# Jet Engines: How Do They Move Forward?

• makster246
In summary, a jet engine gains thrust by pushing heated air out of its nozzle, which in turn pushes the engine forward. This is due to the hot gas pushing on the back of the compressor blades, similar to how a rocket engine works. This explains why rockets can function without atmosphere.
makster246
O.k i understand that a jet engine gains its thrust by pushing heated air out its nozzel, but i was wondering if that the reason it goes forward is because the speed of it being released out the rear nozzel is moving faster than the air can get pushed out of the way so the some of the force is used to push air out the way, and the remaining is used pushing the jet forward
is this correct?

No it's a lot simpler than that.
Consider a rocket engine (it's a little simpler )
You burn fuel in a closed box , the fuel creates hot gas which expands pushing on all the walls of the box equally - so no movement.
Now make a hole in the back of the box, the hot gas at the back doesn't push on this any more, but there is still gas pushing on the front of the box - so the box moves forward. This is why rockets can work without atmosphere.

A jet engine is basically the same except that instead of storing the oxygen it pulls it in from the air at the front. Instead of pushing on the front of the rocket chamber the hot gas is pushing on the back of the compressor blades.

Thanks very much that explains a lot :), your a star

makster246 said:

A white dwarf, to be specific... :uhh:

Okay, I'm leaving now.

Danger said:
A white dwarf, to be specific...
I prefer to think of myself as 5' 6 1/2" of slightly degenerate matter

## 1. How do jet engines produce thrust?

Jet engines produce thrust through the principle of Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. In a jet engine, this is achieved by compressing air and mixing it with fuel, igniting it, and then rapidly expelling the hot gases out of the back of the engine. This creates a forward force that propels the aircraft forward.

## 2. What type of fuel do jet engines use?

Most modern jet engines use a type of fuel called Jet A or Jet A-1, which is a type of kerosene. This fuel is highly combustible and has a high energy density, making it ideal for powering jet engines. Some military aircraft may use a higher grade of fuel, such as Jet B or JP-8, which have a higher flash point for safety reasons.

## 3. How do jet engines differ from propeller engines?

Jet engines differ from propeller engines in that they do not rely on a rotating fan or propeller to produce thrust. Instead, they use the principle of jet propulsion, where hot gases are expelled from the back of the engine at high speeds to create thrust. This allows jet engines to achieve much higher speeds and altitudes than propeller engines.

## 4. How do jet engines stay cool during operation?

Jet engines have various cooling systems in place to prevent them from overheating during operation. The most common method is through the use of compressor bleed air, where a small amount of compressed air is diverted from the engine and used to cool the hot components. In addition, some engines also use fuel as a coolant, where it is sprayed over the engine's exterior to absorb heat.

## 5. How have jet engines evolved over time?

Jet engines have undergone significant advancements since their invention in the 1930s. They have become more fuel-efficient, quieter, and more powerful, allowing for faster and more efficient air travel. Modern jet engines also incorporate advanced technologies such as computer controls and composite materials to improve their performance and reduce their environmental impact.

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