Vertical wind turbines suffer from the problem that their blades cause a huge amount of drag when rotating around into the wind. Today’s invention aims to overcome that.
A (blue) platform carries a fin and is free to rotate into the wind like a weathercock. On this platform stands a vertical cylinder with a semicylindrical blade attached via a springloaded hinge (shown in red).
The wind, blowing from the bottom half of the diagram, rotates the cylinder anticlockwise about its axis on the platform (A). Rollers attached to the platform then close the blade, removing its drag component and compressing the sprung hinge (B).
Inertia carries the cylinder around until the blade is released for another cycle (C). More blades of course would be better.