Many sites describe their windmills in terms of wind speed, minimum or max etc. Can anyone share with me how much force in terms of how much torque or kg force is needed to get it rotating? Is there any conversion formula to it? I'm sure different size of generator would require different force and at different force will give a different rpm. Anywhere to find this information? Assume a very small unit like 600W generator or maybe a better one at 2KW. What would be the force needed and what rpm would it go at?