Airfoil Data
FX78K140

The FX 78-K-140/20 is a 11.4% chord-thickness airfoil with a maximum camber of 5.7% at 43% 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 -5.7°.

Thin airfoil theory predicts a stall angle near 11.6° and a peak lift-to-drag ratio around 67 at typical UAV and light-aircraft Reynolds numbers — useful benchmarks before running a full XFOIL or NeuralFoil polar. The 11% thickness provides structural depth for main-spar placement without excessive drag penalty at moderate speeds.

Designers evaluating the FX78K140 typically compare it against profiles of similar thickness: FX 78-K-140 A/20, NASA NLF(1)-0215F, EPPLER 49 AIRFOIL, GOE 549 AIRFOIL, GOE 758 AIRFOIL. The FX 78-K-161 is another reference profile frequently considered alongside it.