Patent Publication Number: US-11034447-B2

Title: Unmanned aerial vehicle (UAV) tethered wing recovery

Description:
FIELD OF THE DISCLOSURE 
     This disclosure relates generally to aircraft and, more particularly, to unmanned aerial vehicle (UAV) tethered wing recovery. 
     BACKGROUND 
     In recent years, unmanned aerial vehicles (UAVs) or drones have been used to fly significant distances to transport payloads (e.g., packages, supplies, equipment, etc.) or gather information. Some UAVs land on runways while others are captured in flight by UAV recovery systems. Such recovery systems enable a UAV to not carry a landing gear system or landing components. However, the recovery systems can subject a UAV to significant loads during a recovery process due to sudden deceleration of the UAV during an impact with recovery devices. Such significant loads can cause damage to the UAV or necessitate strengthening components or features, thereby potentially increasing cost and weight of the UAV. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example unmanned aerial vehicle (UAV) in which examples disclosed herein can be implemented. 
         FIG. 2  is a top view of an example detachable wing section in accordance with teachings of this disclosure. 
         FIGS. 3A and 3B  depict the example detachable wing section of  FIG. 2  shown in exterior and cutaway views, respectively, while in a coupled state. 
         FIGS. 4A and 4B  depict the example detachable wing section of  FIG. 2  shown in exterior and cutaway views, respectively, while in a de-coupled state. 
         FIGS. 5A and 5B  are detailed perspective views of an example lock that can be implemented in examples disclosed herein. 
         FIG. 6  is a detailed cross-sectional view of an example lock cavity that may be implemented in examples disclosed herein. 
         FIGS. 7A and 7B  are detailed perspective views of an alternative example lock that may be implemented in examples disclosed herein. 
         FIG. 8  is a flowchart of an example method to implement examples disclosed herein. 
     
    
    
     The figures are not to scale. Instead, the thickness of the layers or regions may be enlarged in the drawings. In general, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. As used in this patent, stating that any part is in any way on (e.g., positioned on, located on, disposed on, or formed on, etc.) another part, indicates that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween. Stating that any part is in contact with another part means that there is no intermediate part between the two parts. 
     DETAILED DESCRIPTION 
     Unmanned aerial vehicle (UAV) tethered wing recovery is disclosed. Some known UAV recovery systems can subject a UAV to relatively high loads during impact of the UAV with a UAV recovery system. In particular, the UAV can undergo significant impact forces when the wing of the UAV impacts a net or pole of the UAV recovery system. To avoid potential damage to the UAV from such an impact, some known UAVs implement structural reinforcements, which can add significant weight, cost and/or complexity to the UAV. 
     Examples disclosed herein provide effective impact force dissipation during recovery of an aircraft (e.g., a UAV). In particular, examples disclosed herein enable a detachable portion of a wing to be separated from a fixed portion of the wing when the UAV is being recovered, thereby relieving impact forces that would otherwise potentially damage the UAV. Examples disclosed herein implement a lock to enable the detachable portion of the wing to disengage from the fixed portion upon contact of the wing with a recovery device. Further, a tether extends between the detachable and fixed portions, thereby enabling additional impact force dissipation. Examples disclosed herein enable weight, cost and volume savings for aircraft that land with recovery systems by reducing (e.g., eliminating) a need for reinforcing materials, structures and/or components that would otherwise be needed for recovery. 
     In some examples, the tether is at least partially composed of an elastic cable and/or fiber that can stretch or elongate to dissipate impact energy of an aircraft. In some examples, the tether is disposed within a guide that aligns fixed and detachable portions of a wing relative to another. In some such examples, the tether is coiled within the guide when the fixed and detachable portions are coupled thereto. In some examples, the guide includes a generally trapezoidal shape. In some examples, the lock includes a frangible element, such as a shear pin, for example. The shear pin can be disposed in a barrel nut to break upon impact of a wing with a recovery device. In other examples, the lock includes a spring (e.g., a canted coil spring, a ring spring, a toroidal spring, etc.) that is to be received by a curved annular surface of a shaft such that the spring disengages from the curved annular surface when a wing impacts a recovery device. 
