Question: Curve fitting

Geetings!

I try to fit curve through set of points that I read  from a graph. Then use equation of this curve to define a function function. Only bspline approximation gave acceptable result. But how can I use it in defining a function?

XvalsCf := [0, 5, 10, 25, 50, 100, 140, 200, 250, 300, 400]

valsCf := [0.5e-2, 0.4e-2, 0.3e-2, 0.26e-2, 0.23e-2, 0.21e-2, 0.2e-2, 0.19e-2, 0.18e-2, 0.175e-2, 0.15e-2]

Another issue is in "surface fitting". Graph shows propeller efficiency curves. I'd like to get equation of surface spread on those curves.  Axis x is an angle, axis y V/nD and z is efficiency.

Again using spline/bspline approximation is nesssary to get accurate results.

I will use this efficiecny surface function equation in drive optimization .

Is creation of such surface/function  possible in maple.

Thank you in addvance for your help.

Smagliczka