Windmill sails Vane - Any of several usually relatively thin, rigid, flat, or sometimes curved surfaces radially mounted along an axis, as a blade in a turbine or a sail on a windmill, that is turned by or used to turn a fluid.
It's called "blade" or a "sail".
vane - Any of several usually relatively thin, rigid, flat, or sometimes curved surfaces radially mounted along an axis, as a blade in a turbine or a sail on a windmill, that is turned by or used to turn a fluid.
I don't think there is another name other than blade.
airplane shape flat on one side round on the other at 5 deg angle
it is the square blade
It can vary, but they can be very big!
flat
vane
J.S Risdon inventeed it and in December 1872
22/3
Technically, it is. Each blade is a lever, with the axle being the fulcrum of each lever.