Method for estimating the rotor torques of an aircraft capable of hovering and control unit for an aircraft capable of hovering

A method for estimating rotor torques of an aircraft capable of hovering;

• said aircraft comprising:
• a plurality of rotors, which are operatively connected to each other and rotatable relative to respective rotational axes under the action of respective rotor torques;
• and
• at least one first engine, which is operatively connected to said rotors and is adapted to provide said rotors with an engine torque;
• said rotors each comprising a hub and a plurality of blades articulated on said respective hub in such a way that respective collective pitch angles of said plurality of blades relative to the respective rotational axis are adjustable;
• said method comprising the steps of:
• i) calculating a symmetric component of said rotor torques on the basis of said engine torque;
• said symmetric component being equal to said rotor torques, when said collective pitch angles are equal to each other;
• characterized in that it comprises the further steps of:
• ii) receiving a signal associated with said collective pitch angles;
• iii) calculating an asymmetric component of each said rotor torques on the basis of at least a pitch angle difference between said collective pitch angles;
• and
• iv) calculating each said rotor torque as the algebraic sum of said symmetric component and said respective asymmetric component.