A smaller Windmill that I bought

This windmill worked, but it was very noisy when in stronger winds.  At times it would sound like an airplane prop.  The neighbors had mentioned this to me several times, so I took it down.  My larger windmill does not make noise like this due to the slower RPM the blades are doing.

I can see why they say never to mount these smaller units to a house, it would just amplify the noise even more if you had it bolted to a stud, or a wall for a house.  These smaller units have their place, if you have a location that noise is never an issue, then they would be a great way to cheaply put yourself into wind power.