# Water in a Jet's Turbine

**URL:** <https://boards.straightdope.com/t/water-in-a-jets-turbine/448913>\
**Category:** Factual Questions\
**Created:** [May 11, 2008, 12:52pm UTC](https://boards.straightdope.com/t/water-in-a-jets-turbine/448913 "2008-05-11T12:52:20Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\
**Post date:** [May 11, 2008, 12:52pm UTC](https://boards.straightdope.com/t/water-in-a-jets-turbine/448913/1 "2008-05-11T12:52:20Z")

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Why doesn’t rain disturb jet plane’s turbine the way water droplets would tear apart a steam turbine? Is it the higher pressure of operation for a steam turbine, I WAG?

- Jinx

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**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\
**Post date:** [May 11, 2008, 12:54pm UTC](https://boards.straightdope.com/t/water-in-a-jets-turbine/448913/2 "2008-05-11T12:54:54Z")

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Why would it? The droplets would just be vaporized and shot out the back with the rest of the hot gasses.

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**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\
**Post date:** [May 11, 2008, 1:27pm UTC](https://boards.straightdope.com/t/water-in-a-jets-turbine/448913/3 "2008-05-11T13:27:10Z")

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Rain does indeed erode an engine’s airfoils over time. Rain isn’t just water. Each drop forms around a tiny dust particle. Even when the water has passed deeply enough into the engine to vaporize, that solid bit remains and causes damage that accumulates over time. A high-time engine that has seen a lot of rain will look seriously chewed up.

The issue you’re thinking of with steam turbine buckets is mainly thermal - a stream of water hitting something at high temperature can cause shock cooling and local spalling. That can happen with a gas turbine too.

Part of the reason rain (and hail and dust) ingestion in an aircraft engine isn’t all that big a deal is that the big fan up front is a highly effective centrifuge - most solids (and liquids) get flung away from the entrance to the high temp/high pressure core.

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**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\
**Post date:** [May 11, 2008, 1:40pm UTC](https://boards.straightdope.com/t/water-in-a-jets-turbine/448913/4 "2008-05-11T13:40:55Z")

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Some jet aircraft (the Republic F-105 Thunderchief comes to mind) had water injection to increase thrust on take-off.

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**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\
**Post date:** [May 11, 2008, 1:46pm UTC](https://boards.straightdope.com/t/water-in-a-jets-turbine/448913/5 "2008-05-11T13:46:30Z")

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Early B-52’s and KC-135’s, too. Some piston aircraft in WW2 had a similar system.

The idea was that the water would limit combustor temperatures and allow more fuel to be poured in, increasing pressure and power output.