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 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, the translational thrust system including a propeller. A gearbox system is operably connected to the main rotor assembly and the propeller to drive rotation of the main rotor assembly and the propeller. The gearbox is configured to maintain a main rotor assembly tip speed below Mach 0.9 and a propeller helical tip speed below Mach 0.88.

An aircraft is provided including an airframe, an extending tail, and a counter rotating, coaxial main rotor assembly including an upper rotor assembly composed of a plurality of blades and a lower rotor assembly composed of a plurality of blades. A translational thrust system positioned at the extending tail, the translational thrust system providing translational thrust to the airframe. A flight control system to control the upper rotor assembly and the lower rotor assembly, wherein the flight control system is configured to control lift offset of the upper rotor assembly and the lower rotor assembly.

In one embodiment, a vertical stabilizer comprises an airfoil structure configured to be mounted to an aircraft at a vertical orientation. The airfoil structure comprises a leading edge and a trailing edge, wherein the trailing edge is configured to form a blunt shaped edge. The airfoil structure further comprises a root end and a tip end, wherein the airfoil structure is tapered from the root end to the tip end. The airfoil structure is also cambered. Finally, the airfoil structure is further configured to be mounted with a rotor, and is also further configured to house one or more internal components associated with the aircraft.

Embodiments include an apparatus comprising an aircraft wing and a trailing edge aerodynamic surface connected to a trailing edge of the aircraft wing via a piston assembly in which the piston assembly holds the trailing edge aerodynamic surface in a neutral position relative to the aircraft wing at a constant supply pressure. The piston assembly may be implemented using a pneumatic piston or a hydraulic piston. A first end of the piston assembly may be connected to the aircraft wing and a second end of the piston assembly may be connected to the trailing edge aerodynamic surface. The piston assembly may include a pressure relief valve which may open or close, raising or lowering the aerodynamic surface, responsive to lift load on the aircraft wing.

In an embodiment, a rotorcraft includes: a flight control computer configured to: receive a first sensor signal from a first aircraft sensor of the rotorcraft; receive a second sensor signal from a second aircraft sensor of the rotorcraft, the second aircraft sensor being different from the first aircraft sensor; combine the first sensor signal and the second sensor signal with a complementary filter to determine an estimated vertical speed of the rotorcraft; adjust flight control devices of the rotorcraft according to the estimated vertical speed of the rotorcraft, thereby changing flight characteristics of the rotorcraft; and reset the complementary filter in response to detecting the rotorcraft is grounded.

An aircraft includes an airframe having an extending tail and a longitudinal axis extending from a nose of the airframe defining a length of the airframe. A counter rotating, coaxial main rotor assembly is located at the airframe and includes an upper rotor assembly and a lower rotor assembly. The upper rotor assembly and the lower rotor assembly rotate about an axis of rotation. The axis of rotation intersects the longitudinal axis forward of a midpoint of the longitudinal axis.

Systems and methods include providing an aircraft with a fuselage, a tail boom or empennage extending from the fuselage, a main rotor, a tail rotor, and at least one counter torque device. The counter torque device provides counter torque to the fuselage to prevent rotation of fuselage when the main rotor is operated, particularly in right sideward flight (RSF) for conventional helicopters with a counter-clockwise rotating (when viewed from above the helicopter) main rotor.

An aircraft includes an airframe having an extending tail, and a counter rotating, coaxial main rotor assembly located at the airframe including an upper rotor assembly and a lower rotor assembly. A translational thrust system is positioned at the extending tail and providing translational thrust to the airframe. An active vibration control (AVC) system is located and the airframe and includes a plurality of AVC actuators configured to generate forces to dampen aircraft component vibration, and an AVC controller configured to transmit control signals to the plurality of AVC actuators thereby triggering force generation by the plurality of AVC actuators. A method of damping vibration of an aircraft includes receiving a vibration signal at an AVC controller, communicating a control signal from the AVC controller to a plurality of AVC actuators, generating a force at the AVC actuators, and damping vibration of the aircraft via the generated force.

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.