Air travel is a common routine for many. Though people still have the thrill of flying, some people find air travel tiring and boring. If you are the latter kind, you would either sleep or gaze out through the window.
But still, you wouldn't get a good view due to the odd round shape of the aeroplane windows. Why couldn't they just make the windows square or just larger? Well, there is a reason for everything. And here is the reason why planes have round windows!
The reason why planes have round windows revolves around safety. Till the mid-1950s, plane windows were not rounded. In fact, they were square.
The World's First Commercial Jetliner, de Havilland Comet, was first flown in 1949. The British aircraft was aimed at revolutionising air travel industry with high speeds and lesser travel times. However, things didn't go well with the initial design of the Comet. The plane faced two fatal disasters in 1954. Investigations revealed that the accidents occurred due to the plane's design flaw.
Being a jetliner, the Comet could fly at high altitudes and reduce flying costs. At higher altitudes, air density is low and hence the drag acting on aeroplanes will also be low. Low drag, in turn, reduces the load on the engines. This saves fuel and money.
Air pressure lowers with altitude. There will eventually be a point where a plane's cabin pressure is greater than the outside pressure. This might cause the fuselage to expand slightly.
To fly at high altitudes, the cabin should be pressurised for normal human body functioning. The cabin should also be cylindrical in shape. Cylindrical shape resists the changes in pressure inside and the stress produced, by expanding equally in all directions. The stresses will flow smoothly around the fuselage if it has an even surface. But if there is an obstruction to the stress flow, like a window, the stresses will concentrate around the window.
A square window causes stresses to form at its edges. The stresses formed at the edges varies in intensity depending on the difference between the cabin pressure and the outside pressure. Air turbulence also affects the stress intensity. If not checked, the stresses might cause cracks from the edges which could break the plane open.
On the contrary, a round or oval window doesn't restrict the stress flow that much. The stress lines flow smoothly around it. The de Havilland Comet had square windows which caused it to have tragedies in the 1950s.
Since then, aircraft manufacturers opted rounded window designs for the fuselage. Even the later versions of the Comet were also equipped with rounded windows.
So if you thought that round windows on planes were just for looks, you are wrong. Of course, it looks good, but it also has a function. Like a famous designer once quoted, "A design works best when there is an equal balance between aesthetics and functionality".
Thoughts On Why Airplanes Have Round Windows
Aeroplanes are a fascinating creation by man. There is a lot of math and physics involved in the making of an aircraft. With those data come some interesting details worth noticing, such as rounded windows. Now you know the reason why planes have round windows, but do you know why planes do not fly over the Himalayas?