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 vertical take-off and landing (VTOL) aircraft (10) comprises a fuselage (24) first and second forward wings (20, 22) and first and second rearward wings (30, 32), each wing having a fixed leading edge (25, 35) and a trailing control surface (50) which is pivotal about a generally horizontal axis. Electric rotors (60) are mounted to the wings (20, 22, 30, 32), the electric rotors (60) being pivotal with the trailing control surface (50) between a first position in which each rotor (60) has a generally vertical axis of rotation, and a second position in which each rotor (60) has a generally horizontal axis of rotation; wherein at least one of the wings (20, 22, 30, 32) has a first and a second electric rotor (60) which are each mounted having non-parallel axes of rotation so that the thrust lines of the first and second electric rotors are different.

A modal tailboom flight control system for a compound helicopter is operable in a plurality of modes including a forward thrust mode and an anti-torque mode. The modal tailboom flight control system includes a tailboom, a drivetrain extending through the tailboom, an anti-torque system coupled to the drivetrain and rotatable to generate anti-torque thrust for the compound helicopter in the anti-torque mode and a pusher propeller coupled to the drivetrain and rotatable to generate forward thrust for the compound helicopter in the forward thrust mode. The pusher propeller is positioned forward of the anti-torque system.

The present invention includes an a plurality of first variable speed motors arranged in a first matrix pattern and mounted on a tail boom of the helicopter; one or more fixed pitch blades attached to each of the plurality of first variable speed motors; and wherein a speed of one or more of the plurality of first variable speed motors is varied to provide an anti-torque thrust.

A duct configured with a fan to increase thrust. The duct includes an interior surface configured to surround a rotation axis of the fan. The interior surface includes a nozzle portion configured to be located upstream of the fan and a diffuser portion configured to be located downstream of the fan. The interior surface defines an opening configured to introduce additional airflow along the diffuser portion.

The present invention relates to a hybrid helicopter comprising a fuselage, a main rotor, two wings situated on either side of said fuselage, and two propulsion propellers situated respectively on each wing. Each propulsion propeller is inclined, and when it rotates it generates a thrust force (F.sub.d, F.sub.g) along a thrust axis (P.sub.d, P.sub.g) that is inclined relative to a longitudinal direction (X) of said hybrid helicopter. As a result, a longitudinal component and a transverse component of said thrust force (F.sub.d, F.sub.g) of each propulsion propeller act, during hovering flight of said hybrid helicopter, to generate respective torques that combine to form a moment (M.sub.stat) opposing a yaw torque (C.sub.R) of said hybrid helicopter.

An aircraft is provided including an airframe, an extending tail, a counter-rotating, coaxial main rotor assembly having an upper rotor assembly and a lower rotor assembly, and a translational thrust system including a propeller positioned at the extending tail. The translational thrust system is configured to provide translational thrust to the airframe when the aircraft is in a non-autorotation state and to generate power when in an autorotation state. A gearbox interconnects the propeller and the main rotor assembly to drive the main rotor assembly and the translational thrust system in the non-autorotation state. When the aircraft is in autorotation, the power generated by the propeller drives rotation of the main rotor assembly via the gearbox.

An anti-torque system for a rotorcraft includes a first tail fan assembly including a plurality of first fan blades, a second tail fan assembly including a plurality of second fan blades and a motor adapted to provide torque to the first and second fan blades. The first fan blades have a larger rotational inertia than the second fan blades. The second fan blades are adapted to experience a larger angular acceleration than the first fan blades in response to torque from the motor, thereby providing responsive yaw control for the rotorcraft.

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.

A bidirectional aircraft rotor for a rotorcraft tail rotor. The rotorcraft tail rotor uses a hub and a first tail rotor blade affixed to the hub. A pitch of the first tail rotor blade is fixed, and a profile of a leading edge of the first tail rotor blade is identical to a profile of a trailing edge of the first tail rotor blade. The tail rotor is driven by a torque source, such as an electric motor or an engine. The tail rotor uses variable RPM and reversible rotational direction to provide rotorcraft with yaw control.