Airfoil Data
E656

The EPPLER 656 AIRFOIL is a 12.9% chord-thickness airfoil with a maximum camber of 6.4% at 41% chord, suited to high-lift UAV wings, RC sailplanes, and low-Reynolds-number slow-flyers. At zero angle of attack the cambered geometry generates positive lift, giving an estimated zero-lift angle of -6.4°.

Thin airfoil theory predicts a stall angle near 11.3° and a peak lift-to-drag ratio around 70 at typical UAV and light-aircraft Reynolds numbers — useful benchmarks before running a full XFOIL or NeuralFoil polar. The 13% thickness provides structural depth for main-spar placement without excessive drag penalty at moderate speeds.

Designers evaluating the E656 typically compare it against profiles of similar thickness: WORTMANN FX 66-17A-175 AIRFOIL, FX 66-17AII-182 AIRFOIL, FX 66-182 AIRFOIL, EPPLER 1210 AIRFOIL, USA 98 AIRFOIL. The 0.018772 0.005079 is another reference profile frequently considered alongside it.