An aircraft can include a first wing and a second wing. The first wing can extend laterally from an aircraft body to a first tip, and the second wing can extend laterally from the aircraft body to a second tip. The aircraft can include a first end effector and a second end effector, each including a fore winglet and an aft winglet. The fore and aft winglets of the first end effector can be pivotably connected to the first tip. The fore and aft winglets of the second end effector can be pivotably connected to the second tip. The fore and aft winglets of the first and second end effectors can be independently operable. The first and second end effectors can be independently operable. A processor can be operatively connected to control movement of the fore and aft winglets of the first and second end effectors.

A method of retrofitting a wing of a fixed wing aircraft is disclosed including the steps of providing an existing aircraft wing with a main fixed wing portion, and the main fixed wing portion having a tip end and an existing movable flight control surface connected adjacent the tip end. The existing movable flight control surface is then removed from the main fixed wing portion, and a wing tip device and movable flight control surface are selected as a pair to replace the existing movable flight control surface, with the selected movable flight control surface having an aerodynamic surface of different shape to the shape of the flight control surface removed from the wing. The selected wing tip device and movable flight control surface are then fitted to the main fixed wing portion.

A Short Takeoff and Landing (STOL) aircraft has a fuselage with an axis and an engine providing thrust, a first aileron at an end of a first wing, a second aileron at an end of a second wing, a first slot having a length through the first wing proximate the first aileron, orthogonal to the axis; a second slot having a length through the second wing proximate the second aileron, orthogonal to the axis; a first electric motor in the first wing driving a first two-blade propeller in the first slot, a second electric motor in the second wing driving a second two-blade propeller in the second slot, and a control mechanism enabling a user to drive the first and second electric motors in a same rotary direction, to reverse the rotary direction, and to drive the first and second motors at a same rpm.

A flow control device on a structure such that strain in the structure is at least partially transferred to the flow control device is disclosed having at least two states, or shapes, separated by an elastic instability region. The flow control device is arranged to rapidly transition, or snap through, from the first state to the second state when strain in the structure exceeds an activation threshold of the flow control device. A spoiler on an aerofoil has a rest position where it is substantially flush with the low pressure surface and an activated position where it protrudes from the low pressure surface and modifies the airflow over that surface. The spoiler bends to move from the rest position to the activated position when the strain in the aerofoil crosses a threshold. The deployed spoiler reduces the lift on the aerofoil, acting to reduce the lift induced strain of the aerofoil to which the spoiler is attached.

An active wing extension includes a body portion substantially parallel to a wing of an aircraft, as if it were an extension of the wing. The body portion is attachable to an aircraft wing and includes multiple controllable airflow modification devices coupled thereto. By virtue of having multiple controllable airflow modification devices, the wing extension is capable of adjusting control surfaces of the multiple controllable airflow modification devices in response to in-flight conditions, to reduce wing loads, improve wing fatigue characteristics, increase range, and/or increase efficiency.

A fluid foil has a main fixed portion and a tip portion movably mounted at a tip end of the main fixed portion. The main fixed portion has an upper surface and a lower surface, and the tip portion has an upper surface and a lower surface. The fluid foil is operable in: a) a first configuration in which the upper surface of the tip portion is angled downwardly with respect to the upper surface of the main fixed portion; and b) a second configuration in which the tip portion is rotated upwardly with respect to the first configuration such that the upper surface of the tip portion and the upper surface of the main fixed portion are substantially continuous surfaces. The movement of the tip portion with respect to the main fixed portion is exclusively passively actuated by movement of the foil with respect to a surrounding fluid.

A vortex generator apparatus for an aircraft includes a surface section having a receiving recess, a vortex generator having a first edge, an opposite second edge and a vortex generator surface component extending from the first edge to the second edge, wherein the first edge is fixedly arranged in or adjacent to the receiving recess. The vortex generator surface component includes at least one electroactive polymer assembly, wherein the at least one electroactive polymer is switchable into an extended state by applying an electrical voltage and into a neutral state by removing the electrical voltage. The electroactive polymer assembly and the vortex generator surface component are configured to retract the vortex generator surface component completely into the receiving recess in the neutral state of the electroactive polymer assembly and to extend the vortex generator surface component from the receiving recess in the extended state.

An air-redirection formation for a tip portion of an aerofoil such as an aircraft wing includes: a first portion, which includes a first surface which forms a continuation of the aerodynamic lifting surface of the wing, and which is for directing vortices away from the aerofoil; and a second portion, which is spaced from the first portion and which is positioned to generate uplift due to the directed vortices.

The invention relates to a wing with two winglets and a respective airplane. An upstream winglet broadens a region of inclined airflow and a downstream winglet produces a thrust contribution therein.

A retractable vortex generator system for an aircraft. The system comprises a skin, a slot arranged on the skin, a plate comprising a contour configured for energizing the boundary layer of an air current, and driving means configured for rotating the plate between a first and a second position. In the first position at least part of the contour of the plate protrudes through the slot, and in the second position the plate is retracted within the slot.