NACA airfoils have many variations (or series), like 4 digit airfoil, 5 digit airfoil, 6 digit airfoil, and so on. In this post I will explain it to you what a NACA 4 digit series is.
4 digit airfoils have 4 digits after NACA in the form of NACA [m][p][tt]. The 4 digit NACA airfoils are defined by 3 criteria: m, p, tt. They stand for:
m: Maximum camber in %
p: Position of maximum camber of the chord line, in tenth
tt: Maximum thickness in %
The examples of 4 digits are NACA0412, NACA2315, and many more.
NACA 0412 means its maximum camber is 0%, location of maximum camber is at 0.4 of the chord line from the leading edge, and the maximum thickness is 12%.
NACA 2315 means maximum camber of 2%, location of maximum camber is 0.3, and the maximum thickness is 15%.