Hello to all, new member here, stand back! I've built a few prototype vertical axis wind turbines and have been on a major learning curve trying to find the best pma( permanent magnet alternator) to match my mill. At first the reasoning seemed simple. Find a pma and adapt the mill to drive it at the desired rpm. 80 watts later my belts are squealing and pma won't turn any faster. At a ratio of 1:9 I believe I've spent all available torque. So my thoughts are now directed at a low speed pma. My mill is exposed to roughly 6000w of wind energy, keeping betz in mind, I factor that my mill is 10% efficient leaving me with about 600 watts of extracted energy. Heres where I struggle, the low speed pma requires 554nm at 2500watts. I'm sure i won't be producing this much torque but i know my mill is quite strong. Is there a formula or a way to calculate torque with only primative information? Does my reasoning toward this matter seem adequate? Can anyone give me their insights on this matter?