# How Can a Jet Engine Fly in the Rain?

**URL:** <https://boards.straightdope.com/t/how-can-a-jet-engine-fly-in-the-rain/943942>\
**Category:** Factual Questions\
**Created:** [June 10, 2021, 1:39am UTC](https://boards.straightdope.com/t/how-can-a-jet-engine-fly-in-the-rain/943942 "2021-06-10T01:39:59Z")\
**Posts on this page:** 3\
**Page:** 3

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**Author:** ![BrickBat](https://avatars.discourse-cdn.com/v4/letter/b/ac91a4/32.png) [@BrickBat](https://boards.straightdope.com/u/BrickBat)\
**Post date:** [June 14, 2021, 6:37am UTC](https://boards.straightdope.com/t/how-can-a-jet-engine-fly-in-the-rain/943942/41 "2021-06-14T06:37:04Z")

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> [@LSLGuy](#):
>
> Whether net, net the extra complexity buys enough real world improvement to pay for itself seems unclear to me. Of the major manufacturers, only RR has developed and persisted for 30+ years with their 3-spool design. Nobody else sees the same need on even their experimental future tech engines.

That’s my thinking. The two spool design deals with airflow management with variable ( compressor ) stator vanes and low pressure compressor bleed valves, both mechanically operated, using servo fuel pressure as muscle. The former being quite complex with an amazing amount of moving parts. The RR RB211 uses the 3 spool design but still employs LPC bleed valves, although simple poppets actuated by compressor bleed air. It would be interesting to compare the two philosophies via some metrics ( engineering, material, weight, need of supporting subsystems, manufacturing processes etc ) of judging which is the better of the two, especially since they both work very well in service.

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**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\
**Post date:** [June 14, 2021, 1:25pm UTC](https://boards.straightdope.com/t/how-can-a-jet-engine-fly-in-the-rain/943942/42 "2021-06-14T13:25:00Z")

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> [@Melbourne](#):
>
> @LSLGuy: excellent.

Seconded.

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**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\
**Post date:** [June 15, 2021, 9:15pm UTC](https://boards.straightdope.com/t/how-can-a-jet-engine-fly-in-the-rain/943942/43 "2021-06-15T21:15:01Z")

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There was an English Composition teacher in my high school who assigned her class to build a story or essay around the line, “Wet birds never fly at night.” Several of the posts here would have truly dazzled her.

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