中国科技馆三层“科技与生活”展厅“交通之便”展区有一件好玩的展品,名字叫做螺旋推进器。仔细观察,它的主体像一个自行车,但是又没有轮子,车身是悬空的,仅仅靠一根很粗的铁杆连接在中间的轴上。奇怪的是,它的尾部还带着一个大风扇,这是干什么用的呢?难道是给骑自行车的小朋友降温?可是没有轮子,这个自行车又怎么能往前走呢? China Science and Technology Museum on the third floor “technology and life ” exhibition hall “traffic will ” area has a fun exhibits, called spiral propeller. Closer to observe, its main body is like a bicycle, but without wheels, the body is vacant and connected to the central shaft by a very thick iron. Curiously, it has a big fan at the tail, what is the use of this? Is it to cool children who ride bicycles? But without a wheel, how can the bicycle go forward?