Two digits describing the maximum thickness as percent of chord.One digit describing the design lift coefficient in tenths.The subscript digit gives the range of lift coefficient in tenths above and below the design lift coefficient in which favorable pressure gradients exist on both surfaces.One digit describing the distance of the minimum pressure area in tenths of the chord.The airfoil is described using six digits in the following sequence: The following table presents the various camber-line profile coefficients:Īn improvement over 1-series airfoils with emphasis on maximizing laminar flow. The formula for the shape of a NACA 00xx foil, with "xx" being replaced by the percentage of thickness to chord, is y t = 5 t, Plot of a NACA 0015 foil generated from formula These figures and shapes transmitted the sort of information to engineers that allowed them to select specific airfoils for desired performance characteristics of specific aircraft. Engineers could quickly see the peculiarities of each airfoil shape, and the numerical designator ("NACA 2415," for instance) specified camber lines, maximum thickness, and special nose features. By 1929, Langley had developed this system to the point where the numbering system was complemented by an airfoil cross-section, and the complete catalog of 78 airfoils appeared in the NACA's annual report for 1933.
NACA FOUR DIGIT AIRFOIL GENERATOR SERIES
According to the NASA website:ĭuring the late 1920s and into the 1930s, the NACA developed a series of thoroughly tested airfoils and devised a numerical designation for each airfoil - a four digit number that represented the airfoil section's critical geometric properties. NACA initially developed the numbered airfoil system which was further refined by the United States Air Force at Langley Research Center.