Abstract: A rotor blade configured to be installed on a rotary wing aircraft includes a spar including an inboard portion extending from a root of the rotor blade to a first spanwise position of the rotor blade and an outboard portion meeting the inboard portion at the first spanwise position. The rotor blade further includes an upper skin and a lower skin coupled the outboard portion of the spar. The first spanwise position is defined by a most inboard point at which the upper and lower skins are coupled to the spar. The inboard portion includes a top layer, a bottom layer, and an inner cavity. The top layer has a substantially constant first thickness and the bottom layer has a substantially constant second thickness, and the distance between an outer surface of the top layer and an outer surface of the bottom layer is substantially constant.

Abstract: A method of modifying a rotor blade is provided for a rotor blade including a spar having an inboard portion with a substantially constant overall height, the inboard portion further including a top layer having a substantially constant first thickness and a bottom layer having a substantially constant second thickness. The method includes removing a root portion of the inboard portion to thereby modify the rotor blade and installing a cuff configured to couple to the rotor blade to an aircraft.

Abstract: A rotor blade for a rotary wing aircraft includes a leading edge and a trailing edge defining a chordwise direction. The leading edge defines a forward end of the rotor blade and the trailing edge defines an aft end of the rotor blade. The rotor blade has a center of gravity and an aerodynamic center along the chordwise direction. The center of gravity is aft of the aerodynamic center.

Abstract: A method of modifying a rotor blade is provided for a rotor blade including a spar having an inboard portion with a substantially constant overall height, the inboard portion further including a top layer having a substantially constant first thickness and a bottom layer having a substantially constant second thickness. The method includes removing a root portion of the inboard portion to thereby modify the rotor blade and installing a cuff configured to couple to the rotor blade to an aircraft.

Abstract: An electrical conductor assembly for a rotor blade includes a substrate and at least one electrical conductor. The substrate includes an inboard end portion and an outboard end portion. The at least one electrical conductor is attached to the substrate and extends between the inboard end portion and the outboard end portion. The at least one electrical conductor is configured to transmit electricity along a length of the rotor blade. The inboard end portion and the outboard end portion are structured such that when the electrical conductor assembly is installed within the rotor blade, the inboard end portion is securable relative to the rotor blade and the outboard end portion is movable relative to the rotor blade.

Abstract: A structural member for use in a rotor system which rotates about a rotational axis includes a pin which extends substantially perpendicular to the rotational axis, a filler component positioned adjacent the pin, and a plurality of layers of composite material having fibers oriented lengthwise along a central axis which is perpendicular to the rotational axis. The plurality of fibers in the layers of composite material is wrapped about the pin and the filler component such that the fibers extend along the central axis and the plurality of layers form an opening filled by the filler component and which decreases as a function of distance from the pin along the central axis.

Abstract: A structural member for use in a rotor system which rotates about a rotational axis includes a pin which extends substantially perpendicular to the rotational axis, a filler component positioned adjacent the pin, and a plurality of layers of composite material having fibers oriented lengthwise along a central axis which is perpendicular to the rotational axis. The plurality of fibers in the layers of composite material is wrapped about the pin and the filler component such that the fibers extend along the central axis and the plurality of layers form an opening filled by the filler component and which decreases as a function of distance from the pin along the central axis.

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 method of forming an in-wing device-retention assembly includes inserting a first plate into a wing, the wing having a wide end and a narrow end. The method includes inserting a second plate into the wing, inserting a wedge plate into the wing and positioning the wedge plate between the first plate and the second plate, and applying a force to the wedge plate in a direction toward the narrow end to fix the first plate, the second plate and the wedge plate within the wing.

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 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 method of forming an in-wing device-retention assembly includes inserting a first plate into a wing, the wing having a wide end and a narrow end. The method includes inserting a second plate into the wing, inserting a wedge plate into the wing and positioning the wedge plate between the first plate and the second plate, and applying a force to the wedge plate in a direction toward the narrow end to fix the first plate, the second plate and the wedge plate within the wing.

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 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.