{"id":498354,"date":"2023-08-24T08:00:00","date_gmt":"2023-08-24T12:00:00","guid":{"rendered":"https:\/\/www.nasa.gov\/?post_type=migration&p=498354"},"modified":"2023-10-18T15:06:25","modified_gmt":"2023-10-18T19:06:25","slug":"nasa-has-helped-hush-aircraft-engine-noise-for-decades","status":"publish","type":"post","link":"https:\/\/www.nasa.gov\/general\/nasa-has-helped-hush-aircraft-engine-noise-for-decades\/","title":{"rendered":"NASA Has Helped Hush Aircraft Engine Noise for Decades"},"content":{"rendered":"<div id=\"\" class=\"padding-top-5 padding-bottom-3 width-full maxw-full hds-module hds-module-full wp-block-nasa-blocks-article-intro\"><div class=\"width-full maxw-full article-header\"><div class=\"margin-bottom-2 width-full maxw-full\"><p class=\"label carbon-60 margin-0 margin-bottom-3 padding-0\">4 min read<\/p><h1 class=\"display-48 margin-bottom-2\">NASA Has Helped Hush Aircraft Engine Noise for Decades<\/h1><\/div><\/div><\/div>\n\n\n<p>Modern jet engines are loud, but they used to be much louder. NASA\u2019s Glenn Research Center has been at the forefront of the nation\u2019s efforts to reduce aircraft engine noise for over 70 years. During this time, the center has built an array of test facilities to carry out this work, culminating in the <a href=\"https:\/\/www1.grc.nasa.gov\/facilities\/aapl\/\" rel=\"noopener\">Aero-Acoustic Propulsion Laboratory<\/a> (AAPL), a world-class noise-reduction research facility.<\/p>\n\n\n\n<p>The AAPL, referred to as \u201cthe dome,\u201d contains multiple test rigs enclosed in a large, echo-free chamber. The unique 130-foot diameter and 65-foot-high hemispherical structure stands out on Glenn\u2019s campus. Its triangular sections make it appear like a golf ball rising from the ground. The interior is covered in spiky, fiberglass sound-dampening wedges and an overhead array of microphones that capture engine noise data.<\/p>\n\n\n<div id=\"\" class=\"hds-media hds-module wp-block-image\"><div class=\"margin-left-auto margin-right-auto nasa-block-align-inline\"><div class=\"hds-media-wrapper margin-left-auto margin-right-auto\"><figure class=\"hds-media-inner hds-cover-wrapper hds-media-ratio-none \"><a href=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg\"><img fetchpriority=\"high\" decoding=\"async\" width=\"985\" height=\"788\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg?w=985\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"A white, half-dome shaped building with triangular sections on its exterior is illuminated at nighttime on NASA Glenns campus. Through the facilitys open door, test rigs can be seen inside.\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg 985w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg?resize=300,240 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg?resize=768,614 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg?resize=400,320 400w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg?resize=600,480 600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg?resize=900,720 900w\" sizes=\"(max-width: 985px) 100vw, 985px\" loading=\"eager\" \/><\/a><\/figure><figcaption class=\"hds-caption padding-y-2\"><div class=\"hds-caption-text p-sm margin-0\">The Aero-Acoustic Propulsion Laboratory in October 1991, shortly after the dome was completed. The Nozzle Acoustic Test Rig is to the left and the Powered Lift Facility is to the right. <\/div><div class=\"hds-credits\">Credits: NASA\/Quentin Schwinn<\/div><\/figcaption><\/div><\/div><\/div>\n\n\n<p>Jet propulsion has been a cornerstone of NASA Glenn\u2019s research since the center\u2019s establishment as a National Advisory Committee for Aeronautics (NACA) laboratory in the early 1940s. The lab\u2019s improvements to the nation\u2019s first generations of turbojet engines contributed to making the first jet airliners possible in the mid-1950s.<\/p>\n\n\n\n<p>Jet aircraft are much louder than their piston-engine counterparts, though, and communities near airports complained about the increased noise. The center began studying its causes in the early 1950s. Since it is difficult to evaluate noise in the wind tunnels and test chambers normally used to test engines, Glenn researchers mounted engines on simple steel stands near the lab\u2019s hangar and placed microphones around them to measure noise levels.