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Mar 25th 2009
From Economist.com Blimps equipped with remote-sensing electronics are cheaper than drones Aerostar International SPYING is supposed to be a sophisticated operation. But that can make it expensive. Gathering military intelligence using unmanned aircraft can be prohibitively so. Predator and Global Hawk, two types of American drone
（无人驾驶飞机） frequently flown in Afghanistan and Iraq, cost, respectively, about $5,000 and $26,500 an hour to operate. The aircraft themselves each come in at between $4.5m and $35m, and the remote-sensing equipment they carry can more than double the price. Which is why less elegant but far cheaper balloons are now being used instead.（这句话不完整，是不是ECO前面的，用错了？） Such blimps（小型飞船，有时候也可以指代一个人很老顽固） can keep surveillance
（监视监督） and ordnance-guiding（大炮的监管） equipment aloft for a few hundred dollars an hour. They cost hundreds of thousands, not millions, of dollars. And they can stay aloft for more than a week, whereas most drones fly for no more than 30 hours at a time. They are also easy to deploy（部署
调动）. No airfield is needed. A blimp can be stored in the back of a jeep, driven to a suitable location, launched in a couple hours and winched down even faster. Unlike other aircraft, blimps do not need to form a precise aerodynamic（空气动力的） shape. This means they can lift improbable objects into the sky, such as a dozen metres of dangling（摇晃） radar equipment.（在说到一个地方的时候会有解释） At altitudes of just a few hundred metres, a blimp carrying 20kg of remote-sensing electronics (including radar and infrared thermal-imaging cameras（红外线热成像相机）) can seek out, track and provide images of combatants dozens of kilometres away—day or night. It can also help commanders to aim the lasers that guide their missiles. Blimps often operate beyond the range of machine guns and rocket-propelled grenades
（掷弹兵）. Even if they are hit, though, they do not explode because the helium
（He） that keeps them lighter-than-air is not inflammable（易燃的） (Engineers abandoned the use of hydrogen in 1937 after the Hindenburg, a German airship, was consumed by flames in less than a minute.) Moreover, they usually stay aloft even when punctured: the pressure of the helium inside a blimp is about the same as that of the air outside it, so the gas does not rush out. Indeed, towards the end of 2004, when a blimp broke its tether
（拴住） north of Baghdad and started to drift towards Iran, the American air force had some difficulty in shooting it down. At least 20 countries use blimps—both global military powers, such as America, Britain and France, and smaller regional ones, including Ireland, Pakistan, Poland and the United Arab Emirates. Many are employed in Iraq. In November 2008 Aerostar International of Sioux Falls, South Dakota, began filling a $1.8m order for 36 blimps to be deployed by American forces in Iraq. But Afghanistan may prove a bigger market. That is because it is difficult to pick satellite signals up directly in the valleys of that mountainous country. As a result blimps, adjusted to hover at appropriate heights, are often used to relay data to and from satellites. As politicians around the world seek to cut public spending, the attractions of blimps are growing. In January America’s defence secretary, Robert Gates, told the Senate’s armed-services committee that the Department of Defence would pursue greater quantities of “75% solutions” that could be realised in weeks or months instead of “99% exquisite systems” that would take more than a decade to develop. Barry Watts, an analyst at the Centre for Strategic and Budgetary Assessments, a think-tank（智囊团） in Washington, DC, says America’s air force has been criticised by officials at the Pentagon for not providing enough aerial data to “insatiable” ground forces. Blimps, Mr Watts reckons(正式会员), will help them to sate that appetite. | 
发表于 2009-3-26 13:53:47
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