Abstract:
A pin configured for use in a rotor blade movable between an aligned position and a folded position and having a rotor blade airfoil contour is provided including a cylindrical body configured to couple a first section and a second section of the rotor blade when the rotor blade is in the aligned position. A handle is mounted to an end of the cylindrical body and has an airfoil contour complementary to the rotor blade airfoil contour. The handle is movable between an open position and a closed position. When the handle is in the closed position, the handle is flush with an adjacent portion of the rotor blade. When the handle is in the open position, the handle is accessible to pull the cylindrical body from the first and second section s of the rotor blade.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. provisional patent application Ser. No. 61/871,074 filed Aug. 28, 2013, the entire contents of which are incorporated herein by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    This invention was made with Government support under Technology Investment Agreement No. W911W6-13-2-0003 with the United States Army. The Government has certain rights in the invention. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    Exemplary embodiments of the invention relate to a blade fold assembly for a rotary wing aircraft, and more particularly, to a handle for operating a blade fold system. 
         [0004]    The flight capabilities of rotary-wing aircrafts make them effective for a wide variety of missions; however, operation of rotary-wing aircraft in certain environments may be limited by the overall structural envelopes thereof. The radial dimensions of a rotary-wing aircraft main rotor assembly results in a rotary-wing aircraft having relatively large structural envelopes which may impact its utility in some environments. For example, space on a ship or vessel is generally at a premium and the structural envelope of a rotary wing aircraft may require a significant allocation of such limited space. Furthermore, strategic and tactical considerations in the military utilization of rotary-wing aircrafts has led to a requirement for rotary-wing aircrafts having main rotor assemblies that may be readily reconfigured for rapid deployment, routine transport, and/or stowage by reducing the structural envelope. 
         [0005]    One way to reduce the structural envelope of rotary-wing aircraft to facilitate rapid deployment, routine transport, stowage, and reduce the vulnerability thereof to environmental conditions is to design the main rotor assembly so that the main rotor blades fold relative to the main rotor hub. However, conventional blade folding systems are cumbersome and are susceptible to drag, thereby decreasing the efficiency of the rotary wing aircraft in flight. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0006]    According to one embodiment of the invention, A pin configured for use in a rotor blade movable between an aligned position and a folded position and having a rotor blade airfoil contour is provided including a cylindrical body configured to couple a first section and a second section of the rotor blade when the rotor blade is in the aligned position. A handle is mounted to an end of the cylindrical body and has an airfoil contour complementary to the rotor blade airfoil contour. The handle is movable between an open position and a closed position. When the handle is in the closed position, the handle is flush with an adjacent portion of the rotor blade. When the handle is in the open position, the handle is accessible to pull the cylindrical body from the first and second sections of the rotor blade. 
         [0007]    In addition to one or more of the features described above, or as an alternative, in further embodiments the cylindrical body is configured to extend through an aligned first opening in the first section and a second opening in the second section. 
         [0008]    In addition to one or more of the features described above, or as an alternative, in further embodiments the handle is positioned adjacent at least one fairing of the rotor blade and the handle has an airfoil contour complementary to the airfoil contour of the at least one fairing. 
         [0009]    In addition to one or more of the features described above, or as an alternative, in further embodiments the locking device is configured to retain the handle in the closed position. 
         [0010]    In addition to one or more of the features described above, or as an alternative, in further embodiments upon removal of the locking device, a biasing mechanism is configured to bias the handle from the closed position to the open position. 
         [0011]    According to another embodiment of the invention, a rotor blade is provided including a first section and a second section. The first section includes a first connector having at least one first opening. The second section includes a second connector having at least one second opening. The second section is rotatably coupled to the first section and is configured to rotate between an aligned position and a rotated position. The first section and the second section have a generally complementary rotor blade airfoil contour. At least one pin is configured to extend through an aligned first opening and second opening when the second section is in the aligned position. The pin includes a cylindrical body and a handle mounted to an end of the cylindrical body. The handle is movable between an open position and a closed position. The handle has an airfoil contour generally complementary to the rotor blade airfoil contour such that when the handle is in the closed position, the handle is substantially flush with the adjacent first section and second section. When the handle is in an open position, the handle is accessible to pull the cylindrical body from the first and second sections of the rotor blade. 
