A flow control method is a flow control method of controlling flow around a blade of a rotary wing, a plasma actuator being disposed at the blade. The flow control method includes: determining a characteristic frequency ratio that is a characteristic value among frequency ratios, each of the frequency ratios being a ratio between an actuator driving frequency and an angle of attack changing frequency, the actuator driving frequency being a frequency of an applied voltage applied to the plasma actuator, the angle of attack changing frequency being a frequency at which an angle of attack of the blade changes in accordance with a rotation angle of the blade; setting the actuator driving frequency such that the frequency ratio becomes the characteristic frequency ratio; and applying a voltage of the set actuator driving frequency to the plasma actuator to control the flow around the blade.

A foil, such as an aerofoil, having a leading edge and a trailing edge, of which at least a portion of one or both of the leading edge and trailing edge has a serrated profile comprising a plurality of adjoining teeth, each tooth having a tip point that represents a local maximum chord-wise extent of the tooth and, on each side span-wise of the tip point, a root point that represents a local minimum chord-wise extent of the tooth and at which the tooth adjoins a respective adjacent tooth, wherein the tooth edge profile varies with an ogee-like curve between tip point and root point such that the tooth is sharper in the neighbourhood of the tip point and in the neighbourhood of the root point than at locations in between.

An intentional fluid manipulation apparatus (IFMA) assembly that includes an upstream intentional momentum shedding apparatus (IMSA) configured to impart a first induced velocity to a local free stream flow during a nominal operation requirement. The upstream IMSA creates a streamtube. The IFMA includes a downstream IMSA, with some or all of the downstream IMSA being located in a downstream portion of the streamtube. The downstream IMSA imparts a second induced velocity to the local free stream flow within the streamtube. The second induced velocity at the location of the downstream IMSA has a component in a direction opposite to the direction of the first induced velocity at the location of the downstream IMSA.

A lift control device actively controls the lift force on a lifting surface. The device has a protuberance near a trailing edge of its lifting surface, which causes flow to separate from the lifting surface, generating regions of low pressure and high pressure which combine to increase the lift force on the lifting surface. The device further includes a means to keep the flow attached around the protuberance or to modify the position of the protuberance in response to a command from a central controller, so as to provide an active control of the lift between a maximum value and a minimum value.

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.

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed are systems, methods, and apparatus for actively adjusting the shape of a propeller blade of an aerial vehicle during operation of the aerial vehicle. For example, the propeller blade may have one or more joints that adjust to alter the shape of the propeller blade. The altered shape of the propeller blade causes the propeller to generate different frequencies of sound as it rotates. By altering multiple propeller blades of the aerial vehicle, the different sounds generated by the different propeller blades may effectively cancel or reduce the total sound generated by the aerial vehicle, and/or alter the total frequency generated.

The invention discloses an aircraft generating a larger thrust and lift by fluid continuity. First open channels used to extend fluid paths are formed in front parts and/or middle parts of windward sides of wings of the aircraft and extend from sides, close to the fuselage, of the wings to sides, away from the fuselage, of the wings, and the first open channels are concave channels or convex channels, so that a pressure difference in a direction identical with a moving direction is generated from back to front due to different flow speeds of fluid flowing over the windward sides of the wings in a lengthwise direction and a widthwise direction to reduce fluid resistance, and a larger pressure difference and lift are generated due to different flow speeds on the windward sides and leeward sides of the wings.

A foil, such as an aerofoil, having a leading edge and a trailing edge, of which at least a portion of one or both of the leading edge and trailing edge has a serrated profile comprising a plurality of adjoining teeth, each tooth having a tip point that represents a local maximum chord-wise extent of the tooth and, on each side span-wise of the tip point, a root point that represents a local minimum chord-wise extent of the tooth and at which the tooth adjoins a respective adjacent tooth, wherein the tooth edge profile varies with an ogee-like curve between tip point and root point such that the tooth is sharper in the neighbourhood of the tip point and in the neighbourhood of the root point than at locations in between.

An active flow control system for generating yaw control moments for an aircraft during hover 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. 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 trinary 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 and forward 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 bypass air combines with engine exhaust in the exhaust system to provide forward thrust generating the wing-borne lift.