Abstract:
A micro air vehicle having a bendable wing enabling the micro air vehicle to fly. The bendable wing may be bent downwards so that the wingspan may be reduced for storing the micro air vehicle. The bendable wing may be formed from one or more layers of material, and the wing may have a camber such that a concave surface of the wing faces downward. The wing may substantially resist flexing upwards and may transfer uplift forces to a central body of the micro air vehicle. In addition, the wing may be bent severely downwards by applying a force to tips of the wing. The micro air vehicle is capable of being stored in a small cylindrical tube and may be deployed from the tube by simply releasing the micro air vehicle from the tube.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/431,920, filed Dec. 9, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention is directed generally to micro air vehicles, and more particularly, to wing configurations for micro air vehicles.  
         BACKGROUND  
         [0003]    Micro air vehicles can trace their beginnings to model airplanes, which typically resemble full size airplanes. Micro air vehicles generally encompass all relatively small unmanned flying objects, such as those having wingspans less than about 36 inches. Micro air vehicles are often powered by small gasoline or electric propeller driven engines. Micro air vehicles are relatively lightweight vehicles capable of being used for a variety of purposes, such as for recreation, reconnaissance, and other purposes. Because of their small size, micro air vehicles lend themselves to a variety of uses.  
           [0004]    Many micro air vehicles have fixed, rigid wings that are incapable of having their wing span reduced for storage. Micro air vehicles having fixed wings are often difficult to store and do not lend themselves for storage in a knapsack or other item typically carried by military personnel in reconnaissance missions. Some micro air vehicles have collapsible wings that pivot about one or more pivot points. Typically, these micro air vehicles require a series of assembly steps to transform the micro air vehicle from a deployable condition to a storage condition, and vice versa.  
           [0005]    Because of their small size and ability to go relatively unnoticed, micro air vehicles have been outfitted with cameras, both still frame cameras and video cameras, and used in hostile areas for reconnaissance purposes. However, many of the micro air vehicles are inconvenient to be carried by military personnel because of their cumbersome wing span and shape. Thus, a need exists for a micro air vehicle having wings capable of having their wingspan reduced. In addition, other micro air vehicles having wings with reduceable wingspans require a plurality of assembly steps to transform the wings of the micro air vehicle from a deployable condition to a storage condition, and vice versa. Such requirements prevent these micro air vehicles from being deployed quickly and without human interaction. If micro air vehicles were able to be transformed between a storage condition and a deployable condition without assembly steps, the micro air vehicles could be used in a greater variety of applications. Thus, a need exists for a micro air vehicle capable of being transformed between a storage condition and a deployable condition without assembly steps.  
         SUMMARY OF THE INVENTION  
         [0006]    This invention is directed to a micro air vehicle having a bendable wing enabling the micro air vehicle to be stored in containers substantially smaller than the micro air vehicle and enabling the bendable wing to go from a storage condition to a deployable condition without assembly or user interaction. Rather, the forces used to hold the wing tips of the wing need only be abated.  
           [0007]    The micro air vehicle may be formed from a central body and one or more wings. The wing may be formed from one or more layers of a resilient material having a camber forming a concave surface facing downward. The wing may be bendable from a steady state position in a first direction such that tips of the wing may be bent toward the concave surface but not in a second direction that is generally opposite to the first direction. In other words, the wing may bent downwards but not upwards. The wing may also be capable of returning to the steady state position upon release the tips of the wing.  
           [0008]    The wing may have a camber such that a bottom surface of the wing has a generally concave configuration when viewed parallel to a longitudinal axis of the wing. The camber may contribute to the stability of flight of a micro air vehicle to which the wing is attached and allow the wing to be bent downwards by not upwards. Thus, the wing may absorb and transfer uplift forces to the central body and allow the wing to be bent downward for storage.  
           [0009]    In an alternative embodiment, the wing may be formed from a support structure covered by a layer of material. The support structure may be formed from one or more ribs, which may be, but are not required to be, generally parallel to each other. The layer of material covering the support structure may be, but is not limited to being, latex or other appropriate materials.  
           [0010]    The bendable wing enables the wing to be stored is containers smaller than the micro air vehicle to which the wing is attached. For instance, the bendable wing having a wing span of about ten inches may be bent around the central body of a micro air vehicle so that the wing may be stored in a container having a diameter of about three inches. Such a characteristic enables a micro air vehicle to which the bendable wing is attached to be used for reconnaissance missions, for deployment from missiles just prior to impact for bomb damage assessment, and carried by special forces operatives in the field on their person.  
           [0011]    An advantage of this invention is that a micro air vehicle incorporating the bendable wing of this invention may be stored in a small container and deployed without any actions taken to assemble the wings other than to release the tips from restraint. Releasing the wings enables the wings to return to the steady state position.  
