An aircraft includes an airframe having an extending tail, a counter rotating, coaxial main rotor assembly disposed at the airframe including an upper rotor assembly and a lower rotor assembly, and a translational thrust system positioned at the extending tail and providing translational thrust to the airframe, the translational thrust system including a propeller. A gearbox system is operably connected to the main rotor assembly and the propeller to drive rotation of the main rotor assembly and the propeller. The gearbox is configured to maintain a main rotor assembly tip speed below Mach 0.9 and a propeller helical tip speed below Mach 0.88.

An aircraft is provided including an airframe, an extending tail, and a counter rotating, coaxial main rotor assembly including an upper rotor assembly composed of a plurality of blades and a lower rotor assembly composed of a plurality of blades. A translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe. A flight control system to control the upper rotor assembly and the lower rotor assembly, wherein the flight control system is configured to control lift offset of the upper rotor assembly and the lower rotor assembly.

An aircraft is provided including an airframe, an extending tail, and a counter rotating, coaxial main rotor assembly including an upper rotor assembly composed of a plurality of blades and a lower rotor assembly composed of a plurality of blades. A translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe. A flight control system to control the upper rotor assembly and the lower rotor assembly, wherein the flight control system is configured to control lift offset of the upper rotor assembly and the lower rotor assembly.

A rotor assembly for a rotary wing aircraft includes a rotor hub having a central axis. The rotor hub is rotatable about the central axis. A plurality of flexible structural members extend radially outwardly from the rotor hub. Each flexible structural member is substantially U-shaped having a first arm extending from the hub, a second arm extending from the hub, and an end portion connecting the first arm to the second arm at a radially outboard end of the flexible structural member. The first arm, the second arm and/or the end portion have a cross section with a height along the central axis greater than a thickness of the cross section to increase stiffness of the rotor assembly along the central axis. The rotor assembly further includes a plurality of rotor blades, each rotor blade being secured to each flexible structural member of the plurality of flexible structural members.

A rotor assembly for a rotary wing aircraft includes a rotor hub having a central axis. The rotor hub is rotatable about the central axis. A plurality of flexible structural members extend radially outwardly from the rotor hub. Each flexible structural member is substantially U-shaped having a first arm extending from the hub, a second arm extending from the hub, and an end portion connecting the first arm to the second arm at a radially outboard end of the flexible structural member. The first arm, the second arm and/or the end portion have a cross section with a height along the central axis greater than a thickness of the cross section to increase stiffness of the rotor assembly along the central axis. The rotor assembly further includes a plurality of rotor blades, each rotor blade being secured to each flexible structural member of the plurality of flexible structural members.

A rotor blade rotated about a rotor hub is provided including a first section configured to mount to the rotor hub. The first section includes a spindle and an inboard torque tube surrounding a portion of the spindle. A second section of the rotor blade includes a flexbeam and an outboard torque tube attached to and surrounding the flexbeam. An inboard end of the flexbeam is rotatable coupled to a first end of the spindle. The second section is configured to rotate about a blade axis between an aligned position and a rotated position. A transitional brace configured to surround a portion of the rotor blade adjacent the coupled flexbeam and spindle is movable between a first position and a second position. When in the first position, the transitional brace limits movement of the second section about the blade axis.

A rotor blade rotated about a rotor hub is provided including a first section configured to mount to the rotor hub. The first section includes a spindle and an inboard torque tube surrounding a portion of the spindle. A second section of the rotor blade includes a flexbeam and an outboard torque tube attached to and surrounding the flexbeam. An inboard end of the flexbeam is rotatable coupled to a first end of the spindle. The second section is configured to rotate about a blade axis between an aligned position and a rotated position. A transitional brace configured to surround a portion of the rotor blade adjacent the coupled flexbeam and spindle is movable between a first position and a second position. When in the first position, the transitional brace limits movement of the second section about the blade axis.

An embodiment includes a system for controlling blade pitch in a rotorcraft having an engine; a drive shaft with a first end and a second end and connected at the first end to the engine; a rotor with two or more blades connected to the second end of the drive shaft; and one or more actuators positioned adjacent to the rotor blades operable to change a blade pitch of the rotor blades.

An embodiment includes a system for controlling blade pitch in a rotorcraft having an engine; a drive shaft with a first end and a second end and connected at the first end to the engine; a rotor with two or more blades connected to the second end of the drive shaft; and one or more actuators positioned adjacent to the rotor blades operable to change a blade pitch of the rotor blades.

A tension torsion strap by which a blade is connectable with a hub of a propulsor is provided. The tension torsion strap includes an elongate body formed to define attachment features at opposite ends thereof, the attachment features being connectable to the blade at one of the opposite ends and to the hub at the other of the opposite ends, fibrous materials extending along the elongate body and around the attachment features and pretension flanges elastically interposable between the hub and the elongate body. The pretension flanges are configured to maintain pretension in the fibrous materials above a predefined pretension level when the attachment features are connected to the blade and the hub.