A propeller system combines innovative strategies to create a new methodology to reduce propeller or rotor noise. The propeller is specifically aimed for ultra-quiet electrically powered aircraft for use in high proximity aviation, but its low-noise advantages will extend to other purposes. The propeller blade includes geometries, along with size and operational limitations that minimize rotational and vortex noise, vibration and span-wise air flow on the blade. To further reduce noise, the propeller provides greater relative thrust on the inboard portions of the blade than do conventional propellers and provides less than conventional relative thrust including negative thrust at the outermost portions of the blade. The propeller blade includes stepped changes in local blade stiffness at calculated intervals that can reduce resonant blade vibrations and their resultant noise. This ultra-quiet propeller design can also be used for quieting hovercraft, drones, surveillance aircraft, indoor fans, wind tunnels and other applications.

An aircraft (5) including a wing (3) and a winglet (1) at the end of the wing, the winglet including: a root (7); a tip (9); a transition region (11) extending away from the root; and a wing-like region (13) extending from the distal end of the transition region to the tip. When the aircraft wing (3) is under the worst-case static loading, the tip of the winglet is located at the maximum spanwise extent of the winglet (1), but when the aircraft wing (3) is under the no-load condition, the wing-like region (13) is canted inboard such that the tip (9) of the winglet (1) is located inboard of the maximum spanwise extent of the winglet.

A wing tip device for fixing to the outboard end of a wing, the wing defining a wing plane, the wing tip device comprising: an upper wing-like element projecting upwardly with respect to the wing plane and having a trailing edge; and a lower wing-like element fixed with respect to the upper wing-like element and having a root chord and a trailing edge, the lower wing-like element root chord intersecting with the upper wing-like element, and the lower wing-like element projecting downwardly from the intersection, wherein the upper wing-like element is larger than the lower wing-like element and the trailing edge of the lower wing-like element is adjacent the trailing edge of the upper wing-like element at the intersection, and wherein an included angle between the upper and lower wing-like elements at the intersection is less than, or equal to, 160 degrees. Also, a wing with the wing tip device; an aircraft with the wing; a method of fitting, or retro-fitting, the wing tip device to a wing; a method of modifying an existing wing tip device; and a method of operating a wing with the wing tip device.

A wingtip of a lifting surface of an aeronautical vehicle, the lifting surface having a span, a leading edge, a trailing edge, an upper surface and a lower surface, the wingtip being in a range of five percent to fifteen percent of an end portion of the span of the lifting surface, the wingtip including: an elliptical shape between the leading and trailing edges, the elliptical shape tapering in a direction towards an outer edge of the wing tip, wherein the tapering occurs in a plurality of geometric parameters of the lifting surface including spanwise chord distribution between the leading and trailing edges, spanwise mean camber distribution between the leading including and trailing edges, spanwise maximum thickness between the upper and lower surfaces, and spanwise twist of a mean average of the spanwise chord distribution of the wingtip.

Vortex reduction apparatus for use with airfoils are disclosed. An example vortex reduction apparatus includes a housing to couple to a tip of an airfoil. The housing defines a volute fluid flow passageway between an inlet and an outlet. The volute fluid flow passageway is structured to induce a rotational fluid flow in a first rotational direction opposite a second rotational direction of a shed vortex induced at the tip of the airfoil during flight.

This invention is an apparatus for vortex generation by combining the function of means for vortex generation with the functions of the leading-edge aerodynamic surface, the airfoil, and/or the trailing-edge aerodynamic surface.

A boundary layer suction design using wingtip vortex for a lift-generating body that has optimized aerodynamic performances. Holes or slots connected to the tip of the lift generating body via a plenum sucked a part of the boundary layer to delay flow transition or separation. Thus, with a more stable boundary layer, the lift is increased while the drag is reduced. Also, a valve is used to control the pressure in the plenum and optimized the suction mechanism.

A method of improving performance of an aircraft, including attaching a wing tip to a wing of the aircraft. The wing tip includes a winglet and a ventral fin. The winglet includes a winglet leading edge, a winglet trailing edge, an adapter section, a transition section attached to the adapter section, a blade section attached to the transition section, and a first tip section attached to the blade section. The ventral fin is coupled to the winglet at an attachment location adjacent the transition section. The ventral fin includes a second tip section. The wing has a wing leading edge and a wing trailing edge in a wing chord plane. Attaching the wing tip to the wing includes connecting the adapter section to the wing such that the winglet leading edge continuously transitions from the wing leading edge, and the winglet trailing edge continuously transitions from the wing trailing edge.

A noise attenuation element can be arranged for connection to an air directing structure such as a wing flap. The element has a non-uniform lattice density across at least a portion of the body of the element.

A wing-lip arrangement couplable with a wing of an aircraft includes a connection region for coupling or integration with the wing end region, at least one tip, at least one upper surface and at least one lower surface, which extend between a leading edge and a trailing edge of the wing-tip arrangement from the connection region to the at least one tip, and at least one vortilon. The local dihedral of the wing-tip arrangement changes between the at least one tip and the connection region, such that at least a part of the wing-tip arrangement projects at an angle relative to the wing. The at least one vortilon includes a vortilon base and a vortilon tip. The vortilon base is attached to at least one of the at least one lower surface of the wing-tip arrangement. The vortilon tip faces in an upstream direction.