Airfoil Data
E431

The EPPLER 431 AIRFOIL is a 11.8% chord-thickness airfoil with a maximum camber of 5.9% at 42% 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 -5.9°.

Thin airfoil theory predicts a stall angle near 11.6° and a peak lift-to-drag ratio around 68 at typical UAV and light-aircraft Reynolds numbers — useful benchmarks before running a full XFOIL or NeuralFoil polar. The 12% thickness provides structural depth for main-spar placement without excessive drag penalty at moderate speeds.

Designers evaluating the E431 typically compare it against profiles of similar thickness: GOE 414 AIRFOIL, EPPLER 344 AIRFOIL, DU 80-176 V1, AH 83-159, FX 78-PK-188/20. The GOE 239 (MVA H.31) AIRFOIL is another reference profile frequently considered alongside it.