Abstract: An airfoil of a wind-driven wheel consists of a spar and several vanes pivotable independently of each other, the spar and the airfoil being located next to each other in a form-locked manner so as to form a streamlined airfoil section, pivot bearings and return springs of the vanes are provided inside the spar, a web passes through an aperture in the side wall of the spar and connects the vane to the pivot bearing, the vane being swivelable in the direction of excessively strong wind pressure so as to stress a return spring, the web remote from the hub and the region of the vane is removed from the hub has a larger angle of incidence with respect to the direction of the wind than the web nearer to the hub and the region of the airfoil nearer to the hub, the spar being rotatable in a spar root so that angle of incidence can be varied, the pivot bearings which are in connection with the same vane are connected by a crossbar, stress in the return spring can be adjusted by a retention and cover strip covers the