A control system for a multi-rotor aircraft is described that results in lower operating noise. Allowing blades to flap during flight reduces aerodynamic interference as blades pass by other aircraft components, such as wings or the fuselage. Pitch links coupled to a rotational swashplate can be used to allow flapping during flight. The swashplates can allow the canting of the rotors to change a rotational or out-of-plane angle of the blades to decrease noise.

A motor mounted on a drone includes a rotor including a propeller mounting portion with a propeller detachably attached, the rotor being rotatable about a central axis, a stator radially facing the rotor with a gap therebetween, and an auto-balancer capable of automatically correcting dynamic balance of the rotor.

Embodiments herein describe mitigating flexible modes in an airframe of an aircraft by operating a battery for the aircraft as a tuned mass damper. One embodiment comprises an Unmanned Aerial Vehicle (UAV). The UAV includes a flexible airframe, a plurality of propulsors coupled to the flexible airframe that generate thrust for the UAV, a battery that provides electrical power for the plurality of propulsors, and a suspension system that suspends the battery from the flexible airframe and operates the mass of the battery as a tuned mass damper to dampen flexible modes generated in the flexible airframe during flight.

A laminated elastomeric journal bearing has an outer sleeve having an inner surface, at least a portion of each end of the inner surface being a concave surface of revolution, and an inner sleeve having an outer surface, at least a portion of each end of the outer surface being a convex surface of revolution. Alternating layers of elastomer and metal are located between the sleeves, with adjacent surfaces of the layers and the sleeves being adhered to each other.

An exemplary tiltrotor aircraft includes a fuselage carrying a wing, a pylon assembly coupled to the wing such that the pylon assembly is rotatable to selectively operate the tiltrotor aircraft between a helicopter mode and an airplane mode, a vibration isolator assembly connected to the pylon assembly and the wing including a first vibration isolator configured to isolate vibration in a vertical plane a second vibration isolator configured to isolate vibration in a lateral plane.

A rotor for a rotary wing aircraft having a single blade with a longitudinal pitch axis and that is hinge mounted on the rotary shaft for rotating the rotor, the hinge being about an axis that is transversal relative to the rotary shaft, said rotary wing describing a cone when its pitch angle is not zero, the rotor possessing a balancing flyweight device for balancing the resultant of the horizontal component of the lift force and of the rotary drag force of the blade, the device being mounted to rotate with the rotary wing about its rotary shaft and, under the effect of the centrifugal force to which it is subjected while the rotary wing is rotating, generating a horizontal force that is applied to the rotary shaft of the motor and that opposes the above-mentioned resultant with a magnitude of that is a function of the position of the flyweight(s) of the balancing device relative to the rotary shaft of the rotor.

A hydroelastic damper comprising at least a first resilient assembly that is provided with a first inner strength member engaged at least in part in a first outer strength member, a first resilient member providing resilient return for the first outer strength member and the first inner strength member towards a rest position (POSREP). The hydroelastic damper comprises at least one hydraulic assembly provided with a first hydraulic chamber and a second hydraulic chamber in communication with each other via a connection provided in a first wall of the hydraulic assembly. A first floating piston is movable at least in translation along the longitudinal axis relative to the first inner strength member and to the first outer strength member, the first hydraulic chamber being defined at least by the first floating piston and the first wall in order to protect the first resilient member.

A tail-rotor vibration dampener system for an aircraft is provided. The system includes a fuselage and an open rotor assembly including a powerplant and a set of rotor blades. The system further includes at least one actuator unit connecting the open rotor assembly to the fuselage. The actuator unit includes a hydraulic actuator controlling a position of the open rotor assembly in relation to the fuselage and a dampening device operable to cancel a vibration emanating from the open rotor assembly. The system further includes a computerized vibration dampening controller, including programming to determine a frequency of the vibration emanating from the open rotor assembly and control the dampening device to cancel the vibration emanating from the open rotor assembly based upon the frequency.

Provided is a vibration control system for a compound helicopter with a rotor and a fixed wing. The fixed wing includes a movable flap that is mounted on a rear edge of the fixed wing. The vibration control system periodically moves the movable flap so as to periodically change lift of the fixed wing such that vibration aerodynamically generated by the fixed wing is in anti-phase with vibration caused by rotation of the rotor.

A damper assembly includes a housing defining at least one or more cavities. A piston is in operable communication with the housing. A rod end is operatively coupled to the piston, the rod end having at least two cartridges.