What size DC motor do i need to generate 12v 10amps

Any DC motor will produce electricity when it's turned. The trick to producing a specific voltage is in turning the motor at the correct speed. if you can't turn the motor at a consistent speed, you need a voltage regulator. A motor that's made to run on 12vdc at a given rpm will produce roughly 12vdc when turned at that speed. The same with amps; a motor rated for say 10 amps can give 10 amps when turned at the right speed. With a wind turbine the speed is unpredictable, so you'll need to take the extremes into account. Think of the worst case scenario and design from there. If you think a 60mph wind is the strongest your turbine is likely to encounter, design your turbine for an 80mph wind. You'll have to do trial and error to find out how fast your turbine will spin, then get a motor that when spun at that speed will not burn up, or gear it down so that it won't spin too fast. When you gear your motor in it will add resistance and slow down your blades, then when you add electrical load (the compressor), it will add even more resistance. Your blades may not turn at all! if you can find an old treadmill somewhere, the motors in those are very often 120vdc. They have to spin pretty fast to get to 120vdc, so your safe. You only have to spin it at a fraction of it's rated rpm to get your 12vdc. If you don't want to buy a voltage regulator you can use one or more 12v batteries as a kind of regulator. The motor charges the batteries, the batteries provide a steady 12vdc. I could go on and on, but I'll let you have some of the fun. Be prepared for a lot of research and a lot of disappointment. At the end of it all you'll be glad you did it!

Not unless it has a pm field

Yes, it must be a permanent magnet motor. Check this by placing a piece of steel near the motor housing.

Thanks Tom. However I do vaguely remember a kind where only a very small residual field is needed, building up of course with rotation. Technically it's still a pm, and I'd look it up if Mac/Apple would restore access to my Little Bookmark Box