A method of controlling noise of an aircraft includes storing a plurality of predefined noise modes; receiving a selection of a selected noise mode from the plurality of predefined noise modes, the selected noise mode identifying at least one operational parameter; and controlling the aircraft in response to the at least one operational parameter.

An aircraft includes an airframe; an extending tail; a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly; a translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe; an upper hub fairing positioned at the upper rotor assembly; a lower hub fairing positioned at the lower rotor assembly; and a shaft fairing disposed between the upper hub fairing and the lower hub fairing; wherein the upper hub fairing is substantially sealed to the shaft fairing and the lower hub fairing is substantially sealed to the shaft fairing.

An aircraft includes an airframe, an extending tail, a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly, a translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the air-frame; and a horizontal stabilizer positioned at the extending tail, the horizontal stabilizer having one or more elevators; wherein the aircraft is configured to mix at least two of the main rotor assembly collective pitch, the main rotor assembly cyclic pitch, the elevator deflection, and the translational thrust system thrust to trim the aircraft attitude.

An aircraft includes an airframe; an extending tail; a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly; and a translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe; wherein a ratio of (i) the hub separation between the hub of the upper rotor assembly and the hub of the lower rotor assembly to (ii) a radius of the upper rotor assembly is between about 0.1 and about 0.135.

A rotary wing aircraft includes an airframe, one or more engines supported by the airframe, and a plurality of rotor blades operatively connected to the one or more engines. Each of the plurality of rotor blades includes a rotor lift-to-drag (L/De) ratio greater than 9 at airspeeds between about 150 KTAS and about 210 KTAS, and the rotary wing aircraft includes an aircraft lift-to drag (L/D) ratio of greater than about 4 between about 99 KTAS and about 210 KTAS.

A flight control system for a rotorcraft includes a controller configured to receive input indicative of ambient conditions, determine a threshold rotor blade tip speed based on the input, and to output rotor control commands to prevent rotor blade tips from exceeding the threshold speed. An aircraft includes an airframe, a main rotor assembly operatively connected to the airframe, and a flight control system as described above. The flight control system is operatively connected to control the main rotor assembly. It is contemplated that the main rotor assembly can be a counter rotating coaxial main rotor assembly including an upper rotor assembly with a plurality of blades and a lower rotor assembly having a plurality of blades, wherein the flight control system is operatively connected to control both upper and lower rotor assemblies to prevent any blade tips of the upper and lower rotor assemblies from exceeding the threshold speed.

An aircraft includes an airframe having an extending tail and a counter rotating, coaxial main rotor assembly disposed at the airframe including an upper rotor assembly and a lower rotor assembly. A translational thrust system is positioned at the extending tail and provides translational thrust to the airframe. An airframe parasitic drag of the airframe is greater than a main rotor assembly drag of the main rotor assembly. An aircraft includes an airframe having an extending tail and a counter rotating, coaxial main rotor assembly disposed at the airframe including an upper rotor assembly and a lower rotor assembly. A translational thrust system is positioned at the extending tail and provides translational thrust to the airframe. A main rotor assembly drag is at or between about 25% and 40% of a total aircraft drag.

An aircraft is provided including an airframe, an extending tail, and a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly. A translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe. A horizontal stabilizer with a left elevator and right elevator positioned at the extending tail. A flight control computer to independently control one or more of the main rotor assembly and the elevator through a fly-by-wire control system. The flight control computer is configured to mix a collective pitch of the main rotor assembly and a deflection of the elevator.

An aircraft is provided including an airframe, an extending tail, one or more engines supported by the airframe, and a counter rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly. A translational thrust system positioned at the extending tail. The translational thrust system providing translational thrust to the airframe. A gearbox configured to transfer power from the engine to the main rotor assembly. A flight control computer to independently control one or more of the engine, the upper rotor assembly, the lower rotor assembly, and the translational thrust system. The flight control computer, in response to at least one control command, engages or disengages the translational thrust system, while maintaining controlled powered flight.

An aircraft includes an airframe having an extending tail, a counter rotating, coaxial main rotor assembly disposed at the airframe including an upper rotor assembly and a lower rotor assembly and a translational thrust system positioned at the extending tail and providing translational thrust to the airframe. A flight control computer is configured to control a main rotor rotational speed of the upper and the lower rotor assemblies of the main rotor assembly as a function of airspeed of the aircraft. A method of operating an aircraft includes retrieving a threshold main rotor rotational speed of the dual coaxial main rotor assembly and calculating an actual main rotor rotational speed according to an environment of the aircraft. The actual main rotor rotational speed is maintained to remain at or below the threshold main rotor speed according to an airspeed of the aircraft.