Abstract:
An airborne vehicle having a deployable airfoil with an elevon wherein the deployment of the airfoil and the control of the elevon are both powered by a single servo mechanism. A shear pin prevents relative movement between the elevon and the airfoil until the airfoil is in the deployed position. A stop mechanism locks the airfoil in the deployed position, whereafter operation of the drive mechanism fractures the shear pin, thereby allowing the elevon to be controlled by the drive mechanism.

Description:
This application claims benefit to U.S. Provisional 60/090,732 filed Jun. 25, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to the field of airborne vehicles having deployable wings or fins, and more particularly to a vehicle having a deployable wing with a control surface, and specifically to an airborne vehicle having both a deployable wing and a control surface that are operated by a single drive mechanism. 
     It is known that the performance of an airborne vehicle, such as a missile, artillery shell or other projectile can be improved by the use of one or more fins or wings deployed along the longitudinal axis of the airborne vehicle. Such fins are used to improve the stability of the vehicle during its flight as well as to provide a steering mechanism to improve the targeting accuracy of the vehicle. In many instances it is necessary to store the fins within the body of the vehicle before deployment. The conventional method for doing so is to pivot the fin at one end and to deploy it radially outward after the vehicle is launched. The energy to deploy such a fin may be supplied by a motor or solenoid, a spring, a pressurized fluid or gas cylinder, or the aerodynamic force of the air passing over the vehicle during its flight. Drive mechanisms for such applications are often expensive to design and to manufacture because they are required to survive severe acceleration loads during the launching of the vehicle. 
     Certain designs for airborne vehicles require the use of both a lifting airfoil as well as a control surface associated with the airfoil. The mechanism used to deploy such an airfoil/control surface assembly and to control the assembly once it is deployed can be expensive, heavy and large, thereby limiting the size of airborne vehicle upon which it may be utilized. It is known, for instance, to utilize one motor for the deployment of a fin or wing, and a second motor for control of that fin or wing or a control surface associated therewith. The use of redundant motors adds to the expense, weight and size of such a design. 
     U.S. Pat. No. 5,108,051 issued on Apr. 28, 1992 to Montet et al. teaches a mechanism for deployment and control of an airborne vehicle fin that utilizes a single motor. A single actuator is utilized to rotate a fin from a first position in line with the axis of flight of the airborne vehicle to a second position perpendicular to the direction of flight. The aerodynamic forces acting on the fin are then utilized to cause the fin to pivot about a second axis so that it becomes aligned with the axis of rotation of the actuator. Thereafter operation of the actuator will perform a steering function by causing the deployed fin to pivot about its first axis. This system provides the advantage of utilizing only one actuator, however, it is limited in its application due to its reliance on the use of aerodynamic forces, as well as being limited by providing actuating forces along only a single axis. What is needed is a deployment mechanism for an airborne vehicle that can provide deployment and control forces along a plurality of axes without the need for a plurality of actuators. 
     Therefore, it is an object of this invention to provide an airborne vehicle having a deployable wing and an associated control surface that can be deployed and controlled by a single drive mechanism. It is a further object of this invention to provide an airborne vehicle having an airfoil which can be deployed from a storage to an extended position and can thereafter be controlled as a control surface by a simple, light, and relatively inexpensive deployment and control mechanism. 
     SUMMARY OF THE INVENTION 
     These and other objects of the invention are satisfied by An airborne vehicle having: a frame; a drive mechanism connected to the frame; a first drive link connected to the drive mechanism; a second drive link connected to the first drive link; a base; a control surface connected to the second drive link and to the base; a means for preventing relative movement between the first and the second drive links so that forward movement of the first drive link will move the base from a storage position to an extended position relative to the frame; a stop operable when engaged to prevent movement of the base relative to the frame once the base reaches the extended position; wherein operation of the drive mechanism with the stop engaged will release the means for preventing relative movement between the first and the second drive links so that movement of the drive mechanism will cause movement of the control surface relative to the frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The aforementioned objects and advantages of the present invention will be more fully understood as a result of a detailed description of the invention when taken in conjunction with the following drawings in which: 
     FIG. 1 is a perspective view of a portion of an airborne vehicle having a deployment and control mechanism for a wing and an elevon in accordance with the present invention. 
     FIG. 2 illustrates a wing and control surface for an airborne vehicle utilizing a linear drive having a single motor in accordance with the current invention. 
     FIG. 3 is a perspective view of a mechanism for a airborne vehicle having three sequential articulation stages in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a portion of an airborne vehicle  10  having a deployable airfoil  12  associated with an elevon  14 . The airfoil  12  is formed as an extension of a wing base  16 . The wing base  16 , airfoil  12 , and elevon  14  may be deployed from a stowed position  18  within the outermost envelope of an airframe  20 , to an extended position  22  perpendicular to the line of flight of airborne vehicle  10 . Attached to and mounted within airframe  20  is a drive mechanism  24 . The drive mechanism  24  may be a servo motor, solenoid, or other form of actuator known in the art. In the embodiment of FIG. 1, drive mechanism  24  is illustrated as a servo motor operable to provide rotational movement to a first drive link  26 . First drive link  26  is illustrated as being a drive shaft having a spiral gear assembly  28 ,  30 , on both ends. Spiral gear assembly  30  connects the first drive link  26  with a second drive link  32 . Second drive link  32  is illustrated as a drive shaft connected to elevon  14 . In the embodiment illustrated in FIG. 1, airfoil  12  provides lift for extending the useful range of airborne vehicle  10 . Elevon  14  provides a control surface for guiding the airborne vehicle more precisely toward its target and developing the lifting contour in combination with the airfoil  12 . 