         [0012]    In addition to one or more of the features described above, or as an alternative, in further embodiments the first section includes a blade retention fairing and the second section includes a blade root fairing. 
         [0013]    In addition to one or more of the features described above, or as an alternative, in further embodiments the airfoil contour of a first end of the blade retention fairing and the airfoil contour of an adjacent first end of the blade root fairing are generally complementary. 
         [0014]    In addition to one or more of the features described above, or as an alternative, in further embodiments when the second section is in the aligned position, a space exists between a portion of the first end of the blade retention fairing and a portion of the first end of the blade root fairing. 
         [0015]    In addition to one or more of the features described above, or as an alternative, in further embodiments the space extends from adjacent the aligned first opening and second opening to an outer edge of the blade retention fairing and blade root fairing. 
         [0016]    In addition to one or more of the features described above, or as an alternative, in further embodiments the first connector includes a generally parallel first upper arm and a first lower arm. The at least one first opening extends through both the first upper arm and the first lower arm. 
         [0017]    In addition to one or more of the features described above, or as an alternative, in further embodiments the second connector includes a generally parallel second upper arm and second lower arm. The at least one second opening extends through both the second upper arm and the second lower arm. 
         [0018]    In addition to one or more of the features described above, or as an alternative, in further embodiments a locking device is configured to retain the handle in the closed position. 
         [0019]    In addition to one or more of the features described above, or as an alternative, in further embodiments upon removal of the locking device, a biasing mechanism is configured to bias the handle from the closed position to the open position. 
         [0020]    Technical effects include a folding system for a rotor blade including handles having a shape complementary to an airfoil contour of the rotor blade. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0022]      FIG. 1  is a side view of an example of a rotary wing aircraft; 
           [0023]      FIG. 2  is an cross-sectional view of a main rotor system of the aircraft illustrated in  FIG. 1 ; 
           [0024]      FIG. 3  is a top view of a portion of a rotor blade of the main rotor system according to an embodiment of the invention; 
           [0025]      FIG. 4  is a cross-sectional view of the first and second connectors of a rotor blade in an aligned position according to an embodiment of the invention; 
           [0026]      FIG. 5  is a perspective view of a portion of a rotor blade in an aligned position having handles in an open position according to an embodiment of the invention; 
           [0027]      FIG. 6  is a top view of a portion of a rotor blade in an aligned position according to an embodiment of the invention; 
           [0028]      FIG. 7  is a perspective view of a portion of a rotor blade in an aligned position having handles in a closed position according to an embodiment of the invention; and 
           [0029]      FIG. 8  is a side view of a locking device configured to retain the handles of the rotor blade in a closed position according to an embodiment of the invention. 
       
    
    
       [0030]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0031]      FIG. 1  illustrates an exemplary vertical takeoff and landing (VTOL) rotary-wing aircraft  10  having a dual, counter-rotating, coaxial rotor system  12  which rotates about an axis of rotation A. The aircraft  10  includes an airframe  14  which supports the dual, counter rotating, coaxial rotor system  12  as well as an optional translational thrust system T which provides translational thrust generally parallel to an aircraft longitudinal axis L. Although a particular aircraft configuration is illustrated in the disclosed embodiment, other counter-rotating, coaxial rotor systems and non-coaxial rotor systems will also benefit from the present invention. 
         [0032]    A main gearbox  26  which may be located above the aircraft cabin drives the rotor system  12 . The translational thrust system T may be driven by the same main gearbox  26  which drives the rotor system  12 . The main gearbox  26  is driven by one or more engines (illustrated schematically at E). As shown, the main gearbox  26  may be interposed between the gas turbine engines E, the rotor system  12  and the translational thrust system T. 
         [0033]    Referring to  FIG. 2 , the dual, counter-rotating, coaxial rotor system  12  includes an upper rotor system  16  and a lower rotor system  18 . Each rotor system  16 ,  18  includes a plurality of rotor blade assemblies  20  mounted to a rotor hub assembly  22 , 24  for rotation about a rotor axis of rotation A. A plurality of the main rotor blade assemblies  20  project radially outward from the hub assemblies  22 ,  24 . Any number of main rotor blade assemblies  20  may be used with the rotor system  12 . 
