# How can I calculate the power required to make an air turbine spin at a constant rpm?

Say I have an air turbine with diameter $$d$$, number of blades $$N$$, and moment of inertia $$\frac {d^{2}*M_{Blade}^{**1}}{4}$$ (at the tip of the blade). How do I calculate the power required to spin this turbine at a constant $$RPM$$, ignoring all the dissipative forces, except for the air drag on the blades$$^{**1}$$?

$$^{**1}$$: $$M_{total} = M_{Blade}+M_{Air}$$