Build a Helicopter. Lift, and hp?

Helicopter propellers are usually called rotors and 4 has some maintenance reducing advantages. What does 27 x10 mean? A smaller rotor diameter can safely run at 9000 rpm, but the tips should move less than about 600 miles per hour to avoid breaking the sound barrier. If these are inexpensive 9.6 hp motors, they likely will not be able lift their own weight. One man helicopter use several hundred hp, I think. Neil