Airfoil Data
E636

The EPPLER 636 AIRFOIL is a 9.1% chord-thickness airfoil with a maximum camber of 4.5% at 27% 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 -4.5°.

Thin airfoil theory predicts a stall angle near 11.7° and a peak lift-to-drag ratio around 61 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 E636 typically compare it against profiles of similar thickness: BOEING 737 ROOT AIRFOIL, MH 201 13.08%, NACA 66,2-(1.8)15.5 A=.6 P-51 ROOT AIRFOIL, NACA 23015, Gottingen 765 airfoil (recovered). Thick: .144 LE radius: 0.02062 LE slope: 0.17300. The AS6093 | Ananda-Selig | AIAA Paper 2018-0310 is another reference profile frequently considered alongside it.