Pendulum dampers are described. The pendulum dampers include a damper body having a first end and a second end, with an axial direction defined between the first end and the second end with a heater bore passing through the damper body in the axial direction from a tail port at the second end toward the first end and a cartridge heater installed within the heater bore, the cartridge heater configured to generate heat and heat a material of the damper body.

A stowable lift rotor is coupled to an airframe of a VTOL aircraft. The VTOL aircraft is convertible between a VTOL flight mode and a forward flight mode. The stowable lift rotor includes a lift arm. The proximal end of the lift arm is coupled to the airframe of the VTOL aircraft. The stowable lift rotor also includes a rotor assembly including rotor blades coupled to the distal end of the lift arm. The lift arm is movable between various positions including an extended position in the VTOL flight mode, a stowed position in the forward flight mode and intermediate positions therebetween such that the distance between the rotor assembly and the airframe is greater in the extended position than in the stowed position.

An aircraft, has an airframe, a transmission, and a liquid inertia vibration elimination (LIVE) system disposed between the airframe and the transmission via spherical bearings of two legs and via a central spherical bearing.

In an embodiment, a rotorcraft includes an airframe; a main rotor transmission; one or more brackets mounting the main rotor transmission to the airframe, longitudinal axes of the one or more brackets being substantially parallel with a longitudinal axis of the rotorcraft; and one or more restraints mounting the main rotor transmission to the airframe, the one or more restraints being mounted at an angle non-orthogonal to the longitudinal axis of the rotorcraft and a lateral axis of the rotorcraft.

In some examples, an oscillatory pumping system comprises: one or more active piston, a fluid, and two motors. The one or more active piston is disposed in a channel fluidically coupling two fluid chambers. The passive piston has a frequency response operable to counteract a vibratory displacement. The fluid is disposed in the channel and the two fluid chambers. The two motors couple to the one or more active piston. The two motors are operable to selectively change the frequency response of the passive piston based on oscillating the one or more active piston.

A rotor for a hover-capable aircraft is described, comprising: a hub rotatable about an axis and, in turn, comprising a plurality of blades; a mast connectable to a drive member of the aircraft and operatively connected to the hub to drive the hub in rotation about the axis; and damping means for damping vibrations transmitted to the mast, which comprise a mass designed to oscillate in a plane transversal to the axis so as to contain flexural vibrations of the mast generated by rotation of the blades; the damping means also comprise elastic means having a desired stiffness along the axis and operatively connected to the mass to contain vibration of the mast along the axis.

A rotor-regulation system includes a rotor comprising a plurality of blades, a mechanically driven hydraulic pump, a rotor drive shaft operable to drive the rotor and the mechanically driven hydraulic pump, and a throttling valve coupled to the mechanically driven hydraulic pump and operable to modulate rotation of the rotor.

A strut assembly for a vibration isolation device is disclosed, comprising a piston spindle; a first elastomeric member and a second elastomeric member bonded to the piston spindle and in contact with an upper housing and a lower housing, respectively; a first strut support and a second strut support attached to or integral with the upper housing and the lower housing, respectively; a first strut spindle and the second strut support configured to be placed in the first strut support and the second strut support, respectively; and one or more removable struts configured to be engaged to the first strut spindle and to the second strut spindle, wherein at least one of the first or second strut spindles is removable such that the one or more struts can be replaced without breaking a bonding of the first elastomeric member, the second elastomeric member, or both.

An inner middle rotor is rotated while an inner front rotor, an inner back rotor, and an outer rotor are not rotated. The inner middle rotor is surrounded by the inner front rotor, the inner back rotor, the outer rotor, and a fuselage. After rotating the inner middle rotor while not rotating the inner front rotor, the inner back rotor, and the outer rotor, the inner middle rotor, the inner front rotor, the inner back rotor, and the outer rotor are simultaneously rotated.

A method of analyzing a vibratory signal derived from rotation of at least one moving part belonging to a rotary mechanism forming all or part of a drive train for transmitting drive torque, the rotary mechanism being fitted to an aircraft and the method comprising at least one first measurement step including measuring vibration in at least one direction and generating a vibratory signal representative of the operation of the rotary mechanism as a function of time, the first measurement step being performed by means of at least one vibration sensor; and at least one second measurement step including measuring an angular position of the moving part, the moving part having at least one degree of freedom to move in rotation about a respective axis of rotation Z. Such an analysis method makes it possible to determine at least one usable range for the vibratory signal.