Patent ID: 7093792

Claim:
A laminar-flow airfoil comprising: an upper wing surface, a lower wing surface, a leading edge and a trailing edge, wherein said upper wing surface includes: a front profile portion which has a positive curvature radius, and which is provided to extend from the leading edge to a largest-thickness point located in a range of 30% to 50% of a wing chord length, the front profile portion forming a laminar-flow boundary layer; a central profile portion which has a positive curvature radius, and which is provided to extend from the largest-thickness point to the vicinity of a position corresponding to approximately 90% of the wing chord length at which a value obtained by dividing a thicknesswise difference between the position and the largest-thickness point by a distance in a direction of a wing chord from the largest-thickness point is equal to or smaller than 0.12, the central profile portion forming a gentle pressure gradient to suppress separation of the boundary layer; and a rear profile portion which is curved concavely outwards, and which is provided to extend from the vicinity of a position corresponding to approximately 95% of the wing chord length to the trailing edge, the rear profile portion forming a pressure gradient steeper than that formed by the central profile portion to induce slight separation of the boundary layer, whereby a head-lowering pitching moment about an aerodynamic center is decreased.