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
111
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.
The upwash experience may save propelling energy as well as reducing resistance.
选项
A、True
B、False
答案
T
解析
复现结构。分析本题的关键线索,发现本题主要提及了upwash experience的概念,即The upwash experience may save propelling energy as well as reducing resistance. 据此去原文定位,确定原文第二段在阐述这个概念,再对第二段进行对比分析,发现第二段明确说明了upwash experience reduced drag and spend less energy propelling themselves,这个意思符合本题的表述。因此本题的答案为T。
转载请注明原文地址:https://kaotiyun.com/show/enMD777K
0
考研英语二
相关试题推荐
Peoplegenerallyassumethatwhentheyconsideranotherpersona"friend,"thatpersonalsothinksofthemasafriend,whichme
Skepticsofhighereducationoftencomplainthatuniversitiesoffertoomanyboringdegreeswithlittlevalueintheworkplace.【
Everyonewantstobeauthentic.Youwanttobetruetoyourself,notaslavishfollowerofsocialexpectations.Youwantto"liv
Everyonewantstobeauthentic.Youwanttobetruetoyourself,notaslavishfollowerofsocialexpectations.Youwantto"liv
CopyingBirdsMaySaveAircraftFuelBothBoeingandAirbushavetrumpetedtheefficiencyoftheirnewestaircraft,the787
Inourcontemporaryculture,theprospectofcommunicatingwith—orevenlookingat—astrangerisvirtuallyunbearable.Everyone
Inourcontemporaryculture,theprospectofcommunicatingwith—orevenlookingat—astrangerisvirtuallyunbearable.Everyone
[A]Staycalm.[B]Stayhumble.[C]Don’tmakejudgments.[D]Berealisticabouttherisks.[E]Decidewhethert
Happypeopleworkdifferently.They’remoreproductive,morecreative,andwillingtotakegreaterrisks.Andnewresearchsugge
随机试题
如主管人员现场指导营业人员的销售活动,发现不符合标准或违反规定,立即予以纠正,这属于()
下列哪种情况不宜用雌激素治疗的是
在直流稳态电路中,电阻、电感、电容元件上的电压与电流大小相等时,其电阻分别为()。
下列关于城镇化的叙述,错误的是()。
依据《生产安全事故报告和调查处理条例》,安全生产监督管理部门和负有安全生产监督管理职责的有关部门接到事故报告后,应当依照有关规定上报事故情况,并通知公安机关、劳动保障行政部门、工会和人民检察院。必要时,安全生产监督管理部门和负有安全生产监督管理职责的有关部
监督借款人按规定的用途用款,是保证银行贷款安全的主要环节。()
随机生成一个首位不为0的七位数字的QQ号码,则每个数位上的数字各不相同的概率是多少?
根据以下资料,回答下列问题。2012年该省加工贸易进出口总额比一般贸易多:
()是“民族乐派”的代表人物。
Languageisasystemof______vocalsymbolsusedforhumancommunication.
最新回复
(
0
)