Propeller length/rpm to lift weight ratio.

[Mr. Ninja]

Hi,

I am in the design process of a quadrotor helicoptor (might not get past that, lol) and I was wondering, how do you calculate the lift power of a propeller (four blades) at x diameter and x rpm?

I'm looking at a weight of 25-30 pounds, with an optimum lifting power of 35-40 to overengineer and allow for gaining height (it's a big 'un), and would need to know this to know the sizing of the rotors.

Thanks,
Mr. Ninja

[waltr]

Try googling "propeller thrust"