c hinds wrote

How are they decoded? The aircraft I am constructing has the NACA
Airfoil number of 65(3)518-A7

6 is the series number (near-laminar, low drag), the first 5 is the
location of minimum pressure (50% chord), the second 5 is the
design lift coefficient x 10 (0.5) 18 is the thickness (% chord).
The subscript 3 means it's near-laminar (or low-drag) within
+/- 0.3 CL of the design CL, or at lift coefficients from
0.2 to 0.8. The a-number (should be less than 1) is the
chordwise percentage of the airfoil that has a uniform pressure
distribution, in this case (probably) 70%.

Clear as mud.

Dave 'keep it clean' Hyde