Abstract:
A compact, purely mechanical wing deployment assisting mechanism uses torsion springs and lever arms to apply a deploying force to a guidance wing during its initial deployment through a wing slot in a rocket or missile, thereby assisting the wing to burst through a cover seal protecting the wing slot. The wings are then fully deployed by centrifugal force. Various embodiments include two “extreme duty” springs and two lever arms per wing, working in parallel. Embodiments provide a total of at least 24 pounds of force per wing at the end of a spring travel of 0.30 inches. In some embodiments, the entire mechanism weighs less than 0.5 pounds and/or occupies less than 2.5 cubic inches per wing. In embodiments, an assembled group, including two springs and two lever arms, is located between each pair of wings, whereby each assembled group applies one lever arm to each adjoining wing.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/322,461, filed Apr. 9, 2010, herein incorporated by reference in its entirety for all purposes. 
     
    
     STATEMENT OF GOVERNMENT INTEREST 
       [0002]    The invention was made with United States Government support under Contract No. W31P4Q-06-C-0330 awarded by the Navy. The United States Government has certain rights in this invention. 
     
    
     FIELD OF THE INVENTION 
       [0003]    The invention relates to ballistic weaponry, and more particularly to apparatus for deploying guidance wings on folding fin aerial rockets and missiles. 
       BACKGROUND OF THE INVENTION 
       [0004]    Aerial rockets and missiles which include folded, deployable guidance wings have been in use at least since the late 1940&#39;s, with the FFAR (Folding Fin Aerial Rocket) being used in the Korean and Vietnam conflicts, and the more recent Hydra 70 family of WAFAR (Wrap-Around Fin Aerial Rocket) and Advanced Precision Kill Weapon System (APKWS) laser guided missile. For many such weapons, the guidance wings are folded in a stowed configuration within the main fuselage until the weapon is launched, at which point the wings deploy outward through slots provided in the fuselage. 
         [0005]    Typically, a rocket or missile is spun during its flight for increased accuracy and stability. For many missiles and rockets with folded, deployable guidance wings, the guidance wings are released from their folded and stowed configuration upon launch, and are deployed by the centrifugal force which results from the spinning of the weapon in flight. In some cases, the wing slots arc covered by frangible seals which protect the interior of the missile from moisture and debris during storage, transport, and handling. In these cases the guidance wings must be deployed with sufficient initial force to enable them to penetrate the seals. 
         [0006]    Clearly, wing deployment through frangible cover seals becomes more dependable as the initial deployment force is increased. However, there is a practical limit to how rapidly a missile can be spun. In one example, the average centrifugal force on the tip of a guidance wing at the beginning of deployment is only approximately 7.7 pounds at the minimum spin rate. This amount of centripetal energy may not be sufficient by itself to enable the wings to burst through the frangible slot covers. As a result, some weapons that include deployable folded guidance wings and frangible wing slot covers have demonstrated a tendency for the guidance system to fail due to a lack of proper guidance wing deployment. This problem can be addressed by a wing deployment initiator, which assists the deployment of the guidance wings by providing an initial burst of energy to help the wings break through the frangible covers. 
         [0007]    In some designs, the wing deployment initiator uses explosives to push the wings through the frangible covers. However, this approach can be undesirable due to the violent forces produced by the explosives, and due to concerns about the safety and the long-term chemical stability of the explosives during storage of the weapon. 
         [0008]    A mechanical solution would be desirable. However, only very limited space is available for a wing deployment initiator to occupy. Also, the weight of the deployment initiator must be as low as possible. Therefore, it can be very difficult to provide a mechanical wing deployment initiator which can provide sufficient force to enable the guidance wings to break through the frangible covers while also fitting within the available space and remaining sufficiently light in weight. 
