# How a Turbine Engine Works

A cutaway jet engine that shows how air is pulled in, squeezed, burned and blown out to make thrust

By nimble\-panda\-5d1331a2

Topic: Machines

[Open the interactive Jig](https://ask.jig.com/j/BBEJOZ0ydSA3)

## Transcript

### 1. A jet engine, opened up

This is a turbofan, the kind of jet engine that carries airliners\. Part of its skin is cut away so you can see inside\. Drag to turn it around and look from any side\.

A real engine like this is about 1\.7 metres across the fan, taller than most adults\.

### 2. Suck: the giant fan

The big fan at the front grabs huge gulps of air\. Most of it flows around the middle of the engine, through the bypass duct\. Only a small share goes into the core, the hot heart of the engine\.

In engines like this, about six times more air goes around the core than through it\.

### 3. Squeeze: the compressor

Inside the core, row after row of small spinning blades push the air into a smaller and smaller space\. Fixed blades between them straighten the flow\. Squeezed air gets hot, just as a bicycle pump warms up\.

Big airliner engines squeeze the air to about 30 times its normal pressure\.

### 4. Burn: the combustor

The squeezed air enters a ring\-shaped chamber called the combustor\. Fuel sprays in and burns in one steady flame, not in bangs like a car engine\. The hot gas swells and rushes toward the back\.

Only about 1 kilogram of fuel burns for every 50 kilograms of air\.

### 5. Blow: the turbine

The hot gas blasts through the turbine, rows of blades like little windmills, and spins them very fast\. The turbine then turns the compressor and the fan through long shafts\. The gas leaves cooler, its pressure spent\.

The gas can be hotter than the metal's melting point\. Cooler air flowing out of tiny holes in each blade protects it\.

### 6. Two shafts, one inside the other

The engine has two spinning parts\. The core shaft, shown in amber, joins the front turbine to the compressor and spins fastest\. The fan shaft, shown in blue, runs through its hollow middle and joins the rear turbines to the fan\.

Each shaft can turn at its own best speed\.

### 7. Push: making thrust

Air leaves the back much faster than it came in\. Throwing air backwards pushes the engine forwards, like a balloon zooming away when you let it go\. Slide the throttle to change how hard it pushes\.

In an airliner, most of the push comes from the cool fan air, not the hot exhaust\.

### 8. Start it up

To start, a starter spins the core shaft until air is rushing through\. Then sparks light the fuel, and the engine keeps itself running, because its own turbine now drives the compressor\. Press start and watch it come to life\.

Suck, squeeze, burn, blow: every jet engine does these four jobs at once, without stopping\.