The thickness distribution is given by the following equation ahead of the maximum thickness:

y = A_{0} sqrt(x) + A_{1} x + A_{2} x**2 +
A_{3} x**3

where ** denotes exponentiation, (t/c) is the maximum thickness to chord ratio of the airfoil, x is the position as fraction of chord, and y is the half-thickness as fraction of chord.

and by the following equation from maximum thickness to trailing edge:

y = D_{0} + D_{1}(1-x) + D_{2} (1-x)**2 +
D_{3} (1-x)**3

The constants
A_{0}, A_{1}, A_{2}, A_{3},
D_{0}, D_{1}, D_{2}, D_{3}
are calculated from the values of maximum thickness, position of maximum thickness, and
leading edge radius that are specified by the user.

The airfoil must satisfy the following constraints:

- y = one half the maximum thickness when x/c = m, the specified location of maximum thickness (as fraction of chord).
- The leading edge radius = 1.1019/36.0*((t/c)*leIndex))**2 [ see p.117 in Abbott & von Doenhoff]
- The first and second derivatives of the forward function and the aft function match exactly at the point of maximum thickness.
- The coefficient D
_{1}is given by the following table:

m | D_{1} |

0.2 | 1.000 t |

0.3 | 1.170 t |

0.4 | 1.575 t |

0.5 | 2.325 t |

0.6 | 3.500 t |

D_{1} is the negative of the trailing edge slope.

These conditions are sufficient to determine all of the A and D terms in the polynomial equations.