wind generator blade speed
Okay. now I have a grasp on my amp (or should I say watt) draw. I now need to figure how to make this wind turbine produce what I need.
I've bought a small 200 VDC motor to build my first turbine from. This is just my 1st hobby wind generator to see if I can & how well. Probably the wrong one, but it's cheap enough and sure I'll use it for something in the future.
400 rpm seems really fast to generate 12v! So that's my first question... is it?
To achieve this speed , in my area (Class 2) I can expect 4 hrs a day wind of only 3-7 mph (trying to stay very modest), so I assume I need multiple blades and gearing.
2nd question; How do I determine how many blades, of what size I should make to obtain a certain rpm in a particular wind speed?
Not sure I asked that correctly, so please bear with me.
Once I have this generator in hand I will be able to measure the torque needed to turn it. Then I assume I need to determine a blade size and count to meet this need. If that is still not enough, I assume I will then need to gear it and re-calculate the blades.
Anyone out there have the math to figure this?