     Prior to the launch of airborne vehicle  10 , the airfoil  12 , elevon  14  and airframe  20  are in stowed position  18 . In order to limit the vibrational movement of the assembly during the highly stressful launching event, a sheer pin  34  may be provided as a means for preventing relative movement between the wing base  16  and the airframe  20 . A similar means (not shown) may be provided for preventing relative movement between the airfoil  12  and/or elevon  14  and the airframe  20  during the launch of the airborne vehicle  10 . Subsequent to the launch, sheer pin  34  may be withdrawn by an actuator  36 . Alternatively, shear pin  34  may be designed to fracture and to fail upon the operation of drive mechanism  24 . Once the airborne vehicle  10  is in flight, drive mechanism  24  is energized to provide rotational movement of drive shaft  26 . A sheer pin  38  or other means for preventing relative movement between the first drive shaft  26  and the second drive shaft  32  may be provided. Other embodiments of a means for preventing relative movement between the first drive shaft  26  and the second drive shaft  32  may include a clutch mechanism, a ball detent mechanism, and an actuator. Because the second drive shaft  32  is prevented from rotating relative to the first drive shaft  26 , the forward rotation of the drive shaft  26  will result in the movement of the wing base  16 , airfoil  12 , and elevon  14  from the storage position  18  to the extended position  22  relative to the airframe  20 . 
     Once the wing base  16  reaches the fully extended position  22 , it is held in that position by a stop mechanism  40 . The stop mechanism  40  is operable, when engaged, to prevent the movement of the wing base  16  relative to the airframe  20 . The stop mechanism may be an actuator or it may be a spring loaded pin and detent mechanism. Once the stop mechanism  40  is engaged, continued operation of the drive mechanism  24  will serve to fracture sheer pin  38  or otherwise release the means for preventing relative movement between the first drive shaft  26  and the second drive shaft  32 . Once sheer pin  38  has been fractured, rotation of first drive shaft  26  will cause rotation of second drive shaft  32 , thereby causing rotation of the elevon  14  relative to the wing base  16 . In this manner, both the deployment of the wing base  16  and the control of the elevon  14  are provided by a single drive mechanism  24 . 
     FIG. 2 illustrates in an embodiment of this invention utilizing a linear actuation system. An airborne vehicle  50  includes an airframe  52 , a wing  54 , and an aileron  56 . The wing  54  is illustrated in an extended position and can also be withdrawn to at least a partially retracted position within frame  52 . A single drive mechanism  58  connected to frame  52  is utilized both for extending the wing  54  from the withdrawn to the extended positions and for control of aileron  56 . A first drive link  60  is connected to a second drive link  62  by a bellcrank  64 . Sheer pin  66  is utilized to prevent he movement of bellerank  66  relative to wing  54 , thereby preventing relative movement between first link  60  and second link  62 . When sheer pin  66  is engaged, the forward operation of drive mechanism  58  will function to move wing  54  from its withdrawn to its extended position. Once the wing  54  is fully extended, a mechanical stop  68  will engage to lock the wing in its extended position. Mechanical stop  68  may be, for example, a spring loaded pin mounted in frame  52  which engages a hole (not shown) in wing  54  at the fully extended position. Once the mechanical stop  68  is engaged, further forward operation of drive mechanism  58  will fracture sheer pin  66 , thereby allowing the operation of drive mechanism  58  to control the position of the aileron  56  in relation to the wing  54 . In this manner, FIG. 2 illustrates the use of a single linear actuator  58  for the dual purposes of extending a wing  54  and controlling an aileron  56  in an airborne vehicle  50 . 
     FIG. 3 illustrates a portion of an airborne vehicle  70  having multiple articulated stages being deployed by a single actuator. A rotary drive mechanism  72  connected to a portion of an airframe  74  is utilized to drive a first stage  76 , a second stage  78 , and a third stage  80 . Drive mechanism  72  operates through a geared drive shaft  82  to provide rotary motion to first drive link  84 , second drive link  86 , and third drive link  88 . Sheer pin  90  is operable to prevent the relative motion of first drive link  84  and second drive link  86 . Similarly sheer pin  92  is operable to prevent relative motion between second drive link  86  and third drive link  88 . When both sheer pins  90 ,  92  are engaged, operation of drive mechanism  72  will serve to rotate an assembly consisting of first stage  76 , second stage  78 , and third stage  80  about the axis of first drive link  84 . A ball detent mechanism  94  will engage to act as a mechanical stop when first stage  76  reaches a predetermined position. Continued operation of drive mechanism  72  with ball detent mechanism  94  engaged will serve to fracture sheer pin  90 , thereby allowing second drive link  86  to rotate in response to the rotation of first drive link  84 . In this second mode of operation, an assembly consisting of second stage  78  and third stage  80  will be rotated about the axis second drive link  86  by the operation of drive mechanism  72 . A mechanical stop  96  is provided to lock second stage  78  in a predetermined position in relation to first stage  76 . Once stop  96  has been engaged, continued operation of drive mechanism  72  will function to fracture sheer pin  92 , thereby allowing third drive link  88  to rotate in response to the rotation of second drive link  86 . In this third mode of operation, third stage  80  will rotate about the axis of third drive link  88  as a result of the operation of drive mechanism  72 . It can be appreciated that further stages can be driven by a single drive mechanism in a manner similar to the operation of the three stages of FIG.  3 . 
     The embodiments described herein are provided for the purposes of illustration but not limitation, and the full scope of the applicants invention is as claimed below.