静如鬼魅：新型离子推进飞机不用螺旋桨
When Wilbur and Orville Wright’s famous airplane, the Wright Flyer, first flew in 1903 it must have made quite a racket, with its crude gasoline engine spinning twin propellers via drive chains.
1903年，威尔伯·莱特和奥维尔·莱特的著名飞机"莱特飞行者"首次试飞时，其粗糙的汽油发动机通过传动链旋转着两个螺旋桨，肯定制造了不小的噪音。
Nearly 115 years later, another type of plane has taken flight as quiet as a ghost, without a single moving part.
近115年后，另一种类型的飞机在没有任何移动部件的情况下，却可以像幽灵一样安静地飞行。
The new type of aircraft could usher in silent drones and perhaps far simpler planes—if researchers can overcome the daunting task of scaling up the technology.
如果研究人员能够克服把这项技术规模扩大这种艰巨任务，这种新型飞机可能会带来无人驾驶飞机，或许还会出现更简单的飞机。
Instead of relying on a propeller or a jet engine, the plane, about the size of a single-person kayak, pushes itself through the air using electroaerodynamics (EAD).
与螺旋桨或喷气发动机不同，这架单人皮划艇大小的飞机利用电空气动力学(EAD)在空中推进，而不是依靠螺旋桨或喷气发动机。
This form of propulsion uses electric effects to send air backward, giving the plane an equal push forward.
这种推进方式是利用电的作用将空气向后送，从而给飞机一个等大的推力。
Aeronautical engineers have long theorized that planes could be powered by EAD, says Steven Barrett, an aeronautical engineer at the Massachusetts Institute of Technology (MIT) in Cambridge.
位于剑桥的麻省理工学院(MIT)的航空工程师史蒂芬·巴雷特(Steven Barrett)说，航空工程师们长期以来一直认为飞机可以由电空气动力学提供动力。
But no one had ever constructed an EAD plane capable of lifting its own weight.
但是还从来没有人造出过能够支撑自身重量的EAD飞机。
When Barrett and colleagues finally succeeded, they stood in awed silence, he says.
巴雷特说，当他和同事们终于成功时，他们都惊讶得说不出话来。
"It had taken about 7 years of work just to get off the ground.”
“让它能够离地起飞花了我们七年的时间。”
In an EAD propulsion system, a strong electric field generates a wind of fast-moving charged particles called ions, which smack into neutral air molecules and push them behind the plane, giving the aircraft a push forward.
在EAD推进系统中，一个强大的电场会产生一种叫做离子的快速移动带电粒子风，这些带电粒子会撞击中性空气分子，把中性空气分子推到飞机后面，给飞机一个推力。
The technology—also called ion drive, ion wind, or ion propulsion—has already been developed for use in outer space by NASA, and is now deployed on some satellites and spacecraft.
这项技术—也被称为离子驱动、离子风或离子推进—已经被美国国家航空航天局开发用于外太空，现在已经部署在一些卫星和航天器上。
Because space is a vacuum, these systems bring along a fluid, like xenon, to ionize, whereas Barrett’s aircraft is designed to ionize nitrogen molecules in the ambient air.
由于太空是真空的，这些系统会携带一种像氙这样的液体来电离，而巴雷特的飞行器则被设计用来电离周围空气中的氮分子。
The team tested the airplane inside a gymnasium at MIT, working at odd hours to avoid running into sports teams.
该团队在麻省理工学院的一个体育馆对这架飞机进行了测试，为了避免撞上运动队，他们在球队休息的时间工作。
“There were some pretty epic crashes,” Barrett says.
巴雷特说:“发生了一些非常严重的坠机事故。”
Eventually, the team devised a slingshotlike apparatus to help launch the aircraft.
最终，研究小组设计了一种类似弹弓的装置来帮助发射飞机。
After hundreds of failed attempts, the aircraft was finally able to propel itself enough to remain airborne.
经过数百次失败的尝试，这架飞机终于能够推动自己飞起来了。
Over 10 test flights, the plane flew up to 60 meters, a little farther than the Wright brothers’ first flight, in about 10 seconds, with an average altitude of half a meter, the researchers report this week in Nature.
研究人员本周在《自然》(Nature)杂志上报道称，经过10多次试飞，这架飞机在大约10秒钟内飞行了60米，比莱特兄弟的第一次飞行更远一些，平均高度为半米。
Drew thinks we’re more likely to one day see a swarm of smaller EAD aircraft.
德鲁教授认为我们更有可能在未来看到一群小型的EAD飞机。
In that context, Barrett thinks the biggest advantage of EAD aircraft will be the lack of noise.
在这种情况下，巴雷特认为EAD飞机最大的优点是噪音小。
“If we want to use drones all around our cities for delivering things and monitoring air quality, all that buzzing and noise pollution would get quite annoying.”
“如果我们想在城市里到处使用无人机运送物品和监测空气质量，那么嗡嗡声和噪音污染就会变得相当恼人。”
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