A special contour near the trailing edge (24) of an airfoil (20) which improves the airfoil effectiveness. The contour is a combination of a blunt airfoil base (28), a local region of high surface curvature, typically on the airfoil lower surface, and upper surface and lower surface trailing edge slopes that diverge from each other (30).

Divergent trailing-edge airfoil

An auxiliary flap is movably arranged on a planar trailing edge of an aerodynamic element such as a wing, rudder, stabilizer, or flap. The auxiliary flap is rotatable and/or slidable relative to the aerodynamic element, to move selectively into three positions. In a first position, a free edge of the auxiliary flap protrudes into an airflow boundary layer on one side of the aerodynamic element, to decrease lift. In a second position, a free edge of the aerodynamic element protrudes into an airflow boundary layer on the other side of the aerodynamic element, to increase lift. In a third neutral position, the auxiliary element does not protrude into either boundary layer, so as not to influence lift. The auxiliary flap is simple and rapidly acting. The flap protrudes substantially perpendicularly into the boundary layer flow. The auxiliary flap has a planar plate shape.

Flap arrangement for varying the aerodynamic lift generated by an aerodynamic element of an aircraft

The invention is a small flap like device (18) for attachment to the trailing edge (14) of an aircraft wing (10) which improves the coefficient of lift and reduces the coefficient of drag providing an overall increase in fuel economy. The flap (18) is a flat plate-like member having a length (19) of between 0.5% to 1.5% of the chord of the airfoil and at a downward angle (21) to the chord of between 5° and 25°.

Micro flap trailing edge device for an aircraft wing

The invention concerns a blade profile for aircraft rotor, comprising, between a leading edge (1A) and a trailing edge (1B), a suction face (2) and a blade face (3) whereof the geometric locus of the equidistant points of the latter defines the curvature. The invention is characterised in that the value of the ratio of the maximum curvature to the maximum thickness develops linearly with the profile (1) relative thickness and ranges between 0.13 and 0.19 for a relative thickness of 7 % of the chord (C) and ranges between 0.18 and 0.24 for a relative thickness of 15 % of the chord (C).

Blade profile for aircraft rotor and rotor comprising same

The present invention relates to a blade section for rotating wings of an aircraft comprising, between the leading edge and the trailing edge, a convex lower surface and an upper surface which is convex over the greater part of its length, but concave near the trailing edge. According to the invention, the upper surface of the section comprises a region of small extent, close to the leading edge but not contiguous thereto, in which the curvature is substantially constant. The invention is applicable to the improvement of the performances in maneuvering flight, while hovering and in advance flight of the aircraft.

Blade section for rotating wings of an aircraft

A family of airfoils for use in rotary wing aircraft, particularly helicopters, is disclosed. The family is characterized by having a maximum c 1 .sbsb.max at M=0.4 and maximum delay in drag divergence while maintaining zero lift pitching moment levels c m .sbsb.o correctable within the range of -0.01 to +0.01. The present family of airfoils provide high lift at maximum angle of attack when the blade is retreating and maximum delay in drag rise or drag divergence when the blade is advancing. The airfoil section of the family enable a helicopter rotor to counteract, more efficiently, the rolling moment which would otherwise be induced by a rotorcraft's forward flight; this is achieved by the present family of airfoils while maintaining the airfoil sectional pitching moment coefficient at or about zero thereby enabling the blade in which the airfoil sections are incorporated to impose minimum structural loads on the rotorcraft's control system.

Dadone Leone U

Papers

Advanced airfoils for helicopter rotor application

Rotorblatt fuer drehfluegelflugzeuge