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  • Silent skies

    How a military design could carry passengers if people learned to love it—but its fuel efficiency, not its quietness, is what matters most


    ANYONE who lives on a flight path knows how noisy aircraft can be as they come in to land. At Heathrow airport in west London an aircraft lands every 45 seconds, starting at four o'clock in the morning and continuing until almost midnight. The direction of the prevailing wind means that for most of the time the planes must fly over central London. Because the airport is often congested, aircraft are frequently directed to circle over the capital, increasing the misery. More than 1m people live under the flight path into Heathrow and the Department of Transport in Britain estimates that 375,000 people are affected by the noise to the extent that conversation is regularly and frequently interrupted. So the unveiling of a design for a new “silent” aircraft this week was met with uncritical approval.

    Actually the design is anything but novel. The idea to create an aeroplane based on a blended wing and body, one that looks like a flying wing, is an old one. Stealth bombers, for example, are flying wings. What the researchers have done is to modify the design to make the aircraft quieter. The work is part of a wider effort to mitigate the environmental impact of aviation: not only the noise it makes, but also the air pollution close to airports and the impact of emissions at high altitudes on climate change.

    Aircraft are at their noisiest when they come in to land. About half of this noise is generated by the engine, with the exhaust and the fans being the biggest culprits. But the frame of the aircraft itself is to blame for the other half: the bumpy air flow over the undercarriage and the slots and flaps of the wings creates the rest of the racket.

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