As a pet project I'd like to make a small windmill. I'm in the very beginning stages so I'm still researching components to use and have a lot of questions so I came here to start my journey. I was thinking of using a brushless motor (as small as possible) without the control circuitry, and connect the windmill blades to the shaft. Let's say I expect 50-200 CFM of airflow, and I just want to output as much power output as I can. First, are there small brushless motors with a high enough efficiency to produce a considerable amount of voltage say 5, or even 12V, also is there a rule of thumb regarding current output for different sized motors? Also again, when looking for brushless motors without the extra circuitry inside what applications should I look for, brushless motors for RC drones, or planes?
Now let's say I found the perfect motor for my needs and I am doing the calculations for the EMF and the terminal voltage, do I need knowledge of how large my load is? if not how would I calculate the terminal voltage, because I though the formula was V = emf - (load current * armature resistance). and emf = number of poles * rotation speed * magnetic field strength * number of conductors / number of return paths. If there's a certain amount of torque required to move the shaft is that information available on the the device datasheet? will it have a noticeable effect on the output voltage? is the only to know for me to make a test jig and run some experiments?
Thanks for all the help, sorry if this is a noob post.