Abstract: A ducted fan assembly for generating thrust during edgewise forward flight. The ducted fan assembly includes a duct having an inlet with a leading portion and a diffuser with a trailing portion during the edgewise forward flight. A fan disposed within the duct is configured to rotate relative to the duct about a fan axis to generate an airflow through the duct from the inlet to the diffuser. An active flow control system includes a plurality of injectors including a first injector configured to inject pressurized air substantially tangential with the leading portion of the inlet and a second injector configured to inject pressurized air substantially tangential with the trailing portion of the diffuser such that when the injectors are injecting pressurized air, flow separation of the airflow at the leading portion of the inlet and the trailing portion of the diffuser is reduced.

Abstract: An active flow control system for generating roll control moments for an aircraft during hover flight. The system includes right and left roll 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 roll effectors. Based upon which of the injectors is injecting pressurized air, the right and left roll effectors generate no roll control moment, generate a roll right control moment or generate a roll left control moment.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 unitary 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 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 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.

Abstract: A modular tandem tiltrotor aircraft in which the tiltrotor assemblies are operably coupled at the forward and aft ends of the fuselage of the aircraft is disclosed. The modular tandem tiltrotor assemblies are capable of rotating between a vertical lift position and a horizontal flight position. The modular tandem tiltrotor aircraft can be structurally more efficient and lower drag than a conventional tiltrotor, has better control authority and lifting capacity than hybrid-quads and tail-sitters, and has more range than a helicopter or multi-rotor. The modular tandem tiltrotor aircraft can orbit and search over a broad area, or can hover for long periods, depending on the application. Instead of providing a multi-function tandem tiltrotor aircraft that is generally suited for all applications, but not optimized for any, the modular tandem tiltrotor aircraft allows for customized configuration to optimize the aircraft for a particular application.

Abstract: A method for an aircraft may include determining a transition from an airplane mode to a helicopter mode for a propulsion system of the aircraft, wherein the propulsion system comprises a plurality of rotor blades; determining whether a descent rate condition is satisfied, wherein the descent rate condition is associated with a maximum allowable descent rate for the aircraft; and controlling a collective pitch angle for the plurality of rotor blades based on the descent rate condition.

Abstract: An aircraft comprising a pair of ducted thrusters. Each of the ducted thrusters comprises a duct surrounding a rotor assembly with a rotor hub having a plurality of rotor blades extending therefrom, wherein the plurality of rotor blades have a modulated angular distribution about a central longitudinal axis of the duct. Each of the ducted thrusters further comprises a stator assembly having a stator hub with a plurality of stator vanes extending from the stator hub to an interior surface of the duct, wherein each of the plurality of the stator vanes are angularly modulated around the stator hub such that angular spacing between pairs of adjacent vanes of the plurality of stator vanes varies for each pair of the adjacent vanes.

Abstract: A pitot-static array system for a tail-sitting aircraft has a disk with a plurality of edge ports arrayed about an edge of the disk. Each of a plurality of pressure transducers is configured to measure air pressure at one of the edge ports. The edge ports are arrayed about an axis parallel to a pitch axis of the aircraft.

Abstract: A pitot-static array system for a tail-sitting aircraft has a disk with a plurality of edge ports arrayed about an edge of the disk. Each of a plurality of pressure transducers is configured to measure air pressure at one of the edge ports. The edge ports are arrayed about an axis parallel to a pitch axis of the aircraft.

Abstract: An aircraft has a ducted thruster. The ducted thruster includes a duct having an inner wall, a stator hub disposed within the duct, a first stator extending along a first longitudinal axis between the inner wall and the stator hub, and a second stator. The second stator extends along a second longitudinal axis between the inner wall and the stator hub. The second longitudinal axis is either (1) substantially perpendicular to the first longitudinal axis or (2) substantially parallel to the first longitudinal axis and offset from the first longitudinal axis.

Abstract: A rotorcraft featuring a fuselage, a forward fuselage ducted fan located in the fuselage, and an aft fuselage ducted fan located in the fuselage. The rotorcraft is directly powered by electricity and can be supplemented with additional powers sources. Two sets of pivoting ducted fans provide additional lift and thrust as needed to control the rotorcraft.

Abstract: A rotor system is provided in one example embodiment and may include a first pair of rotor blades comprising a first pitch and a first diameter; and a second pair of rotor blades comprising a second pitch and a second diameter, wherein the first pitch of the first pair of rotor blades and the second pitch of the second pair of rotor blades are different.

Abstract: A tandem tiltrotor aircraft in which the tiltrotor assemblies are operably coupled at the forward and aft ends of the fuselage of the aircraft is disclosed. The tiltrotor assemblies are capable of rotating between a vertical lift position and a horizontal flight position. The in-line location of the tiltrotor assemblies allow the aircraft to have the vertical take-off and landing capabilities, and, in combination with the at least one wing, can be used in horizontal flight. The nacelles can be disposed on the fuselage they are coaxial in forward flight and do not add to the drag profile like wing-tip nacelles would. When wing-borne flight is desired some or all of the rotors can rotate down so the thrust vector is in a generally horizontal plane.

Abstract: A method for an aircraft is provided in one example embodiment and may include determining a transition from an airplane mode to a helicopter mode for a propulsion system of the aircraft, wherein the propulsion system comprises a plurality of rotor blades; determining whether a descent rate condition is satisfied, wherein the descent rate condition is associated with a maximum allowable descent rate for the aircraft; and controlling a collective pitch angle for the plurality of rotor blades based on the descent rate condition.

Abstract: A rotor system is provided in one example embodiment and may include a rotor duct; at least one rotor blade, wherein the at least one rotor blade comprises a tip end; and a tip extension affixed at the tip end of the at least one rotor blade, wherein the tip extension is comprised, at least in part, of a flexible material and the rotor blade has a fixed extended length based on the tip extension. The tip extension may provide a clearance distance between the tip extension and the rotor duct.

Abstract: A rotor system is provided in one example embodiment and may include a rotor duct; at least one rotor blade, wherein the at least one rotor blade comprises a tip end; and a tip extension affixed at the tip end of the at least one rotor blade, wherein the tip extension comprises a plurality of flexible elements and the rotor blade has a fixed extended length based on the tip extension. The tip extension may provide a clearance distance between the tip extension and the rotor duct.

Abstract: An aircraft comprising a pair of ducted thrusters. Each of the ducted thrusters comprises a duct surrounding a rotor assembly with a rotor hub having a plurality of rotor blades extending therefrom, wherein the plurality of rotor blades have a modulated angular distribution about a central longitudinal axis of the duct. Each of the ducted thrusters further comprises a stator assembly having a stator hub with a plurality of stator vanes extending from the stator hub to an interior surface of the duct, wherein each of the plurality of the stator vanes are angularly modulated around the stator hub such that angular spacing between pairs of adjacent vanes of the plurality of stator vanes varies for each pair of the adjacent vanes.