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Why Are Airplane Windows Round?

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While some passengers might be too terrified—or sedated—to notice, frequent travelers may sometimes wonder why the windows that line airplane rows are round. Windows in the home are rectangular; car partitions are angled, but mostly rectangular. Why don’t planes follow suit?

It’s actually not an aesthetic choice. Airplanes used to have square windows. And they wound up crashing because of them.

When commercial airlines graduated to faster and larger jets beginning in the 1950s, planes would sometimes essentially disintegrate midair. Two of them, both de Havilland Comets, fell apart within months of one another in 1954 and killed a total of 56 passengers. Investigators traced the flaw to the squared-off corners of windows, which collect the stress of a pressurized cabin and can be prone to fracture. During one test, the Royal Aircraft Establishment found that up to 70 percent of the airplane’s stress was concentrated on the window's sharp angles.

Circular windows, which are able to disperse that pressure more evenly, immediately became the new standard in passenger aviation. And for every one you see, there are actually three panes at work: one bears the burden of pressurization, another inner pane acts as a failsafe in case the outer pane fails—which is rare—and one “scratcher” pane faces the occupant, so that you can smudge and dirty it up to your heart’s content.

As for that little hole at the bottom: It’s there to make sure the working pane takes the brunt of the air pressure, maintaining the emergency pane for, well, emergencies.

Mystery solved.

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History
How the Wright Brothers' Plane Compares to the World's Largest Aircraft
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The Wright brothers famously built the world’s first powered, heavier-than-air, controllable aircraft. But while the siblings revolutionized the field of aviation, their early plane looks tiny—and dare we say quaint-looking—when compared to the aerial giants that came after it.

In Tech Insider’s video below, you can see how the Wright brothers’ flyer stacks up against the scale of other aircrafts. You'll notice that size doesn't always guarantee a successful journey. The Hughes H-4 Hercules—the largest flying boat ever made—never made it past the prototype stage, performing only one brief flight in 1947. And the Hindenburg, which was 804 feet long and could fit 80 Olympic swimming pools, famously exploded on May 6, 1937.

Today’s longest commercial airliner is the Boeing 747-8, which measures 251 feet from nose to tail. While slightly shorter (238 feet), the Airbus A380 is certified to hold more people than any other plane in the air—a total of 850 passengers. That record won't last long, though: In a few years, the Stratolaunch carrier—the widest aircraft ever built—will dwarf its contemporaries when it takes to the skies in 2019. Built to launch rockets into orbit, its wingspan is about the size of a football field, even bigger than that of the Hughes H-4 Hercules.

Still, what the Wright brothers’ plane lacked in size, it made up for in ingenuity. Without it, these other giants may never have existed.

[h/t: Tech Insider]

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Microsoft’s Autonomous Gliders Stay in the Air by Mimicking Birds of Prey
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When designing different ways for vehicles to move, engineers will often look to nature. Animals have had millions of years to evolve locomotion methods that get them where they’re going fast without burning a ton of energy. Now, researchers at Microsoft have chosen the hawk, a master of energy-efficient air travel, as the model for their new autonomous gliders.

As Co.Design reports, the tech company’s “infinite soaring machine” can move through the skies without generating its own propulsion. Instead, it seeks out warms streams of air to provide the upward push, much like a hawk does.

While riding air currents doesn't take up a lot of energy, it does require some sophisticated artificial intelligence. As a substitute for millennia of animal instinct, Microsoft “trained” its glider to fly by plugging it into a video game-like simulator that showed hawks in flight. By repeatedly subjecting the technology to these virtual experiments, researchers eventually developed algorithms capable of recreating the scenes in the real world.

Using onboard sensors, the sailplane can independently navigate the skies without a motor. The gliders are no more than a few feet long, which means they don’t serve much of a practical purpose outside of research. But the aircraft’s simple design is exactly what makes them appealing to engineers.

With less hardware to worry about, they can focus on refining AI software which can be used in different types of autonomous vehicles in the future. And by testing AI navigation in the air instead of on the road, Microsoft gives themselves a much bigger test track to work with.

You can watch the infinite soaring machine take to the skies in the video below.

[h/t Co.Design]

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