         [0034]    While not required in all aspects, the shown rotor system  12  also includes a rotor hub fairing system Fh generally located between and around the upper and lower rotor systems  16 ,  18  such that the rotor hub assemblies  22 ,  24  are at least partially contained therein. The rotor hub fairing system Fh preferably includes an upper hub fairing Fu, a lower hub fairing Fl and a shaft fairing Fs therebetween. The shaft fairing Fs is preferably attached to the counter-rotating, coaxial rotor system  12  through a bearing arrangement Bu, Bl such that the shaft fairing Fs is aligned with the relative wind in forward flight but may be free to pivot during low speed maneuvering. The upper bearing Bu and the lower bearing Bl are respectively located adjacent an upper portion and a lower portion of the shaft fairing Fs. The upper bearing Bu is preferably attached to one rotor shaft  12 U while the lower bearing Bl attached to the other rotor shaft  12 L such that the bearings counter-rotate and net bearing drag is relatively low. 
         [0035]    Referring now to  FIGS. 3-5 , at least one of the rotor blade assemblies  20  includes a rotor blade  28  configured to fold about a fold axis X ( FIG. 2 ), generally perpendicular to the blade chord at or near the fold axis X. The rotor blade  20  is divided into a first section  30  and a complementary second section  50 . The first section  30  includes an attachment member or spindle  32 , a first end  34  of which is mounted to a rotor hub, such as rotor hub  22  or  24  for example, such that the attachment member  32  extends radially outward from the hub. The second end  36  of the attachment member  32  includes a first connector  38  having at least one opening  40 . In the illustrated, non-limiting embodiment, the first connector  38  includes a first opening  40   a  and an adjacent second opening  40   b.  The plurality of openings  40  may, but need not be, substantially similar in size and shape. The first connector  38  may resemble a clevis including an upper arm  42  and a lower arm  44  such that each opening  40  of the first connector  38  includes a pair of generally vertically aligned openings ( FIG. 4 ). The first section  30  of the rotor blade  28  also includes a blade retention fairing  46  having an airfoil contour that generally surrounds the attachment member  32 . A portion of the first connector  38  including the at least one opening  40  is positioned beyond a first end  48  of the blade retention fairing  46 . 
         [0036]    The second section  50  of the rotor blade  28  includes a blade spar  52  (best shown in  FIG. 5 ) having a second connector  56  coupled to or integrally formed with the end  54  of the blade spar  52  adjacent the first section  30 . The second connector  56  also includes at least one opening  58  complementary to an opening  40  of the first connector  38 . In one embodiment, the plurality of openings  58  of the second connector  56  is substantially equal to the plurality of openings  40  of the first connector  40 . In addition, the second connector  56  may resemble a clevis having an upper arm  60  and a lower arm  62  such that each opening  58  formed in the second connector  56  includes a vertically aligned first opening and second opening as shown in  FIG. 4 , although it is understood that the openings need not be vertically aligned in all aspects. As shown in  FIG. 4 , the openings  40   a,    40   b  are formed in upper arm  42  and lower arm  44  of the first connector  38 , and the openings  58   a,    58   b  are formed in upper arm  60  and lower arm  62  of the second connector  56 . However, the specific overlap and numbers of arms is not limited to the shown number and orientation in other aspects of the invention. 
