As we observe in commercial aircraft, that there are four or two front end nozzles for gas emission in the air.

What is the reason for this variable of 4 or 2 nozzles? Why is it not a constant?

aircraft with four nozzles aircraft with two nozzles

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    $\begingroup$ Got a photo of what you are talking about? $\endgroup$ – Michael Hall Nov 19 '20 at 5:39
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    $\begingroup$ I’m unclear of what you are asking. Are you talking about engine intakes? $\endgroup$ – Carlo Felicione Nov 19 '20 at 5:42
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    $\begingroup$ @PrashantAkerkar I suggest you have a look at this question: How do jet engines work? $\endgroup$ – Bianfable Nov 19 '20 at 8:57

the "front-end nozzles" you mention are the air inlets for the plane's jet engines- one inlet per engine. The outlet that emits exhaust gases at great speed is in the rear of the engine. Some jets have only one engine, and one inlet. Some have two, some three, some four engines; the B-52 has eight engines and eight inlets.

Greater numbers of engines are used to power bigger, heavier planes. Early engines were not very powerful and so older planes that were big and heavy (B-47, B-52, 707, DC-8, 747, etc.) had many engines. Modern engines are much more powerful and so fewer of them are needed, even on big planes.


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