Airfoil Data
BTE-FK

The BTE-FK is a thin 7.6% chord-thickness airfoil with a maximum camber of 3.8% at 34% 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 -3.8°.

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 BTE-FK typically compare it against profiles of similar thickness: GOE 399 AIRFOIL, NACA 23012 12%, BOEING 737 MIDSPAN AIRFOIL, DFVLR R-4 AIRFOIL, EPPLER 360 AIRFOIL. The NACA 66-209 is another reference profile frequently considered alongside it.