Abstract:
A rotor blade spar for use in a rotor blade is provided comprising a housing defining an interior and having an open end. An end cap is affixed to and sealed on the open end to seal the interior from an exterior outside of the housing. The end cap includes a first port and a second port fluidly coupling the interior to the exterior. A port sealing system closes the first and second ports. The first port is connectable to an external device configured to generate a pressure differential between the interior and the exterior sufficient to create an airflow through the first and second ports which removes a liquid disposed in the housing through one of the first and second ports.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority of U.S. Provisional Application No. 62/103,249 filed Jan. 14, 2015, the disclosure of which is incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Exemplary embodiments of the invention relate to a rotary wing aircraft, and more particularly, to a method and apparatus for manufacturing a rotor blade of a rotary wing aircraft. 
         [0003]    A rotor blade includes a blade spar, which is a hollow cavity providing structural support to the rotor blade. To prevent water from entering the spar, the end of the spar can be sealed. However, water can enter the spar even with a seal. For example, during fabrication, the formation of a fastener hole can allow water to enter the blade spar. Another example would be through a broken seal, or where the blade is stored in a container that has water leaking into it. Water can also come from changes in temperature causing condensation inside the spar. Once the water enters the blade spar, the water becomes trapped in the closed tip of the blade. The water must then be removed since the water can affect the balance of the blade during usage. To remove any water accumulated therein, the sealed end cap of the blade spar must be removed during which potential for damaging the remainder of the blade spar exists. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    According to one embodiment of the invention, a rotor blade spar for use in a rotor blade is provided comprising a housing defining an interior and having an open end. An end cap is affixed to and sealed on the open end to seal the interior from an exterior outside of the housing. The end cap includes a first port and a second port fluidly coupling the interior to the exterior. A port sealing system closes the first and second ports. The first port is connectable to an external device configured to generate a pressure differential between the interior and the exterior sufficient to create an airflow through the first and second ports which removes a liquid disposed in the housing through one of the first and second ports. 
         [0005]    In addition to one or more of the features described above, or as an alternative, in further embodiments the port sealing system comprises a first valve arranged in the first port and a second valve arranged in the second port. The first valve and the second valve are opened when the pressure differential is created and closed when the pressure differential is not created. 
         [0006]    In addition to one or more of the features described above, or as an alternative, in further embodiments the external device is configured blow air into the interior. 
         [0007]    In addition to one or more of the features described above, or as an alternative, in further embodiments the external device is a vacuum. 
         [0008]    In addition to one or more of the features described above, or as an alternative, in further embodiments at least one of the first and second ports includes an opening extending through the end cap and the sealing system comprises a plug removably inserted within the opening. When the plug is removed, the external device may be fluidly coupled to at least one of the first and second port. 
         [0009]    In addition to one or more of the features described above, or as an alternative, in further embodiments wherein the sealing system includes a one way valve configured to allow fluid to flow through the first port in a first direction. 
         [0010]    In addition to one or more of the features described above, or as an alternative, in further embodiments the first port includes a one way valve configured to allow air to flow into the interior of the object and the second port includes a one way valve configured to allow air and the liquid to flow out of the interior. 
         [0011]    According to another embodiment of the invention, a method of removing water from an interior of a rotor blade spar is provided comprising fluidly coupling an external device to an inlet port of an end cap mounted at and sealing an inboard end of the spar. The inlet port is arranged in fluid communication with an interior of the spar. A pressure differential is generated between an exterior of the spar and the interior of the spar such that the water flows from the interior of the spar through an outlet port in the end cap. 
         [0012]    In addition to one or more of the features described above, or as an alternative, in further embodiments the external device is configured to blow air into the object. 
         [0013]    In addition to one or more of the features described above, or as an alternative, in further embodiments the external device is a vacuum. 
         [0014]    In addition to one or more of the features described above, or as an alternative, in further embodiments at least one of the inlet port and the outlet port includes a plug removably inserted within an opening formed in the end cap. 
         [0015]    In addition to one or more of the features described above, or as an alternative, in further embodiments removing the plug from a respective opening prior to fluidly connecting the external device to the opening. 
         [0016]    In addition to one or more of the features described above, or as an alternative, in further embodiments at least one of the inlet port and the outlet port includes a one way valve. 
         [0017]    Technical effects include a rotor blade having minimal water accumulation within an interior thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    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: 
           [0019]      FIG. 1  is a perspective view of an example of a rotary wing aircraft; 
           [0020]      FIG. 2  is perspective view of a rotor blade assembly of a main rotor system of a rotary wing aircraft according to an embodiment of the invention; 
           [0021]      FIG. 3  is a perspective view of a rotor blade assembly having an end cap configured to allow water accumulated within an interior of the rotor blade to be removed according to an embodiment of the invention; 
           [0022]      FIG. 4  is a perspective view of an end cap having an inlet port and an outlet port according to an embodiment of the invention; and 
           [0023]      FIG. 5  is a cross-sectional view of a rotor blade assembly including an end cap having an inlet port and an outlet port according to an embodiment of the invention. 
       
    
    
       [0024]    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 
       [0025]      FIG. 1  schematically illustrates a rotary wing aircraft  10  having a main rotor assembly  12 . The aircraft  10  includes an airframe  14  having an extended tail  16  which mounts a tail rotor system  18 , such as an anti-torque system, a translational thrust system, a pusher propeller, a rotor propulsion system, and the like. The main rotor assembly  12  includes a plurality of rotor blade assemblies  22  mounted to a rotor hub  20 . The main rotor assembly  12  is driven about an axis of rotation A through a main gearbox (illustrated schematically at T) by one or more engines E. Although a particular helicopter configuration is illustrated and described in the disclosed embodiment, other configurations and/or machines, such as high speed compound rotary wing aircrafts with supplemental translational thrust systems, dual contra-rotating, coaxial rotor system aircrafts, tilt-rotors and tilt-wing aircrafts, and fixed wing aircrafts, will also benefit from embodiments of the invention. 
