Building a Turbojet Engine

This is a fan.

When it spins, it pushes air and creates thrust.

But the thrust is too weak.

So you place it inside a metal tube and add more blade stages.

Yet the thrust still does not increase much.

You quickly find the problem.

After passing through one set of blades, the airflow changes direction

and cannot efficiently drive the next set.

So you add stationary guide vanes between the blades

to redirect the airflow at the best angle.

But fans alone still cannot produce enough thrust.

So you add another set of blades inside a narrowing tube.

As the fan spins, each stage compresses the air into a smaller space,

creating hot, high-pressure air.

Then you add a combustion chamber and fuel injectors.

When fuel is sprayed in, the hot compressed air ignites it instantly,

raising the temperature above 1,000 centigrade.

The hot air expands rapidly and blasts out the exhaust,

creating much greater thrust.

But there is still a problem.

The system depends on the front fan being powered.

If power stops, the engine fails.

So you add a turbine behind the combustion chamber.

Hot gases spin the turbine as they pass through.

You connect the turbine and compressor on the same shaft.

Now exhaust drives the turbine, and the turbine drives the compressor,

creating a self-sustaining cycle.

But the engine becomes so efficient that temperatures exceed

2,000 centigrade, enough to melt turbine blades.

So you split the airflow into two paths.

One goes into the combustion chamber for burning fuel.

The other bypasses the chamber and cools the system,

lowering temperature to around 1,600 centigrade.

Now the turbine survives, and the engine can run continuously.

Congratulations, you have built a turbojet engine.