<\/p>\n\n\n<div id=\"\" class=\"hds-media hds-module wp-block-image\"><div class=\"margin-left-auto margin-right-auto nasa-block-align-inline\"><div class=\"hds-media-wrapper margin-left-auto margin-right-auto\"><figure class=\"hds-media-inner hds-cover-wrapper hds-media-ratio-none \"><a href=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/early_stand.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"985\" height=\"791\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/early_stand.jpg?w=985\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"A black-and-white image of a metal frame holding up a jet engine outside at NASA Glenn. A researcher inspects the frame, sitting below the engine.\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/early_stand.jpg 985w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/early_stand.jpg?resize=300,241 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/early_stand.jpg?resize=768,617 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/early_stand.jpg?resize=400,321 400w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/early_stand.jpg?resize=600,482 600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/early_stand.jpg?resize=900,723 900w\" sizes=\"(max-width: 985px) 100vw, 985px\" \/><\/a><\/figure><figcaption class=\"hds-caption padding-y-2\"><div class=\"hds-caption-text p-sm margin-0\">A General Electric J-47 installed on a thrust rig outside NASA Glenn’s hangar in 1954. It was being used to test the effectiveness of a screen behind the nozzle to reduce on-the-ground noise at airports. <\/div><div class=\"hds-credits\"> Credits: NASA\/Bill Bowles<\/div><\/figcaption><\/div><\/div><\/div>\n\n\n<p>Researchers found that the primary source of noise was not the mechanical elements of engines, but the mixing of the cold atmosphere with their narrow, high-speed stream of hot exhaust gases. In response, researchers tested <a href=\"https:\/\/www1.grc.nasa.gov\/historic-facilities\/altitude-wind-tunnel\/jet-engines-mature\/#pratt-whitneys-j57\" rel=\"noopener\">unique nozzle and ejector<\/a> designs and worked to balance sound-reducing hardware\u2019s effects on engine performance and weight.<\/p>\n\n\n\n<p>The introduction of turbofan engines, which offered increased efficiency and lowered noise levels, proved to be a breakthrough in the 1960s. But with more airliners, new Federal Aviation Agency standards, and an increased interest in vertical and short-takeoff and landing (V\/STOL) aircraft, continued noise reduction research was needed.<\/p>\n\n\n\n<p>In the late 1960s and early \u201970s, NASA Glenn constructed a new, more robust array of outdoor test stands at sites across campus to study fan noise, including three rigs at the site of the current APPL. The Powered Lift Facility (PLF) was added to the site in 1986 to provide data on V\/STOL concepts. Complaints from the local community about the PLF\u2019s noise levels, however, led to the suspension of testing in 1989.<\/p>\n\n\n<div id=\"\" class=\"hds-media hds-module wp-block-image\"><div class=\"margin-left-auto margin-right-auto nasa-block-align-inline\"><div class=\"hds-media-wrapper margin-left-auto margin-right-auto\"><figure class=\"hds-media-inner hds-cover-wrapper hds-media-ratio-none \"><a href=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/plf.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"985\" height=\"788\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/plf.jpg?w=985\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"Metal hardware, pipes, and machinery for the Powered Lift Facility, pictured outside on NASA Glenns campus.\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/plf.jpg 985w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/plf.jpg?resize=300,240 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/plf.jpg?resize=768,614 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/plf.jpg?resize=400,320 400w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/plf.jpg?resize=600,480 600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/plf.jpg?resize=900,720 900w\" sizes=\"(max-width: 985px) 100vw, 985px\" \/><\/a><\/figure><figcaption class=\"hds-caption padding-y-2\"><div class=\"hds-caption-text p-sm margin-0\">The Powered Lift Facility as it appeared in November 1989 after operations were suspended due to complaints about the noise from nearby residents. <strong>Credits: <\/strong><\/div><div class=\"hds-credits\">Credits: NASA\/Angela Coyne<\/div><\/figcaption><\/div><\/div><\/div>\n\n\n<p>In 1990, NASA initiated the <a href=\"https:\/\/www.nasa.gov\/centers\/langley\/news\/factsheets\/HSR-Overview2.html\">High-Speed Research<\/a> (HSR) program to develop technologies for supersonic transportation, so Glenn started designing the Nozzle Acoustic Test Rig (NATR), a 53-inch diameter wind tunnel that could test acoustic and aerodynamic performance of nozzles. This testing was inherently loud, so the center decided to construct a structure to cover both the PLF and NATR.