Abstract:
A mounting assembly for connecting a first surface to a second surface and for holding a first servo which moves an adjacent first component is provided including a leg. A first end of the leg is attachable to the first surface and a second end of the leg is attachable to the second surface. The leg is generally bent such that the first end of each leg is arranged at an angle to the second end of each leg so as to transmit forces between the first and second surface. A bracket connected to the leg includes a notch configured to receive the first servo. When the first servo is positioned within the first notch, a free end of the first servo is operably coupled to the adjacent first component and the leg reacts forces generated by the first servo into the first and second surfaces.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional patent application Ser. No. 61/871,129 filed Aug. 28, 2013 and U.S. provisional patent application Ser. No. 61/871,199 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. W911W6-11-2-0007 with the Department of 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 rotary wing aircraft, and more particularly, to a mounting assembly of the main rotor system of the rotary wing aircraft. 
         [0004]    The main rotor assembly of a helicopter develops large magnitude dynamic and static longitudinal, lateral, vertical, and torsional loads. Known helicopter design methodology utilizes a support structure to integrate elements of the main rotor assembly, such as the rotor mast and the engine transmission within the helicopter airframe. Such support structures also provide main rotor servo attachment lugs which provide lower attachment points for the rotor servo actuators which are operable to articulate a main rotor swash plate. 
         [0005]    As the support structure and particularly the attachment lugs must resist large magnitude loads, known support structures are commonly manufactured of rigid metallic materials, such as titanium. This metal support structure is costly and adds weight to the aircraft. 
         [0006]    As with other aerospace components, there is a desire to reduce the cost and weight and complexity of the support structure and main rotor servo attachment lugs. Accordingly, it is desirable to provide a support structure which is lightweight, inexpensive, relatively simple to manufacture, and easily secured to the helicopter main rotor system and airframe. It is also desirable to provide a structure for supporting the main rotor servos that is integral to the support structure and resistant to large magnitude axial and transverse loads. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0007]    According to one embodiment of the invention, a mounting assembly for connecting a first surface to a second surface and for holding a first servo which moves an adjacent first component is provided including a leg. A first end of the leg is attachable to the first surface and a second end of the leg is attachable to the second surface. The leg is generally bent such that the first end of each leg is arranged at an angle to the second end of each leg so as to transmit forces between the first and second surface. A bracket connected to the leg includes a notch configured to receive the first servo. When the first servo is positioned within the first notch, a free end of the first servo is operably coupled to the adjacent first component and the leg reacts forces generated by the first servo into the first and second surfaces. 
         [0008]    In addition to one or more of the features described above, or as an alternative, in further embodiments the first end of the leg is shaped to be coupled to a cylindrical sleeve arranged about a rotating shaft 
         [0009]    In addition to one or more of the features described above, or as an alternative, in further embodiments including additional legs, wherein the leg and the additional legs are spaced equidistantly about the cylindrical sleeve. 
         [0010]    In addition to one or more of the features described above, or as an alternative, in further embodiments the second end of the leg is configured to couple to an airframe of a rotary wing aircraft. 
         [0011]    In addition to one or more of the features described above, or as an alternative, in further embodiments each bracket further comprises a second notch configured to receive a second servo. 
         [0012]    In addition to one or more of the features described above, or as an alternative, in further embodiments when the second servo is positioned within the second notch, a free end of the second servo is operably coupled to an adjacent second component. 
         [0013]    In addition to one or more of the features described above, or as an alternative, in further embodiments the adjacent first component comprises a first stationary swashplate, and the free end of the first servo is operably coupled to the first stationary swashplate and the adjacent second component comprises a second stationary swashplate, and the free end of the second servo is operably coupled to the second stationary swashplate. 
         [0014]    According to another embodiment of the invention, a mounting assembly for connecting a first surface to a second surface and for holding a first servo which moves an adjacent first component is provided including a leg. A first end of the leg is attachable to the first surface and a second end of the leg is attachable to the second surface. The leg is generally bent such that the first end of each leg is arranged at an angle to the second end of each leg so as to transmit forces between the first and second surface. A rib extends from the leg near the second end thereof. The rib is configured to connect to and support a portion of an active vibration control system. 
         [0015]    In addition to one or more of the features described above, or as an alternative, in further embodiments the portion of the active vibration control system includes at least one force generator. 
         [0016]    In addition to one or more of the features described above, or as an alternative, in further embodiments the rib is integrally formed with the leg. 
