with the base line airfoil preferred airfoil 10 terminates in a very narrow base 40 having a vertical dimension of about 0 1 of the chord length the narrow base is desirable to minimize base drag and a base having a vertical dimension of less than 0 2 of the chord is preferred referring to fig4 the camber 30 of the preferred airfoil is compared with the camber 30 39 of the aft portion of the base line airfoil the camber 30 of the preferred airfoil has significant curvature over the last 3 5 4 of the chord compared to the base line airfoil where the camber 30 39 appears to be essentially linear the curvature of the curled trailing edge of the airfoil of the present invention becomes more apparent in fig5 where the slope of the camber i e the first derivative of the camber line is plotted for the base line airfoil and for the preferred embodiment of the present invention referring to fig5 it is apparent that the slope 42 39 of the camber of the base line airfoil 10 39 remains almost linear up to the trailing end however the slope 42 of the camber of preferred embodiment 10 shows significant non linearity starting at about the 96 chord position in particular the camber slope 42 of preferred embodiment 10 changes from about 0 175 at.