         [0026]    Referring now to the example rotor blade assembly  22  illustrated in  FIG. 2 , a generally hollow, tubular spar  30  configured to couple to the rotor hub  20  at an inboard end  32  extends over at least a portion of the length of the rotor blade assembly  22 . In one embodiment, the spar  30  may extend to the outboard end  24  of the rotor blade assembly  22 . The cross-section of the spar  30  may, but need not vary in size and shape over the length of the spar  30  depending on the contour of the rotor blade assembly  22 . The spar  30  is a structural member having a high torsional and axial stiffness and strength and, therefore, may be made from a high strength material, including but not limited to metal, graphite, fiberglass or some combination thereof 
         [0027]    Referring now to  FIGS. 3-5 , when the rotor blade assembly  22  is not attached to the rotor hub  20 , an end cap  40  is permanently or removably affixed to the spar  30  to close or seal an end thereof, such as inboard end  32  for example. The end cap  40  has a substantially solid body  42  formed from any suitable material, including but not limited to aluminum, titanium, or a composite for example. The shape of the end cap  40  is generally complementary to an interior (not separately labeled) of the spar  30  such that the end cap  40  may be inserted therein and an exterior surface  46  of the end cap  40  may be bonded to the adjacent interior surface  38  of the spar  30 . Alternatively, the end cap  40  may be a plate having a contour generally complementary to an adjacent portion of the spar  30  such that a surface (not shown) of the end cap  40  may directly contact the inboard end  32  of the spar  30 . In either embodiment, when the end cap  40  is mounted to the spar  30 , a surface of the end cap  40 , such as surface  46  for example, is substantially flush with the inboard end  32  of the spar  30 . The end cap  40  may be permanently affixed when the rotor blade assembly  22  is connected to the rotor hub  20  in aspects. In other aspects, the end cap  40  may be attached during storage and transportation of the rotor blade assembly  22 , and may be removed when the rotor blade assembly  22  is connected to the rotor hub  20 . 
         [0028]    During manufacturing of a rotor blade assembly  22  having a blade spar  30  with a closed inboard end  32  formed by an end cap  40 , water may accumulate inside the spar  30 . For example, during drilling or machining of one or more holes in the blade spar  30 , water used to cool the manufacturing equipment may be deposited inside the spar  30 . 
         [0029]    According to an embodiment of the invention, the end cap  40  includes at least one port configured for removing any water accumulated therein. In the illustrated, non-limiting embodiment, the end cap  40  includes an inlet port  50  and an outlet port  52 , separated from one another by a distance. Although the inlet port  50  and the outlet port  52  are shown arranged adjacent opposing ends of the end cap  40 , embodiments where at least one of the ports  50 ,  52  is formed near a central portion of the end cap  40  is within the scope of the invention. 
         [0030]    An external device  60 , such as an air supply for example, may be connected to the inlet port  50  to blow air into the interior  36  of the spar  30 . As a result of the pressure difference between the interior  36  and the exterior of the spar  30  generated by the input air, the air and any water accumulated within the spar  30  will flow out of the spar  30  through the outlet port  52 . In other embodiments, the external device  60  is a vacuum used to create the pressure differential between the interior  36  and the exterior of the spar  30  such that the water is sucked into the device  60 . Orienting the spar  30  at an angle as shown in  FIG. 5 , such that any water accumulated within the spar  30  is collected adjacent the outlet port  52  will additionally improve the water removal process. 
         [0031]    In the embodiment illustrated in  FIG. 4 , at least one of the inlet port  50  and the outlet port  52  includes an opening  62  extending through the entire thickness of the substantially solid  42  having a removable plug  64  inserted therein. The plug  64  may be formed from any suitable material, such as titanium, aluminum, composite, and PVC for example. In such embodiments, the plug  64  remains installed within the opening  62  during the machining of the blade spar  30  and also during storage and transport when not connected to the rotor hub  20  as well as during operation of the rotary wing aircraft  10 . The plug  64  is generally only detached from the end cap  40  when water or other small debris is being removed from the interior  36  of the spar  30 . In another embodiment, at least one of the inlet port  50  and the outlet port  52  includes a one-way valve. For example, a one-way valve used as the inlet port  50  would be configured to allow air to flow into, but not out of, the interior  36  of the spar  30 , and a one-way valve used as the outlet port  52  would be configured to allow water and air to flow out of the interior  36  of the spar  30 . As such, by producing a pressure differential, the air enters the interior  36  via the inlet port  50 , and exits the interior  36  along with the water via the outlet port  52 . 
         [0032]    By forming at least one port  50 ,  52  within the end cap  40  affixed to the spar  30 , any water or other small debris accumulated within the interior  36  of the spar  30  can be easily removed without causing damage to the spar  30 . Because the end caps  40  of the spar  30  will no longer need replacing, use of an end cap  40  as described herein during manufacture of the rotor blade assemblies  22  greatly reduces work costs and improves the manufacturing process associated therewith. Although the end cap  40  is illustrated and described herein with respect to a blade spar  30 , the end cap  40  may be used to seal the end of any object having a hollow interior and to prevent damage during manufacture thereof, such as for cleaning gas and/or water pipelines, perform plumbing maintenance, or the like. 
         [0033]    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. By way of example, the first housing may be a single piece as opposed to separate first and second portions. Further, while described in terms of water, it is understood that other liquids can be removed from the blade spar. 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. 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. 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.