a convex curve to a halfway thickness of approximately 0 24 u2033 to a maximum thickness of the section c being approximately 0 30 u2033 that is spaced approximately 1 99 u2033 from the rounded leading edge 30 le a halfway thickness of approximately 0 29 u2033 is located on a downwardly convex curve slope between the maximum thickness point and the rounded leading edge 30 le fig4 d shows the cross section d of fig2 3 having a width of approximately 4 18 u2033 a flat bottom and an aerodynamic upper surface that starts from blunt trailing edge 40 te sloping upward along a convex curve to a halfway thickness of approximately 0 24 u2033 to a maximum thickness of the section d being approximately 0 29 u2033 that is spaced approximately 1 90 u2033 from the rounded leading edge 30 le a halfway thickness of approximately 0 28 u2033 is located on a downwardly convex curve slope between the maximum thickness point and the rounded leading edge 30 le fig4 e shows the cross section e of fig2 3 having a width of approximately 4 03 u2033 a flat bottom and an aerodynamic upper surface that starts from blunt trailing edge 40 te sloping upward along a convex curve to a halfway thickness of approximately 0 23 u2033 to a maximum thickness of the section e being approximately 0 28 u2033 that is spaced approximately 1 81 u2033 from the rounded leading edge 30 le a halfway thickness of approximately 0 27 u2033 is located on a downwardly convex.