Airfoil Data
NACA4421

The NACA 4421 is a 14.3% chord-thickness airfoil with a maximum camber of 7.1% at 30% 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 -7.1°.

Thin airfoil theory predicts a stall angle near 10.8° and a peak lift-to-drag ratio around 72 at typical UAV and light-aircraft Reynolds numbers — useful benchmarks before running a full XFOIL or NeuralFoil polar. The 14% thickness provides structural depth for main-spar placement without excessive drag penalty at moderate speeds.

Designers evaluating the NACA4421 typically compare it against profiles of similar thickness: GOE 604 AIRFOIL, Glenn Martin 2, GOE 620 AIRFOIL, NACA M27 AIRFOIL, FX 73-170 A. The NACA 4412 is another reference profile frequently considered alongside it.