Airfoil Data
CAP21C

The CAP 21 (TraCFoil) is a 8.3% chord-thickness airfoil with a maximum camber of 4.2% at 16% chord, suited to general-aviation and UAV wing design. At zero angle of attack the cambered geometry generates positive lift, giving an estimated zero-lift angle of -4.2°.

Thin airfoil theory predicts a stall angle near 11.8° and a peak lift-to-drag ratio around 59 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 CAP21C typically compare it against profiles of similar thickness: GOE 115 (MVA MK.2) AIRFOIL, GOE 362 AIRFOIL, RAF 34 AIRFOIL, GOE 369 AIRFOIL, Falcon. The Eiffel 430 (Lachassgne) is another reference profile frequently considered alongside it.