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  • Modern day fighter jets can travel faster than the speed of sound without breaking a

  • sweat, but until, 70 years ago on October 14 of 1947; no human had ever traveled that

  • fast.

  • Those who came close saw their aircraft become uncontrollable, or shake themselves to pieces,

  • leading some to believe that manned flight faster, than the speed of sound, was impossible.

  • There seemed to be a “sound barrier.”

  • And we wanted to break it.

  • You may be wondering why the speed of sound is important in aviation at all, and to understand

  • that you have to remember what sound is in the first place.

  • Watching a wave travel down a slinky is a good visualization.

  • In a gas, sound travels as a longitudinal wave, meaning that it propagates when air

  • molecules bunch together and then space out again.

  • Watching a wave travel down a slinky is a good visualization.

  • [pause]

  • As planes fly through the air, they create sound waves.

  • But if the planes go fast enough, they start to catch up with their own sound waves.

  • Air molecules get rammed into each other faster than they can get out of the way, and the

  • waves pile up to form a powerful shock wave -- that famous sonic boom observers hear when

  • a supersonic jet goes by.

  • But, the sudden and extreme air pressure is just the start.

  • As the air behind the shock wave breaks up in a turbulent wake, it can swirl and violently

  • slap at different parts of the plane, causing buffeting and increased drag.

  • For the airplanes of old, this was bad news.

  • First, there was the problem of the propulsion system.

  • As a propeller spins, the tips of the blades can actually break the sound barrier.

  • When that happens, the air starts swirling and increasing drag, and the prop's efficiency

  • drops.

  • Maybe these problems could be overcome with a radically different propeller design, but

  • by the end of WWII, rockets had advanced and the jet engine had been invented, so there

  • wasn't much point trying to force the poor propeller to do a job it wasn't suited for.

  • Even with the jet engine replacing old propellers, there was another problem to overcome at speeds

  • close to the speed of sound: the wings.

  • Wings on old aircraft were straight as a 2x4 and when we were puttering around at subsonic

  • speeds, they worked just fine.

  • But when airplanes are right around that magical sound barrier, at what's known as transonic

  • speeds, the airflow over straight wings does something you might not expect.

  • Namely, it actually goes faster than the speed of sound.

  • This makes sense when you consider how a wing fundamentally works.

  • They've got that curved shape on top to make the air on that side travel faster.

  • But if the air on top of the wing goes faster than the speed of sound it'll form, you

  • guessed it, a shock wave.

  • And just like before, the air behind that shock wave gets all turbulent as it expands,

  • increasing drag dramatically and maybe even separating airflow from the wing's surface

  • altogether.

  • Which is bad.

  • So, the solution was as simple as it was genius: sweep the wings back.

  • By placing the wings at an angle, some of the air travels down the wingspan, and the

  • rest accelerates across the wing more slowly, so the aircraft can fly faster before running

  • into the problems of a shock wave on the wing.

  • That means the fighter jet doesn't have to work as hard to break through the sound

  • barrier completely, and when it does shock waves that form on top of the wing travel

  • to the trailing edge where they cause less drag.

  • With powerful jet engines and swept wings, the sound barrier that once seemed so solid

  • is now routinely smashed.

  • It makes you wonder what other things that seem impossible today will be routine in the

  • future.

  • For more epic stories of innovation that shaped our future, check out TheAgeOfAerospace.com

  • If you liked this video I vote you go ahead and subscribe.

  • Did you know it's possible to create something like a sonic boom but with light waves?

  • No?

  • Trace explains how, here.

  • What's the next big innovation you'd like to see in flight?

  • Low earth orbit passenger routes?

  • Affordable supersonic transport?

  • Wider arm rests?

  • Let us know in the comments and I'll see you next time on Seeker.

Modern day fighter jets can travel faster than the speed of sound without breaking a

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让我们飞得比音速快的简单发现(The Simple Discovery That Let Us Fly Faster Than the Speed of Sound)

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    joey joey 發佈於 2021 年 04 月 28 日
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