One example of a rotor assembly comprises: a rotor hub operable to rotate based on rotation of a mast; a first rotor blade pivotally attached to the rotor hub; a bracing member pivotally attached to the rotor hub at a first end and pivotally attached to the first rotor blade at a second end; and a linkage mechanism coupling the first rotor blade to a second rotor blade. The bracing member is operable to transfer a coning movement of the first rotor blade to a movement of the linkage mechanism and a corresponding coning movement of the second rotor blade.

An aircraft is provided including an airframe, an extending tail, and a counter rotating, coaxial main rotor assembly including an upper rotor assembly with an upper blade and a lower rotor assembly with a lower blade. A first antenna in one of upper blade and the lower blade, and a second antenna in the other of the upper blade and the lower blade. An oscillator to apply an excitation signal to the first antenna. A blade proximity monitor to monitor a magnitude of the excitation signal and an output signal from the second antenna to determine a distance between the upper blade and the lower blade.

A propeller locking mechanism for an aircraft includes a mounting ring having a locking extension with an aperture. A solenoid is configured with a solenoid pin which interacts with a first arm of a lever. The lever includes a pivotable second arm configured with a spring and locking pin. The second arm is able to pivot and insert the locking pin into the aperture of the locking extension on the mounting ring. The spring biases the locking pin in the locked orientation. Upon sufficient motor torque, the spring force is overcome allowing the locking pin to be removed from the aperture and the mounting ring to be unlocked.

The present embodiments disclose a torque dependent and resonant operating thrust-generating rotor assembly including a cyclic pitch control system for controlling tilting moments about a longitudinal rotor blade axis of one or more rotor blades, in order to control the pitch angle of the rotor blades and thereby also the horizontal movements of a helicopter vehicle or a rotary wing aircraft. A rotor torque assembly of the rotor assembly is further configured to operate in resonance, thereby providing a resonant gain effecting a rotational offset in relation to changes in torque generated by the motor.

Embodiments disclosed herein present a spring system for use in a torque dependent rotor assembly designed to operate in resonance, where changes in applied torque controls the blade pitch angle and ultimately the movements of a rotary wing aircraft. More specifically, the present invention relates to a spring system used in such a rotor assembly where the stiffness of an associated spring member is allowed to vary in response to the torque applied from a motor to the assembly.

A propulsion assembly for a rotorcraft includes a mast and a proprotor hub assembly coupled to the mast and having a gimballing degree of freedom relative to the mast. The propulsion assembly includes a gimbal lock assembly positioned about the mast and including a plurality of radially outwardly extending and circumferentially distributed rollers. The gimbal lock assembly is movable between a disengaged position and an engaged position relative to the proprotor hub assembly. In the disengaged position, the gimbal lock assembly enables the gimballing degree of freedom. In the engaged position, the rollers of the gimbal lock assembly contact the proprotor hub assembly to disable the gimballing degree.

A propulsion assembly for a rotorcraft includes a mast and a proprotor hub assembly coupled to the mast and having a gimballing degree of freedom relative to the mast. The proprotor hub assembly includes a hook receiver. The propulsion assembly includes a gimbal lock positioned about the mast. The gimbal lock includes a locking ring and a gimbal lock hook. The gimbal lock is movable between a disengaged position and an engaged position relative to the proprotor hub assembly. The gimbal lock enables the gimballing degree of freedom in the disengaged position and disables the gimballing degree of freedom in the engaged position. The gimbal lock hook is hooked to the hook receiver in the engaged position to secure the locking ring to the proprotor hub assembly.

An aircraft includes an airframe having an empennage, a counter rotating, coaxial main rotor assembly located at the airframe including an upper rotor assembly and a lower rotor assembly, and a translational thrust system positioned at the empennage and providing translational thrust to the airframe. At least two control surfaces located at the empennage are independently operable via commands from one or more flight control computers. A method of operating an aircraft includes transmitting a first signal from one or more flight control computers to a first control surface located at a first lateral side of a translational thrust system, and actuating the first control surface to a first position via the first signal. A second signal is transmitted to a second control surface located at a second lateral side opposite the first lateral side, and the second control surface is actuated to a second position via the second signal.

A rotor hub assembly includes an open rotor hub assembly with an open rotor hub and a mounting plate. The open rotor hub includes an annular base portion with periphery and a plurality of rotary member portions arranged about the annular base portion that each define an aperture for receiving a rotor blade. The mounting plate spans the annular base portion and is coupled to the annular base portion by a resilient member to accommodate radially expansion and contraction of the annular base portion according to loads exerted on the rotor hub by rotor blades seated in the apertures of the rotary member portions.

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. A flight control computer is configured to control a main rotor rotational speed of the upper and the lower rotor assemblies of the main rotor assembly as a function of airspeed of the aircraft. A method of operating an aircraft includes retrieving a threshold main rotor rotational speed of the dual coaxial main rotor assembly and calculating an actual main rotor rotational speed according to an environment of the aircraft. The actual main rotor rotational speed is maintained to remain at or below the threshold main rotor speed according to an airspeed of the aircraft.