Airfoil Data
HQ3518

The HQ 3.5/18 AIRFOIL is a 12.4% chord-thickness airfoil with a maximum camber of 6.2% at 35% chord, suited to high-lift UAV wings, RC sailplanes, and low-Reynolds-number slow-flyers. At zero angle of attack the cambered geometry generates positive lift, giving an estimated zero-lift angle of -6.2°.

Thin airfoil theory predicts a stall angle near 11.5° and a peak lift-to-drag ratio around 69 at typical UAV and light-aircraft Reynolds numbers — useful benchmarks before running a full XFOIL or NeuralFoil polar. The 12% thickness provides structural depth for main-spar placement without excessive drag penalty at moderate speeds.

Designers evaluating the HQ3518 typically compare it against profiles of similar thickness: CLARK YM-18 AIRFOIL, GOE 320 (HANSA-BRANDENBURG II.1) AIRFOIL, DAI 1336, GOE 413 AIRFOIL, NACA 2421. The EPPLER 543 AIRFOIL is another reference profile frequently considered alongside it.