MULTI-MEMBER TIP Russian patent published in 1998 - IPC

FIELD: aeronautical engineering; tips of aircraft lifting surfaces and tips of helicopter blades. SUBSTANCE: end of lifting surface is provided with multi-member tip which is mounted in horizontal plane for reduction of induced drag; it is made in form of split wing consisting of at least three small wings having their own aerodynamic profile, aerodynamic and geometric twist and mounted at optimal angles of attack relative to tip chord of lifting surface. Aerodynamic profiles, angle of attack, twist, as well as mean geometric chord are selected on the condition of prevailing intensity of tip vortex at given section of tip chord of lifting surface under optimal cruising conditions of flight. Shape in plan of small wings may be different: it is dictated by specific features of aerodynamic profile of lifting surface acting of intensity of tip vortex at definite section of tip chord. EFFECT: reduction of induced drag at subsonic and transonic speeds through change in redistribution of load over lifting surface and weakening intensity of tip vortex due to flow of air from lower to upper surface at operational angles of attack. 2 dwg