21.   A scramjet engine only works when air flows through it at supersonic speeds.

22.   In order to understand what charging is, you first have to know a bit about how an internal combustion engine works.

23.   One of the pilots noticed the engine was not working and the aircraft made an emergecy landing.

24.   The engines worked as designated.

25.   Using liquid hydrogen and liquid oxygen, cryogenic engines work at extremely low temperatures.