For a 230 camber-line profile (the first 3 numbers in the 5-digit series), k 1 = 15.957 is used. Finally, constant k 1 is determined to give the desired lift coefficient. The constant r is chosen so that the maximum camber occurs at x=p for example, for the 230 camber line, 0.3/2=0.15 and r = 0.2025. Where the chordwise location x and the ordinate y have been normalized by the chord. Where m is the maximum camber (100 m is the first of the four digits), p is the location of maximum camber (10 p is the second digit in the NACA xxxx description).įor example, a NACA 2412 airfoil uses a 2% camber (first digit) 40% (second digit) along the chord of a 0012 symmetrical airfoil having a thickness 12% (digits 3 and 4) of the chord.įor this cambered airfoil, because the thickness needs to be applied perpendicular to the camber line, the coordinates ( x U, y V) and ( x L, y L) and (, of respectively the upper and lower airfoil surface, become The formula used to calculate the mean camber line is The simplest asymmetric foils are the NACA 4-digit series foils, which use the same formula as that used to generate the 00xx symmetric foils, but with the line of mean camber bent. Symmetrical 4-digit series airfoils by default have maximum thickness at 30% of the chord from the leading edge.Įquation for a cambered 4-digit NACA airfoil Now the coordinates (x u, y u) of the upper airfoil surface (x L, y L) of th elower airfoil surface are The leading edge approximates a cylinder with a chord-normalized radius of to −0.1036) will result in the smallest change to the overall shape of the airfoil. If a zero-thickness trailing edge is required, for example for computational work, one of the coefficients should be modified such that they sum to zero. In this equation, at x = 1 (the trailing edge of the airfoil), the thickness is not quite zero. T = maximum thickness as a fraction of the chord (so t gives the last two digits in the NACA 4-digit denomination divided by 100). He half thickness at a given value of x (centerline to surface), X = position along the chord from 0 to 1.00 (0 to 100%), The formula for the shape of a NACA 00xx foil, with "xx" being replaced by the percentage of thickness to chord y t = 5 t The 15 indicates that the airfoil has a 15% thickness to chord length ratio: it is 15% as thick as it is long.Įquation for a symmetrical 4-digit NACA airfoil The NACA 0015 airfoil is symmetrical, the 00 indicating that it has no camber.
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