Abstract:
Methods and apparatus for delivering a missile may operate in conjunction with a missile comprising an outer skin. The missile may be configured in a closed position and an open position. In the open position, an aperture is opened in the outer skin, for example to supply air to an air-breathing engine. In the closed position, the aperture is closed.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to air inlets, such as air inlets for missiles.  
       BACKGROUND OF THE INVENTION  
       [0002]     A cannon-fired missile typically operates in a series of steps. A first launching charge provides the pressure required to eject the missile from a gun barrel in a desired direction. After this discharge step, the missile initiates a propulsion system, such as a propulsion force comes from an engine contained in the missile body. Engines used in missile design include rocket engines, gas turbine engines, and pulse jet engines, among others. Operation of a gas turbine or other air-breathing engine may require that the missile provide those systems typical of turbine operation, including for example, an air flow system from the exterior region of the missile to an engine inlet. Thus, designs for cannon-fired missiles often call for openings in the missile body that allow air to be pulled from the exterior of the missile and into the turbine engine section. In typical turbine engine operation, the air (or a portion of the air) that is pulled into the turbine engine section is then compressed, mixed with fuel, ignited, and discharged through a nozzle section to propel the missile.  
         [0003]     A missile structure, and particularly those missile structures associated with cannon-fired missiles, may be subjected to high G forces during launching, including set back and balloting forces. Additionally, post-launching actions, such as air guide deployment and engine start-up, may further stress the missile structure. During flight missiles may also encounter the general turbulence and stresses associated with projectile flight. However, openings in the missile skin, such as an opening to allow air flow from the exterior of the missile to the interior of the missile, may present points of weakness in the missile structure.  
         [0004]     Space and weight are often important factors in turbine engine design. This minimal engine weight then allows, among other advantages, for the range of the missile to be extended.  
       SUMMARY OF THE INVENTION  
       [0005]     Methods and apparatus for delivering a missile may operate in conjunction with a missile comprising an outer skin. The missile may be configured in a closed position and an open position. In the open position, an aperture is opened in the outer skin, for example to supply air to an air-breathing engine. In the closed position, the aperture is closed.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in connection with the following illustrative figures. In the following figures, like reference numbers refer to similar elements and steps throughout the figures.  
         [0007]      FIG. 1  is a perspective view of a missile that may include an air inlet with a multi-position air frame according to an embodiment of the present invention;  
         [0008]      FIG. 2  is cut-away view of an aft portion of the missile;  
         [0009]      FIG. 3  is a cross-sectional view of a portion of the missile in a closed position;  
         [0010]      FIG. 4  is a cross-sectional view of a portion of the missile in an open position; and  
         [0011]      FIG. 5  illustrates a trajectory of a missile. 
     
    
       [0012]     Elements and steps in the figures are illustrated for simplicity and clarity and have not necessarily been rendered according to any particular sequence. For example, steps that may be preformed concurrently or in different order are illustrated in the figures to help to improve understanding of embodiments of the present invention.  
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0013]     The present invention may be described in terms of functional block components and various processing steps. Such functional blocks may be realized by any number of hardware or software components configured to perform the specified functions and achieve the various results. For example, a system according to various aspects of the present invention may employ various frameworks, telescoping mechanisms, slidable elements, air inlet apertures, and the like, which may carry out a variety of functions. In addition, the present invention may be practiced in conjunction with any number of missile systems, projectiles, and/or inlet systems, and the system described is merely one exemplary application for the invention. Further, a system according to the present invention may employ any number of conventional techniques for opening and/or closing an aperture, forming the aperture, and the like.  
         [0014]     Referring now to  FIGS. 1 and 2 , a missile  10  according to various aspects of the present invention is configured to selectively open an aperture  19  after launch, for example to admit air for an air-breathing engine. The missile  10  may include any suitable components, such as an outer skin  11 , a nose section  12 , and an aft section  13 . The missile  10  may include control surfaces to control flight, such as aft fins  14  positioned on the aft section  13  of the missile  10  and forward canards  15  on the nose section  12 . The missile  10  may comprise a self-propelled missile, and may also include one or more engine outlets  16  or nozzles positioned on the aft section  13 . An engine  21  may comprise any suitable engine for propelling the missile  10 , for example a gas turbine engine, rocket engine, and pulse jet engine.  
