Abstract: A pitch bearing for connecting first and second articles is provided. The first article includes a first curved outer surface and the second article includes a second curved outer surface opposite the first curved outer surface. The pitch bearing includes an axisymmetric structure interposed between the first and second curved outer surfaces. The axisymmetric structure includes compliant layers and stabilizing layers interleaved between the compliant layers. The compliant layers and the stabilizing layers proximate to the first article haves a curvature matching that of the first curved outer surface. The compliant layers and the stabilizing layers proximate to the second article have a curvature matching that of the second curved outer surface. A shear stiffness of each of the stabilizing layers is greater than a shear stiffness of each of the compliant layers.

Abstract: A spar for a rotor blade assembly is provided including a generally hollow tubular body. A spacer protrudes from at least one surface of the body along a length of the body. A hole extends through the body and the spacer. The hole is configured to align with a through hole in an adjacent flexbeam assembly. The spacer is configured to contact a surface of the adjacent flexbeam assembly to create a match fit between the body and the flexbeam assembly.

Abstract: A rotor hub assembly for a helicopter includes a rotor hub operably connectable to a shaft of a helicopter. One or more flex beams extend through the rotor hub, with each end of each flex beam operably connectable to a rotor blade. One or more inner bearings are located at the rotor hub to spherically support the one or more flex beams in the rotor hub. A rotor assembly for a helicopter includes a rotor hub operably connectable to a shaft of a helicopter. One or more flex beams extending through the rotor hub and one or more inner bearings are located at the rotor hub to spherically support the one or more flex beams in the rotor hub. A plurality of rotor blades are operably connected to the ends of the one or more flex beams.

Abstract: A rotor blade assembly includes a flex-beam member and a torque tube surrounding the flex-beam member and extending partially along a rotor blade assembly length. A rotor blade surrounds the flex beam member and extends from the torque tube to a blade tip. A connecting assembly secures the rotor blade and the torque tube at the flex-beam member. The connecting assembly includes a first connecting member extending at least partially into the rotor blade assembly through the rotor blade from a first rotor blade side and a second connecting member located at a second rotor blade side. A clamping load between the first connecting member and the second connecting member secures the rotor blade and torque tube to the flex-beam member.

Abstract: A rotor blade assembly includes a flex-beam member and a torque tube surrounding the flex-beam member and extending partially along a rotor blade assembly length. A rotor blade surrounds the flex beam member and extends from the torque tube to a blade tip. A connecting assembly secures the rotor blade and the torque tube at the flex-beam member. The connecting assembly includes a first connecting member extending at least partially into the rotor blade assembly through the rotor blade from a first rotor blade side and a second connecting member located at a second rotor blade side. A clamping load between the first connecting member and the second connecting member secures the rotor blade and torque tube to the flex-beam member.

Abstract: A rotor blade assembly includes a flex-beam member and a torque tube surrounding the flex-beam member and extending partially along a rotor blade assembly length. A rotor blade surrounds the flex beam member and extends from the torque tube to a blade tip. A connecting pin assembly secures the rotor blade and the torque tube at the flex-beam member. The connecting pin assembly includes a first pin member having a first shaft extending at least partially into the rotor blade assembly through the rotor blade from a first rotor blade side and a second pin member located at a second rotor blade side. A clamping load between the first pin member and the second pin member secures the rotor blade and torque tube to the flex-beam member.

Abstract: A pitch bearing for connecting first and second articles is provided. The first article includes a first curved outer surface and the second article includes a second curved outer surface opposite the first curved outer surface. The pitch bearing includes an axisymmetric structure interposed between the first and second curved outer surfaces. The axisymmetric structure includes compliant layers and stabilizing layers interleaved between the compliant layers. The compliant layers and the stabilizing layers proximate to the first article haves a curvature matching that of the first curved outer surface. The compliant layers and the stabilizing layers proximate to the second article have a curvature matching that of the second curved outer surface. A shear stiffness of each of the stabilizing layers is greater than a shear stiffness of each of the compliant layers.

Abstract: A rotor blade assembly includes a flex-beam member and a torque tube surrounding the flex-beam member and extending partially along a rotor blade assembly length. A rotor blade surrounds the flex beam member and extends from the torque tube to a blade tip. A connecting pin assembly secures the rotor blade and the torque tube at the flex-beam member. The connecting pin assembly includes a first pin member having a first shaft extending at least partially into the rotor blade assembly through the rotor blade from a first rotor blade side and a second pin member located at a second rotor blade side. A clamping load between the first pin member and the second pin member secures the rotor blade and torque tube to the flex-beam member.

Abstract: A rotor system includes a lead stop mounted to a spindle and a lead stop plate mounted to a rotor hub arm, the lead stop operable to contact the lead stop plate over a lead angle range.

Abstract: A rotor blade assembly includes one or more flex-beam members and a torque tube surrounding the one or more flex-beam members and extending at least partially along a rotor blade assembly length. A pitch bearing assembly is supportive of the torque tube relative to the one or more flex-beam members and includes at least two outer bearing members secured to the torque tube and an inner bearing member positioned at least partially within the at least two inner bearing members and secured to the one or more flex beam members. A change in a stiffness of the inner bearing member changes one or more dynamic characteristics of the rotor blade assembly.

Abstract: A spar for a rotor blade assembly is provided including a generally hollow tubular body. A spacer protrudes from at least one surface of the body along a length of the body. A hole extends through the body and the spacer. The hole is configured to align with a through hole in an adjacent flexbeam assembly. The spacer is configured to contact a surface of the adjacent flexbeam assembly to create a match fit between the body and the flexbeam assembly.

Abstract: A rotor hub assembly for a helicopter includes a rotor hub operably connectible to a shaft of a helicopter. One or more flex beams extend through the rotor hub, with each end of each flex beam operably connectible to a rotor blade. One or more inner bearings are located at the rotor hub to spherically support the one or more flex beams in the rotor hub. A rotor assembly for a helicopter includes a rotor hub operably connectible to a shaft of a helicopter. One or more flex beams extending through the rotor hub and one or more inner bearings are located at the rotor hub to spherically support the one or more flex beams in the rotor hub. A plurality of rotor blades are operably connected to the ends of the one or more flex beams.

Abstract: A rotor system includes a lead stop mounted to a spindle and a lead stop plate mounted to a rotor hub arm, the lead stop operable to contact the lead stop plate over a lead angle range.