经济学人下载:太阳能动力飞行 日间时刻

Science and technology
科学技术

Solar-powered flight
太阳能动力飞行

Its moment in the sun
日间时刻

An attempt to fly around the world in a solar-powered plane
尝试驾驶太阳能飞机环游世界

A REVOLUTIONARY solar-powered aircraft touched down recently at Moffett Airfield, in the heart of Silicon Valley.
一架革命性的太阳能飞机近日在硅谷中心的墨菲特联邦机场着陆。

No champagne corks were popped, however, for it arrived disassembled in the belly of a 747 cargo jet.
可却没有香槟酒庆贺，因为这是一架由波音747喷气式货机运输的解体飞机。

The aircraft will be reassembled by the end of March and then begin flight tests.
它会在三月底重新组装，继而进行飞行测试。

If all goes well, by May it should be ready to fly across America, stopping in four cities before landing in New York.
万事顺利的话，它将在5月底横越美洲，途径四座城市，最终抵达纽约。

However, this aircraft is just an experimental prototype for a much bigger exploit.
然而，人们希望利用这架供以实验的原型机实现更加宏伟的目标。

The team behind the project, called Solar Impulse, are using their prototype to learn what will be required to build a second aircraft capable of circumnavigating the globe using only the power of the sun.
作为此次计划的执行团队—太阳驱动，通过研究该原型机，获得了一系列能使太阳能飞机实现环球飞行的参数。

After carrying out a number of successful test flights of the prototype from their base at an airfield in Payerne, Switzerland, construction of their second aircraft began.
团队成员在位于佩耶纳某一机场的总部对原型机进行了一系列成功的飞行测试后，便开始着手建造第二架太阳能飞机。

But last July the Solar Impulse project suffered a big setback.
但就在去年七月，太阳脉冲团队遭受了一个巨大的挫折。

The second aircraft failed a critical safety check.
第二架飞机的一项关键性安全检查不达标。

Its main wing spar, the backbone of any aeroplane, broke during structural tests.
在结构测试中，支撑飞机的主翼梁发生了断裂。

There is always a risk of pushing technology too far when doing something new.
不切实际地尝试新技术总会留下隐患。

Bertrand Piccard, one of Solar Impulse's founders, had been in the same situation before and knew that success comes by learning from mistakes and moving on.
太阳驱动的创始人之一—伯特兰·皮卡德也曾深陷此境，他深知技术的推进只能是吃一堑，长一智。

In 1999 he co-piloted Orbiter 3, the first balloon to circumnavigate the globe.
1999年，皮卡德曾担任轨道飞行器3号的副驾驶，这是第一个实现环球飞行的热气球。

It was when he landed in the Egyptian desert with just 40kg of propane left from the 3.7 tonnes he had taken off with 20 days earlier that Mr Piccard decided his next challenge would be to repeat the flight using no fuel at all.
在飞行了20天以后，气球在埃及的沙漠中着陆，此时原本携带的3.7吨丙烷就只剩下40千克，这激发了皮卡德向无燃料环球飞行发起挑战。

He teamed up with Andre Borschberg, a fighter pilot and engineer, to form the Solar Impulse project.
于是他与战斗机飞行员兼工程师—安德烈·博尔施伯格通力合作，共同发起了太阳驱动计划。

Mr Piccard comes from a line of adventurers.
皮卡德来自探险之家。

His grandfather, Auguste, was the first to fly a balloon into the stratosphere.
他的祖父，奥古斯特，是驾驶气球飞入平流层的第一人。

His father, Jacques, plunged to record depths in a deep-sea submersible.
而他的父亲，雅克，专注于深海潜探，并创造了下潜深度的历史记录。

Making the most of it
万般皆有用

The problem with the wing spar has set back the team a year.
这个团队花费了一年时间来解决翼梁故障。

Making a new one, completing the second aircraft and waiting for suitable weather means that the round-the-world flight is now scheduled for 2015.
在实现环球飞行之前，他们必须制造一架新飞机，完成第二架飞机的组装，在适宜的天气下试航，所有这一切都要在2015年才能完成。

In the meantime, the team decided to make the best of their enforced delay by flying their prototype across America.
与此同时，尽管受客观条件制约，团队成员还是决定利用此次机会驾驶原型机飞跃美洲。

This will provide more valuable operating experience and help with the development of the technologies they will need.
此举不仅能提供更多弥足珍贵的操作经验，还能推动所需技术的改良。

Plus, if anything goes wrong, it is easier to land on dry land than the ocean.
再者说，如果飞行遭遇意外，陆地着降总要比海面着降轻松许多。

Solar-powered aircraft are not new.
太阳能飞机由来已久。

One of the earliest, Solar Challenger, flew across the English Channel in 1981.
早在1981年，太阳挑战号就成功飞越英吉利海峡。

It was built by the late Paul MacCready, an American aeronautical engineer.
这架飞机由已故美国航空工程师保罗?麦卡克莱迪建造。

Its 14.3-metre wing was covered in photovoltaic cells.
其14.3米长的机翼上布满了光生伏打电池。

These powered two electric motors, which in turn drove a single propeller.
推动唯一螺旋桨发动的两台电动机正是由这些电池供电。

The Solar Impulse project is a very different beast.
然而太阳驱动计划却开辟了一片新天地。

The prototype aircraft which will fly across America has a wingspan of 63.4 metres, which is as big as a jumbo jet's.
飞越美国的原型机翼展宽达63.4米，与巨型喷气式飞机同宽。

Yet its fuselage is as slender as a glider's and its single-person cockpit is cramped.
而其机身却与滑翔机一般大小，窄小的驾驶舱只能容下一名飞行员。

