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直升机的飞行奥秘 – 译学馆
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直升机的飞行奥秘

How Do Helicopters Fly Without Wings?

直升机看着像背上长着旋转脚的胖虫子
Helicopters kinda look like fat bugs lyingon their backs flailing their legs around…
所以为何直升机能比飞机更精准的飞行呢?
so how exactly can they fly with more precisionthan an airplane?
飞机能够飞行 是因为它们机翼的形状是上弧下扁的
Airplanes fly because their wings are curvedon the top and flat on the bottom, allowing
所以得以利用伯努利原理
them to harness the Bernoulli Principle.
随着速度的增加 产生浮力时机翼上方的空气密度小于机翼下方
With speed, the air passing over the wingis less dense than the air under it, creating lift.
直升机的水平旋翼也提供了浮力
Helicopters have rotor blades that also createlift.
旋翼的旋转带动空气流动
As the blades spin they move the air.
低密度空气流过旋翼上方的同时高密度空气从下方通过
Less dense air passes over the blades withdenser air passing underneath it.
听起来很简单但是操作起来很难
Put that way it sounds simple, but it’sfar more complicated, because while airplanes
因为飞机的浮力是在空气中自然运动得到的而直升机不得不自发产生
get lift naturally by moving through the airhelicopters have to constantly generate it themselves.
所以它们能起飞 垂直降落 倒飞 转弯和原地盘旋
This is how they can takeoff and land vertically,and also fly backwards, sideways, and hover in place.
但是如果部件故障它们就不能滑翔因为没有飞机那样的空气动力
But they can’t glide if something goes wrong;they aren’t aerodynamic like planes.
直升机借助纯粹蛮力飞行 确实难以置信但也给他们带来了一些限制
Helicopters fly by sheer brute force, whichis really incredible, but gives them some limits.
飞机可以倒置 机翼是固定的这意味着空气流过机翼
Planes can fly upside-down — the fixed wingmeans that as long as air is moving over the
向上轻微的倾斜机鼻仍然有浮力
wing, usually by tilting the nose upwardsslightly, it still has lift.
当直升机转动水平旋翼时产生随浮力方向向上移动的推力
As a helicopter’s rotor spins, the generatedthrust moves upwards with the direction of
因此上下颠倒会要求旋翼进行重定向
lift, so flying upside-down would demand redirectingthe blades so the thrust is the opposite way,
颠倒机体需要反方向推力的支持
supporting an upside-down vehicle.
这意味着如果速度足够快直升机可以在飞行中横向翻滚
That said, a helicopter could fly a barrelroll if it was moving fast enough, but that’s
但只是个噱头只可能在新机飞越城市上空 做特技表演时看到
a stunt you’re more likely to see at anairshow than from a news helicopter over a city.
说到直升机飞越城市你总能知道它何时飞到哪了
Speaking of helicopters over cities, you alwaysknow when one is out there.
因为它们很响
Because they’re loud.
它们很响不是因为引擎而是旋翼间气流分裂的结果
They’re loud not because of the engine,but because the blades are running into turbulence
这被称为涡流噪声
from each other, properly called the blade–vortexinteraction: the tips of the rotor blades
旋翼的尖端在空气中摆动振动时会发出噪声
vibrate against the air as they whip around.
飞机机翼已经变化多次现有可变形襟翼以应对各种飞行环境
Airplane wings have changed overtime to haveflaps and malleable shapes that react to flight conditions.
直升机也做了一些改进变化动旋翼和翼尖的形状
Helicopters have done this too; differentblade shapes, tip shapes, and even materials
甚至为了减少噪声而改进旋翼材料
have shown to decrease the noise of a helicopter.
其中一种旋翼为了减少涡流噪声
One kind of blade has flaps on edge of thatmove 15 to 40 times a second to reduce the
在边缘装有每秒扇动15到40次的襟翼
noisey blade-vortex interaction.
甚至美国航空航天局也在开发更优旋翼来为机身降躁
Even NASA is looking into developing betterblades for a quieter helicopter, looking to
也许未来直升机可以扩充载客量 往返城市间
a future where larger, versions can carrya sizable passenger load between cities.
无跑道的通勤直升机可限制空中交通堵塞
Without runways, commuter chopper flightscould limit air traffic congestion.
但是单旋翼的直升机只能承载一定的重量
But helicopters with one rotor can only liftso much.
这就是为什么像支奴干这样更大的直升机有两个旋翼
Which is why bigger choppers like the Chinookhave two.
更多的旋翼能提供更多的浮力但它也增加了机身的重量和复杂性
More blades can provide more lift, but italso adds weight and complexity.
对一架较重的直升机来说附旋翼的额外浮力有时至关重要
For a heavier helicopter the extra lift fromthe added blades is sometimes vital.
不仅为了炫酷 也是为了实用
Not only do those look cool, but they’reuseful.
成就直升机该有的样子
Just like a helicopter should be.
如想了解更多塑造未来的史诗级创新请访问航天时代网站
For more epic stories of innovation that shapedour future, check out TheAgeOfAerospace.com
说到飞行 为什么会有人晕机呢?
Speaking of flying, every wonder why we getairsick?
在下个视频里会有答案
We’ve got the answer in this video righthere.
你对直升机还有什么问题吗?
Do you still have questions about helicopters?
在评论中提出你的疑问如果你喜欢我们的视频 请给我们点赞
Let us know in the comments, be sure to likethis video, and subscribe for more Seeker.

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视频概述

直升机是如何飞翔的?他如何能做出上下左右翻滚的飞行动作?两个螺旋桨的直升机你见过吗?答案尽在本视频中

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视频来源

https://www.youtube.com/watch?v=pVMT4hqFzQg

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