         [0009]    What is needed, therefore, is a mechanical wing deployment initiator which will not add excessive weight to a missile or rocket, will fit within available space within the guidance wing storage region of the missile or rocket, and will provide sufficient added force during the initial guidance wing deployment so as to ensure that the wings are reliably able to burst through frangible wing slot cover seals and be fully deployed. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention is a mechanical wing deployment initiator for use with missiles and rockets which include deployable folded guidance wings. The deployment initiator provides added wing deployment force during the initial stage of wing deployment, so as to ensure that the guidance wings are able to burst through frangible seals covering the wing slots. Once the wings have burst through the seals, they are able to be fully and successfully deployed by the centrifugal force supplied by the spinning of the rocket or missile. In one embodiment, the deployment mechanism provides 24 pounds of initial deployment force, which is added to approximately 7 pounds of centrifugal force supplied by the spinning of the missile. 
         [0011]    The wing deployment mechanism of the present invention is light in weight and fits into a limited space within the guidance wing storage region of the missile or rocket. It uses a combination of torsion springs and lever arms to apply the required additional deployment force to the guidance wings as they break through the cover seals. In embodiments, each of the guidance wings is pushed by two “extreme duty” torsion springs and two lever arms. 
         [0012]    In some of these embodiments, the torsion springs and lever arms are combined into compactly assembled groups, whereby each assembled group includes a bracket on which are mounted two torsion springs and two lever arms. In these embodiments, the total number of assembled groups is equal to the total number of guidance wings, with one such assembled group being located between each pair of wings. For each of the assembled groups, one of the two lever arms pushes on the wing which is adjacent on the left, and the other lever arm pushes on the wing which is adjacent on the right, so that the two lever arms pivot about axes which differ in direction by an angle of 360°/N, where N is the number of guidance wings. For example, if there are four guidance wings, the two lever arms in each assembled group pivot about axes which differ in angle by 90°. Each wing in these embodiments is thereby pushed by two torsion springs and two lever arms, one of the springs and one of the lever arms being part of the assembled group which is adjacent to the wing on the left side, and the other spring and lever arm being part of the assembled group which is adjacent to the wing on the right side. 
         [0013]    In various embodiments, the two springs working in parallel create a mechanical advantage providing 24 pounds of force to each wing at the end of the spring travel, where the total spring travel is 0.30 inches. In embodiments, the lever arms focus the applied forces at the most accessible regions of the wings, which may not be near the ends of the wings. 
         [0014]    In some embodiments, the entire wing deployment mechanism weighs less than ½ pound and occupies less than 2.5 cubic inches per wing. 
         [0015]    The present invention is a wing deployment initiating mechanism for increasing an initial deployment force applied to a guidance wing of a rocket or missile so as to propel the guidance wing outward from a stowed configuration at least through an initial phase of movement toward a deployed configuration of the guidance wing. The wing deployment initiating mechanism includes at least one lever arm pivotally fixed to the rocket or missile, the lever arm being cooperative with the guidance wing so as to propel the guidance wing outward from the stowed configuration when the lever arm is pivoted outward, and at least one torsion spring cooperative with the lever arm and configured to apply a deploying force tending to pivot the lever arm outward. 
         [0016]    In embodiments, the torsion spring is an extreme duty torsion spring. 
         [0017]    In various embodiments, each guidance wing is propelled by two lever arms and two torsion springs. In some of these embodiments a first lever arm, a second lever arm, a first torsion spring, and a second torsion spring are included in a compact assembly. In certain of these embodiments the wing deployment assisting mechanism includes N compact assemblies, where N is the number of guidance wings included in the rocket or missile. In various of these embodiments a compact assembly is located between each pair of adjacent guidance wings. In some of these embodiments for each of the compact assemblies, the first torsion spring and the first lever arm apply a deploying force to the guidance wing on a first side of the compact assembly; and the second torsion spring and the second lever arm apply a deploying force to the guidance wing on a second side of the compact assembly. And in certain of these embodiments the first and second lever arms pivot about axes which differ in angle by 360°/N. 
         [0018]    In various embodiments the deploying force is sufficient to enable the guidance wing to break through a frangible seal covering a wing slot in a fuselage of the rocket or missile. 
