# AF30-X Engine Cooling Fan

There is always a buzz in the engineering office when we are asked to work on a large diameter fan project, whether this is with or without a fan clutch. Going back to our fan fundamentals is always a real joy.

Power is proportional to the cube of the shaft speed:

MathJax example

${P1 \over P2} = ({N1 \over N2})^3$

Fixed Diameter fan (D)
P is the shaft power (kW)
N is the rotational speed (rpm)