Airfoil Data
E851

The EPPLER E851 AIRFOIL is a thin 6.2% chord-thickness airfoil with a maximum camber of 3.1% 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 -3.1°.

Thin airfoil theory predicts a stall angle near 11.9° and a peak lift-to-drag ratio around 53 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 E851 typically compare it against profiles of similar thickness: S6061 9%, AG24 Bubble Dancer DLG by Mark Drela | The AG2x airfoils are intended to be used on composite versions of the Bubble Dancer and the Allegro-Lite., MH 62 9.3%, GIII BL450 AIRFOIL, E168 (12.45%). The GOE 600 AIRFOIL is another reference profile frequently considered alongside it.