Airfoil Data
NACA664221

The NACA 66(4)-221 is a 11.6% chord-thickness airfoil with a maximum camber of 5.8% at 45% chord, suited to general-aviation and UAV wing design. At zero angle of attack the cambered geometry generates positive lift, giving an estimated zero-lift angle of -5.8°.

Thin airfoil theory predicts a stall angle near 11.6° and a peak lift-to-drag ratio around 68 at typical UAV and light-aircraft Reynolds numbers — useful benchmarks before running a full XFOIL or NeuralFoil polar. The 12% thickness provides structural depth for main-spar placement without excessive drag penalty at moderate speeds.

Designers evaluating the NACA664221 typically compare it against profiles of similar thickness: EPPLER 397 AIRFOIL, GOE 534 AIRFOIL, GOE 412 AIRFOIL, EPPLER 585 AIRFOIL, MILEY M06-13-128. The NACA 63,3-418 is another reference profile frequently considered alongside it.