Airfoil Data
E420

The EPPLER 420 AIRFOIL is a thick 17.4% chord-thickness airfoil with a maximum camber of 8.7% at 36% 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 -8.7°.

Thin airfoil theory predicts a stall angle near 9.7° and a peak lift-to-drag ratio around 75 at typical UAV and light-aircraft Reynolds numbers — useful benchmarks before running a full XFOIL or NeuralFoil polar. The 17% thickness provides structural depth for main-spar placement without excessive drag penalty at moderate speeds.

Designers evaluating the E420 typically compare it against profiles of similar thickness: WORTMANN FX 77-W-258 AIRFOIL, GOE 244 (MVA PR.4) AIRFOIL, N-24, GOE 421 AIRFOIL, GOE 572 AIRFOIL. The RUTAN WING AIRFOIL is another reference profile frequently considered alongside it.