Airfoil Data
AH21-7

The AH21 7% version (Andrew Hollom) is a thin 6.6% chord-thickness airfoil with a maximum camber of 3.3% at 40% 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 -3.3°.

Thin airfoil theory predicts a stall angle near 11.9° and a peak lift-to-drag ratio around 54 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 AH21-7 typically compare it against profiles of similar thickness: NPL 9660 AIRFOIL, NPL 9615 AIRFOIL, EPPLER 818 HYDROFOIL AIRFOIL, GOE 563 AIRFOIL, RG 14 10% AIRFOIL. The HQ 0/7 AIRFOIL is another reference profile frequently considered alongside it.