         [0017]    According to another embodiment of the invention, a rotary wing aircraft is provided including an airframe and a main rotor system configured to rotate about a first axis of rotation. A first stationary swashplate is operably coupled to at least one first blade of the main rotor system. A mounting assembly is configured to transfer loads from the main rotor system to the airframe. The mounting assembly includes a first leg having a first end and a second end. The first end of the first leg is coupled to the main rotor system and the second end of the first leg is connected to the airframe. A bracket integrally formed with the first leg includes a first notch configured to receive a first servo. A free end of the first servo is operably coupled to the first stationary swashplate. 
         [0018]    In addition to one or more of the features described above, or as an alternative, in further embodiments operation of the first servo adjusts a pitch of the at least one first blade via the first stationary swashplate. 
         [0019]    In addition to one or more of the features described above, or as an alternative, in further embodiments a second stationary swashplate is operably coupled to at least one second blade of the main rotor system. The bracket further comprises a second notch configured to receive a second servo such that a free end of the second servo is operably coupled to the second stationary swashplate. Operation of the second servo adjusts a pitch of the at least one second blade via the second stationary swashplate. 
         [0020]    In addition to one or more of the features described above, or as an alternative, in further embodiments a portion of an active vibration control system is mounted to the first leg of the mounting assembly. 
         [0021]    In addition to one or more of the features described above, or as an alternative, in further embodiments the portion of the active vibration control system includes at least one force generator mounted to the leg. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    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: 
           [0023]      FIGS. 1A-1B  are general views of an example of a rotary wing aircraft; 
           [0024]      FIG. 2  is a side perspective view of a mounting assembly according to an embodiment of the invention; 
           [0025]      FIG. 3  is a front view of a bracket of a mounting assembly according to an embodiment of the invention; 
           [0026]      FIG. 4  is a top perspective view of the mounting assembly according to another embodiment of the invention; and 
           [0027]      FIG. 5  is a top view of a portion of a leg of the mounting assembly according to an embodiment of the invention. 
       
    
    
       [0028]    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 
       [0029]      FIGS. 1A and 1B  illustrate an exemplary vertical takeoff and landing (VTOL) rotary-wing aircraft  10  having a dual contra-rotating, coaxial main rotor system  12 , which rotates about an axis of rotation A. The aircraft  10  includes an airframe  14  which supports the dual, contra-rotating, coaxial main rotor system  12 , as well as a translational thrust system  30 , 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 as well as non-coaxial rotor systems will also benefit from the present invention. 
         [0030]    The main rotor system  12  includes a first rotor system  16  and a second rotor system  18 , and each rotor system  16 ,  18  includes a multiple of rotor blades  20  mounted to a rotor hub  22 ,  24 . The main rotor system  12  is driven by a main gearbox  26 . The translational thrust system  30  may be any propeller system including, but not limited to a pusher propeller, a tractor propeller, a nacelle mounted propeller, etc. In one embodiment, the translational thrust system  30  includes a pusher propeller system  32  as illustrated with a propeller rotational axis P oriented substantially horizontal and parallel to the aircraft longitudinal axis L to provide thrust for high speed flight. The translational thrust system  30  may alternatively or additionally include side mounted thrusters, forward mounted thrusters, or other prop or jet powered systems separate from the main rotor system  12 . The illustrated embodiment mounted the propeller system  32  with an aerodynamic cowling  34  at the rear of the airframe  14 . The translational thrust system  30  is preferably driven through the main gearbox  26  which drives the rotor  12 . 
         [0031]    The main gearbox  26  is driven by one or more engines E (two shown). In the case of a rotary wing aircraft, the gearbox  26  is interposed between one or more gas turbine engines, the rotor system  12 , and the translational thrust system  30 . The main gearbox  26  may be a split torque gearbox which carries torque from the engines E through a multitude of drive train paths. 
         [0032]    Referring now to  FIGS. 2 and 3 , a mounting assembly  50  is configured to transmit the loads from the main rotor system  12  to the airframe  14 . Positioned about the lower rotor shaft  40  of the main rotor system  12 , adjacent the airframe  14  and gearbox  26 , is a stationary cylindrical sleeve  42 . The lower rotor shaft  40  is configured to rotate within the cylindrical sleeve  42 . The mounting assembly  50  includes a plurality of generally bent or angled legs  52  such that a first end  54  of each leg  52  is arranged generally perpendicular to a second, opposite end  56  of each leg  52 . The legs  52  are equidistantly spaced about the lower rotor shaft  40  and the first end  54  of each of the plurality of legs  52  is connected to the cylindrical sleeve  42 , such as with a spline and cone connection or a fastener for example. In the mounted position, the first end  54  of each of the plurality of legs  52  is orientated substantially parallel to the axis of rotation A of the lower rotor shaft  40  and the second end  56  of each leg  52  is configured to couple, such as with a fastener (not shown) for example, to an adjacent surface of the airframe  14 . As a result, the forces generated by the main rotor system  12  are transferred to the airframe  14  via the plurality of legs  52 . 
