An aircraft lifting surface attached to the rear or frontal end of the aircraft fuselage with a variable sweep angle α in an inboard part and with a constant sweep angle α1 in an outboard part. The aircraft lifting surface can be for example a horizontal tail plane or a vertical tail plane attached to the rear end fuselage or a canard attached to the frontal end fuselage.

A fixed wing aircraft has a wing with an aerofoil cross-section defining an upper and lower geometric surfaces which meet at a geometric leading edge of the wing. The wing has an upper and lower aerodynamic surfaces while in flight. The upper aerodynamic surface and the lower aerodynamic surface meet at an aerodynamic leading edge at the intersection with an attachment line dividing the air that passes over the upper aerodynamic surface from the air that passes over the lower aerodynamic surface. The lower geometric surface adjacent the geometric leading edge has a roughness strip with a step height of at least 50 microns over the lower geometric surface. The roughness strip is located on the lower aerodynamic surface of the wing when the aircraft is flown at a load factor of 1 g and is located on the upper aerodynamic surface when the load factor is above 1.2 g.

A fixed wing aircraft has a wing with an aerofoil cross-section defining an upper and lower geometric surfaces which meet at a geometric leading edge of the wing. The wing has an upper and lower aerodynamic surfaces while in flight. The upper aerodynamic surface and the lower aerodynamic surface meet at an aerodynamic leading edge at the intersection with an attachment line dividing the air that passes over the upper aerodynamic surface from the air that passes over the lower aerodynamic surface. The lower geometric surface adjacent the geometric leading edge has a roughness strip with a step height of at least 50 microns over the lower geometric surface. The roughness strip is located on the lower aerodynamic surface of the wing when the aircraft is flown at a load factor of 1 g and is located on the upper aerodynamic surface when the load factor is above 1.2 g.

The invention relates to a wing for an airplane having at least two winglets, wherein a local angle of attack at the upstream winglet shall be reduced by a passive elastic morphing in heavy load conditions and wherein stall shall occur for the downstream winglet, then. Both serves for limiting and reducing the forces and torques produced by the winglets.

The invention relates to a profiled structure, elongated in a direction in which the structure has a length exposed to an airflow, and transversely to which the structure has a leading edge (164) and/or a trailing edge, at least one of which is profiled and has, in said direction of elongation, serrations (28a) defined by successive teeth (30) and depressions (32).

Along the profiled leading edge and/or profiled trailing edge, the successive teeth (30) and depressions (32) extend only over a part of said length exposed to the flow over which the amplitude and/or spacing of the teeth varies monotonically except for the few teeth nearest each end of said part, a remaining part (280) of said length being smooth.

An aircraft capable of vertical takeoff and landing, stationary flight and forward flight, includes a closed wing that provides lift whenever the aircraft is in forward flight, a fuselage at least partially disposed within a perimeter of the closed wing, and one or more spokes coupling the closed wing to the fuselage. One or more motors are disposed within or attached to the spokes. Three or more propellers are proximate to a leading edge of the one or more spokes, distributed along the one or more spokes, and operably connected to the one or more motors to provide lift whenever the aircraft is in vertical takeoff and landing and stationary flight and provide thrust whenever the aircraft is in forward flight.

An aircraft capable of vertical takeoff and landing, stationary flight and forward flight, includes a closed wing that provides lift whenever the aircraft is in forward flight, a fuselage at least partially disposed within a perimeter of the closed wing, and one or more spokes coupling the closed wing to the fuselage. One or more motors are disposed within or attached to the spokes. Three or more propellers are proximate to a leading edge of the one or more spokes, distributed along the one or more spokes, and operably connected to the one or more motors to provide lift whenever the aircraft is in vertical takeoff and landing and stationary flight and provide thrust whenever the aircraft is in forward flight.

Provided is a flight efficiency improving system for a compound helicopter with a rotor and fixed wings. In forward flight of the compound helicopter, the flight efficiency improving system does not perform a cyclic pitch control of the rotor so as to allow a difference in lift generated by the rotor between an advancing side and a retreating side of the rotor, or the flight efficiency improving system performs the cyclic pitch control to an extent that does not completely eliminate the difference. The fixed wings are provided respectively on left and right sides of a body and are asymmetric to each other so that influence of an aerodynamic interference between the rotor and the fixed wings is reduced.

A request for transport services that identifies a rider, an origin, and a destination is received from a client device. Eligibility of the request to be serviced by a vertical take-off and landing (VTOL) aircraft is determined based on the origin and the destination. A transportation system determines a first and a second hub for a leg of the transport request serviced by the VTOL aircraft and calculates a set of candidate routes from the first hub to the second hub. A provisioned route is selected from among the set of candidate routes based on network and environmental parameters and objectives including pre-determined acceptable noise levels, weather, and the presence and planned routes of other VTOL aircrafts along each of the candidate routes.

A multi-segment oblique flying wing aircraft which has three distinct segments including two outer wing segments and a central wing segment. The central segment may be thicker in the vertical direction and adapted to hold pilots and passengers. The outer wing segments may be substantially thinner and may taper as they progress outboard from the wing center. The multi-segment oblique flying wing aircraft be adapted for rotating into a high speed flight configuration, or may be adapted for take-off and cruise at a constant angle. In an extreme flight case, the central wing segment may rotate to a local sweep of ninety degrees.