CLOSE
Original image
Flickr User Tony Webster // CC BY 2.0

How Do Power Outlets On An Airplane Stay Grounded?

Original image
Flickr User Tony Webster // CC BY 2.0

Airlines know we can’t go a few hours without our precious electronic devices, which is why many airplanes feature power outlets to help people stay plugged-in. Being able to charge your laptop like you would at home is a perk, but how is the electrical socket grounded when you’re 35,000 feet above the Earth?

A plug's grounding pin and the corresponding hole you see on an outlet you have at home is there for safety. In case of a lightning strike or power surge, that prong is connected to the Earth, which gives the excess electrical current somewhere to go besides an appliance (or through you while you are holding said appliance). Wiring airplane power outlets to the Earth below is obviously out of the question, so something else has to take the ground's place as a conductor to dissipate electric current. Luckily, an aircraft’s metal frame is perfectly suited for the job.

“If the third pin (‘ground’) on the receptacle were connected at all, it would be to the metallic structure of the airplane,” electrical engineer Roger L. Boyell tells mental_floss over email.

Grounding, after all, is just a term. As long as it can complete its circuit, electricity couldn’t care less about where the Earth is.

“Grounding on the airframe is analogous to grounding to the Earth,” turbomachinery expert Steven B. Kushnick tells mental_floss, also over email. To electricity, the airplane’s metal frame is a much more desirable conductor than a person, and any time there is stray or excess current, it will always take the easiest path.

Kushnick explains it thusly:

If you had one hand on the stainless steel sink in the lavatory (ground); and one hand on, perhaps, an electric razor that is plugged in and properly wired with a ground-prong, then stray electric currents would have no ‘desire’ to enter your razor-holding hand to get to your sink-touching hand (and shock you in the process) because the stray currents have a shorter circuit to travel: through the ground-prong to ground (airframe).

This remains true even in the event of lightning strikes. “Modern airplanes are frequently hit by lightning,” Boyell says. “Their skin is made electrically conductive to pass the current, much like through a wire, with no effect.” At most, this could “leak through to induce an electromagnetic field inside the airplane,” Boyell says, adding that it “could momentarily disrupt electronic instruments.” Even still, “an electrical device will be unaffected by whether it is plugged into a power outlet on the airplane or not.”

arrow
History
When Chuck Yeager Tweeted Details About His Historic, Sound Barrier-Breaking Flight

Seventy years ago today—on October 14, 1947—Charles Elwood Yeager became the first person to travel faster than the speed of sound. The Air Force pilot broke the sound barrier in an experimental X-1 rocket plane (nicknamed “Glamorous Glennis”) over a California dry lake at an altitude of 25,000 feet.

In 2015, the nonagenarian posted a few details on Twitter surrounding the anniversary of the achievement, giving amazing insight into the history-making flight.

For even more on the historic ride, check out the video below.

Original image
arrow
History
How the Wright Brothers' Plane Compares to the World's Largest Aircraft
Original image

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]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios