Closed 3D curve

Hello all,

I want to design an airfoil using 3D curve in CATIA and I need to use "Control points" as the creation option. The airfoil has a sharp end. I tried to draw this foil with a single 3D curve, but it does not allow me to close the end. Knowing these three constraints:
1. the foil is sharp edged
2. using just one single 3D curve
3. implementation of "Control points" as the Creation type
is there any way that I can do that?

Thank you.