十万个为什么·科学启蒙30篇（4）

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为什么飞机高空舷窗多为圆形

Early jet planes had square windows, but several crashes revealed dangerous structural weaknesses at the corners.
Sharp corners concentrate stress when cabin pressure increases during flight at high altitudes.
Round windows distribute that pressure evenly across the curved surface without creating weak points.
At cruising altitude, the air pressure inside the cabin is much higher than outside the plane.
This pressure difference pushes outward on every part of the fuselage, especially around openings.
Engineers use rounded shapes because they resist cracking under repeated pressurization cycles.
Modern aircraft undergo thousands of simulated flights to test window durability and fatigue resistance.
Even small imperfections near square corners can grow into serious cracks over time.
Today’s acrylic and polycarbonate window materials also work best with smooth, curved designs.
This simple shape change dramatically improved passenger safety in commercial aviation history.