Airfoil Data
E540

The EPPLER 540 AIRFOIL is a 10.0% chord-thickness airfoil with a maximum camber of 5.0% at 40% 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 -5.0°.

Thin airfoil theory predicts a stall angle near 11.7° and a peak lift-to-drag ratio around 63 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 E540 typically compare it against profiles of similar thickness: S2027, NACA 747A315, AS6098 | Ananda-Selig | AIAA Paper 2018-0310, NASA/LANGLEY MS(1)-0317 AIRFOIL, Prandtl-D Centerline NASA TP-2016-219072. The Legionair 140 (digitized and smoothed by MSelig) is another reference profile frequently considered alongside it.