     As used herein, the term “fixed portion” refers to a portion of a wing that remains attached to a fuselage or body of an aircraft. Accordingly, the term “detachable portion” refers to a portion of a wing that separates from the fixed portion. As used herein, the term “lock” refers to an assembly and/or component that is used to couple (e.g., releasably couple) two components together. As used herein, the term “frangible” refers to a consumable component and/or assembly that can be broken or damaged for intended later replacement. As used herein, the term “guide” refers to a component used for relative alignment of components when the components are coupled together and/or moved towards one another. 
       FIG. 1  illustrates an example unmanned aerial vehicle (UAV)  100  in which examples disclosed herein can be implemented. The example UAV  100  includes a fuselage  102  with a guidance portion  104 , a propulsion system  106 , wings  110 , a tail (e.g., a tail section)  112  and a hook (e.g., a distal end recovery hook, a distal hook)  114 . As can be seen in  FIG. 1 , the UAV  100  is being recovered by a recovery system  120 , which includes a recovery line (e.g., a recovery tether, a recovery net, etc.)  122  and a corresponding support structure  124 . 
     To recover the UAV  100  while the UAV  100  is in flight, the UAV  100  is flown within range of the recovery line  122  to bring one of the wings  110  (e.g., a distal end of one of the wings  110 ) toward the recovery line  122 . As a result of a portion along a span of the wing  110  contacting the recovery line  122 , the hook  114  engages the recovery line  122 , thereby causing the UAV  100  to decelerate. This deceleration of the UAV  100  can result in significant force(s) applied to the fuselage  102  and the wing  110 . In particular, the engagement of the hook  114  to the recovery line  122  can cause the UAV  100  to spin laterally, thereby potentially damaging a joint or interface between the wing  110  and the fuselage  102 . 
     Examples disclosed herein enable the wing  110  to be separated from the UAV  100  while allowing the wing  110  to be loaded along a direction such that the wing can withstand high impact forces from an impact of the UAV  100  with the recovery line  122 . For example, a long slender wing (e.g., a high aspect ratio wing) can have reduced strength in bending when loaded in a direction to cause tension along a length of the wing. As a result, structural reinforcements, such as structural components or bracing, are not necessitated, thereby saving weight and cost of the UAV  100 . 
       FIG. 2  is a top view of an example detachable wing section  200  in accordance with teachings of this disclosure. The example detachable wing section  200  is implemented in the wing  110  and includes a fixed portion  202 , a detachable portion  204 , and a lock (e.g., a lock system, a coupling system, a lock assembly, etc. etc.)  206  having arm locks (e.g., barrel nut bore locks, arm lock bores, locking collars, release collars, etc.)  208  and receptacle locks (e.g., locking receptacles, locking nuts, cam locks, cam lock bores, etc.)  210 . In some examples, the detachable wing section  200  includes a guide (e.g., a spar joiner, structural joint, etc.)  212 . In this example, the detachable wing section  200  also includes a tether  214 . 
     In operation, an edge  216  of the detachable portion  204  is separated from an edge  218  of the fixed portion  202  along a direction generally indicated by an arrow  220  when the detachable portion  204  and/or the wing  110  impacts a recovery device, such as the recovery line  122  shown in  FIG. 1 . In particular, the impact of the recovery line  122  with the detachable portion  204  causes the recovery line  122  to slide along a front edge of the wing  110 . In turn, the arm locks  208  are loaded in a new direction not seen during flight and separate from the corresponding receptacle locks  210 . This separation of the arm locks  208  from the corresponding receptacle locks  210  can dissipate a portion of the impact energy encountered during the impact. As will be discussed in greater detail below with  FIGS. 5-6B , the lock assembly  206  can be implemented with frangible components (e.g., inexpensive frangible components) that are replaced after being damaged (e.g., failing) subsequent to the impact. In other examples, the arm locks  208  separate from the receptacle locks  210  without component breakage, as will be discussed in greater detail below in connection with  FIGS. 7A and 7B . 
