Aircraft that achieve forward propulsion by expelling a stream of fluid are called what?

Aircraft that achieve forward propulsion by expelling a stream of fluid are called jet engines. Jet engines are a type of internal combustion engine that uses the expansion of hot gases to create thrust. Jet engines are used in aircraft, missiles, and other vehicles. There are two main types of jet engines: turbojets and turbofans. Turbojets are the simplest type of jet engine and they use a single spool to compress and expand the air. Turbofans are more complex and they use two spools to compress and expand the air. This allows turbofans to produce more thrust and be more efficient than turbojets.