         [0033]    Integrally formed with each leg  52  is an L-shaped bracket  60  configured to support at least one servo  62 , such as a hydraulic or electro-mechanical servo for example. Each L-shaped bracket includes a vertical member  64  and a base  66 , the vertical member  64  being arranged generally parallel to the lower rotor shaft  40 . In the illustrated, non-limiting embodiment, a front surface  68  of the vertical member  64  is integrally formed with a first side  58  of a corresponding leg  52  such that the base  66  extends through the opening  68  formed between the leg  52  and the airframe, towards the opposite side  59  of the leg  52 . Such integral formation can be accomplished through casting processes, additive manufacturing techniques, or other mechanisms where the combination is created as a single piece of the same material. However, it is understood that the front surface  68  of the vertical member  64  can be connected to the first side  58  using fasteners, splines or other like mechanisms. 
         [0034]    A first notch  72  is formed in a first side  70  of the vertical member  64  of the L-shaped bracket  60 . The size and shape of the first notch  72  is generally complementary to the servo  62  configured to be received therein. A first end  74  of the servo  62  positioned within the first notch  72  is configured to engage a first stationary swashplate  76 , such as a lower swashplate for example. Operation of the servo  62  located within the first notch  72  adjusts the pitch of at least one of the plurality of blades  20  of the upper or lower rotor system  16 ,  18  via the first swashplate  76 . In one embodiment, illustrated in  FIG. 3 , a second notch  77 , similar to or different from the first notch  72 , is formed in a second, opposite side  75  of the vertical member  64  of the bracket  60 . The second notch  77  is also configured to receive a servo  62 . The servo  62  located within the second notch  77  may be substantially identical to or different from the servo  62  located within the first notch  72 . In one embodiment, the servos  62  are fastened within the first and second notch  72 ,  77 , such as with a bolt or other fastener for example. When a servo  62  is positioned in the second notch  77 , a free end  78  of the servo  62  is configured to engage a second stationary swashplate (illustrated schematically at  80 ), such as an upper swashplate for example. The servo  62  located within the second notch  77  is similarly configured to adjust the pitch of at least one of the plurality of blades  20  of the other of the upper or lower rotor system  16 ,  18  via the second swashplate  80 . 
         [0035]    Referring now to  FIGS. 4 and 5 , in another embodiment, at least one of the plurality of legs  52  of the mounting assembly  50  is configured to support a portion of an active vibration control system  90  of the aircraft  10 , such as one or more force generators  92  for example. The other components of the active vibration control system  90  are generally positioned near the legs  52  to minimize the weight of the system  90 . A rib  82  is positioned near the second, outboard end  56  of one or more of the legs  52  and extends generally outwardly therefrom. As illustrated in  FIG. 5 , the rib  82  is received centrally between and coupled to a center opening formed in a force generator  92 . The rib  82  may be integrally formed with the leg  52  and may extend generally parallel to the length of the leg  52 , or may extend generally across the width of the leg  52 . 
         [0036]    In embodiments where a force generator  92  is mounted to each of a plurality of legs  52 , at least one of the force generators  92  has a different orientation relative to the other force generators  92 . In the illustrated, non-limiting embodiment, the force generators  92  mounted to the legs  52  forward of the main rotor system  12  (between the main rotor system  12  and a nose  13  of the airframe  14 ) have a first orientation, and the force generators  92  mounted to the legs  52  aft of the main rotor system  12  (between the main rotor system  12  and a tail  15  of the airframe  14 ) have a second orientation. The first orientation and the second orientation are arranged generally at an angle to one another, such as perpendicular for example, to distribute the various loads from the main rotor system  12 . Having the force generators  92  disposed offset from the center of rotation A maximizes an effective moment arm to cancel vibratory roll, pitch and yaw moments and allows for smaller force generators  92  to be used. Further, placement of the force generators  92  on the legs  52  positions the force generators  92  on a primary load path of the vibratory load and upstream from. While shown without the bracket  60 , it is understood that the force generators  92  could be mounted on legs  52  also having the bracket  60  in aspects of the invention. 
         [0037]    By coupling a plurality of legs  52 , each having an integrally formed L-shaped bracket  60 , to the sleeve  42  of the lower rotor shaft  40  of the main rotor system  12 , the forces generated by the first and second rotors  16 ,  18  are distributed through the mounting assembly  50  to the airframe  14 . In addition, the legs  52  provide a location for mounting the servos  62  configured to provide pitch control of the blades  20  and a location for mounting the force generators of the active vibration control system  90 . As a result, the overall weight and complexity of the aircraft  10  is reduced. 
         [0038]    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. 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.