There is a Hole In Airplane Windows, Every Wondered Why?

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When you travel in a plane you may notice a small hole on the bottom of the window and you might ask the question why there is a hole at the bottom of an airplane window. I can assure you it is not created by some destructive brat with a pencil but it is a common feature of passenger planes and Director of Technology, Marlowe Moncur, from GKN Aerospace explained its importance. It is part of the safety features of the aircraft.

The hole is responsible for regulating the pressure within the cabin.These holes keep the external atmospheric pressure constant within the panes. The pressure created by the engines of the airplane compresses it to create the thrust. This air is maintained within the cabin with the outflow valve.

Thus, this breather hole in the airplane functions as a bleed valve. The sensors determine the amount of pressure present in the cabin upon which the valve releases the air at a constant rate in order to maintain a certain level of air pressure.

Philip Spiers, Head of Advanced Structural Testing Centre at the University of Sheffield Advanced Manufacturing Research Centre (AMRC) added, “Planes have a higher pressure inside than outside. It’s like a bottle of Coca-Cola – shaking a bottle makes it go stiff and hard but when you undo it, it becomes floppy again. This stretches the skin around the plane.”

This hole helps maintain the pressure differential and directs it onto the outer pane rather than the inner pane. ‘If the pane was sealed [and didn’t have a hole in it], all the pressure in the cabin would act on the inside pane of glass’

Typically the air inside the cabin is maintained at around 11PSI, the levels of pressure experienced at around 7,000 feet (2,130 metres). And this change in pressure is what causes a person’s ears to pop. To maintain this pressure, the plane’s structure and its windows need to be able to handle the differential between the cabin pressure and the outside of the plane.


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