Why are airplane windows round instead of square or rectangular?

 

Why are airplane windows round instead of square or rectangular?

When commercial air travel began in the mid-20th century, airlines began flying at higher altitudes to save money. But for passengers to survive 30,000 feet, the cabin would need to be pressurized.

To enable this, the cabin was made cylindrical to aid internal pressure. But first, aircraft manufacturers left the standard square.

As a result, in 1953, two aircraft broke apart in flight, resulting in 56 fatalities. After an investigation was completed, the cause of the crash was determined to be the plane's rectangular windows.

Ascending from sea level to cruising altitude, the fuselage is heavily loaded. It bends easily because it has to withstand a lot of pressure.

Repeated flexing can cause metal fatigue, which can eventually lead to severe hull fractures.

This vulnerability is potentially dangerous as it can cause mechanical failures and threaten human life.

Fortunately, the designers spotted the design flaw fairly quickly. It now has a nice round window that can withstand the pressure of cruising altitude.