Airfoil Data
FX77W121

The FX 77-W-121 is a 10.7% chord-thickness airfoil with a maximum camber of 5.3% at 31% 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 -5.3°.

Thin airfoil theory predicts a stall angle near 11.7° and a peak lift-to-drag ratio around 65 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 FX77W121 typically compare it against profiles of similar thickness: EPPLER 547 AIRFOIL, EPPLER 682 AIRFOIL, MH 82 13.31%, EPPLER 562 AIRFOIL, EPPLER 557 AIRFOIL. The FX 77-W-270 is another reference profile frequently considered alongside it.