Prior to this, airfoil shapes were first created and then had their characteristics measured in a wind tunnel. A new approach to airfoil design pioneered in the s, in which the airfoil shape was mathematically derived from the desired lift characteristics. In addition, for a more precise description of the airfoil all numbers can be presented as decimals. Four- and five-digit series airfoils can be modified with a two-digit code preceded by a hyphen in the following sequence. This results in a theoretical pitching moment of 0. For example, the NACA profile describes an airfoil with design lift coefficient of 0.Ĭamber lines such as makes the negative trailing edge camber of the series profile to be positively cambered. The NACA five-digit series describes more complex airfoil shapes. įor this cambered airfoil, because the thickness needs to be applied perpendicular to the camber line, the coordinates. 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. The leading edge approximates a cylinder with a radius of. 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. The formula for the shape of a NACA 00xx foil, with "x" being replaced by the percentage of thickness to chord, is. The NACA airfoil is symmetrical, the 00 indicating that it has no camber. The parameters in the numerical code can be entered into equations to precisely generate the cross-section of the airfoil and calculate its properties.
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