首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
Copying Birds May Save Aircraft Fuel Both Boeing and Airbus have trumpeted the efficiency of their newest aircraft, the 787
Copying Birds May Save Aircraft Fuel Both Boeing and Airbus have trumpeted the efficiency of their newest aircraft, the 787
admin
2022-12-06
34
问题
Copying Birds May Save Aircraft Fuel
Both Boeing and Airbus have trumpeted the efficiency of their newest aircraft, the 787 and A350 respectively. Their clever designs and lightweight composites certainly make a difference. But a group of researchers at Stanford University, led by Han Kroo, has suggested that airlines could take a more naturalistic approach to cutting jet-fuel use, and it would not require them to buy new aircraft.
The answer, says Dr. Kroo, lies with birds. Since 1914, scientists have known that birds flying in formation—a V-shape—expend less energy. The air flowing over a bird’s wings curls upwards behind the wingtips, a phenomenon known as upwash. Other birds flying in the upwash experience reduced drag and spend less energy propelling themselves. Peter Lissaman, an aeronautics expert who was formerly at Caltech and the University of Southern California, has suggested that a formation of 25 birds might enjoy a range increase of 71%.
When applied to aircraft, the principles are not substantially different. Dr. Kroo and his team modelled what would happen if three passenger jets departing from Los Angeles, San Francisco and Las Vegas were to assemble over Utah, assume an inverted V-formation, occasionally change places so all could have a turn in the most favourable positions, and proceed to London. They found that the aircraft consumed as much as 15% less fuel (coupled with a reduction in carbon-dioxide output). Nitrogen-oxide emissions during the cruising portions of the flight fell by around a quarter.
There are, of course, knots to be worked out. One consideration is safety, or at least the perception of it. Would passengers feel comfortable travelling in companion? Dr. Kroo points out that the aircraft could be separated by several nautical miles, and would not be in the intimate groupings favoured by display teams like the Red Arrows. A passenger peering out of the window might not even see the other planes. Whether the separation distances involved would satisfy air-traffic-control regulations is another matter, although a working group at the International Civil Aviation Organisation has included the possibility of formation flying in a blueprint for new operational guidelines.
It remains to be seen how weather conditions affect the air flows that make formation flight more efficient. In zones of increased turbulence, the planes’ wakes will decay more quickly and the effect will diminish. Dr. Kroo says this is one of the areas his team will investigate further. It might also be hard for airlines to co-ordinate the departure times and destinations of passenger aircraft in a way that would allow them to gain from formation flight. Cargo aircraft, in contrast, might be easier to reschedule, as might routine military flights.
As it happens, America’s armed forces are on the case already. Earlier this year the country’s Defence Advanced Research Projects Agency announced plans to pay Boeing to investigate formation flight, though the programme has yet to begin. There are reports that some military aircraft flew in formation when they were low on fuel during the Second World War, but Dr. Lissaman says they are unsubstantiated. "My father was an RAF pilot and my cousin the skipper of a Lancaster lost over Berlin," he adds. So he should know.
Formation flight is more comfortable because passengers can not see the other planes.
选项
A、True
B、False
答案
F
解析
复现结构。分析本题的关键线索,发现本题主要提及了Formation flight、comfortable和passengers,即Formation flight is more comfortable because passengers can not see the other planes. 据此去原文定位,确定原文第四段有几处提及了这些线索,第四段开头提到有很多问题需要解决,其中一个就是飞机结伴飞行时乘客是否会感到舒服,由此可知,该问题目前还没有得到解决,而题干中说会更舒服,因此不符合原文意思。故本题答案为F。
转载请注明原文地址:https://kaotiyun.com/show/lnMD777K
0
考研英语二
相关试题推荐
[A]Workforyourdream[B]Apennysavedisapennyearned[C]Don’tcompareyourselftoothers[D]Betruetoyou
Skepticsofhighereducationoftencomplainthatuniversitiesoffertoomanyboringdegreeswithlittlevalueintheworkplace.【
Skepticsofhighereducationoftencomplainthatuniversitiesoffertoomanyboringdegreeswithlittlevalueintheworkplace.【
A.HelptodetectasuspectB.DiscoverthepotentialhealthproblemsearlierC.RevealtheunknownsofthefamilyD
CopyingBirdsMaySaveAircraftFuelBothBoeingandAirbushavetrumpetedtheefficiencyoftheirnewestaircraft,the787
Inourcontemporaryculture,theprospectofcommunicatingwith—orevenlookingat—astrangerisvirtuallyunbearable.Everyone
Inourcontemporaryculture,theprospectofcommunicatingwith—orevenlookingat—astrangerisvirtuallyunbearable.Everyone
Inourcontemporaryculture,theprospectofcommunicatingwith—orevenlookingat—astrangerisvirtuallyunbearable.Everyone
[A]Staycalm.[B]Stayhumble.[C]Don’tmakejudgments.[D]Berealisticabouttherisks.[E]Decidewhethert
随机试题
内镜下微波凝固疗法可用于晚期胃癌的辅助治疗。
适用于膝关节伸展不良、膝过度伸展、肌肉无力患者的是
吲哚试验检测的细菌代谢产物是
慢性肾炎主要病变部位是
清热解毒定惊,治高热动风,小儿急惊宜选
环境质量评价,是()。
我国国家预算实行一级政府一级预算。现设立中央、省(自治区、直辖市),设区的市(自治州)、县(不设区的市、自治县、市辖区)、乡(民族乡、镇)五级预算。()
民事行为部分无效,不影响其他部分的效力的,其他部分仍然有效。()
教师的教育、教学能力属于()。
在管制过程中,人民警察可以采取必要手段强制驱散,并对拒不服从的人员()。
最新回复
(
0
)