Guarantee "Micro Cooling Fan" blade pitch will not be too large, the impact of wind pressure, high diameter is relatively small (ie, relatively thin) fan blades increase the number of multi-use method to make up for. No matter how much or little the number of blades, axial fan number of blades is often the 3,5,7,11 and so odd, this is due to the use of a symmetrically shaped blades even-numbered sheet, and no adjustment is good balance, it is easy to make the resonance system, if the "Micro Cooling Fan" Blade Material and Unable to resist vibration fatigue, will make the blades or spindle breakage, so much designed as an odd piece about the axis of asymmetric fan designs. This principle is commonly used include the various parts of the helicopter propeller blades including . Design fan blade spacing: the distance between the blades is too small, will result in flow disturbances, increasing the friction surface of the blade, reduce "Micro Cooling Fan" efficiency; distance between the blades is too large, it will lead to increase in pressure loss, the wind insufficient pressure.