<\/p>\n\n\n<div id=\"\" class=\"hds-media hds-module wp-block-image\"><div class=\"margin-left-auto margin-right-auto nasa-block-align-inline\"><div class=\"hds-media-wrapper margin-left-auto margin-right-auto\"><figure class=\"hds-media-inner hds-cover-wrapper hds-media-ratio-none \"><a href=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"985\" height=\"994\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg?w=985\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"An overhead shot of construction equipment and partially built triangular frame segments for the dome for NASA Glenns Aero-Acoustic Propulsion facility.\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg 985w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg?resize=150,150 150w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg?resize=297,300 297w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg?resize=768,775 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg?resize=50,50 50w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg?resize=100,100 100w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg?resize=396,400 396w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg?resize=595,600 595w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/appl_construction.jpg?resize=892,900 892w\" sizes=\"(max-width: 985px) 100vw, 985px\" \/><\/a><\/figure><figcaption class=\"hds-caption padding-y-2\"><div class=\"hds-caption-text p-sm margin-0\">Construction of the geodesic dome over the Powered Lift Facility in January 1991.<\/div><div class=\"hds-credits\">Credits: NASA\/Marvin Smith<\/div><\/figcaption><\/div><\/div><\/div>\n\n\n<p>The new facility was completed in 1991 and named the Aero-Acoustic Propulsion Laboratory (AAPL). Its geodesic dome not only prevents noise from exiting the facility, but also protects against outside sounds and weather.<\/p>\n\n\n<div id=\"\" class=\"hds-media hds-module wp-block-image\"><div class=\"margin-left-auto margin-right-auto nasa-block-align-inline\"><div class=\"hds-media-wrapper margin-left-auto margin-right-auto\"><figure class=\"hds-media-inner hds-cover-wrapper hds-media-ratio-none \"><a href=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/natr.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"985\" height=\"639\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/natr.jpg?w=985\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"A Learjet engine nozzle peeks out from NASA Glenns Nozzle Acoustic Test Rig, a cylinder surrounded by tan wedges. The walls of the Aero-Acoustic Propulsion Facility, also covered in wedges, glow blue in the background.\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/natr.jpg 985w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/natr.jpg?resize=300,195 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/natr.jpg?resize=768,498 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/natr.jpg?resize=400,259 400w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/natr.jpg?resize=600,389 600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/natr.jpg?resize=900,584 900w\" sizes=\"(max-width: 985px) 100vw, 985px\" \/><\/a><\/figure><figcaption class=\"hds-caption padding-y-2\"><div class=\"hds-caption-text p-sm margin-0\">Testing of a Learjet engine nozzle in the Nozzle Acoustic Test Rig in 2018. <\/div><div class=\"hds-credits\">Credits: NASA\/Rami Daud<\/div><\/figcaption><\/div><\/div><\/div>\n\n\n<p>The NATR has become the center\u2019s workhorse for acoustic testing. In addition to the HSR program, the NATR also performed testing for the Advanced Subsonic Technology program and conducted the first successful test of a chevron nozzle in 1997.<\/p>\n\n\n\n<p>The Advanced Noise Control Fan (ANCF) rig and the Small Hot Jet Acoustic Rig (SHJAR) were added in the mid-1990s and 2000, respectively. Researchers used the ANCF to study acoustic liners and fan noise, and the SHJAR was more economical to operate for smaller tests than the NATR.