Airfoil Data
E678

The EPPLER 678 AIRFOIL is a 12.6% chord-thickness airfoil with a maximum camber of 6.3% at 44% 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 -6.3°.

Thin airfoil theory predicts a stall angle near 11.4° 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 E678 typically compare it against profiles of similar thickness: EPPLER 655 AIRFOIL, AH 93-W-174, GOE 256 (JUNKERS E) AIRFOIL, ONERA HOR20 AIRFOIL, NACA 65(4)-421. The BOEING 737 MIDSPAN AIRFOIL is another reference profile frequently considered alongside it.