Power calculations for Hovering

[rosshalz]

Hi,

I have a very basic question. Theoretically,I need to make a load hover (in real terms I'm makin a heli).

I wanted to do the calculations for how much power is needed by the prime mover (engine/motor doesn matter) to hover. i.e to give thrust(T) = weight of (load+Motor).
Can someone please tell me this equation that relates Power(P) and Thrust(T) at zero velocity i.e hovering.

Dont worry about prop diameter/aerodynamic characteristics etc at this moment. I'm just looking for the minimum power of the prime mover(energy source) to give me the ability to hover a certain weight

Thanks!

 

[Lsos]

Unfortunately it's not that simple.

The formula for power is quite simple: Force x Velocity. So the quick answer to your question is that no matter how much your load weighs, the minimum power required is "0", since your velocity is zero. If you think about it, this is precisely true...after all, how much power does it take for the ground to hold up a mountain?

Obviously this isn't the answer you're looking for. A helicopter is not supported by the ground, but by the air. It does this by accelerating a mass of air down, with the reaction keeping it up. The greater this mass of air that is accelerated the closer you can get to the theoretical "0" requirement. Essentially this means that the larger your propeller diameter, the less power you need.