<\/p>\n\n\n\n<p>In the early 2000s, the AAPL was outfitted with a new acoustic arena that allows simultaneous testing on multiple rigs and the measurement of flyby and sideline noise. Use of the PLF declined over the years, and it was eventually decommissioned in 2007. The ANCF was removed in 2021 to create space for the DGEN AeroPropulsion Research Turbofan (DART) rig, a small-scale engine testbed useful for a variety of research.<\/p>\n\n\n<div id=\"\" class=\"hds-media hds-module wp-block-image\"><div class=\"margin-left-auto margin-right-auto nasa-block-align-inline\"><div class=\"hds-media-wrapper margin-left-auto margin-right-auto\"><figure class=\"hds-media-inner hds-cover-wrapper hds-media-ratio-none \"><a href=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"2048\" height=\"1314\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?w=2048\" class=\"attachment-2048x2048 size-2048x2048\" alt=\"The DGEN AeroPropulsion Research Turbofan test rig is illuminated by lights inside of NASA Glenn\u2019s Aero-Acoustic Propulsion Laboratory. The walls of the facility, covered in wedges, glow blue in the background.\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg 3216w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?resize=300,193 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?resize=768,493 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?resize=1024,657 1024w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?resize=1536,986 1536w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?resize=2048,1314 2048w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?resize=400,257 400w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?resize=600,385 600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?resize=900,578 900w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?resize=1200,770 1200w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/grc-2017-c-02264.jpg?resize=2000,1284 2000w\" sizes=\"(max-width: 2048px) 100vw, 2048px\" \/><\/a><\/figure><figcaption class=\"hds-caption padding-y-2\"><div class=\"hds-caption-text p-sm margin-0\">The DGEN AeroPropulsion Research Turbofan (DART) test rig includes a DGEN 308 turbofan engine that is used to conduct an array of research prior to testing with full-scale turbofan engines.<\/div><div class=\"hds-credits\">Credits: NASA\/Bridget Caswell<\/div><\/figcaption><\/div><\/div><\/div>\n\n\n<p>The AAPL continues to play a key role in NASA\u2019s testing efforts. Researchers are comparing noise data collected from scale-model nozzles inside the facility to data from Learjet 25 flight tests. This work may improve researchers\u2019 ability to predict takeoff noise for future supersonic commercial aircraft.<\/p>\n\n\n\n<p><strong>Robert S. Arrighi<\/strong><br><strong><em>NASA\u2019s Glenn Research Center<\/em><\/strong><\/p>\n\n\n<div id=\"\" class=\"nasa-gb-align-full width-full maxw-full padding-x-3 padding-y-0 hds-module hds-module-full wp-block-nasa-blocks-related-articles\">\t\t<section class=\"hds-related-articles padding-x-0 padding-y-3 desktop:padding-top-7 desktop:padding-bottom-9\">\n\t\t\t<div class=\"w-100 grid-row grid-container maxw-widescreen padding-0 text-align-left\">\n\t\t\t\t<div class=\"margin-bottom-4\"><h2 style=\"max-width: 100%;\" class=\"width-full w-full maxw-full\">Explore More<\/h2><\/div>\n\t\t\t<\/div>\n\t\t\t<div class=\"grid-row grid-container maxw-widescreen padding-0\">\n\t\t\t\t\t\t\t\t\t\t<div class=\"grid-col-12 desktop:grid-col-4 margin-bottom-4 desktop:margin-bottom-0 desktop:padding-right-3\">\n\t\t\t\t\t\t<a href=\"https:\/\/www.nasa.gov\/aeronautics\/armd-solicitations\/\" class=\"color-carbon-black\">\n\t\t\t\t\t\t\t<div class=\"margin-bottom-2\">\n\t\t\t\t\t\t\t\t<div class=\"hds-cover-wrapper cover-hover-zoom bg-carbon-black minh-mobile\">\n\t\t\t\t\t\t\t\t<figure class=\"hds-media-background  \"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"161\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/02\/explore-flight-HI-RES-no-meatball.jpg?w=300\" class=\"attachment-medium size-medium\" alt=\"\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/02\/explore-flight-HI-RES-no-meatball.jpg 1600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/02\/explore-flight-HI-RES-no-meatball.jpg?resize=300,161 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/02\/explore-flight-HI-RES-no-meatball.jpg?resize=768,411 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/02\/explore-flight-HI-RES-no-meatball.jpg?resize=1024,548 