Do You Know Why Aeroplane Windows Are Rounded Or Curved

While travelling in an aeroplane, have you ever pondered why those windows are rounded in shape. Well, we got the answer for you.

Aircraft engineering improvising at a great pace and it should be, because it’s a matter of lives of millions of airplane travelers.

Now as you are getting us, there is a scientific reason and engineering behind the design of aircraft windows.

 For those who want answers in one line: The aeroplane windows are rounded and not square because square windows experience more stress. Due to which in 1950s 2 airlines cracked and fell apart in the air. 
why aeroplane windows round
via ScienceAlert

The aeroplane windows were not always round

The windows were not always round- planes had rectangular/square windows, just we have in our homes and cars.

But as aerospace engineering started making progress in their technology. Unfortunately, it took two carrier accidents before engineers understood the problem that square windows were causing. In the 1950s, when jetliners were started to become standard, the de Havilland Comet came into fashion, which could go higher and quicker than other air-crafts, because of a pressurized cabin. Be that as it may, the plane had square windows and in 1953 two planes fell apart in the air, resulting in 56 casualties.

From then, the windows were started to be made rounded or oval.

Now you know a new thing that you can use to start a quick chitchat with the stranger sit next to you on  the flight next time.

aeroplane window view
via Tumblr

Have a look at technicalities: Why airplane windows round?

This seems like a simple question but let’s take a look.

As passenger planes became more popular, planes needed to fly higher. Flying higher means less drag because air density is lower in the upper atmosphere, so less fuel is wasted. Flying high also means a more comfortable flight because the plane can now fly above the turbulent lower atmosphere but some design changes need to be made to allow this. First the cabin has to be pressurized to create a survivable environment for the passengers, second the cabin must be cylindrical in shape because a cylinder can resist the new internal pressure.

oval windows of airplane
via Tumblr

But one design flaw was not corrected when cabin pressurization was first introduced, the windows remain square; so why is this a problem- as a plane increases in altitude he external atmospheric pressure lowers more than the internal cabin pressure. This creates a pressure difference between the inside and outside of the plane causing the plane to expand ever so slightly. When the material changes shape like this, stress is created in the material as the material is stretched more and more, stress begins to rise eventually the stress can rise so high that the material breaks and there are a lot of factors that can elevate this stress. One of them is the shape of the material- In planes the shape of the windows has a huge effect on the level of stress. Stress will flow smoothly through material but if an obstacle is placed in it’s path- like a window it needs to change direction and this causes the pressure to build in certain locations, this is called stress concentration.

Comparing modern-day oval windows and square windows, you can see that the square windows provide a larger barrier to the smooth flow stress and his means that the stress builds on the sharp corners of the window and this elevated stress created by the square windows actually cause cracks to form into the de Havilland Comet causing three tragic crashes. Investigations that followed led to a greater understanding of stress concentration and that is why aeroplane windows are now oval in shape and not the square.

Cover Photo Credit: ScienceAlert

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