During a flight, we all look out the window, but none of us think about why aircraft windows are not as Angular as in our homes. Really, why are the windows of airplanes round?
Over the years, Aerospace Engineering has made huge leaps in aircraft technologies. The most obvious example that can be given to these breakthroughs is the fact that more passengers are being transported on planes and that planes can travel longer distances at a faster rate. During this development process, which took years, of course, there were changes in the structures of aircraft, and part of this change was glass.
Especially 20. with the increase in commercial flights in the middle of the century, airlines began to fly their aircraft from higher elevations. Because as it rose to heights, the air density decreased, making the planes less resistant. That meant reducing the cost of the flight.
But high altitudes have brought various problems, as well as advantages. For example, 30,000 feet (10,000 meters) at altitudes over, does not have the proper conditions for human life, and as you can imagine this is a big problem for hundreds of people carrying a metal box. In order to eliminate this, the cabs were made cylindrical to support internal pressure; however, The Shape of the windows was not changed in the first place. This meant disaster.
The de Havilland Comet aircraft, owned by the De Havilland company and very popular in the 1950s, was known for its pressurized cabin, higher altitude and faster flying compared to other aircraft of the era. But the aircraft's windows were designed in a square shape, as we are used to from homes. Three aircraft were wrecked in mid-air in 1953. A total of 43 people were killed. And what caused the planes to fall apart? It turned out that the design of the windows was responsible for the error. You see, the history of aviation (and the rules of aviation) was once again written with disasters.
Every angular structure has weak points in these corners structurally. This is because the stress (i.e. the force falling on the unit area) at pointed corners increases exponentially. Think of it this way: if there were no obstacles in front of a moving fluid, it could continue straight ahead. But if you put an obstacle in front of it in the form of a square with corners, this fluid would have to change direction to travel around the object. Changing direction means increasing pressure at that point. This is called stress concentration (It is the ratio of the mass or volume of a given substance in a medium to the mass or volume of the medium in which it is located.).
Because each material has a certain resistance, the materials in these pointed corners are much more likely to break down. Depending on The Shape of the object, the amount of this change of direction also varies. Shapes that are more compatible with the fluid's movement profile, usually flatter, cause the effect of this change of direction to be less. In angular bodies, however, since the change of direction is much sharper, higher pressure accumulations are experienced. As you know, the Square has four corners, which indicates that there are 4 different weak points in the windows of old planes. This, in turn, causes aircraft to disintegrate as a result of various pressure factors, such as air pressure.
By curving the glass, the pressure factor that would break the glass from the corners was distributed, reducing the chance of breaking the glass. Circular shapes are also stronger and more resistant to deformation. Therefore, in many architectural designs that should be resistant, you will find that pointed corners are avoided.
This simple design change allowed them to become much more resistant to the huge pressure differences inside and outside the aircraft. In this way, the circular windows we now use can withstand the pressure of the cruising altitude.