     According to the illustrated example, the guide  212  exhibits a generally trapezoidal or tapered shape (e.g., a tapered trapezoidal shape, a prismatic shape, etc.) and is used to guide a relative alignment of the detachable portion  204  to the fixed portion  202  when coupled thereto. In this example, the guide  212  is received (e.g., matably received) by an aperture (e.g., an opening, a cavity, etc.)  222  of the fixed portion  202 . In particular, the aperture  222  has a complementary trapezoidal shape to receive the guide  212 . The example guide  212  carries wing bending loads during flight, but enable separation of the detachable portion  204  from the fixed portion  202  when the lock(s)  206  are released and/or frangibly detached. Further, the example tether  214  couples the detachable portion  204  to the fixed portion  202  and extends from within the guide  212 . 
     In some examples, the tether  214  is implemented as an elastic line (e.g., an elastic rope, an elastic cable, etc.). In such examples, the tether  214  dissipates separation energy as it is stretched after separation of the detachable portion  204  from the fixed portion  202 . Additionally or alternatively, the tether  214  is at least partially composed of polyester, nylon, and/or a high toughness nylon rope. While the arm locks  208  are mounted to the fixed portion  202  in this example, the arm locks  208  can instead be mounted to the detachable portion  204  while the receptacle locks  210  are disposed in the fixed portion  202 . In some other examples, the detachable portion  204  is instead directly coupled to the fuselage  102  (shown in  FIG. 1 ). In such examples, the entire wing  110  is detached from the fuselage  102  upon impact of the wing  110  with the recovery line  122 . In some examples, the guide  212  acts a load-bearing structural member of the wing  110  by carrying loads (e.g., flight loads, cruise loads, take off loads, landing loads, etc.) from the fixed portion  202  to the detachable portion  204  and vice-versa. 
       FIGS. 3A and 3B  depict the example detachable wing section  200  of  FIG. 2  shown in exterior and cutaway views, respectively, while the detachable wing section  200  is in a coupled state. In this particular example, the receptacle locks  210  are disposed on the fixed portion  202 . Further, the fixed portion  202  exhibit a rectangular cross-section, and could be implemented as any aerodynamic profile, as shown in  FIGS. 1 and 2 . Turning to  FIG. 3A , the detachable portion  204  is coupled to and aligned with the fixed portion  202 . In particular, a collar (e.g., a shoulder, a joint, a joint housing, etc.)  302 , which includes openings  304 , couples and aligns the detachable portion  204  to the fixed portion  202 . Further, the coupling portion  302  mounts a boom  306  that extends to the tail section  112  of  FIG. 1 . 
     To fasten and/or lock the detachable portion  204  to the fixed portion  202 , the receptacle lock  210  (shown in  FIG. 2 ) is accessed via the openings  304 . In particular, the example receptacle lock  210  is rotated via a tool to constrain, align and/or operatively couple the receptacle lock  210  relative to the arm lock  208 . In some examples, a frangible component is assembled to or within the lock  206  so that the easily-replaceable frangible component breaks during impact of the wing  110  with the recovery line  122 . 
     Turning to  FIG. 3B , a cutaway view is shown of the detachable wing section  200  with the detachable portion  204  coupled to the fixed portion  202 . According to the illustrated example of  FIG. 3B , the guide  212  includes an internal volume (e.g., a chamber, a recess, a cavity, etc.)  310  extending along a longitudinal length of the guide  212 . Accordingly, the tether  214  is coiled and/or folded within the volume  310 . In particular, the example guide  212  includes a post  312 , which a loop  314  of the tether  214  wraps around at a first end  313  of the tether  214 . To facilitate a fit of the loop  314  over the post  312 , the loop  314  exhibits a generally oblong or teardrop shape. However, any appropriate shapes and/or mating structures can be implemented instead. At a second end  317  of the tether  214  opposite the aforementioned first end  313 , an opening  315  of the guide  212  positions a plug (e.g., a captivating plug or bulb)  316  of the tether  214 . Alternatively, the termination of the plug  316  can be extended further down the length of the wing to allow for additional energy absorption with the plug  316  or an alternative anchor disposed in the detachable portion  204 . 
