vertical-hub_airscrews

A typical wind-power plant consists of many (even hundreds) of towers, each topped with a waht is essentially a classical windmill design: a horizontal axle points the mill so as to be perpendicular to the airflow. Another way of doing the same job, is as follows: Imagine three wheel-spokes joined at 120 degrees angle. Now extrude them so as to make a solid of 3-spoke cross-section. Next, imagine that the extuded shape is rotated on it's 'axle' as it extrudes - the result is like a barleycorn (if you know what I mean) or maybe somewhat resembling a DNA helix. Now, if you're still with me, this twisted extrusion is sculpted so as to fit inside a cone. Only about 270 degrees-of-twist of the extrusion are used in the cone. What we have now ought to resemble something you might get if you sanded the outside off a snailshell. This shape can be mounted vertically and be rotated by wind from any direction. I remember seeing similar shapes in old petrol-pumps with machanical metering of petrol flow, in a little translucent bubble stuck onto the delivery tube. The 'rotor', being of fairly compact shape, as opposed to the long-bladed windmill airscrews, can be made of any sturdy composite material, and therefore have a low radar-profile (air defences often object to wind-power). Whereas normal windmills use sophisticated gearing and blade-feathering to vary power delivered, this rotor can vary it's cross-section by lowering itself into a recess to reduce the power it takes. (in very stormy conditions, normal blades risk being destroyed unless they can carefully reduce thier profile to absolute minimum). These rotors would also need less altitude and would interfere less with birds and planes; They could also be built nmuch larger than windmills can today (eg. radii of 100m versus 25m).