Transcript for the Piece Audio version of jet - word of the day

This is the etymology moment, and I'm Charles Hodgson. Today we'll hear the story behind the word jet.
It was in the 1930s that the idea of a jet engine that could be used on aircraft was finally put into practice. It was 1944 when the word jet was first used to describe an aircraft powered by these things. The idea of how such an engine might work had been around for millennia. A NASA website credits an ancient Egyptian of 150 BC with coming up with the idea of a turbine engine. How it works is that air gets sucked in at the front end and compressed down into a central chamber where fuel is sprayed into the passing breeze and set alight. The resulting explosion is a controlled one but it has the effect of considerably increasing the pressure of the gasses inside the engine at this point. Aside from extracting a little energy to use for sucking in more new air, the rest of the jet engine is dedicated to skillfully directing the flow of exhaust and expanding it so that when it emerges at the back end it is very close to the atmospheric pressure of the air around it. Here the energy that once manifested itself as pressure now manifests itself as speed so that exhaust shoots out of the back of a jet engine like a bat out of hell. A jet engine is literally throwing its exhaust out the back end as fast as it can. As Isaac Newton said "for every action there is an equal and opposite re-action" so that if a jet engine throws enough exhaust out its back end, and throws it fast enough, it tends to move forward. And it is due to this throwing action that the jet takes its name. The French word for "throw" is jeter.