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If you have ever lived near an airport, or if you have visited someone who does, you will be familiar with the roar of the window that can prevent many homes from sleeping at night. NASA has taken the initiative to tackle the problem by testing three new noise reduction technologies on a series of Acoustic Research Measurement (ARM) flights and reducing noise by over 70%. of the cell during landing.
For this project, NASA is focused on reducing the noise of the cell, which is not created by the engines but by the wind that rushes beyond the plane's frame . To test the new technologies, three experimental designs were mounted on a Gulfstream III research aircraft, which flew at an altitude of 350 ft (107 m) on a set of 185 microphones located on the Rogers Dry Lake at the Air Force Base. # 39; Edwards. .
"The number one public complaint received by the Federal Aviation Administration relates to aircraft noise," said Mehdi Khorrami, principal investigator for Acoustic Research Measurement. "NASA's goal was to dramatically reduce aircraft noise in order to improve the quality of life of communities near airports. We are very confident that with the technologies tested, we can reduce considerably the total noise of the aircraft, which could make a lot of thefts. quieter."
The landing gear of an aircraft approaching an airport has been identified as one of the main makers of the noise of the cell, so two of the new technologies have been designed to improve this area. To reduce the noise of air passing over fairings, NASA has designed a full version of tiny pores on the front, which allows some of the air to flow through. while pushing the rest around the landing gear. This idea has already been used, but NASA says that this design is based on detailed computer simulations that maximize the balance between noise reduction and drag.
The cavities of the landing gear, the openings in the lower part of the aircraft body in which the landing gear retracts, are also notoriously noisy. While they are open, the air rushes and bounces loudly on the interior walls. To reduce this, the team added sawtooth patterns called rafters to the area just in front of the cavity, and stretched a net through the opening. This allows the air to flow more efficiently, while a soft sound-absorbing foam on the rear inner wall reduces the sound of incoming air.
The last piece of the puzzle targets the wing flap, the part that elevates and lowers the trailing edge of the wing to give more lift to the takeoff or help slow down the wing. Plane when landing. But these mechanical parts leave spaces between them and the rest of the body of the wing, which can become noisy and reduce fuel consumption.
NASA's response to this problem is the ACTE (Adaptive Compliant Trailing Edge) wing flap, a technology that has been tested for several years. This new version is flexible and seamless, folding to do the job without leaving holes in the surface of the wing.
After the ARM test flights completed in May, NASA reports that the three new technologies have managed to reduce cell noise during landing by over 70%.
"This reduction of cell noise produced by NASA's technology is really important, and the best part is that it directly benefits the public," said Kevin Weinert, ARM project manager. "While there are obvious potential economic gains for the industry, it benefits people who live near major airports and have to deal with the noise of planes landing, which could significantly reduce Noise impact on these communities.
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