A bearing system includes an inboard bearing assembly and an outboard bearing assembly. The inboard bearing assembly includes an inboard fitting and an inboard race. The inboard fitting includes a plate with a convex mating surface and a first aperture formed through the plate for receiving a blade root of a rotor blade. The inboard race comprising a concave mating surface configured to receive the convex mating surface a second aperture formed the inboard race. The outboard bearing assembly includes an outboard bearing assembly comprising an outboard fitting having an aperture formed therethrough for receiving the blade root of the rotor blade.

A blade speed control apparatus and method. The apparatus includes a rotor assembly a first blade assembly movably attached to the rotor assembly at a first initial position, a second blade assembly movably attached to the rotor assembly at a second initial position, and a movement mechanism configured to move the rotor assembly in a first lateral direction along a y-axis such that a first angle exists between the first blade assembly with said respect to the second blade assembly. The movement mechanism is configured to move a portion of the rotor assembly in a first lateral direction along a y-axis such that a first angle exists between the first blade assembly with said respect to the second blade assembly. The first angle does not comprise an angle of 180 degrees.

A blade speed control apparatus and method. The apparatus includes a rotor assembly a first blade assembly movably attached to the rotor assembly at a first initial position, a second blade assembly movably attached to the rotor assembly at a second initial position, and a movement mechanism configured to move the rotor assembly in a first lateral direction along a y-axis such that a first angle exists between the first blade assembly with said respect to the second blade assembly. The movement mechanism is configured to move a portion of the rotor assembly in a first lateral direction along a y-axis such that a first angle exists between the first blade assembly with said respect to the second blade assembly. The first angle does not comprise an angle of 180 degrees.

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.

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.

A fracture-resistant double shear joint including a clevis having a first end defining a first bore and a second end defining a second bore, and a reaction load member defining a third bore, wherein the first bore, the second bore, and the third bore are colinear. The fracture-resistant double shear joint can further include a first spacer positioned within the first bore, a second spacer positioned within the second bore, and a shear pin positioned within each of the first bore, the second bore, and the third bore. The shear pin may include an outer cylinder, an inner shear bolt threaded on both ends, and nuts at either end that engage the threads. The nuts may be tightened to place the outer cylinder in compression. The spacers in the first and second bore may include a low friction liner that interfaces with the outer cylinder of the shear pin. The ends of the spacers may be set back from the ends of the first and second bores (that are next to the third bore).

A fracture-resistant double shear joint including a clevis having a first end defining a first bore and a second end defining a second bore, and a reaction load member defining a third bore, wherein the first bore, the second bore, and the third bore are colinear. The fracture-resistant double shear joint can further include a first spacer positioned within the first bore, a second spacer positioned within the second bore, and a shear pin positioned within each of the first bore, the second bore, and the third bore. The shear pin may include an outer cylinder, an inner shear bolt threaded on both ends, and nuts at either end that engage the threads. The nuts may be tightened to place the outer cylinder in compression. The spacers in the first and second bore may include a low friction liner that interfaces with the outer cylinder of the shear pin. The ends of the spacers may be set back from the ends of the first and second bores (that are next to the third bore).

A helicopter includes a gimbal assembly, a first rotor assembly, a second rotor assembly, a fuselage, and a controller. The first rotor assembly, the second rotor assembly, and the fuselage are mechanically coupled to the gimbal assembly. The first rotor assembly includes a first rotor and the second rotor assembly includes a second rotor, the first rotor including a plurality of first fixed-pitch blades and the second rotor including a plurality of second fixed-pitch blades. Each of the plurality of first and the second fixed-pitch blades are coupled to a hub of its respective rotor via a hinge mechanism that is configured to allow each of the fixed-pitch blades to pivot from a first position to a second position, the first position being substantially parallel to the fuselage and the second position being substantially perpendicular to the fuselage.

A helicopter includes a gimbal assembly, a first rotor assembly, a second rotor assembly, a fuselage, and a controller. The first rotor assembly, the second rotor assembly, and the fuselage are mechanically coupled to the gimbal assembly. The first rotor assembly includes a first rotor and the second rotor assembly includes a second rotor, the first rotor including a plurality of first fixed-pitch blades and the second rotor including a plurality of second fixed-pitch blades. Each of the plurality of first and the second fixed-pitch blades are coupled to a hub of its respective rotor via a hinge mechanism that is configured to allow each of the fixed-pitch blades to pivot from a first position to a second position, the first position being substantially parallel to the fuselage and the second position being substantially perpendicular to the fuselage.

A hinge assembly such as a lead-lag hinge can include a hinge pin assembly. The hinge pin assembly can include an outer cylinder, a shear pin that extends through the outer cylinder and having a first threaded end and a second threaded end, a first nut threaded on the first threaded end and a second nut threaded on the second end. An opposing force between the first nut and the second nut applies a compressive stress to the outer cylinder that may increase a resistance of the hinge pin assembly to wear and damage. In the case of complete failure of the outer cylinder, the shear pin can maintain structural integrity of the hinge pin assembly and of the hinge assembly.