When we were kids, we were taught that while drawing, make the windows in square shape. After some time, we noticed that even in real life, the windows are made in square or rectangular shape. The rooms, houses, vehicles, etc. have windows of square or rectangular shape. But when you would have travelled in a flight, certainly there is one thing that you would have noticed. The windows of airplane are not square shape but it has curved ends. Everyone would have given a thought to this question at least once.
The field of aeronautical engineering has developed a lot in the past years. The round windows of the aeroplanes are a result of one such development in this field. The first airplane which was constructed was The De Havilland DH 106 Comet. It had square shaped windows. But when it started its first journey from Singapore to London, it met with an accident just after twenty minutes of its take off. It fell into the sea resulting in the death of many people.
In later years, two more flights faced the same situation and crashed within few minutes of its take off. After three massive accidents, the reason behind the destruction was discovered. It was quite shocking that the death of so many people happened due to a very simple reason: windows! Yes, the reason for all the crash was the structural failure. All the crashed planes had cracks near the window at an angle of ninety degrees and that was how it was discovered.
When the plane is at high altitude, there is a pressure difference inside and outside the plane. The airplane, at high altitude suffers due to the high pressure difference. There is a lot of pressure acting on the structure of the aeroplane. This pressure is acting throughout the body of the aeroplane.
When there is pressure acting around the windows, the pressure builds up at the corners of the windows because windows are the weak ends. Hence, if there is a square window, there would be four weak corners where the pressure will build up. The high pressure at the corners leads to the breaking of the windows and could even lead to the cracks in the body of the aeroplane.
The solution to this window problem was found by Federal Aviation Administration (FAA). According to FAA, in order to solve this problem, more pounds of weight could be added around the square windows to face the high pressure. But this will increase the overall weight of the plane and it would be difficult for the plane to fly.
An alternative to this was changing the shape of the window. Scientists found that if the windows are made in a round shape. The round shape of the window will make the pressure distribution easier. The pressure would circumvent easily around the round window than around windows with corners.
The latter was considered as a better solution and thus, the structure of airplane was modified and round shaped windows were made. This won’t even increase the overall weight of the flight and the possibilities of accidents would also be reduced. This is how we have our present day airplanes with oval windows which not only helps in coping up with high pressure but also in giving a nice look to the airplane!