         [0037]    A blade root fairing  64  having an airfoil contour surrounds a portion of the blade spar  52  of the second section  50 . The openings  58  formed within the second connector  56  extend beyond a first end  66  of the blade root fairing  64 . While not required in all aspects, the second connector  56  extends from the spar  52 , and the first connector  38  extends from a spar (not shown) of the first section  30 . A linkage  70 , illustrated schematically in  FIG. 3 , couples the blade spar  52  to the attachment member  32 , such that the second section  50  is configured to rotate to a desired angle about the blade fold axis X from an aligned position ( FIG. 5 ) to a rotated position ( FIG. 3 ). When the second section  50  is in the generally aligned position relative to the first section  30 , the first connector  38  and the second connector  56  are arranged in an overlapping arrangement. Pins  80  are inserted into the openings  40   a,    58   a,    40   b,    58   b  and are represented by the dashed lines in  FIG. 4 . In embodiments where both the first connector  38  and the second connector  56  are formed as a clevis, as shown in  FIG. 4 , the upper and lower arms  60 ,  62  of one of the connectors, such as the second connector  56  for example, may be positioned between the upper and lower arms  42 ,  44  of the other connector, such as the first connector  38 . Alternatively, the upper and lower arms  42 ,  44 ,  60 ,  62  of both connectors  38 ,  56  may be interposed and need not be equal in number in all aspects such as where arms  42  and  44  are used with arm  60  only. Further, while shown with two sets of openings, the number of openings is not limited thereto and may be increased or decreased according to the types of pins  80  and loadings anticipated. 
         [0038]    The airfoil contour of the first end  48  of the blade root fairing  46  is generally complementary to the airfoil contour at the adjacent end  66  of the blade retention fairing  64 . When the second section  50  is generally aligned with the first section  30 , a space  72  exists between at least one portion of the blade retention fairing  46  and the adjacent blade root fairing  64 . In the illustrated, non-limiting embodiment shown in  FIG. 5 , a first space  72   a  exists adjacent to a first set of aligned openings  40   a,    58   a  and extends from the aligned first openings  40   a,    58   a  to an outer edge  74 . Similarly, a second space  72   b  exists adjacent a second set of aligned openings  40   b,    58   b  and extends from the second openings  40   b,    58   b  to an opposite outer edge  76 . The spaces  72  may be uniform or may vary from adjacent the openings  40 ,  58  to an outer edge  74 ,  76  of the fairings  46 ,  64 . Each space  72  is at least equal in size to the adjacent openings  40 ,  58  to receive the pin configured to fit therein. 
         [0039]    When the first and second sections  30 ,  50  of the rotor blade  28  are aligned, a generally cylindrical pin  80  may be inserted within each set of aligned openings  40 ,  58  to couple the first and second connectors  38 ,  56 . Once the pins  80  are inserted, rotation of the second section  50  relative to the first section  30  may be limited, or blocked entirely. 
         [0040]    Connected to an end  82  of each cylindrical pin  80  is a U-shaped handle  84  configured to pivot between an open position ( FIG. 5 ) and a closed position ( FIG. 6 ). The handles  84  may be formed from a metal material, such as stainless steel or titanium for example. When each handle  84  is in the closed position, the handle  84  is arranged within the space  72  between the blade retention fairing  46  and the blade root fairing  64 . The U-shape of the handle  84  is generally complementary to the airfoil contour of the blade retention fairing  46  and the blade end fairing  64  such that when the handle  84  is in the closed position, the handle  84  is substantially flush with the adjacent fairings  46 ,  64 . This creates a connection between the second section spar  52  and a spindle of the first section  30 . 
         [0041]    A locking device  90 , illustrated in  FIG. 8  and generally known in the art, is configured to prevent the unintentional removal of one or more of the cylindrical pins  80  from a set of aligned openings  40 ,  58 , such as during operation of the rotary wing aircraft  10  for example. The locking device  90 , such as integrally formed with the second end  86  of the handle  84  for example, includes a forked plate  92  having a U-shaped slot  94  dimensioned to engage a groove  83  formed about the circumference of the pin  80  near end  81 . An adjacent flap  96  includes an opening  98  similarly dimensioned to facilitate to facilitate force fitting the flap onto the second end  81  of the cylindrical pin  80 . Together the forked plate  92  and the flap  96  retain the pin  80  and handle  84  in the closed position. 
         [0042]    By adapting the handle  84  to fit within the space  72  and have a contour complementary to the airfoil of the fairings  46 ,  64 , the drag of the rotor blade  28  is reduced while reliably locking the rotor blade  28  about the blade folding axis X. 
         [0043]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. For instance, while shown as being relatively close to the rotor hub, the opening  72  between the first and second sections  30  and  50  could be farther outboard from what is shown. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. By way of example, aspects could be used in fixed wing aircraft, but the invention is not limited to aircraft. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.