           [0012]    Another advantage of this invention is that the bendable wing has sufficient stiffness to absorb and transfer uplift forces to the body while enabling the wings to be bent downwardly for storage.  
           [0013]    Yet another advantage of this invention is that by being able to be stored in such a small container, a micro air vehicle may be conveniently carried on a person, such as military personnel, without consuming much room.  
           [0014]    Still another advantage of this invention is that the bendable wing may be produced relatively inexpensively.  
           [0015]    Another advantage of this invention is that the wing is durable and capable of withstanding crash landings.  
           [0016]    These and other advantages will become obvious upon review of the detailed written description below of these and other embodiments. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the presently disclosed invention(s) and, together with the description, disclose the principles of the invention(s). These several illustrative figures include the following:  
         [0018]    [0018]FIG. 1 is a perspective view of a top side of an embodiment of this invention;  
         [0019]    [0019]FIG. 2 is a perspective view of the embodiment shown in FIG. 1 with a portion of the bendable wing being bent around a central body of a micro air vehicle as a result of a downward force applied to a tip of the wing;  
         [0020]    [0020]FIG. 3 is a front view of a micro air vehicle inserted into a small diameter tube with both sides of the bendable wing bent around the central body of the micro air vehicle;  
         [0021]    [0021]FIG. 4 is a perspective view of an alternative embodiment of the bendable wing of the micro air vehicle;  
         [0022]    [0022]FIG. 5 is a perspective view of the alternative embodiment of the bendable wing shown in FIG. 4 in flexed storage condition with the tips of the wing bent around the central body of the micro air vehicle;  
         [0023]    [0023]FIG. 6 is a perspective view of yet another alternative configuration of the bendable wing of this invention;  
         [0024]    [0024]FIG. 7 is a front view of the embodiment shown in FIG. 6;  
         [0025]    [0025]FIG. 8 is a perspective view of still another embodiment of this invention;  
         [0026]    [0026]FIG. 9 is a front view of another embodiment of this invention; and  
         [0027]    [0027]FIG. 10 is a perspective view of a top side of the embodiment shown in FIG. 9. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]    This invention is directed to a wing  12  for a micro air vehicle  10 , as shown in FIGS. 1-10, that is bendable to enable the wing  12  to be easily stored in, for instance, a tube or other structure. The wing  12  may be attached to a body  14  that may or may not house an engine capable of providing rotational motion to a propeller  16 . The engine may be, but is not limited to, one of many conventional engines used to power miniature aircraft. Body  14  may include a tail  17  for controlling the micro air vehicle  10 . The tail  17  may be positioned generally orthogonal to the wing  12 , as shown in FIGS. 1, 2,  8 , and  10 , generally parallel to the wing  12 , as shown in FIGS. 4 and 5, or in another position. Micro air vehicle  10  may include other components that are typically found on miniature aircraft.  
         [0029]    As shown in FIGS. 4 and 5, wing  12  may be formed one or more layers formed from resilient materials such that the wing  12  is bendable from a steady state position. The wing  12  may be bent in a first direction, as shown in FIG. 5, such that tips  13  of the wing  12  may be bent downwardly toward a concave surface  15  but not substantially in a second direction that is generally opposite to the first direction. The resilient materials have a high degree of elasticity and are therefore capable of returning the wing  12  to the steady state position upon release of the tips  13  of the wing  12 . In at least one embodiment, the camber of the wing  12  is configured such that a bottom surface of the wing  12  forms a concave surface.  
         [0030]    Wing  12 , as shown in FIGS. 1, 4,  6 , and  8 , may be formed from a leading edge portion  18 , a rear portion  19 , and a trailing edge  25 . Leading edge portion  18 , rear portion  19 , and trailing edge  25  may together form a monolithic structure formed from the same material, or may be different structures formed from the same or different materials and coupled together. In at least one embodiment, the wing  12 , as shown in FIG. 4, may be formed from a single layer of material, and, in alternative embodiments, may be formed from two or more layers of material. The wing  12  may be formed from resilient materials, such as, but not limited to: fiber reinforced laminates and fabrics, such as, carbon fiber reinforced polymers, glass reinforced polymers, and aramid reinforced polymers; sheet metal, such as, spring steel, high strength aluminum, stainless steel, and titanium; foam materials; and plastics. In at least one embodiment, leading edge portion  18  may be formed from pre-impregnated carbon/epoxy fiber cloth, which provides sufficient strength to absorb forces encountered from wind gusts while maintaining a sufficiently light weight. In at least another embodiment, the leading edge  18  may be formed from an aramid fiber/epoxy mixture and at least a portion of the remainder of the rear portion  19  may be formed from a single layer of carbon fiber/epoxy weave.  
