# Steam-powered jet engine - possible?

**URL:** <https://boards.straightdope.com/t/steam-powered-jet-engine-possible/638504>\
**Category:** Factual Questions\
**Created:** [October 22, 2012, 11:13am UTC](https://boards.straightdope.com/t/steam-powered-jet-engine-possible/638504 "2012-10-22T11:13:27Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\
**Post date:** [June 29, 2013, 6:49pm UTC](https://boards.straightdope.com/t/steam-powered-jet-engine-possible/638504/21 "2013-06-29T18:49:41Z")

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> [@For You](#):
>
> Interesting point: water boils at 212F at STP, which is sea level: a jet flying at 30K’ would not require as much heat to create steam. OTOH, getting the many many pounds of water needed up to 30K’ would require quite a lot of energy.

The higher the pressure the lower the amount of heat to turn water at boiling point into steam at boiling point. And at sea level thatis a big number. 970 BTUs per pound.

Heating water into steam and then expanding to get thrust would require more energy than compressing air burning fuel in it and then letting it expand to get thrust.

There is a reason new power plants are gas turbines with maybe a waste heat boiler on the exaust then high pressure steam plants. Even most new ships are either gas turbine or diesel. The day if steam is gone. (bummer)

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