In an aspect, a vertical take-off and landing (VTOL) aircraft is disclosed. The VTOL aircraft includes at least a lift component affixed to the aft end of a boom, wherein the lift component is configured to generate lift. The VTOL includes a fuselage comprising a fore end and an aft end. Additionally, VTOL aircraft includes a tail affixed to the aft end of a fuselage. A tail includes a plurality of vertically projecting elements, wherein the plurality vertically projecting elements are affixed at the aft end of the boom and positioned outside of the wake from the at least a lift component.

A rotary wing aircraft includes an airframe including an extending tail. The airframe includes a longitudinal axis that extends through the extending tail. The rotary wing aircraft also includes a main rotor assembly including at least one rotor hub supporting a plurality of rotor blades configured and disposed to rotate about a main rotor axis, at least one elevator arranged at the extending tail, and a control system operably connected to the main rotor assembly and the at least one elevator. The control system is configured and disposed to adjust each of a pitch rate and an attitude of the airframe by selectively adjusting a position of the at least one elevator.

A diverter duct for a propeller includes a second duct element having a semi-annular wedge shape, which is pivotably coupled to the first duct element, a first drive structure configured to drive a pivoting of the second duct element relative to the first duct element and a second drive structure configured to drive a rotation of the first and second duct elements about an axis of rotation of the propeller.

A main rotor blade assembly for a rotary wing aircraft is provided including a main rotor blade root region, a main rotor blade inboard region arranged outboard of said main rotor blade root region, a main rotor blade main region arranged outboard of said main rotor blade inboard region, and a main rotor blade tip region arranged outboard of said main rotor blade main region. At least one of chord, twist, sweep, airfoil shape, and thickness/chord of the main rotor blade assembly has been optimized to achieve balanced high speed forward flight and hover relative to both efficiency and high thrust capability.

A lift fan position lock mechanism is disclosed. In various embodiments, a position lock mechanism includes a ring structure having a first surface, the ring structure including one or more detents defined in the first surface of the ring structure. For each detent, the lock mechanism includes a stationary magnet coupled fixedly to the ring structure at a location adjacent to the detent. The lock mechanism further includes a rotating magnet assembly comprising a magnet of opposite magnetic polarity to at least one of the stationary magnets and a mechanical stop structure of a size and shape to fit into a corresponding detent and engage mechanically with a surface defining at least one extent of said corresponding detent when the rotating magnet assembly is in a locked position.

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 a geometry of at least one of the upper hub fairing and the lower hub fairing progressively blends from a circle to a series of curved elliptical surfaces in an inboard direction.

A rotary wing aircraft includes a fuselage having a plurality of surfaces, at least one engine mounted in the fuselage, and a rotor assembly including a rotor shaft and plurality of rotor blades operatively connected to the rotor shaft. The rotor assembly includes a plurality of surface portions. A rotor shaft fairing extends between the fuselage and the rotor assembly and about at least a portion of the rotor shaft. The rotor shaft fairing includes an outer surface. A plate member is mounted to and projects proudly of the at least a portion of the rotor shaft fairing. The plate member is configured and disposed to increase an aspect ratio of and reduce induced drag on the rotor shaft fairing as well as reduce rotor hub wake size.

A rotorcraft extends longitudinally along a first anteroposterior plane separating a first side from a second side of the rotorcraft. The rotorcraft includes at least one main rotor, an auxiliary rotor, and at least one steerable airfoil. The rotorcraft further includes a processor unit connected to a first measurement system configured to measure a current value of a speed parameter (V) of the rotorcraft and to a second measurement system configured to measure a current value of a power parameter (W) of a power plant of the rotorcraft. The processor unit is configured to adjust the deflection angle of the airfoil as a function of the current speed and power parameter values (V, W) to cause the auxiliary rotor to move towards at least one predetermined operating point which optimizes performance of the rotorcraft and minimizes noise generated by the auxiliary rotor.

One aspect is a flight control system for independent speed and attitude control of a rotary wing aircraft that includes a main rotor system and a translational thrust system. The flight control system includes a flight control computer configured to interface with the main rotor system and the translational thrust system. The flight control computer includes processing circuitry configured to execute control logic. A pitch attitude reference generator provides a pitch attitude reference to a main rotor controller to command the main rotor system based on pilot input. A longitudinal reference generator produces a longitudinal reference as a longitudinal position or longitudinal velocity based on pilot input. An attitude-to-propulsor crossfeed converts the pitch attitude reference into a propulsor trim adjustment. A propeller pitch controller combines the longitudinal reference and the propulsor trim adjustment into a propeller command, and provides the propeller command to the translational thrust system.

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 provides translational thrust to the airframe. An upper hub fairing is positioned at the upper rotor assembly. A lower hub fairing is positioned at the lower rotor assembly. A shaft fairing is disposed between the upper hub fairing and the lower hub fairing. The upper hub fairing is substantially sealed to the shaft fairing and the lower hub fairing is substantially sealed to the shaft fairing.