Why Do Airplane Windows Have Rounded Corners?

An airplane window interrupts a metal cabin that has to hold a pressure difference, flight after flight. Why do rounded corners help—and why is the shape only part of the answer? This episode explains stress concentration and metal fatigue, then follows the Comet investigations from recovered wreckage to a fuselage tested in a giant water tank. You'll learn why openings, rivet holes, testing history and repeated loading all matter, and how the panes in one documented modern window arrangement do different jobs. The familiar story about square passenger windows leaves out crucial details: the investigated openings were not all passenger windows, and early corners already had curves.