Airfoil Data
SP4621HP

The SP4621HP is a 13.6% chord-thickness airfoil with a maximum camber of 6.8% at 38% 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 -6.8°.

Thin airfoil theory predicts a stall angle near 11.0° and a peak lift-to-drag ratio around 71 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 SP4621HP typically compare it against profiles of similar thickness: AH 93-W-215, E591, SP4721LA, FX 73-CL2-152, GOE 288 AIRFOIL. The GOE 617 AIRFOIL is another reference profile frequently considered alongside it.