Kristie
there is a world of difference between an airplane prop, helicopter rotor, ship screw and a rotor made to extract power from the wind.
the rotor made for extracting power from the wind relates better to an airplane wing rather than the other examples that are optimized to deliver power to the wind/air.
the reason you don't see many multiblade rotors on windmachines is because each blade leaves turbulence behind it for the next blade to deal with. turbulence equates to lost lift, loss of lift relates to reduced power.
the best design in theory therefore is a single blade rotor, however from a practical standpoint the counterweight needed is problematic.
the next best is the double blade rotor, the problem with it is vibration and gyroscopic issues as the rotor changes with wind direction and issues with tower shading.
that is why the next best is the three blade, it doesn't have the shading issues, less vibration, no gyro issues, although it loses a bit to turbulence. it is the best all around compromise.
remember power is made from torque and rpm,
multibladed props make lots of low wind torque, but very low rpm
the issues with turbulence limit their ability to utilize higher winds effectively therefore they cannot spin as fast as a 3blade prop.
the three blade prop, will make very high rpm's relative to the multiblade prop, even though the torque is lower the speed more than makes of for the loss of torque. the end result is higher rpm even with lower torque equates to more shaft horsepower.
this doesn't consider issues with the generator, most of which make more power the faster they can be driven, very low speed generators such as something suitable for a multiblade prop would be very large in order to have the rim speed of the field fast enough to make more power... then you still have the limited amount of power the multiblade prop is able to deliver.
i can't remember for sure, but many of the old water pumpers only made something less than one hp at the shaft at rated windspeed. that is something less than 745 watts max output. then you have to deal with generator efficiency so you would be doing good to get half that "if" and "only if" you either have a very large generator or a gear train to increase the output speed to something useful for a common aircore generator. remember the gear train introduces losses of its own, so maybe you end up with a couple hundred watts output in 8-10mph winds and the machine will not make more power in higher winds, because it is unable to utilize the increased windspeed effectively.
maybe you already know all this? if so maybe it will be useful to someone else.
bob g