WOW - From ANCIENT Tunisia (3000 BC - 900 AD) - The Future Of Wind Power?

[muriel_volestrangler]

29. No, the analogy to a bridge rectifier is unfounded

In that, an EMF reverses direction, and diodes allow an alternate path for current to flow, so that the output still has the same direction of current as before. But the force due to the wind does not reverse. When a force is in the same direction as a part moves, you can extract energy from it (eg with a piston). But when the force is in the opposite direction to the movement, you need another force to oppose the wind force. Just think of it as a weight moving up and down - the force of gravity is constantly down, and you can extract energy as the weight moves down, but you can't extract energy again as the weight moves up.

To be like a rectifier, you'd need valves to reverse the flow of air over the sail. You could do that, in a tunnel, but it's not what this is doing.

What objects were you playing with? Did they have a flexible stem, for instance? Or are you saying the wind sucked the cup back, against the flow of the wind - and, if so, why does it suck when the object is moving in one direction, and blow when it's moving in the other?