Have you ever asked yourself why airplanes have rounded windows? Perhaps when you had your last flight you gave it a little thought and concluded that circular windows are a design preference or maybe a scientific idea. But the answer is easy: it is aircraft engineering.
Ancient aviation professionals made rectangular plane windows. But as the technology behind planes manufactures advanced, planes had to fly higher. This was done to avoid instability in the lower atmosphere and to minimize drag and fuel usage. And to make this possible cabins’ comfort level in the rarefied atmosphere had to be increased with more pressure.
When a cabin must be pressurized, a cylindrical shape has to be created. This circular shape will then create a difference in pressure between the air inside the cabin and that outside the cabin when the plane flies higher. Also, as the body of the airplane slightly expands, stress is exerted, and now the shape of the plane windows becomes crucial.
With a rectangular window, the stress flow is substantial and causes pressure buildup in the corners. Increased pressure could crack the airplane body and shutter the glass. An oval window puts the stress level at equilibrium.
According to BBC reports, engineers had to witness two plane crashes to discover that square windows were the problem. That’s when they made circular windows. The same engineering skill is applied to cabin and cargo doors, space aircraft and ships.
Rounded airplane windows have a hole too. It is designed to regulate pressure that is caused by the increase of internal and external pressure. A window has three layers and breather hole balances the air pressure between the outer and middle panels. Hence, cabin pressure is exerted on the outer pane while the center one is reserved for an emergency situation.