       FIGS. 4A and 4B  depict the example detachable wing section  200  of  FIG. 2  shown in exterior and cutaway views, respectively, while in a detached state. Turning to  FIG. 4A , the detachable portion  204  is shown separated from the fixed portion  202 . In particular, the tether  214  extends out of the guide  212 . Further, the arm locks  208  have remained coupled to the detachable portion  204  in this example. 
       FIG. 4B  is similar to the view of  FIG. 4A , but shown as a cutaway view. According to the illustrated example, the tether  214  is shown fully extended out of the internal volume  310  of the guide  212 . In particular, the tether  214  is stretched by an engagement of the loop  314  with the post  312 , as well as an engagement of the plug  316  with the opening  315  when the detachable portion  204  separates from the fixed portion  202 , subsequent to an impact of the detachable portion  204  with the recovery line  122 . 
       FIGS. 5A and 5B  are detailed perspective views of the example lock  206 . Turning to  FIG. 5A , the lock  206  of the illustrated example includes the receptacle lock  210 , which includes a cylindrical body  502 , a tool interface or slot  503 , an annular groove  504  and a slotted opening (e.g., a contoured opening)  506 . The lock  206  also includes an arm (e.g., a swivel arm, a locking arm, a stem, etc.)  508 , which includes the cam shaft portion  510  with a distal enlarged portion  511 , and an interfacing portion (e.g., an interface shaft, an interface collar, a shaft receptacle, etc.)  512  having an interfacing shaft  513  coupled thereto. Further, the example lock  206  also includes the arm lock  208  with a barrel nut  514  having a cylindrical body  516 . In this example, the cylindrical body  516  includes a bore  518  longitudinally extending therethrough. 
     Turning to  FIG. 5B , which depicts the lock  206  in a cross-sectional view, a locking pin (e.g., a shear pin, a breakable pin, a frangible pin, etc.)  520  extends through both the bore  518  of the cylindrical body  516  and an aperture  524  of the interfacing shaft  513 , thereby constraining the arm lock  208  to the arm  508 . Further, the interfacing shaft  513  is threadably coupled to the interfacing portion  512  via a threaded interface  525 . In some examples, the locking pin  520  includes a restraining screw  526  to restrain the locking pin  520 . 
     To separate or couple the arm  508  from/to the receptacle lock  210 , a tool is inserted into the slot  503 , and an enlarged section  528  of the slotted opening  506  is rotated along a direction generally indicated by a double arrow  530 . As a result, the arm  508  can be separated from the receptacle lock  210  because the enlarged section  528  of the slotted opening  506  faces an orientation at which the enlarged portion  511  of the arm  508  can be removed therefrom. 
     To enable the arm lock  208  to separate from the arm  508  during an impact of the wing  110  and/or the hook  114  with the recovery line  122 , movement and/or displacement of the barrel nut  514  relative to the arm  508  causes the locking pin  520  to shear and, in turn, break or fracture in some examples. As a result, the guide  212  separated from the fixed wing section, thereby relieving the wing  110  from encountering significant bending forces that can potentially result in structural damage. 
     As mentioned above, the interfacing shaft  513  is threaded to the interfacing portion  512  via the threaded interface  525 . However, any appropriate attachment method can be implemented instead including, but not limited to, a mechanical fastener, an interfacing fit (e.g., a dovetail design), a snap, a magnet, a chemical fastener, etc. In some examples, the barrel nut  514  is at least partially composed of aluminum or titanium. 
       FIG. 6  is a detailed cross-sectional view of an example cavity and/or cavity system  601  to align and constrain the lock  206  of  FIG. 2 . The cavity  601  of the illustrated example includes an arm lock cavity  602  to captivate the arm lock  208 , and an arm cavity  604  to captivate the arm  508 . Further, the example arm cavity  604  includes cylindrical openings  606 ,  608 . According to the example of  FIG. 5 , the cavity  601  includes a cylindrical opening  610  to capture the receptacle lock  210 . 
