Sign up ×
Aviation Stack Exchange is a question and answer site for aircraft pilots, mechanics, and enthusiasts. It's 100% free, no registration required.

I was doing research about jet engines, and they seem really difficult to fully understand. So, can anyone explain it in a simple way?

Jet Engine Image

How do jet engines work?

share|improve this question
I gotta say, that engine doesn't seem to be terribly well tethered. I guess those two longer guy wires and the short turnbuckle (per side) are sturdier than they look. – FreeMan Jan 9 at 16:19

2 Answers 2

up vote 10 down vote accepted

In the simplest of terms:

  • Suck - Air is sucked into the turbine. For efficiency reasons, most aircraft let some of that just pass through the outer part of the fan, rather than through the whole engine.
  • Squeeze - The compressor squeezes that air together to a high pressure. This helps with ignition.
  • Boom - Fuel is injected and ignited. As the air gets hot, it expands.
  • Blow - The hot air drives the low-pressure turbine (driving the whole shaft holding the engine together), sucking new air in, and is itself blown out the back.


share|improve this answer
There's a great interactive animated GIF at NASA's K-12 page on jet engines. – egid Mar 26 '14 at 18:44
if some of the air bypasses the engine it is called a turbofan engine. but that is semantics – ratchet freak Mar 26 '14 at 19:05
the "suck" part is in effect only at startup/on ground. During cruise is the motion of the aircraft w.r.t. the air that makes the air enter the engine. The fan effectively pushes the air towards the back. – Federico Mar 27 '14 at 13:43
@ratchetfreak I'd always heard that a "low-bypass" jet engine was still a turbojet and not a turbofan, but other definitions refute that. Some specialized engines, like those for the SR-71, had variable bypass; they were technically turbojets up to Mach 2, then the bypasses were opened and air flowed directly to the afterburners. – KeithS May 27 at 2:56
@Federico - The "suck" part is always in effect; turbofan engines are highly efficient in part because the get engine drives a larger compressor blade that moves air around the turbojet core, increasing thrust. If that mechanism didn't work at speed, there'd be no point in having it. – KeithS May 27 at 2:59

A jet engine is an overcomplicated ramjet with extra turbines to let it work at lower speeds.

A ram jet works by igniting compressed incoming by mixing it with fuel and providing a spark.

share|improve this answer
hmmm... a ramjet lacks (moving) compressor stages, which are an essential component of a jet engine, and there is no bypass component and most of the time no supersonic flow. So perhaps more distant relatives than siblings? – yankeekilo Mar 26 '14 at 19:32
@yankeekilo that's why I said overcomplicated :) – ratchet freak Mar 26 '14 at 19:38
LOL, but then a barrel of fuel and some matches may also claim commen ancestry :D – yankeekilo Mar 26 '14 at 19:44
A ramjet is almost totally different from a turbojet (and its derivatives). It lacks a fan/compressor and a turbine, so it would only confuse people to compare them. Once you have a turbojet down, you can look at pulsejets, ramjets, scramjets, and other more esoteric forms. – Phil Perry Mar 26 '14 at 22:49
I don't see why you say it's "overcomplicated" -- it seems that a jet engine is exactly as complicated as it needs to be for its intended operating environment. – Johnny Mar 26 '14 at 23:43

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.