Airfoil Data
S1091

The S1091 is a thin 7.8% chord-thickness airfoil with a maximum camber of 3.9% at 38% chord, suited to high-speed UAVs, sailplane tip sections, and propeller blade design. At zero angle of attack the cambered geometry generates positive lift, giving an estimated zero-lift angle of -3.9°.

Thin airfoil theory predicts a stall angle near 11.8° and a peak lift-to-drag ratio around 57 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 S1091 typically compare it against profiles of similar thickness: GOE 415 AIRFOIL, EPPLER 325 AIRFOIL, Bergey BW-3 (smoothed), FX 60-100 (126) AIRFOIL, MARSKE PIONEER IID TIP AIRFOIL (NACA 431012A*.833 HYBRID). The WORTMANN FX 05-188 AIRFOIL is another reference profile frequently considered alongside it.