BACKGROUND

The subject matter disclosed herein generally relates to the art of rotary wing aircraft and, more particularly, to a dual flex-beam assembly for a folding rotor blade.

In typical flex-beam helicopter rotors, a flex-beam extends from a hub member and is connected to a torque tube and blade via a bolted joint at, for example, midspan of the rotor. The joint comprises a pattern of two or more fasteners. In some rotors four or six fasteners, such as bolts, extend through the torque tube, rotor blade and flex-beam at the midspan. The joint is utilized to restrict relative motion of the torque tube, rotor blade and flex-beam. The joint also provides a load path for loads acting on the rotor blade to be transmitted to the flex-beam and then into the hub member. For a folding rotor, a hinge may be arranged at a point inboard from the midspan. The point inboard from the midspan may not provide enough area or length to support a flex-beam that will provide desired stiffness characteristics.

BRIEF DESCRIPTION

According to an embodiment, a rotor blade for a rotary wing aircraft includes a rotor hub including a first flex-beam attachment member and a second flex-beam attachment member, a rotor blade member which generates lift for the rotor blade, and a flex-beam assembly supporting the rotor blade and connected to the rotor hub. The flex-beam assembly includes a flex-beam support member spaced from the rotor hub and having an attachment end and a wrapping end. The rotor blade member is rotatably attached to and extends from the flex-beam support member. A first flex-beam includes a first end, a second end and an intermediate portion. The first end of the first flex-beam is connected at the first flex-beam attachment member and the second end of the first flex-beam being connected to the attachment end of the flex-beam support member. A second flex-beam includes first end portion, a second end portion and an intermediate section. The first end portion of the second flex-beam is connected at the first flex-beam attachment member, the second end portion of the second flex-beam being connected at the second flex-beam attachment member and the intermediate section extending about the wrapping end of the flex-beam support member.

In addition to one or more of the features described above, or as an alternative, in further embodiments a third flex-beam includes a first end section, a second end section and an intermediate segment, the first end section of the third flex-beam being connected at the second flex-beam attachment member and the second end section of the third flex-beam being connected at the attachment end of the flex-beam support.

In addition to one or more of the features described above, or as an alternative, in further embodiments the first flex-beam defines a inner beam and the second flex-beam defines an outer beam.

In addition to one or more of the features described above, or as an alternative, in further embodiments the first flex-beam is connected to the flex-beam support member with at least one fastener.

In addition to one or more of the features described above, or as an alternative, in further embodiments the flex-beam support member defines a hinge end having an opening between the attachment end and a wrapping end, the rotor blade member being attached to the hinged end.

In addition to one or more of the features described above, or as an alternative, in further embodiments a torque tube mounted to the at least one of the first and second flex-beams.

In addition to one or more of the features described above, or as an alternative, in further embodiments the torque tube includes a pivoting blade member arranged at the hinge end.

In accordance with another aspect of an exemplary embodiment, a rotary wing aircraft includes a fuselage, at least one prime mover supported in the fuselage, and a rotor assembly operatively connected to the at least one prime mover. The rotor assembly includes a rotor hub having a first flex-beam attachment member, a second flex-beam attachment member, and a rotor blade mounted to the rotor hub. The rotor blade includes a flex-beam assembly supporting the rotor blade and connected to the rotor hub. The flex-beam assembly includes a flex-beam support member spaced from the rotor hub and having an attachment end and a wrapping end, the rotor blade member rotatably attached to and extending from the flex-beam support member. A first flex-beam includes a first end, a second end and an intermediate portion, the first end being connected at the first flex-beam attachment member and the second end being connected to the attachment end of the flex-beam support member. A second flex-beam includes first end portion, a second end portion and an intermediate section. The first end portion being connected at the first flex-beam attachment member, the second end portions being connected at the second flex-beam attachment member and the intermediate section extending about the wrapping end of the flex-beam support member.

In addition to one or more of the features described above, or as an alternative, in further embodiments a third flex-beam includes a first end section, a second end section and an intermediate segment, the first end section being connected at the second flex-beam attachment member and the second end section being connected at the attachment end of the flex-beam support.

In addition to one or more of the features described above, or as an alternative, in further embodiments the first flex-beam defines an inner beam and the second flex-beam defines an outer beam.

In addition to one or more of the features described above, or as an alternative, in further embodiments wherein the first flex-beam is connected to the flex-beam support member with at least one fastener.

In addition to one or more of the features described above, or as an alternative, in further embodiments the cantilevered end defines a hinge end having an opening between the attachment end and a wrapping end, the rotor blade member being attached to the hinged end.

In addition to one or more of the features described above, or as an alternative, in further embodiments a torque tube extending about the flex-beam assembly.

In addition to one or more of the features described above, or as an alternative, in further embodiments the rotor blade is connected to the torque tube, the rotor blade being configured to pivot about the hinge end.

In addition to one or more of the features described above, or as an alternative, in further embodiments . . . .

The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. However, it should be understood that the following description and drawings are intended to be exemplary in nature and non-limiting.

