Why Are Jet Engines So Loud?
You’re sitting at the gate, and the plane next to you starts up.
Suddenly, it’s like standing next to a tornado made of steel.
Jet engines are loud. Really loud.
But have you noticed? They’re not as loud as they used to be.
Let’s dive into why jet engines make your ears ring, and how modern aviation is making them quieter.
Why Are Jet Engines So Loud?
Jet engines are essentially giant air-sucking machines. Here’s what creates all that noise:
Air Compression: Huge amounts of air are sucked in and compressed rapidly.
Combustion: That compressed air mixes with fuel and ignites in a high-pressure explosion.
Exhaust: Hot gases shoot out the back at supersonic speeds, creating massive turbulence and noise.
The result?
A high-pitched scream + low rumble + thunderous roar = the unique jet engine soundtrack.
The Noise Is Not Just From the Engine
It’s also caused by:
Fan blades spinning at over 10,000 RPM
Air slamming into the fuselage and wings
Shockwaves from the exhaust stream
Even micro-vibrations in the cabin
A Boeing 747 at takeoff produces around 140 decibels close to a gunshot or rock concert.
Why Jet Engines Are Getting Quieter
Over the last few decades, jet noise has dropped dramatically and here’s how:
Bigger Fans, Slower Speeds
Newer engines (like the LEAP or GEnx) use larger front fans that move more air at lower speeds, reducing turbulence and noise.
High Bypass Ratios
In modern turbofans, most of the air bypasses the combustion chamber entirely it flows around it, like a “soft shell” of quieter airflow.
More bypass = less noise.
Chevron Nozzles
Ever noticed the zigzag pattern on the back of some engines? Those are called chevrons they help mix exhaust with surrounding air more smoothly, reducing sound.
Advanced Materials
New composites and designs absorb sound and dampen vibration before it escapes the engine.