A thrust producing unit for producing thrust in a predetermined direction, comprising at least two rotor assemblies and a shrouding that accommodates at most one of the at least two rotor assemblies, wherein the shrouding defines a cylindrical air duct that is axially delimited by an air inlet region and an air outlet region, and wherein the air inlet region exhibits in circumferential direction of the cylindrical air duct an undulated geometry.

A thrust producing unit for producing thrust in a predetermined direction, comprising at least two rotor assemblies and a shrouding that accommodates at most one of the at least two rotor assemblies, wherein the shrouding defines a cylindrical air duct that is axially delimited by an air inlet region and an air outlet region, and wherein the air inlet region exhibits in circumferential direction of the cylindrical air duct an undulated geometry.

In one aspect, described herein is an aircraft capable of carrying at least 400 pounds of payload. An embodiment has four rotors systems, each of the rotor systems being independently driven by an electric motor or other torque-producing source. Each of the rotor systems provide sufficient thrust such that the aircraft is capable of controlled vertical takeoff and landing, even if one of the variable pitch rotor systems is inoperable. An electronic control system is configured to control the rotational speed and pitch of at least one of the rotor systems.

A coaxial tilt-rotor unmanned aerial vehicle (CTRUAV) and a control method thereof. CTRUAV comprises three rotor modules, five rotors with motors respectively and a control system. Three rotor modules are in an inverted triangle layout. The left and right coaxial tiltable rotor modules in the front of the CTRUAV can rotate around the plane of a fuselage. A rear rotor is installed on the rear fixed-axis rotor module. Two pairs of coaxial rotors are respectively installed on the left and right coaxial tiltable rotor modules. Namely, the left and right coaxial tiltable rotor modules consists of an upper rotor and a lower rotor respectively; the upper rotor and the lower rotor have opposite rotation directions and the same rotation speed during the flight. Moreover, in the two pairs of coaxial rotors, the rotors on same layers have opposite rotation directions, and therotors on different layers have the same rotation directions.

A coaxial tilt-rotor unmanned aerial vehicle (CTRUAV) and a control method thereof. CTRUAV comprises three rotor modules, five rotors with motors respectively and a control system. Three rotor modules are in an inverted triangle layout. The left and right coaxial tiltable rotor modules in the front of the CTRUAV can rotate around the plane of a fuselage. A rear rotor is installed on the rear fixed-axis rotor module. Two pairs of coaxial rotors are respectively installed on the left and right coaxial tiltable rotor modules. Namely, the left and right coaxial tiltable rotor modules consists of an upper rotor and a lower rotor respectively; the upper rotor and the lower rotor have opposite rotation directions and the same rotation speed during the flight. Moreover, in the two pairs of coaxial rotors, the rotors on same layers have opposite rotation directions, and therotors on different layers have the same rotation directions.

An axial flow turbomachine (102) for producing thrust to propel an aircraft is shown. The turbomachine has an inner duct (202) and an outer duct (204), both of which are annular and concentric with one another. An inner fan (206) is located in the inner duct, and is configured to produce a primary pressurised flow (P). An outer fan (207) is located in an outer duct, and is configured to produce a secondary pressurised flow (S). The outer fan has a hollow hub (208) through which the inner duct passes. A swept area of the outer fan is from 2 to 20 times greater than a swept area of the inner fan.

An aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a forward flight orientation. The aircraft has a blended wing body and includes first and second engines, a binary lift fan system, first and second forced air bypass systems and first and second exhaust systems. The engines have turboshaft and turbofan modes. The lift fan system includes ducted fans in a tandem longitudinal orientation. In the VTOL orientation of the aircraft, the engines are in the turboshaft mode coupled to the lift fan system such that the engines provide rotational energy to the ducted fans generating the thrust-borne lift. In the forward flight orientation of the aircraft, the engines are in the turbofan mode coupled to the forced air bypass systems such that the bypass air combines with the engine exhaust in the exhaust systems to provide forward thrust generating the wing-borne lift.

A rotor unit is disclosed. The rotor unit includes a hub and a stacked rotor blade. The hub is configured to rotate about an axis in a first rotation direction. The stacked rotor blade is rotatable about the axis and further includes a first blade element and a second blade element. The first blade element has a first leading edge and the second blade element has a second leading edge. The blade elements are arranged in a stacked configuration. A leading edge of the stacked rotor blade is formed by at least a portion of the first leading edge of the first blade element as well as at least as portion of the second leading edge of the second blade element. In some embodiments, the rotor unit is coupled to an unmanned aerial vehicle.

A rotor unit is disclosed. The rotor unit includes a hub and a stacked rotor blade. The hub is configured to rotate about an axis in a first rotation direction. The stacked rotor blade is rotatable about the axis and further includes a first blade element and a second blade element. The first blade element has a first leading edge and the second blade element has a second leading edge. The blade elements are arranged in a stacked configuration. A leading edge of the stacked rotor blade is formed by at least a portion of the first leading edge of the first blade element as well as at least as portion of the second leading edge of the second blade element. In some embodiments, the rotor unit is coupled to an unmanned aerial vehicle.

Apparatuses and systems are provided herein for unducted propulsion systems. The system includes a forward housing for high efficiency for high subsonic sustained flight. A plurality of blades are affixed to the forward housing, wherein the forward housing defines a flowpath curve extending from the forward-most end of the forward housing through the axial extent of a forward blade root. The flowpath curve is described by an axial direction parallel to an axis of rotation and a radius from the axis of rotation. The flowpath curve includes a first point having a first radius where the radius reaches a maximum forward of the forward blade root and a second point aft of the first point having a second radius where the radius stops decreasing. The ratio of the first radius to the second radius is greater than or equal to 1.029.