Patent ID: 7207526

Claim:
A method for providing a foil, comprising: (a) providing a foil having an inward portion, a tip portion, a lower surface, an upper surface, a leading edge and a trailing edge, said foil having relative movement to a fluid medium in a manner capable of creating an upward lifting force on said foil relative to the plane of said relative movement, said upward lifting force is substantially directed from said lower surface toward said upper surface; (b) providing said foil with a vortex generator connected to said foil near said tip portion, said vortex generator having a substantially streamwise alignment relative to said foil between a vortex generator leading edge and a vortex generator trailing edge that is oriented at a predetermined angle of attack relative to said relative movement, said vortex generator extending below said lower surface of said foil and terminating at a lower end of said vortex generator, said vortex generator having an outward surface and an inward surface, said inward surface being arranged to form a region of relatively lower pressure along said inward surface relative to said outward surface so as to create an inward directed lifting force on said vortex generator that is substantially directed from said outward surface toward said inward surface, said inward directed lifting force being sufficient to create an inward directed cross flow condition in the wake behind said lower end of said vortex generator that is substantially directed from said tip portion of said foil toward said inward portion of said foil relative to said lower surface of said foil; (c) arranging the direction of said inward lifting force created by said vortex generator to be oriented sufficiently perpendicular to said upward lifting force created by said foil to substantially prevent a significantly strong downward directed vector component of said inward lifting force from forming on said vortex generator which could significantly oppose said upward lifting force generated by said foil, wherein said inward lifting force on said vortex generator is able to create said inward directed cross flow without simultaneously creating a significant reduction in said upward lifting force on said foil; and d) wherein said inward surface has a predetermined contour capable of forming a forward directed vector component of said inward lifting force along said inward surface.