Airfoil Data
M665

The M6 (65%) is a thin 5.3% chord-thickness airfoil with a maximum camber of 2.7% at 30% 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 -2.7°.

Thin airfoil theory predicts a stall angle near 11.9° and a peak lift-to-drag ratio around 50 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 M665 typically compare it against profiles of similar thickness: GIII BL207 AIRFOIL, NACA M4 AIRFOIL, USA 49 AIRFOIL, BOEING-VERTOL VR-8 AIRFOIL WITH TAB, BOEING-VERTOL VR-8 AIRFOIL. The NACA 63(2)-615 is another reference profile frequently considered alongside it.