The wings are covered in almost 12,000 photovoltaic cells, which can simultaneously run its four electrically driven propellers while charging four packs of lithium-polymer batteries.
机翼覆盖着12000块光生伏打电池，在为四组锂聚合物电池充电的同时，还能一同支撑四个电驱动螺旋桨运转。

The batteries are needed because the aircraft has to be able to fly through the night.
之所以携带电池，是因为飞机需要在晚间飞行。

The second aircraft will have to do that non-stop for five-to-six days at a time.
第二架在建的环球航行飞机需实现一连5、6天不间断飞行。

The plan is to take off in an easterly direction and land on every continent that touches the Tropic of Cancer.
飞机将于东部地区起飞，随后在北回归线附近的每一块陆地降落。

This will involve long flights across oceans.
期间包括漫漫的洋面飞行。

With only as much power as a motor scooter, the planned aircraft will cruise at just 70kph.
按计划飞行动力与小型摩托车一般，因而只能以70km/h的速度匀速行驶。

Its ultimate range will be limited by the physical ability of the pilot to remain alert, with little room to move or to store much food and water.
狭小的机内空间，加之有限的食物与饮用水，飞机的最大航行距离就完全取决于飞行员自身的身体素质。

With current technology, the team reckon, a two-person solar plane would be too heavy.
团队成员认为，以目前的技术，双驾驶太阳能飞机负重过大。

To give Mr Piccard and Mr Borschberg room to exercise and lie down, the next aircraft will be about 15% bigger than the prototype, which tips the scales at just 1,600kg.
为了给皮卡德和博尔施伯格足够的空间移动和躺卧，新的飞机将比原型机大15%，总重达1600千克。

Weight is the critical factor.
重量是关键性问题。

The wing spar that broke had been redesigned with an ultralight carbon-fibre process to shed the grams.
先前破损的翼梁用超轻型碳纤维材料重新打造以降低克重。

But we went too close to the limits, confesses Mr Borschberg.
博尔施伯格不得不承认，这已是我们所能之极限。

There is little scope for a full autopilot system, and it would weigh too much.
完整的自动驾驶系统会使飞机不堪重负。

However, Altran, an engineering consultancy based in France and one of the project's supporters, is developing a partial system.
不过项目支持商之一的法国Altran工程咨询公司，部分解决了自动驾驶问题。

In calm weather, it will keep the aircraft pointing in the right direction.
风和日丽之时，这套系统会帮助飞机沿着正确的方向前行。

And if turbulence causes a wing to dip by more than five degrees, a cuff on the pilot's right or left arm will vibrate to tell him which way to correct course.
如若飞机机翼受气流影响下沉角度超过5度，它就会通过振动驾驶员某一膀臂上的袖带来指引正确的行驶方向。

He must react quickly to keep control.
驾驶员的反应速度决定着飞机平稳与否。

This system will be tried out on the prototype flight in America.
这套系统将在横越美洲的原型机上试用。

The ground crew can monitor both the flight and the pilot with telemetry.
地勤人员可以通过遥测装置对飞机和飞行员进行监控。

When circumnavigating the globe the pilot will be able to lower a seat to lie down and take catnaps of up to 20 minutes.
在环球飞行时，飞行员可以将座位调低，这样便可以躺在上面小憩20多分钟。

That is enough, the team calculate, to ward off some of the effects of sleep deprivation.
团队成员通过计算认为这些时间足够抵御睡眠不足带来的不利影响。

The pilot must not be too groggy if he has to swing suddenly into action.
当飞行员突然驾驶时，他一定不可以过于疲劳。

This procedure has been tested in a flight simulator for 72 hours non-stop, and seems to work.
这套流程已在模拟飞行器中进行了72小时不间断测试，效果卓著。

A typical flight involves taking off in the early morning, when winds are light, and ascending to 10,000 metres to stay above any stormclouds.
普通的飞行包括在风速平稳的清晨起飞，随后上升至10000米的高空以躲避暴风云层。

At this altitude, though, the air is thin and an oxygen supply is needed.
由于海拔较高，空气稀薄，必须提供足够的氧气。

The pilot has to wear an oxygen mask because pressurising the cockpit, as an airliner does with air from its jet engines, is not possible.
飞行员只得佩戴氧气罩，因为太阳能飞机无法像普通大型客机那样利用喷气引擎的气流保持驾驶舱的气压平稳。

Nor do the team want to carry heavy oxygen cylinders.
氧气瓶也因为过于沉重而不切实际。

As an alternative Air Liquide, an industrial-gases firm, is developing a solar-powered system to generate oxygen.
与法国液化空气公司类似的一家工业用气公司正在研制如何利用太阳能产生氧气。

At night the pilot descends slowly, carefully using up the power until dawn.
夜晚时，飞机缓缓下降，在黎明前用尽所有燃料。

Once the sun returns the batteries can recharge in three hours as the plane ascends again.
当太阳升起时，电池会在三个小时内充满，然后飞机便再次起飞。

Landings are also left until the early evening, when winds are light.
同起飞一样，降落也挑选在风速平稳的傍晚。

The flight across America will give the team's meteorologists an opportunity to see how their weather models stand up.
飞越美洲的航行也可以验证团队中气象学家的天气模型是否成立。

Sometimes it is necessary for the pilot to delay a landing to wait for optimum conditions.
有时，飞行员必须延迟降落时间以寻求最佳时机。

Mr Piccard and Mr Borschberg have learned an interesting technique to do that.
皮卡德和博尔施伯格用一种有趣的方式进行观察。

Flying slowly, they turn the nose into a headwind, which can make the aircraft fly backwards.
他们会逆风缓慢飞行，这样飞机就会受气流影响向后移动。

It is not the sort of thing to try in a jumbo jet.
而这在巨型喷气式飞机上是不可想象的。