On Jul 21, 11:00*pm, dpb wrote:
On 7/21/2011 1:29 PM, wrote:
...

If you look at the old stereotypical "prairie" style windmills, that's
how they are. A disk with pie-shaped blades angled at 45 degrees,
facing directly into the wind with the help of a fin.

...

None I've seen were actually flat, though. *All ours had a curve built
into the blades; steeper front attack angle than rear. *Dated from
roughly 1910 on thru the 20's...

The old Delco Windcharger (mid-1910s when ours installed; not sure when
they were actually introduced) did have a three-bladed hub; not quite so
aerodynamic as current but certainly reminiscent.

--

The multi-bladed windmills were designed to develope a high torque at
low speed, most were for pumping water. Avoided the need for a
gearbox.

Electricity production is an entirely different matter.