An exemplary ducted fan with an optimized stator includes a duct surrounding a rotor hub from which blades radially extend and the stator having a stator span extending horizontally across an inside diameter of the duct, the stator having a stator chord extending from a leading edge to a trailing edge, wherein a length of the stator chord varies across the stator span.

An active flow control system for generating yaw control moments for an aircraft during forward flight. The system includes right and left yaw effectors disposed proximate the right and left wingtips of the wing. A pressurized air system includes a pressurized air source and a plurality of injectors operably associated with the right and left yaw effectors that influence the path of airflow above and below the yaw effectors. Based upon which of the injectors is injecting pressurized air, the right and left yaw effectors generate no yaw control moment, generate a yaw right control moment or generate a yaw left control moment.

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 an engine, a binary lift fan system, a forced air bypass system and an exhaust system. The engine has a turboshaft mode and a turbofan mode. The lift fan system includes a plurality of ducted fans in a tandem lateral orientation. In the VTOL orientation of the aircraft, the engine is in the turboshaft mode coupled to the lift fan system such that the engine provides rotational energy to the ducted fans generating the thrust-borne lift. In the forward flight orientation of the aircraft, the engine is in the turbofan mode coupled to the forced air bypass system such that the bypass air combines with the engine exhaust in the exhaust system to provide forward thrust generating the wing-borne lift.

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 an engine, a binary lift fan system, a forced air bypass system and an exhaust system. The engine has a turboshaft mode and a turbofan mode. The lift fan system includes a plurality of ducted fans in a tandem lateral orientation. In the VTOL orientation of the aircraft, the engine is in the turboshaft mode coupled to the lift fan system such that the engine provides rotational energy to the ducted fans generating the thrust-borne lift. In the forward flight orientation of the aircraft, the engine is in the turbofan mode coupled to the forced air bypass system such that the bypass air combines with the engine exhaust in the exhaust system to provide forward thrust generating the wing-borne lift.

A propulsion system for an aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a forward flight orientation. The propulsion system includes an turboshaft engine, a lift fan system, a forced air bypass system and an exhaust system. The engine has a turboshaft mode and a turbofan mode. The lift fan system includes at least one ducted fan. In the VTOL orientation of the aircraft, the engine is in the turboshaft mode coupled to the lift fan system such that the engine provides rotational energy to the at least one ducted fan generating the thrust-borne lift. In the forward flight orientation of the aircraft, the engine is in the turbofan mode coupled to the forced air bypass system such that the bypass air combines with the engine exhaust in the exhaust system to provide forward thrust generating the wing-borne lift.

A propulsion system for an aircraft operable to transition between thrust-borne lift in a VTOL orientation and wing-borne lift in a forward flight orientation. The propulsion system includes an turboshaft engine, a lift fan system, a forced air bypass system and an exhaust system. The engine has a turboshaft mode and a turbofan mode. The lift fan system includes at least one ducted fan. In the VTOL orientation of the aircraft, the engine is in the turboshaft mode coupled to the lift fan system such that the engine provides rotational energy to the at least one ducted fan generating the thrust-borne lift. In the forward flight orientation of the aircraft, the engine is in the turbofan mode coupled to the forced air bypass system such that the bypass air combines with the engine exhaust in the exhaust system to provide forward thrust generating the wing-borne lift.

An unmanned aerial vehicle (UAV) that provides increased operational flight endurance and efficiency. The UAV includes a power generation system, which includes an internal combustion engine and one or more batteries (batteries). The power generation system is configured to generate power for propulsion of the UAV. The internal combustion engine is configured to power a lift propeller, generating vertical lift of the UAV, and the batteries are configured to power a micro-propeller assembly, propelling the UAV in a forward direction or multiple additional directions.

An active flow control system for generating pitch control moments for an aircraft during flight. The system includes a nozzle disposed proximate the aft end of the aircraft. The nozzle is configured to discharge a gas stream in the aftward direction. A pressurized air system includes a pressurized air source and one or more injectors configured to selectively inject pressurized air into the nozzle to influence the path of the gas stream. Based upon which injectors are injecting pressurized air into the nozzle, the gas stream exits the nozzle generating no pitch control moment, generating a pitch down control moment or generating a pitch up control moment.

A method of controlling at least a first pitch of a first propeller and a second pitch of a second propeller of a hybrid helicopter, the hybrid helicopter having a thrust control and a yaw control that are configured to generate orders for modifying respectively a mean pitch component and a differential pitch component of the first pitch and of the second pitch, the hybrid helicopter having a collective pitch control for modifying a collective pitch component of main blades of the lift rotor. The method includes a step of: keeping with the control system the first pitch and the second pitch within a control domain that varies as a function of information relating to the collective pitch component.

A method of controlling at least a first pitch of a first propeller and a second pitch of a second propeller of a hybrid helicopter, the hybrid helicopter having a thrust control and a yaw control that are configured to generate orders for modifying respectively a mean pitch component and a differential pitch component of the first pitch and of the second pitch, the hybrid helicopter having a collective pitch control for modifying a collective pitch component of main blades of the lift rotor. The method includes a step of: keeping with the control system the first pitch and the second pitch within a control domain that varies as a function of information relating to the collective pitch component.