Firstly, it was well known that a square form leads to a stress concentration when de Havilland designed the Comet. The aircraft was designed and tested to withstand the stresses around the windows. ... Likewise, ships had many square windows with rounded corners - much like the Comet.The Strange Reason Why Airplane Windows are Round. ... Square windows. Sharp corners are natural weak spots where stress concentrates, weakened further by air pressure. When subjected to repeated pressurization, four corners on a square window spell disaster.
