Lifting surface with active variable tip member and method for influencing lifting surface behavior therewith

Abstract

A tip member is movable mount at the outboard end of a main lifting member such as a wing or rotor blade. The main lifting member at least at the outboard end has an internal cavity defined therein between pressure-side and suction-side surfaces of the main lifting member. The tip member is movable relative to the main lifting member between a neutral position in which the tip member presents substantially no obstacle to a spanwise component of flow over either suction-side or pressure-side surfaces at the outboard end of the main lifting member, and a position in which a portion of the tip member extends beyond on of the pressure-side and suction-side surfaces of the main lifting member so as to present an obstacle to the spanwise component of flow over that surface at the outboard end of the main lifting member and thereby locally affect the flow at the outboard end. An actuation system for the tip member is disposed in the cavity of the main lifting member and coupled with the tip member for moving the tip member so as to vary a distance by which the tip member extends beyond the surface of the main lifting member. The tip member can be placed in stationary positions, or can be cyclically moved for achieving various effects such a vibration abatement, noise suppression, or lift augmentation.