         [0019]    In some embodiments the mechanism applies at least 24 pounds of deploying force to the wing at the end of a spring travel of 0.30 inches. In certain embodiments, the wing deployment assisting mechanism weighs less than 0.5 pounds. And in other embodiments the wing deployment assisting mechanism occupies less than 2.5 cubic inches per wing. 
         [0020]    The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a perspective view of an APKWS having just been launched from a helicopter, showing its guidance wings deployed; 
           [0022]      FIG. 2  is a perspective view showing the location of the guidance wing storage region of the present invention in an APKWS missile; 
           [0023]      FIG. 3A  is a perspective view showing the APKWS missile of  FIG. 2  in a vertical orientation; 
           [0024]      FIG. 3B  is a perspective view of an embodiment of the present invention shown outside of the missile in the vertical orientation of  FIG. 3A ; 
           [0025]      FIG. 4A  is an perspective view of the disassembled components of an assembled group of springs and lever arms from the embodiment of  FIG. 3B ; 
           [0026]      FIG. 4B  is a perspective view of the assembled group resulting from assembly of the components of  FIG. 4A ; 
           [0027]      FIGS. 5A through 5K  are engineering drawings which illustrate the design of an aft wing retaining plate of an embodiment of the invention; 
           [0028]      FIGS. 6A through 6M  are engineering drawings which illustrate the design of the bracket of the assembled group of  FIG. 4A ; 
           [0029]      FIGS. 7A through 7E  are engineering drawings which illustrate the design of the first lever arm of the assembled group of  FIG. 4A ; 
           [0030]      FIG. 8A through 8E  are engineering drawings which illustrate the design of the second lever arm of the assembled group of  FIG. 4A ; 
           [0031]      FIGS. 9A through 9C  are engineering drawings which illustrate the design of the pivot pins of the assembled group of  FIG. 4A ; 
           [0032]      FIGS. 10A through 10D  are engineering drawings which illustrate the design of the first torsion spring of the assembled group of  FIG. 4A ; 
           [0033]      FIGS. 11A through 11D  are engineering drawings which illustrate the design of the second torsion spring of the assembled group of  FIG. 4A ; 
           [0034]      FIGS. 12A through 12C  are engineering drawings which illustrate the design of the spring mandrels of the assembled group of  FIG. 4A ; 
           [0035]      FIG. 13A  is a side view of a guidance wing configured for use with the embodiment of  FIG. 3B ; and 
           [0036]      FIG. 13B  is a close-up side view of the tip of the guidance wing of  FIG. 13A , showing a notch used to secure the wing in the folded and stowed configuration. 
       
    
    
     DETAILED DESCRIPTION 
       [0037]    The present invention is a wing deployment initiating mechanism which provides added wing deployment force during the initial deployment of guidance wings on folded wing missiles and rockets, so as to augment the centrifugal wing deployment force during the initial phase of wing deployment and ensure that the wings are able to break through frangible seals which cover the wing deployment slots. After bursting through the seals, the wings are fully deployed by the centrifugal force which arises from the spinning of the missile in flight. 
         [0038]    With reference to  FIG. 1 , some aerial rockets and missiles  100  include guidance wings  102  which are typically folded within the main fuselage  104  in a stowed configuration until the weapon is launched, at which point the wings  102  are released and deployed through wing slots  106 . One example is the Advanced Precision Kill Weapon System (APKWS) laser guided missile  100 .  FIG. 1  illustrates an APKWS  100  having just been launched from a helicopter  108 , with its guidance wings  102  deployed. Additional APKWS missiles  110  are shown still attached to the helicopter  108  with their guidance wings not yet deployed. The wing slots  106  in these missiles  110  are covered by frangible cover seals, which protect the interior of the missile from dirt and debris before missile launch. Deployment of the guidance wings  102  therefore requires sufficient initial force to enable the wings  102  to break through the frangible cover seals. 
