Why are Aeroplane Windows Round Instead of Square?

Key Takeaways

• Square windows have sharp corners, and sharp corners create a lot of pressure.

Many of you have travelled on a commercial flight, and you have all sat near the window seat. But have you ever thought, why are aeroplane windows round or oval instead of square or any other shape? 

Many kids or adults have different perceptions about the aeroplane window shape. In this article, explore the scientific details and learn why aeroplane windows are round instead of square.

Why are Aeroplane Windows Round Instead of Square?

Aeroplane windows are round or oval in shape because square windows have corners and joints, and this creates pressure. When a plane flies high in the sky, the air pressure keeps changing inside and outside of the plane.

This pressure pushes the corners of the windows, which creates a high chance of an accident due to a lot of pressure on the plane, but in a round shape or oval shape, there is not a corner, and it releases the pressure in this shape of windows.

Now let’s understand this in detail.

When a plane goes up in the sky, the air outside the plane becomes very thin, and there is not enough oxygen for people to breathe.

So, to make it comfortable for the people, the plane is filled with a good amount of air and oxygen inside the plane. 

So, the pressure inside the plane is much higher than outside, and it makes the difference in the pressure which pushes the walls of the plane from the inside, like the balloons trying to expand and their layers becoming so thin and having a risk of bursting. 

In a plane, it also creates pressure in the same way, and every window and door of the plane exhibits a lot of pressure.

So, to release a lot of pressure, this oval shape is chosen as a shape for windows, not a square one. 

Why are corner shapes of aeroplane windows dangerous? 

In a square shape, there are four corners, and when something is pushing against the square, it does not scatter; instead, it gathers up at the corner, which makes it difficult to release the pressure from the square shape, and this is termed 'stress concentration', which creates a lot of pressure which becomes very dangerous at the corner shapes of a square. That’s why corner shapes of aeroplane windows are very dangerous.

In the early 1950s, an incidence occurred. There was a plane called de Havilland Comet, and it was the first jet plane made for travel for passengers, but this plane had square-shaped windows and made three different planes.

But, unfortunately, all three planes crashed: one in India in 1953, another one in Italy in January 1954, and the third one in Rome in April 1954, and all these planes crashed in the air due to a lot of pressure on the planes.

What is Stress Concentration?

According to Mechref, “stress concentration refers to the increase in stress around small features like holes, notches, or sharp corners in a material.

Imagine you're trying to tear a piece of paper. If you pull it from both ends, it's tough to rip. But if you make a small cut (a notch) first, the tear spreads easily from there. This happens because stress (force per unit area) gets concentrated around sharp edges or holes.”

So, the next time when you are seated near the window seat in any plane, you will know the reason why aeroplane windows are round instead of square.