Why the windows of airplane are oval?

There are many things around us that we pass them simply. For example, one of these cases is the oval windows in the airplane. Have you ever posed this questioned why are all windows of planes as oval-shaped? First, it should be noted that the window of airplane was not oval from the first day and the primary airplanes also enjoyed of rectangular windows. By increasing the development of aviation industry, for some reason engineers had preferred to fly planes at higher altitudes. One of these reasons is reduction of the created turbulence in the high altitude and a point in atmospheric that density is very low. Also the friction generated at high altitude is also very limited, which this issue reduces the fuel consumption. Considering the dilution of the air in the atmosphere, engineers must control inside the plane with more pressure to passengers sit in the cabin with comfort. The cabin due to more pressure in inside than outside, should be in the form of cylindrical and this causes to difference in pressure is created between the outside air and inside the cabin. This pressure difference increases with the height of the plane more than ever and here's where the used windows in plane being matters. Considering the using cylindrical shape in the plane's fuselage, pressure is spread in the whole fuselage, but presence the windows in the fuselage, disrupt this process. As you can see in this video, using the square windows create large changes in pressure of fuselage, but this changes will be much less if you use the oval windows. So engineers prefer to use oval windows in airplanes. If they use of square-shaped windows, when the air pressure gradually increases, there is the possibility of breaking windows and crash. Unfortunately, this scientific fact was discovered by scientists after many examinations after the fall of the two planes. After that airplane manufactures using the oval window placed on the agenda, so that does not get to high pressure to the fuselage. Using the oval shape is also applies for the production of doors and load location. If you have noticed carefully at the sitting time in the window, there is a tiny hole in all windows. Based on the presented information, this small hole is built in order to manage the inside and outside pressure of the plane. Each window in the plane is built of three layers. The presence of these holes cause to internal pressure exchanges with the middle layer pressure and the pressures moderation is developed in this area. The intermediate layer has been considered as a caution layer and pressure is entered to the outer layer of the window.