Abstract: A method of optimizing an operation of a rotorcraft includes measuring actual usage of the tail rotor drive shaft during operation of the rotorcraft, the actual usage including at least a torque measurement. The method further includes a step of adjusting a life of the tail rotor drive shaft based upon the measuring of the actual usage. Another method of the present disclosure includes determining a main rotor mast torque by measuring a tail rotor drive shaft torque and deriving a main rotor mast torque by considering the measured tail rotor drive shaft torque and a total torque output of an engine. A system of the present disclosure is configured for determining the main rotor mast torque in part by measuring the tail rotor torque.

Abstract: A method is disclosed for suppressing an external acoustic signature of an aircraft having at least one pair of non-intermeshing multiple-blade rotors. During operation of the aircraft, the at least one pair of rotors are rotated in an asymmetrically indexed manner that causes the blades of one of each pair of rotors to be consistently out of phase from the blades of the other of each pair of rotors. The selected amount in degrees of asymmetrical indexing is equal to the desired phasing in degrees divided by a number of blades of one of the rotors.

Abstract: A method is disclosed for suppressing an external acoustic signature of an aircraft having at least one pair of non-intermeshing multiple-blade rotors. During operation of the aircraft, the at least one pair of rotors are rotated in an asymmetrically indexed manner that causes the blades of one of each pair of rotors to be consistently out of phase from the blades of the other of each pair of rotors. The selected amount in degrees of asymmetrical indexing is equal to the desired phasing in degrees divided by a number of blades of one of the rotors.