This is a remix of https://www.thingiverse.com/thing:4941/files

Tested (n5)it with a mounting angle of 45 deg, 40 is a good value with the tip at 3.

Can add the hub cone to the blade. It is 1/3 of a cone.

Printed and tested the (m7). Looks good.

The tst1 is due to printer size, make a larger hub with short blades. Nearly the same as having longer blades.
The fins on the cone is not a good idea.

For more shape profiles, go to: http://airfoiltools.com/plotter/index

Openscad has a problem with svg files, so I added a python script to convert them.
The blend is combine shape profiles by aligning the points of openscad to use. The calc is
to work out the settings for different conditions.

The blade3 is a blend of two shape profiles.

The blade4 is for a 5 blade turbine. Not so great .

The curve.py is to get blade segments to merge like a curved line.
The curve_blade.scad uses its output. Tested a variation of it and it works great.