Space & Innovation

What Makes Airplanes Light Enough To Fly?

The materials used to build aircraft have changed a lot since the advent of flight. How do engineers choose what airplanes are made of?

There comes a moment in every airline passenger's travels when the thought occurs: Wait -- this plane weighs several hundred tons. How are we flying through air, again?

Airlines have developed strategies to counter this moment of doubt. But there's plenty of science to help you feel better, too, as Lissette Padilla explains in this DNews dispatch. Aside from interesting physics, there's the matter of lightweight metals.

Aircraft manufacturer Boeing recently unveiled what it's calling the world's lightest metal -- a microlattice structure that's strong, durable and actually around 99.99 percent air. Boeing hopes that the ultralight metal will mark a major shift in aircraft manufacturing.

Boeing's new metal is the latest in a long line of material science innovations driven by the airline industry. Aeronautical engineers have been tinkering with metal elements and alloys since the beginning of commercial air flight. For many decades, aluminum was the go-to option for aircraft.

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Aluminum has many qualities that make aircraft engineers happy: It's relatively strong, extremely light and resists corrosion. Forty years ago, as much as 70 percent of a given aircraft was made from pure aluminum. That number is down to about 20 percent today, largely due to the development of aluminum alloys.

The most common alloy used in aircraft manufacturing is called 7075, which uses a little zinc, magnesium and copper as well as trace amounts of manganese, silicon, iron, titanium, and other metals. New techniques for machining metal have resulted in nanocomposites with improved optical, electrical and magnetic properties.

A huge benefit of composites is that, apart from being light and strong, they can be molded into complex shapes. This reduces the need for heavy fasteners or joints, which are potential failure points.

So next time you're pondering that inevitable question at 30,000 feet, keep in mind that you're surrounded by several hundred different varieties of lightweight metals. Airplanes are heavy, but they're nowhere near as heavy as they could be.

-- Glenn McDonald

Read More:

Aerospace Manufacturing and Design: Aerospace materials - past, present, and future

USA Today: Dreamliner designed so fliers can breathe easy

Discovery News: Fusion Reactor Powers Futuristic Airliner