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  • In 1996, a British Airways plane flew from New York to London

  • in a record-breaking two hours and 53 minutes.

  • Today, however, passengers flying the same route

  • can expect to spend no less than six hours in the airtwice as long.

  • So why, in a world where everything seems to be getting faster,

  • have commercial flights lagged behind?

  • The British-and-French-made Concorde began shuttling passengers

  • across the sky in the 1970s.

  • Jetting between destinations like New York, Paris, Bahrain, and Singapore,

  • it clocked in at over 2,000 kilometers per hour,

  • more than twice the speed of a normal airliner.

  • However this was also about 800 kilometers per hour faster than the speed of sound.

  • And that created a surprising problem for people on the ground.

  • When an object moves at supersonic speed,

  • it generates a continuous moving shockwave known as a sonic boom.

  • This produces a loud, startling noise,

  • as well as rattling windows and dislodging structural elements of buildings.

  • Since a plane flying at an altitude of 15 kilometers

  • can affect an area with an 80 kilometer diameter on the ground below,

  • complaints and concerns from residents in the Concorde's flight path

  • restricted it to mostly ocean routes.

  • Because of these restrictions and other fuel and engineering requirements,

  • supersonic flights turned out to be very expensive

  • for both airlines and passengers.

  • A single transatlantic round-trip could cost the equivalent

  • of more than $10,000 today.

  • With additional strain on the airline industry

  • due to decreased demand for flights after September 11th, 2001,

  • this became unsustainable, and the Concorde was retired in 2003.

  • So even when superfast flights existed, they weren't standard commercial flights.

  • And while we might think that advances in flight technology

  • would make fast flights less expensive, this hasn't necessarily been the case.

  • One of the biggest concerns is fuel economy.

  • Over the decades, jet engines have become a lot more efficient,

  • taking in more air and achieving more thrust

  • traveling further for every liter of fuel.

  • But this efficiency is only achieved at speeds

  • of up to around 900 kilometers per hourless than half the speed of the Concorde.

  • Going any faster would increase air intake and burn more fuel per kilometer flown.

  • A standard transatlantic flight still uses as much as 150,000 liters of fuel,

  • amounting to over 20% of an airline's total expenses.

  • So any reduction in fuel economy and increase in speed

  • would significantly increase both flight costs and environmental impact.

  • What about ways to make a plane faster without burning lots of fuel?

  • Adjusting the wing sweep, or the angle at which wings protrude from the fuselage,

  • to bring the wings closer in can make an aircraft faster

  • by reducing aerodynamic drag.

  • But this means the wings must be longer to achieve the same wingspan,

  • and that means more materials and more weight,

  • which in turn means burning more fuel.

  • So while airplanes could be designed to be more aerodynamic,

  • this would make them more expensive.

  • And generally, airlines have found that customer demand for faster flights

  • is not sufficient to cover these costs.

  • So while military aircraft conduct high speed flights

  • over water and at high altitudes,

  • supersonic commercial flights seemed like a brief and failed experiment.

  • But recent advances may make them feasible again.

  • Research by NASA and DARPA has shown that modifying an aircraft's shape

  • can reduce the impact of its sonic boom by 1/3.

  • Extending the nose with a long spike can break the shockwave into smaller ones,

  • while another proposed design features two sets of wings

  • producing waves that cancel each other out.

  • And new technologies may solve the energy efficiency problem

  • with alternative and synthetic fuels, or even hybrid-electric planes.

  • It may yet turn out that the last few decades of steady flying

  • were just a brief rest stop.

In 1996, a British Airways plane flew from New York to London


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B1 中級 美國腔

為什麼現在的飛機飛比較慢(Why are airplanes slower than they used to be? - Alex Gendler)

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    shuting1215 發佈於 2021 年 04 月 18 日