同学们,你知道空气也能构成墙壁吗?你听了也许会感到相当奇怪;然而事实确是如此,空气墙有时还会把一架坚固的飞机撞得粉身碎骨哩!这究竟是怎么一回事呢?事情是这样的:早期的飞机都是用螺旋桨作推进器的,这种飞机可以达到每小时七百多公里的速度,比汽车要快得多。可是人们还不满足:“声音一小时就可以“跑”1200公里,飞机能不能追上声音呢?”为了达到这一目的,人们设计了一种新式的飞机,这种飞机不用螺旋桨推进,而是靠向后喷射大量高压气体产生的反冲力向前飞 Students, do you know that the air can also form a wall? You may feel very strange when you listen to it; but it is true that the air wall sometimes hits a sturdy plane and it’s completely crushed! What is this all about? What happened like this: Early aircraft used propellers as propellers. Such aircraft could reach speeds of over 700 kilometers per hour, much faster than cars. However, people are not satisfied: “A sound can run for 1,200 kilometers an hour. Can the aircraft catch up with the sound?” To achieve this goal, people have designed a new type of aircraft that does not use propellers. It is to fly forward by jetting backwards with a large amount of high-pressure gas.