Airfoil Data
E664

The EPPLER 664 AIRFOIL is a 11.1% chord-thickness airfoil with a maximum camber of 5.5% at 41% 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 -5.5°.

Thin airfoil theory predicts a stall angle near 11.6° and a peak lift-to-drag ratio around 66 at typical UAV and light-aircraft Reynolds numbers — useful benchmarks before running a full XFOIL or NeuralFoil polar. The 11% thickness provides structural depth for main-spar placement without excessive drag penalty at moderate speeds.

Designers evaluating the E664 typically compare it against profiles of similar thickness: EPPLER 664 (EXTENDED) AIRFOIL, FX 60-177 AIRFOIL, FX 83-W-160, NACA 63,3-418, SM701. The AH 88-K-136/16 is another reference profile frequently considered alongside it.