         [0031]    Wing  12  is bendable so that the overall size of micro air vehicle  10  may be reduced for storage. Wing  12  may be bent by applying a downward force to the tips  13  of wing  12 , as shown in FIGS. 2 and 5. While wing  21  may be bent downwards, wing  12  resists being bent upwardly as a result of the camber of leading edge portion  18  or the wing  12 , or both. More specifically, the leading edge portion  18  is stiff when loaded with upwardly directed loads, such as aerodynamic loads. The camber provides wing  12  with the structural stability to substantially prevent wing  12  from bending upwardly when subjected to an upwardly directed load. Thus, wing  12  can be bent with a downwardly applied force but not with an upwardly applied force because of the configuration of the wing  12  and materials used to form the wing  12 . The wing  12  may be bent so that a substantial portion of the wing  12  may be wrapped around to an opposite side of the body  14  from the steady state position shown in FIGS. 1 and 5.  
         [0032]    In other embodiments, as shown in FIGS. 1, 2, and  6 - 10 , rear portion  19  may be formed from ribs  20  and a skin  22 . Ribs  20  may be formed from unidirectional fibers, such as, but not limited to, carbon fiber strands, and skin  22  may be formed from a lightweight, thin material, such as, but not limited to, latex and other appropriate materials. Ribs  20  may include members positioned generally parallel to body  14 .  
         [0033]    Rear portion  19  may or may not be concave when viewed from below, as shown in FIG. 10. If rear portion  19  is concave, the concave shape of rear portion  19  may or may not be equal to the concave shape of leading edge portion  18 . If the rear portion  19  is not concave, the leading edge portion  18  has a camber forming a concave face on the bottom surface  15  of the wing  12 . The shape of rear portion  19  may be any shape capable of providing aerodynamic lift when coupled to leading edge portion  18 . Rear portion  19  may include a riser  21  at the rear portion of wing  12 . The riser  21  may form a concave portion on an upper surface  23  of the wing  12  in the rear portion  19 . The riser  21  may extend completely across the trailing edge  25  or may extend across only a portion of the trailing edge  25 .  
         [0034]    In one embodiment, leading edge  18  has a greater thickness than the thickness of the rear portion  19 , wherein the characteristic that wing  12  may be bent downwards but not upwards is attributable to the configuration of leading edge portion  18 . In other embodiments, leading edge portion  18  and rear portion  19  may or may not have the same thickness, depending on the strength of the materials used to form leading edge portion  18  and rear portion  19 .  
         [0035]    Wing  12  may have a wing span between about six inches and about twenty four inches. In one embodiment, wing  12  may have a ten inch wing span enabling it to be stored in a cylinder  24 , as shown in FIG. 3, having a diameter less than three inches. Having the capability of being stored in such small cylinders enables micro air vehicle  10  to be used for reconnaissance missions, for deployment from missiles just prior to impact for bomb damage assessment, and carried by special forces operatives in the field on their person. Micro-air vehicle  10  may be used in other applications as well. In other embodiments, wing  12  may vary in length between about three inches and about 24 inches. As shown in FIGS. 7 and 9, the micro air vehicle  10  may include a camera  30 , which may be, but is not limited to being, a video camera, a still photography camera, or other audio or visual recording devices.  
         [0036]    The configuration of wing  12  shown in FIGS. 1-10 and the elastic materials from which the wing  12  is formed enables wing  12  to return to its original, steady state shape, as shown in FIG. 1, 4, and  6 - 10 , after being removed from storage without additional steps or use of mechanical mechanisms, such as servos, motors, piezoelectrics, or shape memory alloys. Instead, wing  12  returns to its original shape because of the elastic characteristics of the wing  12  causes the wing  12  to remain under forces when bent from its original position. These forces abate only when wing  12  is returned to its original position. The materials used to form the wing  12  have great flexibility and elasticity and bend rather than permanently yielding. Thus, micro air vehicle  10  needs only to be removed from a storage container  24 , as shown in FIG. 3, for wing  12  to return to its original shape.  
         [0037]    The wing  12  is configured such that the wing  12  may be bent severely about the body  14  of the micro air vehicle  10 . In fact, the wing  12  may be bent so severely that the wing tips  13  and wing  12  are rolled up around the body  14 , as shown in FIG. 5. This configuration is very advantageous. However, the wing  12  also prevents substantial bending in the opposite direction. This is not to say that the wing will not flex during use. Rather, the wing  12  will flex, or bow, in the opposite direction under normal stresses associated with flight. However, the wing  12  will not bend substantially in the opposite direction.  
         [0038]    The configuration of wing  12  possess numerous aerodynamic advantages including: reduced drag due to the curvature of leading edge portion  18 ; and improved wind gust rejection due to adaptive washout as a result of wing  12  flexing, twisting and decambering. This configuration of wing  12  allows micro air vehicle  12  to fly more smoothly than conventional rigid wing designs in smooth and gusty wind conditions. Wing  12  is also more durable than rigid wings because the configuration of wing  12  bends upon impact with the ground or other structure, rather than breaking.  
         [0039]    The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of this invention. Modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of this invention.