Bird-inspired technologies may be the key to dampening aircraft noise around airports, according to a NASA scientist.
"We are learning to make aircraft more like Mother Nature," said Dennis Huff, chief of the acoustics branch at the NASA Glenn Research Center in Cleveland, Ohio.
For example, Huff's team developed the chevron nozzle, a serrated nozzle that fits on the backside of jet engines.
The design is modeled after the sawtooth pattern of the feathers on the wings of some birds, including owls (read "Owl's Silent Flight May Inspire Quiet Aircraft Tech" [December 2004]).
The jagged edge mixes the airflow coming out of the jet engine in a way that reduces turbulence. Less turbulence translates to less noise, Huff explains.
Current chevron technology reduces noise by about three decibels, Huff adds.
"An analogy I like to use is two lawn mowers running at the same noise level and [then] turning one off. That would be perceived as a three-decibel reduction," he said.
Little Compromise
Terrance Scott is a spokesperson for Boeing Company, an airplane manufacturer based in Seattle, Washington.
Scott says that engineering quiet technology for aircraft requires a host of considerations beyond noise.
"First and foremost, safety is the key consideration," he said in an email.
In addition, engineers must look at how any solution affects emissions, flight performance, maintenance, and cost.
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