false. could be a single blade flapping back and forth horizontally or vertically.
@AshenJewel, there are also bladeless fans now that I have no idea how they work but they do.
@Rowule, Imma let you in on a little secret, most bladeless fans have blades. They're just concealed and air flow deverted.
@AshenJewel, also false is that cooling fans on cars are belt driven by the motor, not electricity
@Rowule, as gallium said, there is a fan and it just diverts the air. There is a horizontal fan at the base of the fan that sucks air in from the bottom and up through the top where the side sits are
@MetalHeadTony, only on cars with inline engines. Transverse engines need electrically powered fans.
@Gallium , but... but... bladeless.