         [0039]    Some rockets or missiles that include guidance wings have demonstrated a tendency for the guidance system to fail due to a failure of the guidance wings to break through the frangible wing covers, and a resultant lack of proper wing deployment. This problem has been addressed in some designs by explosive deployment mechanisms. However, the sudden, violent force delivered by such mechanisms is not optimal, and the safety and long term chemical stability of the explosives can be a concern. 
         [0040]    The present invention addresses the problem of guidance wing deployment through a frangible cover seal by providing a purely mechanical wing deployment initiator which uses torsion springs to assist in the bursting of the guidance wings through the frangible wing slot covers.  FIG. 2  illustrates the guidance wing storage region  200  where an embodiment of the present invention is located within an APKWS missile  100 . 
         [0041]      FIG. 3A  is a perspective view of the APKWS missile  100  of  FIG. 2  in a vertical orientation facing downward.  FIG. 3B  illustrates a torsion spring wing deployment initiator embodiment of the present invention as it appears when it is not installed in a missile, the embodiment being shown in an orientation which corresponds with  FIG. 3A . The torsion spring wing deployment initiator embodiment  300  of  FIG. 3B  includes 8 lever arms  302 A,  302 B, and 8 torsion springs  304 ,  306 , whereby each lever arm  302 A,  302 B is driven by a torsion spring  304 ,  306  and each wing  102  is pushed by a pair of lever arms  302 A,  302 B and torsion springs  304 ,  306  to initiate its deployment. The torsion springs in the embodiment of  FIG. 3B  are classified as “extreme duty” springs which support end of life requirements. The lever arms  302 A,  302 B and torsion springs  304 ,  306  arc supported by four brackets  308  which arc fastened by screws  312  to an aft retainer plate  310 . Before deployment, the wings  102  are locked in their stowed position by tabs on the aft retainer plate  310  which engage with notches  314  provided in the wings. 
         [0042]    The present invention must provide sufficient wing initiating force to enable the wings  102  to break through the cover seals, while also being able to fit into the available space within the guidance wing storage region  200  of the missile  100 .  FIG. 4A  is a perspective view of a collection of components which can be assembled into a compactly assembled group  400  of springs and lever arms for installation within the guidance wing storage region. The embodiment  300  of  FIG. 3B  includes four of these assembled groups  400 , which are mounted by screws to the aft retaining plate  310  and located in the spaces between the four guidance wings  102 . Each assembled group  400  of components includes two lever arms  302 A,  302 B, and two torsion springs  304 ,  306 . The torsion springs  304 ,  306  are rotatably mounted on mandrels  402  which pivot about mounting pins  404 . The lever arms  302 A,  302 B pivot about lever arm pins (see  600 A,  600 B of  FIG. 6A ) which are attached to the bracket  308  and inserted into mounting holes  406 A,  406 B at the ends of the lever arms  302 A,  302 B. 
         [0043]      FIG. 4B  illustrates the assembled group  400  of parts which results when the components of  FIG. 4A  are assembled. It can be seen in  FIG. 4B  that the two lever arms  302 A,  302 B pivot about axes which differ in direction by 90°, so that one of the lever arms  302 A and torsion springs  304  pushes on the wing  102  which is adjacent to the assembled group  400  on the left, and the other lever arm  302 B and torsion spring  306  pushes on the wing  102  which is adjacent to the assembled group  400  on the right. Accordingly, each wing  102  is pushed by two lever arms  302 A,  302 B, one from the assembled group  400  on the right side of the wing  102 , and the other from the assembled group  400  on the left side of the wing  102 . 
         [0044]    The deployment mechanism of this embodiment provides 24 pounds of force to each wing at the end of the spring travel, which is 0.30 inches. This is added to approximately 7 pounds of centrifugal force supplied by the spinning of the missile at its minimum spinning rate. The embodiment weighs less than 0.5 pounds, and occupies less than 2.5 cubic inches per wing. In similar embodiments with N wings, where N is an integer, there are N assemblies  400 , and the springs pivot about axes which differ in angle by 360°/N. 