     According to the illustrated example, the cylindrical opening  610  has an approximate diameter of 0.740 to 0.800 inches (e.g., 0.770 inches). Further, the cylindrical opening  606  is approximately 0.323 to 0.365 inches (e.g., 0.344 inches) in diameter while the cylindrical opening  608  is approximately 0.244 to 0.288 inches (e.g., 0.266 inches) in diameter. Additionally, the example arm lock cavity  602  has a diameter of 0.480 inches to 0.520 inches (e.g., 0.500 inches). In this example, a bottom surface  614  of the cylindrical opening  610  is approximately 0.286 inches to 0.306 inches (e.g., 0.296 inches) from a corresponding centerline  616  that extends through the arm cavity  604 . A top surface  618  of the arm lock cavity  602  is approximately 0.240 inches to 0.260 inches (e.g., 0.250 inches) from the centerline  616  in this example. The aforementioned dimensions are only examples and any appropriate dimensions and/or spacing can be implemented instead. 
       FIGS. 7A and 7B  are detailed perspective views of an alternative example lock  700  that may be implemented in examples disclosed herein. Turning to  FIG. 7A , the lock  700  is similar to the example lock  206  shown and described in connection with  FIGS. 2-6B . However, in contrast to the lock  206 , the lock  700  of the illustrated example includes an interfacing shaft  702  that is coupled to the interfacing portion  512  of the arm  508 . 
     Turning to  FIG. 7B , a cross-sectional view of the example lock  700  is shown. According to the illustrated example, the lock  700  includes a spring (e.g., a canted coil spring, a ring spring, a toroidal spring)  704  that is at least partially captivated in an opening or groove  706  of a barrel nut  708 . Further, the interfacing shaft  702  includes a recess (e.g., an annular recess)  710  to receive the spring  704 . In this particular example, the spring  704  is implemented as a canted coil spring that is received by a contoured surface (e.g., a curved annular surface)  712  of the recess  710 . However, any other appropriate spring type can be implemented instead. Further, the interfacing shaft  702  of the illustrated example is coupled to the interface portion  512  via a threaded interface  714 . 
     In operation, an impact of the wing  110  and/or the hook  114  with the recovery line  122  causes the barrel nut  708  to displace relative to the interfacing shaft  702  and, in turn, the spring  704  disengages from the recess  710 . In particular, the contoured surface  712  of the recess  710  facilitates removal and/or movement of the spring  704  from the interfacing shaft  702  during the impact without translating significant forces to the wing  110 . As a result, the spring  704  encounters little or no significant damage and can be subsequently reused for recovery of the UAV  100 . 
       FIG. 8  is a flowchart representative of an example method  800  to implement examples disclosed herein. The example method  800  begins as an aircraft such as the UAV  100 , is to be flown and recovered without use of a landing gear. 
     At block  802 , the detachable portion  204  is attached to the wing  110 . In particular, the detachable portion  204  is coupled to the fixed portion  202  via the lock  206 . In this example, the guide  212  is used to align the detachable portion  204  relative to the fixed portion  202  during this coupling. 
     The aircraft is flown (block  804 ). In this example, the aircraft is flown in an automated navigational process. 
     The wing  110  of the aircraft is then directed toward a recovery device, such as the recovery line  122 , to recover the aircraft (block  806 ). 
     Next, the detachable portion  204  is detached from the fixed portion  202  when the aircraft impacts the recovery line  122  (block  808 ). In particular, the hook  114  of the wing  110  contacts the recovery line  122  to disengage the lock  206  in this example. Additionally, the tether  214  elastically stretches during the separation of the fixed portion  202  and the detachable portion  204  of the wing  110 . 
     It is then determined whether to repeat the process (block  810 ). If the process is to be repeated (block  810 ), control of the process returns to block  802 . Otherwise, the process ends. This determination can be based on whether the aircraft is to be flown again. 
