Traveling by air is a fascinating experience, and a discerning observer will spot distinctive features of aircraft that are absent in conventional transportation methods. One such feature is the use of rounded-edge windows.
In the early days, rounded-edge windows were uncommon as aerodynamic engineers initially used standard square windows following the invention of the airplane. Significant progress in air travel began in the 1950s with the launch of the Boeing 707, one of the first commercially successful jet airliners. This advancement enabled airlines to operate at higher altitudes, where the thinner air allowed for faster speeds.
Square windows were initially common, but over time, they proved problematic because they created stress points due to the pressure differences between the inside and outside of the plane.
In fact, in 1954, the use of square windows contributed to a plane crash, highlighting an urgent need for a solution. Engineers discovered that higher altitudes resulted in increased atmospheric pressure from outside the aircraft. The four sharp corners of the square windows absorbed 70 percent of the stress, leading to cracks and structural failure.
This led to the introduction of rounded windows on modern aircraft, designed to better manage the air pressure differences inside and outside the plane.
When cruising above 10,000 feet, aircraft cabins are pressurized to counteract the lower atmospheric pressure outside. This pressure difference puts stress on the windows, but their rounded shape ensures an even distribution of pressure across the panel, reducing the risk of damage.
Additionally, the design better withstands deformation, enhancing its durability for long-term use.
The windows consist of three acrylic layers, each serving a distinct function: the outer pane withstands external pressure and weather conditions, the middle pane provides thermal insulation, and the inner pane ensures a clear view while protecting against interior damage.
The outermost layer, being the thickest, absorbs all external pressure, while the middle layer, also substantial in thickness, features a small hole to equalize pressure and safeguard the inner pane. The innermost layer, facing the passenger, is the thinnest and handles only the relatively minor cabin pressure.
While incidents of windows tearing open are now extremely rare, they continue to be a critical focus during safety checks.
Beyond their aesthetic appeal, rounded windows significantly enhance passenger safety compared to windows with sharp edges.