Airfoil Data
HQ2590SM

The HQ 2.5/9.0 smoothed by Eppler is a thin 6.8% chord-thickness airfoil with a maximum camber of 3.4% at 35% 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 -3.4°.

Thin airfoil theory predicts a stall angle near 11.9° and a peak lift-to-drag ratio around 55 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 HQ2590SM typically compare it against profiles of similar thickness: HQ 2.5/9 B AIRFOIL, MH 121 8.76%, GOE 6K AIRFOIL, GOE 566 AIRFOIL, KC-135 BL200.76 AIRFOIL. The CAL2263m is another reference profile frequently considered alongside it.