     From the foregoing, it will be appreciated that example methods, apparatus and articles of manufacture have been disclosed that reduce and/or eliminate damage to an aircraft or vehicle during recovery (e.g., landing without a landing gear) by utilizing a wing and/or portion of the wing that is detachable from a fixed portion such that the load path is aligned with the load vector to more easily handle the impact of the wing with a recovery device. As a result, structural reinforcements, which can involve significant costs and additional weight, are not necessitated for recovery. 
     Example 1 includes an apparatus that includes a detachable portion of a wing that is couplable to a fixed portion of the wing, a lock configured to fasten the detachable portion to the fixed portion, where the lock is configured to disengage the detachable portion from the fixed portion upon contact of the wing with a recovery device, and a tether configured to extend between the detachable and fixed portions. 
     Example 2 includes the apparatus of Example 1, and further includes a guide configured to guide a relative alignment of the detachable portion to the fixed portion when the detachable portion is coupled to the fixed portion. 
     Example 3 includes the apparatus of Example 2, where the guide functions as a structural member of the wing to transfer flight loads from the fixed portion to the detachable portion. 
     Example 4 includes the apparatus of Example 2, where the guide is located on one of the detachable or fixed portions and has a trapezoidal shape to be received by a corresponding aperture of the other one of the detachable or fixed portions. 
     Example 5 includes the apparatus of Example 2, where the tether is contained within a cavity of the guide when the detachable and fixed portions are coupled. 
     Example 6 includes the apparatus of Example 1, where the lock includes a pin. 
     Example 7 includes the apparatus of Example 1, where the lock includes a coil spring of one of the detachable or fixed portions, and where the coil spring is configured to be received by a curved annular surface of the other one of the detachable or fixed portions. 
     Example 8 includes the apparatus of Example 1, where the tether includes an elastic cable. 
     Example 9 includes an aircraft having a wing having a detachable portion couplable to a fixed portion, and a lock configured to couple the detachable portion and the fixed portion, where the lock is configured to enable the detachable portion to disengage from the fixed portion when the wing contacts a recovery device, and a tether configured to extend between the detachable portion and the fixed portion. 
     Example 10 includes the aircraft of Example 9, and further includes a guide configured to guide a position of the detachable portion relative to the fixed portion when the detachable portion is coupled to the fixed portion. 
     Example 11 includes the aircraft of Example 10, where the tether is contained within a cavity of the guide when the detachable and fixed portions are coupled. 
     Example 12 includes the aircraft of Example 9, where an end of the fixed portion is located at a fuselage of the aircraft. 
     Example 13 includes the aircraft of Example 9, where the lock includes a pin to be disposed in a barrel nut. 
     Example 14 includes the aircraft of Example 9, where the lock includes a coil spring of one of the detachable or fixed portions configured to be received by a curved annular surface of the other one of the detachable or fixed portions. 
     Example 15 includes a method with directing a detachable portion of a wing of an aircraft toward a recovery device, and separating the detachable portion from a fixed portion of the wing upon contact of the wing with the recovery device, where a tether extends between the detachable portion and the fixed portion. 
     Example 16 includes the method of Example 15, and further includes coupling the detachable portion to the fixed portion via a lock. 
     Example 17 includes the method of Example 16, where the lock is frangible. 
     Example 18 includes the method of Example 15, where separating the detachable portion from the fixed portion includes breaking a pin disposed in a barrel nut. 
     Example 19 includes the method of Example 15, where separating the detachable portion from the fixed portion includes separating a coil spring of one of the detachable or fixed portions from a curved annular surface of the other one of the detachable or fixed portions. 
     Example 20 includes the method of Example 15, where directing the detachable portion of the wing of the aircraft toward the recovery device includes directing a distal end of the detachable portion toward the recovery device. 
     Although certain example methods, apparatus and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent. While the examples disclosed herein are described in relationship to aircraft and/or UAVs, examples disclosed herein can be implemented with any appropriate recovery applications.