Abstract: Transmission system for an aircraft, particularly a helicopter. The transmission system (1), of supercritical type, comprises at least one rotary transmission tube (4) which is such that at least one natural frequency of said transmission tube (4) is below its nominal rotational speed, and at least one active and controllable magnetic damper (5) capable of generating a magnetic force capable of acting on said transmission tube (4) and which damper is controlled in such a way as to generate a magnetic force making it possible to reduce the vibration of the transmission tube (4), at least when the speed of the transmission tube (4) is within a predetermined range of frequencies defined around said natural frequency.

Abstract: The transmission system (1), of supercritical type, comprises at least one rotary transmission tube (4) which is such that at least one natural frequency of said transmission tube (4) is below its nominal rotational speed, and at least one active and controllable magnetic damper (5) capable of generating a magnetic force capable of acting on said transmission tube (4) and which damper is controlled in such a way as to generate a magnetic force making it possible to reduce the vibration of the transmission tube (4), at least when the speed of the transmission tube (4) is within a predetermined range of frequencies defined around said natural frequency.

Abstract: The present invention relates to a device for reducing the vibrations of the rotor of a rotary-wing aircraft, having an oscillating mass (M1), elastically held radially on the hub (4) of the rotor in the vicinity of its axis (X-X) and fixed to an articulated rod (10) substantially longitudinal to said axis (X-X).According to the invention, said device includes:an adjustment oscillating mass (M2), mounted so that it can move on the rod (10) and having an adjustment position for which the frequency of the resonator formed by said oscillating masses (M1, M2) is matched to the frequency of said vibrations; anddrive means (18) for bringing the adjustment oscillating mass (M2) into said adjustment position.

Abstract: Method for reducing the effect of the vibration generated by the driveline of a helicopter. The helicopter includes at least one rotor, the collective pitch of the blades of which can be controlled by a control system. The values of at least one parameter representing the effect of the vibration generated by the driveline are measured. A control signal for the collective pitch of the blades of the rotor is directly formed from the measured values of the parameter. The control signal to the system for controlling the collective pitch of the blades of the rotor generates a set of forces and of moments which oppose the effect of the vibration generated by the driveline. The control signal thus formed is applied to the system for controlling the collective pitch of blades of the rotor.