         [0045]      FIGS. 5A and 5B  are top and bottom perspective views respectively of the aft retainer plate  310  of the embodiment of  FIG. 3B . Note that the embodiment in  FIG. 3B  is oriented as it would be when mounted in a missile facing downward, so that the “top” of the aft retainer plate  310  faces downward in  FIG. 3B . The aft retainer plate of  FIGS. 5A and 5B  is assembled from a top layer and a bottom layer.  FIG. 5C through 5G  are engineering drawings of the fully assembled aft retainer plate  310  of  FIGS. 5A and 5B . In particular, FIG. SC is a top view,  FIGS. 5E  is a side view, and  FIG. 5F  is a bottom view.  FIG. 5H  is a top view of the top layer of the aft retainer plate  310 ,  FIG. 5I  is a side view of the top layer of the aft retainer plate  310 , and  FIG. 5J  is a bottom view of the top layer of the aft retainer plate  310 .  FIG. 5K  is a bottom view of the bottom layer of the aft retainer plate  310 . 
         [0046]      FIG. 6A  is a perspective view from behind of the bracket  308  of  FIG. 3B . The two lever arm pins  600 A,  600 B on which the pivot holes  406 A,  406 B of the lever arms  302 A,  302 B are mounted can be clearly seen in the figure.  FIGS. 6B ,  6 C, and  6 D arc side, rear, and bottom views respectively of the bracket  308 . Note that the holes  602  through which the mounting screws are inserted are clearly visible in  FIG. 6D . 
         [0047]      FIG. 6E  is a front perspective view,  FIG. 6F  is a rear perspective view,  FIG. 6I  is a side view, and  FIGS. 6G and 6H  are cross-sectional views of the bracket of  FIG. 6A  with the lever arm pins  600 A,  600 B removed.  FIGS. 6K through 6M  are additional engineering views of the bracket  308  of  FIG. 6A . 
         [0048]      FIG. 7A  is a perspective view of the first lever arm  406 A of the embodiment of  FIG. 3B , and  FIGS. 7B through 7E  are engineering drawings of the lever arm of  FIG. 7A , with  FIGS. 7B ,  7 C, and  7 E being side, front, and top views, respectively. 
         [0049]      FIG. 8A  is a perspective view of the second lever arm  406 B of the embodiment of  FIG. 3B , and  FIGS. 8B through 8E  are engineering drawings of the lever arm of  FIG. 8A , with  FIGS. 8B ,  8 C, and  8 E being side, front, and top views, respectively. 
         [0050]      FIG. 9A  is a perspective view of a lever arm mounting pin  404  of the embodiment of  FIG. 3B , and  FIGS. 9B and 9C  are side and end views respectfully of the mounting pin  404  of  FIG. 9A . 
         [0051]      FIG. 10A  is a perspective view of the first torsion spring  304  of the embodiment of  FIG. 3B .  FIGS. 10B through 10D  are side, top, and front views respectfully of the torsion spring  304  of  FIG. 10A . 
         [0052]      FIG. 11A  is a perspective view of the second torsion spring  306  of the embodiment of  FIG. 3B .  FIGS. 11B through 11D  are side, top, and front views respectfully of the torsion spring  306  of  FIG. 11A . 
         [0053]      FIGS. 12Athrough 12C  are perspective, front, and top views respectively of the mandrel  402  of  FIG. 3B . 
         [0054]    With reference to  FIG. 13A , the guidance wings  102  of missiles  100  such as the APKWS typically include variable pitch “flaperons”  1300  which are used to control the direction of flight of the missile. In the case of the APKWS, it is the flaperons  1300  which are engaged in retaining the guidance wings  102  in their folded and stowed configuration.  FIG. 13B  is a close-up view of the flaperon region of a guidance wing  102  used with the embodiment of  FIG. 3B . When the wing is stowed, a tab from the aft retainer is inserted into a notch  306  in the flaperon. 
         [0055]    The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.