Airfoil Data
E817

The EPPLER 817 HYDROFOIL AIRFOIL is a thin 7.3% chord-thickness airfoil with a maximum camber of 3.7% at 47% chord, suited to high-speed UAVs, sailplane tip sections, and propeller blade design. At zero angle of attack the cambered geometry generates positive lift, giving an estimated zero-lift angle of -3.7°.

Thin airfoil theory predicts a stall angle near 11.8° and a peak lift-to-drag ratio around 56 at typical UAV and light-aircraft Reynolds numbers — useful benchmarks before running a full XFOIL or NeuralFoil polar. The slim profile minimises pressure drag at higher speeds but leaves limited spar depth for structural integration.

Designers evaluating the E817 typically compare it against profiles of similar thickness: NASA/LANGLEY RC-12(N)1 AIRFOIL, S4094 (root airfoil designed for and used on the E-flite UMX ASK-21 scale RC sailplane), NACA 66,2-(1.8)12 A=.6 P-51 TIP AIRFOIL, LOCKHEED C-141 BL113.6 AIRFOIL, GOE 417A (GEW. PLATTE) AIRFOIL. The FX 76-MP-160 is another reference profile frequently considered alongside it.