         [0015]     The outer skin  11  suitably defines an exterior  17  and interior region  18  of the missile  10 . The outer skin  11  may comprise any suitable material configured to define at least a portion of the exterior surface of the missile  10 . Positioned within the interior region  18  of the missile  10 , though not fully illustrated in  FIG. 1 , are any suitable missile components, such as a fuel tank  22 , the engine  21 , a guidance system, and a payload, for example an explosive charge. Also positioned within the interior region  18  of missile  10  is a structural framework or airframe. The framework may comprise any suitable system for providing support to the outer skin  11 . The outer skin  11  may be affixed to the framework, for example via rivets, welds, or other suitable attachment mechanism.  
         [0016]     The missile  10  may be configured to assume a closed position in which the aperture  19  is closed. For example, the missile  10  may be configured to be launched through a gun barrel. In one embodiment, when configured for gun barrel launch, the forward canards  15  and aft fins  14  can be positioned flush with the outer skin  11 . Additionally, the engine outlet  16  may be sealed or covered so as to allow a pressure charge to impinge on the aft section  13  of the missile  10  without damage to the engine or engine components. During launch, aperture  19  may be closed. The closure of aperture  19  for launch inhibits high pressure gases from entering into the interior region  18  of missile  10  so as to avoid damage from the gases. Further, the interface where the nose section  12  meets the aft section  13  may be configured to transfer and sustain structural loads associated with launch. For example, the interface may include a stepped lip on each of the nose section  12  and the aft section  13  where the nose section  12  and aft section  13  meet that are configured to mate.  
         [0017]     The missile  10  may be configured to expose the aperture  19  formed in the outer skin  11  of the missile  10  after launch. The aperture  19  may be configured in any suitable manner, such as an annular aperture  19  formed in the outer skin  11 . In an open position, the aperture  19  facilitates air flow from the exterior region  17  of the missile, through the aperture  19 , and into the air-breathing engine  21 .  
         [0018]     The present exemplary missile  10  may open the aperture  19  to expose an air passageway  23  defined by at least one passageway surface, such as a first air surface  24  and a second air surface  25 . The first air surface  24  and second air surface  25  may comprise any suitable surfaces or structures, for example to direct air into an air inlet  28  of the engine  21 . In one embodiment, the first air surface  24  and second air surface  25  each have, at least in part, a generally conical or frusto-conical, shape. The first air surface  24  may be defined by a first conical structure  26 , and the second air surface  25  may be defined by a second conical structure  27 . The first air surface  24  and second air surface  25  may be coordinated in shape and position so as to provide the air passageway  23  with desired airflow properties.  
         [0019]     The missile  10  may include an aperture control system to selectively open the aperture  19  to expose the air passageway  23 . The aperture control system may comprise any suitable system for selectively opening the aperture  19 . For example, referring now to  FIGS. 3 and 4 , the aperture control system may be connected to the outer skin  11 , either directly to the outer skin  11  or indirectly, for example via the framework. In the present embodiment, the aperture control system comprises a telescoping mechanism  35  that moves the aft section  13  and the associated aft skin section relative to the nose section  12  and the associated nose skin section between a closed position ( FIG. 3 ) and an open position ( FIG. 4 ). In one embodiment, the telescoping mechanism  35  includes multiple sets of slidable arms  31 . The slidable arms  31  can move longitudinally from the closed to the open position. The slidable arms  31  are connected to and/or form a portion of the missile framework, and the slidable arms  31  provide a point in the framework at which the framework can extend longitudinally. By moving from the closed to the open position, the slidable arms  31  act to open aperture  19  in the outer skin  11  of missile  10 . The longitudinal movement of the slidable arms  31  from the closed to the open position also acts to extend the overall length of missile  10 . The slidable arms  31  may also provide a structural joint in the airframe structure of missile  10 . The slidable arms  31  are positioned and structured so as to withstand torsional movement that arises from rotation of missile  10 . The slidable arms  31  further withstand the longitudinal pressures and stresses that the missile  10  experiences during flight as well as during launch.  
