint bolts  533 -i, guide  538 -i, canister to sled umbilical  546 -i, and sled to weapon umbilical  544 -i to provide a substantially air-tight environment, in well-known fashion. 
     In the alternative embodiment depicted in  FIGS. 7 and 8 , first coil  536 - 1 , second coil  536 - 2 , and third coil  542 , are substantially immovable with respect to launch structure  752 -i and are located outside canister  750  (as opposed to within canister  530  in the illustrative embodiment). In order to facilitate the generation of sufficient force between the electromagnets comprising sled coil  534  and each of first coil  536 - 1  and second coil  536 - 2 , the walls of canister  750  are thin and constructed of a non-magnetic material. Suitable materials for use in canister walls include polymers, aluminum, ceramics, titanium, and some non-magnetic stainless steels. 
       FIG. 9A  depicts a cross-sectional view of sled  532 -i in accordance with the illustrative embodiment of the current invention. Sled  532 -i comprises sled coil  534 -i, and bearings  954 -i, reflector  561 -i, and sled-to-missile umbilical  544 -i. 
     Each of bearings  954 -i comprises rollers that enable smooth travel of sled  532 -i along guide  538 -i. It will be clear to those skilled in the art, after reading this disclosure, how to make and use alternative embodiments of the current invention in which bearings  954 -i comprise ball bearings, roller bearings, Teflon-coated glide plates, or lubricated glide plates. 
       FIG. 9B  depicts a cross-sectional view of missile  428 -i in accordance with the illustrative embodiment of the current invention. Missile  428 -i comprises warhead  958 -i, chemical-propulsion engine  960 -i, and accelerometer  962 -i. 
     Accelerometer  962 -i provides a signal that is used to (i) blow bolts  533 -i and (ii) initiate ignition of chemical-propellant engine  960 -i. Bolts  533 -i are blown at the instant that sled  532 -i and missile  428 -i begin to decelerate (i.e., are at the maximum velocity), and chemical-propellant engine  960 -i is ignited once missile  428 -i has achieved sufficient clearance from multi-cell electromagnetic launcher  102  but before missile  428 -i has lost aerodynamic stability. It will be clear to those skilled in the art, after reading this disclosure, how to make and use accelerometer  962 -i. Furthermore, 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 use other means of initiating ignition of chemical-propellant engine  960 -i such as a signal from an altimeter, a timing circuit, a fuse, or signal transmitted to missile  428 -i from weapons control system  206 . 
       FIG. 10  depicts a flowchart of the salient tasks associated with a representative launch sequence, in accordance with the illustrative embodiment. Launch sequence  1000  comprises: 
     At task  1001 , weapons control system  206  passes launch authority and targeting information to launch controller  208 ; 
     At task  1002 , launch controller  208  passes target information to missile  428 -i; 
     At task  1003 , launch cell power controller  324  electrifies first coil  536 - 1 -i and sled coil  534 -i in order to generate a propulsive force on sled  532 -i in order to propel sled  532 -i upward along axis  540 -i; 
     At task  1004 , launch cell power controller  324  sequences the current in first coil  536 - 1 -i and second coil  536 - 2 -i in order to substantially maximize propulsion of sled  532 -i; 
     At task  1005 , bolts  533 -i are blown and missile  428 -i is thrown from sled  532 -i; 
     At task  1006 , third coil  542 -i captures the kinetic energy associated with moving, energized sled  532 -i; 
     At task  1007 , current controller  322  changes the current in sled coil  534 -i and first and second coils  536 - 1 -i and  536 - 2 -i in order to change the generated force on sled  532 -i from propulsive to attractive; and 
     At task  1008 , the ignition of chemical-propellant engine  960 -i is initiated after missile  428 -i has achieved sufficient distance from multi-cell electromagnetic launch system  102 . 
     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.