"Cooling Fan Manufacturer" number of blades: Curved variety of fan blades, the same inclination, etc., each fan blade width often depends on the height of the blade pitch in order to ensure not too large, the impact of wind pressure, relatively high diameter. small (i.e., relatively thin) to use more of the fan blades to increase the number of methods to make up. The number of blades is whether much or little, the number of vanes "Cooling Fan Manufacturer" etc. but often 3,5,7,11 odd, this is due to the If using an even slice shape symmetrical blades, but did not adjust the balance, it is easy to make the system resonance, if the blade material is unable to resist vibration fatigue, will make the blades or spindle breakage, so much designed for on-axis odd asymmetry heart piece "Cooling Fan Manufacturer" blade design. This principle is commonly used including some helicopter propeller blades including a variety of designs.