Calculating Torque for Fan Speed

[violin_writer]

Hello, I need figure out the torque is required to spin a fan blade at a certain speed. I know it doesn't particularly matter how big the fan is, but how heavy it is. I know a 1gm fan is much easier to turn than a 2gm fan.

Can anyone help me?

 

[brewnog]

At a constant speed, it's not the weight that matters, it's the size of the fan (well, its design).

Get a fan curve from the manufacturer, this shows you the power required to drive the fan at a range of speeds.

 

[russ_watters]

...and the speed of the fan doesn't actually have a direct impact, it's the operating conditions: the pressure and airflow.

 

[nucleus]

There are three Fan Laws or Affinity Laws that may help you get started:
http://www.nrmurphy.com/fans_laws.html