         [0020]     The slidable arms  31  may be connected to the structural framework of the missile  10 . Forces upon the missile  10  can be transferred from a forward position to an aft position, and vice versa, through the slidable arms  31 . The connection between slidable arms  31  and the framework may comprise conventional connections, such as integral connections, rivets, bolts, and/or welds. In one embodiment, one member, either a male member  32  or female member  33 , is connected to a forward section of the structural framework, and the counterpart member is connected to the opposite section of the structural framework. A typical structural framework used in missile construction may have forms that are lattice-like or honeycombed in overall configuration. The components of the missile  10 , including the structural framework, outer skin  11 , aft fins  14 , forward canards  15 , and slidable arms  31 , may be constructed of conventional materials, such as aluminum or aluminum alloys for missiles and steel or titanium for projectiles.  
         [0021]     In the present embodiment, each slidable arm  31  each includes a male member  32  and a female member  33 . Each pair of male member  32  and female member  33  may be formed so as to allow longitudinal movement between them. The longitudinal movement allowed is sufficient to permit the slidable arms  31  to move from the closed position, as shown in  FIG. 3 , to the open position, illustrated in  FIG. 4 . The male member  32  and female member  33  can take any suitable shape, such as square or rectangular in cross section. The reciprocal rectangular shape allows for a slidable fitting between members  32 ,  33  for longitudinal movement while resisting the twisting that arises from torsional movement of the missile  10 .  
         [0022]     When the male member  32  and female member  33  in the closed or the open position, a locking mechanism (not shown) may resist longitudinal movement of the slidable arms  31 . When a missile  10  is fired from a gun, the slidable arms  31  may locked in the closed position. The locking mechanism for the slidable arms  31  is capable of being unlocked so that, after firing, the slidable arms  31  can move to the open position. The locking mechanism may be selected from any suitable locking mechanism and/or actuator, such as explosive bolts, spring locks, and solenoid-activated bolts.  
         [0023]     When in the open position, as seen in  FIG. 4 , the slidable arms  31  may lock in the open position. The locking mechanism may be any suitable locking mechanism and/or actuator, such as spring locks and solenoid-activated bolts. The degree of locking may be sufficient to resist the torsional and longitudinal forces that the missile  10  encounters during launch and flight.  
         [0024]     The movement of the slidable arms  31  causes a movement of the missile structure along the longitudinal axis of missile  10 . The longitudinal movement of the slidable arms  31 , and the corresponding movement of the missile structure, aligns the first air surface  24  and the second air surface  25 . The degree of travel that occurs in transitioning the missile  10  from the closed to the open position separates these surfaces by a desired amount so as to provide a desired shape to the air passageway  23 .  
         [0025]     The aperture  19  may admit air substantially at all angular positions relative to the longitudinal axis of the missile  10 . In such an embodiment, any obstructions, including the slidable arms  31 , do not significantly restrict air flow through the aperture. The slidable arms  31  may exhibit a small enough cross-section so as not to unduly inhibit air flow through the aperture.  
         [0026]     Referring now to  FIG. 5 , the missile  10  may be loaded into a gun  51 , aircraft, submarine, or other system capable of launching the missile  10 . The missile  10  is initially in the closed posisiton. In the closed position, missile  10  is capable of withstanding the pressures and stresses that would be encountered from firing so as to operate as intended after firing. Further, the aperture  19  may be sealed when in the closed position to inhibit damage to the missile  10  occurring from the penetration of gases through the closure seal into the interior of the missile  10 .  
         [0027]     After the missile  10  is launched, the missile  10  may travels for a distance as a ballistic projectile without any self-propelled force. At some time after firing, the missile  10  may move to the open position and fire the engine  21  to initiate self-propelled flight. The trigger to convert to the open position and begin powered flight can be any suitable event, such as a time after launch or when the missile reaches a desired trajectory point  52 , for example the apogee of the cannon-fired trajectory. Upon opening, missile  10  exposes aperture  19 . The opening of aperture  19  allows engine  21  to receive air through air passageway  23  and into an air inlet  28 . During normal engine operation, the air mixes with fuel, burns, and exits through the nozzle. The continuous operation of the engine may draw a continuous flow of air through aperture  19 .  
         [0028]     The missile  10  may continue powered flight along a desired path  53  until it reaches a desired point in its flight path. The missile  10  can be directed to its target  54  under power or through free fall.  
         [0029]     While the invention has been described with reference to an exemplary embodiment, various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.