Science Behind Jet Engines: Bringing the World Closer with Dr. Newton

Author - Gurman Kaur | OFLY Aviation Ambassador

A special milestone article by an OFLY Aviation Ambassador. This article marks a special milestone as OFLY’s 100th blog, written by our Aviation Ambassador, reflecting the curiosity and learning spirit that define OFLY.

For a long time, when I was young, I used to believe that aircrafts took off purely because the engines were… well, loud enough to scare the runway into letting them go. Later, when I began studying aviation properly, I realised that the truth was far more science-y. Everything I had been watching all those years was actually Newton’s Third Law quietly running the show.

Once this clicked, flying stopped feeling like hocus-pocus, and instead, it became wonderfully logical, almost like solving a puzzle where the final picture is a massive aircraft soaring into the sky.

The law that deserves more credit

Newton’s Third Law is one of those lines we memorize in school without giving it the respect it actually deserves.

“Every action creates an equal and opposite reaction.”

Simple? Yes.

But powerful enough to lift a wide body jet.

Push water backward and you glide forward.

Throw fuel downward and a rocket climbs upward.

Similarly, if a jet engine blasts air backward, the aircraft moves forward.

It is the kind of principle that sounds too simple to matter, until you watch how smoothly a 70-tonne aircraft obeys it.

What the jet engine is really doing

Let’s break it down in the simplest possible way.

First, the engine takes in an impressive amount of air.

Second, it compresses this air until it becomes highly pressurised.

Third, the fuel mixes with the air and ignites.

Finally, the engine throws those hot gases out of the back at very high speed.

That backward rush of gases is the action. The forward movement of the aircraft is the reaction.

Nothing mystical. No hidden secret. No hocus-pocus. Just physics doing its job with quiet confidence in Sir Isaac Newton.

Modern engines use the law with a bit of creativity

Here’s the part that caught my attention the most when I went down a rabbithole of research. Most of the air entering a turbofan engine does not even take part in combustion. Instead, the large fan at the front accelerates it backward, creating huge thrust with surprising efficiency.

It almost feels like the engine is saying, “Why rush a small amount of air when I can move a massive amount more gently and get better results?”

And Newton agrees.

Moving more air at a moderate speed, gives you efficient and powerful thrust. On the contrary, moving very little air too fast gives noise, heat and a grumpy fuel bill.

This innovation changed everything, from fuel efficiency to the familiar soundscape of takeoff. The deep hum comes from the fan. The sharper whine comes from the engine core. Two different sounds. One shared principle.

Pilots use this law all the time, whether we notice it or not

Once I understood this, I started seeing Newton’s Third Law everywhere in an aircraft.

• During takeoff, when the throttle increases, the engines push air backward faster and the aircraft reacts instantly by surging forward.

• During cruise, pilots balance thrust and drag so perfectly that the aircraft glides as if nothing in the world could bother it.

• During landing, reverse thrust simply flips the direction of action so the reaction causes the aircraft to slow down gracefully.

• And if one engine loses thrust, the imbalance in reaction forces makes the aircraft yaw, which is corrected by the pilot.

The entire flight becomes a conversation between action and reaction. Once you see it, you can’t unsee it.

Even future engines still bow to the same law

What I love about aviation is that the technology changes every year, yet the underlying principle does not move an inch. Whether engineers are designing hybrid engines or open rotor systems or experimenting with new airflow concepts, they still come back to the same idea.

Push air backward smarter.

Move the aircraft forward better.

Newton would be proud.

A closing thought

When I think back to the first time I felt an aircraft lift off, I smile, because now I know that the moment isn’t just noise, vibration or thrill; it is Newton’s Third Law in its purest, most impressive form.

A simple principle from classical physics powers machines that connect continents, create memories, and make the world feel smaller. The more I learn, thanks to OFLY, the clearer it becomes that aviation is not just built on technology. It is built on curiosity. Mine included.

My journey with this field began with questions, and every new lesson gives me a few more. Somehow, that is the best part.

Aviation with OFLY keeps you learning. And Newton? He keeps the aircraft moving.