Funneled rotary foil

This invention relates to the field of aerodynamics, and more particularly to improvements in rotatable airfoils such as propellers, helicopter rotors, and wind powered devices for converting wind energy into electrical or mechanical power. All such devices use blades, which are rotatably mounted and have aerodynamic airfoil shapes designed according to well-known a conventional rules using aerodynamic formulas known to those skilled in the art. A funnel strip is added to a rotary airfoil, which utilizes the Bernoulli principle to increase the velocity of air over the suction side of the rotating airfoil to increase the lift. The device is applicable to thrust-producing devices, such as propellers, as well as to wind-powered devices.