NACA Airfoil - Five-digit Series

Five-digit Series

The NACA five-digit series describes more complex airfoil shapes:

  1. The first digit, when multiplied by 0.15, gives the designed coefficient of lift (CL).
  2. Second and third digits, when divided by 2, give, the distance of maximum camber from the leading edge (as per cent of chord).
  3. Fourth and fifth digits give the maximum thickness of the airfoil (as per cent of the chord).

For example, the NACA 12018 airfoil would give an airfoil with maximum thickness of 18% chord, maximum camber located at 10% chord, with a design lift coefficient of 0.15

The camber-line is defined in two sections:

y_c = \begin{cases}\frac{k_1}{6}\left\{x^3-3mx^2+m^2(3-m)x\right\}, & 0<x<p \\ \frac{k_1 m^3}{6}(1-x), & p<x<1\end{cases}

where the chordwise location and the ordinate have been normalized by the chord. The constant is chosen so that the maximum camber occurs at ; for example, for the 230 camber-line, and . Finally, constant is determined to give the desired lift coefficient; for camber-line 230 again, is used.

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