Abstract: A method of determining a trajectory for a rotorcraft, comprising: receiving an initial trajectory defining a planned flight path of the rotorcraft between a starting point and a target point; performing iterations of a loop comprising adding the initial trajectory to a set of selectable trajectories, evaluating a noise indicator of the rotorcraft for the initial trajectory on the basis of a noise-related acoustic footprint and a noise exposure level-related acoustic footprint, adding the evaluated noise indicator to a set of evaluated noise indicators, determining an alternative trajectory defining an alternative flight path of the rotorcraft between the starting point and the target point on the basis of the evaluated noise indicator, and setting the alternative trajectory as initial trajectory; and outputting a trajectory of the set of selectable trajectories associated with a selected noise indicator fulfilling predetermined noise indicator conditions.

Abstract: A method of reducing the noise generated in-flight by a vortex wake caused by each first blade of a main rotor of a hybrid helicopter. The hybrid helicopter includes a main rotor, at least two wings and at least one propeller. The method enables a stabilized flight phase on the level or with a non-zero aerodynamic slope to be implemented by determining a first value of the pitch of the second blades of each propeller and an angle of incidence of the main rotor as function of the flight conditions, then by applying the first pitch value to each propeller and by applying the angle of incidence to the main rotor so as to direct the vortex wake to limit the noisy interactions between the vortex wake and the other first blades and/or the second blades.

Abstract: A method and to a system of reducing the noise generated in-flight by a vortex wake caused by each first blade of a main rotor of a hybrid helicopter. The hybrid helicopter includes a main rotor, at least two wings and at least one propeller. The method enables a stabilized flight phase on the level or with a non-zero aerodynamic slope to be implemented by determining a first value of the pitch of the second blades of each propeller and an angle of incidence of the main rotor as function of the flight conditions, then by applying the first pitch value to each propeller and by applying the angle of incidence to the main rotor so as to direct the vortex wake to limit the noisy interactions between the vortex wake and the other first blades and/or the second blades.