1024w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/02\/explore-flight-HI-RES-no-meatball.jpg?resize=1536,823 1536w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/02\/explore-flight-HI-RES-no-meatball.jpg?resize=400,214 400w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/02\/explore-flight-HI-RES-no-meatball.jpg?resize=600,321 600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/02\/explore-flight-HI-RES-no-meatball.jpg?resize=900,482 900w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/02\/explore-flight-HI-RES-no-meatball.jpg?resize=1200,643 1200w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/figure>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<div class=\"padding-right-0 desktop:padding-right-10\">\n\t\t\t\t\t\t\t\t<div class=\"subheading margin-bottom-1\">7 min read<\/div>\n\t\t\t\t\t\t\t\t<div class=\"margin-bottom-1\"><h3 class=\"related-article-title\">ARMD Solicitations<\/h3><\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"display-flex flex-align-center label related-article-label margin-bottom-1 color-carbon-60\">\n\t\t\t\t\t\t\t\t\t<span class=\"display-flex flex-align-center margin-right-2\">\n\t\t\t\t\t\t\t\t\t\t<svg version=\"1.1\" class=\"square-2 margin-right-1\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" x=\"0px\" y=\"0px\" width=\"16px\" height=\"16px\" viewBox=\"0 0 16 16\" style=\"enable-background:new 0 0 16 16;\" xml:space=\"preserve\"><g><g><path d=\"M8,0C3.5,0-0.1,3.7,0,8.2C0.1,12.5,3.6,16,8,16c4.4,0,8-3.6,8-8C16,3.5,12.4,0,8,0z M8,15.2 C4,15.2,0.8,12,0.8,8C0.8,4,4,0.8,8,0.8c3.9,0,7.2,3.2,7.2,7.1C15.2,11.9,12,15.2,8,15.2z\"\/><path d=\"M5.6,12c0.8-0.8,1.6-1.6,2.4-2.4c0.8,0.8,1.6,1.6,2.4,2.4c0-2.7,0-5.3,0-8C8.8,4,7.2,4,5.6,4 C5.6,6.7,5.6,9.3,5.6,12z\"\/><\/g><\/g><\/svg>\n\t\t\t\t\t\t\t\t\t\t<span>Article<\/span>\n\t\t\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<span class=\"\">\n\t\t\t\t\t\t\t\t\t\t24 hours ago\t\t\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/a>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<div class=\"grid-col-12 desktop:grid-col-4 margin-bottom-4 desktop:margin-bottom-0 desktop:padding-right-3\">\n\t\t\t\t\t\t<a href=\"https:\/\/www.nasa.gov\/general\/researchers-develop-founding-document-on-synthetic-cell-development\/\" class=\"color-carbon-black\">\n\t\t\t\t\t\t\t<div class=\"margin-bottom-2\">\n\t\t\t\t\t\t\t\t<div class=\"hds-cover-wrapper cover-hover-zoom bg-carbon-black minh-mobile\">\n\t\t\t\t\t\t\t\t<figure class=\"hds-media-background  \"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"200\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg?w=300\" class=\"attachment-medium size-medium\" alt=\"\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg 2048w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg?resize=300,200 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg?resize=768,511 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg?resize=1024,682 1024w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg?resize=1536,1022 1536w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg?resize=400,266 400w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg?resize=600,399 600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg?resize=900,599 900w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg?resize=1200,799 1200w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/19728525494-4e20319b8c-c.jpg?resize=2000,1331 2000w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/figure>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<div class=\"padding-right-0 desktop:padding-right-10\">\n\t\t\t\t\t\t\t\t<div class=\"subheading margin-bottom-1\">3 min read<\/div>\n\t\t\t\t\t\t\t\t<div class=\"margin-bottom-1\"><h3 class=\"related-article-title\">Researchers Develop \u2018Founding Document\u2019 on Synthetic Cell Development<\/h3><\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"display-flex flex-align-center label related-article-label margin-bottom-1 color-carbon-60\">\n\t\t\t\t\t\t\t\t\t<span class=\"display-flex flex-align-center margin-right-2\">\n\t\t\t\t\t\t\t\t\t\t<svg version=\"1.1\" class=\"square-2 margin-right-1\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" x=\"0px\" y=\"0px\" width=\"16px\" height=\"16px\" viewBox=\"0 0 16 16\" style=\"enable-background:new 0 0 16 16;\" xml:space=\"preserve\"><g><g><path d=\"M8,0C3.5,0-0.1,3.7,0,8.2C0.1,12.5,3.6,16,8,16c4.4,0,8-3.6,8-8C16,3.5,12.4,0,8,0z M8,15.2 C4,15.2,0.8,12,0.8,8C0.8,4,4,0.8,8,0.8c3.9,0,7.2,3.2,7.2,7.1C15.2,11.9,12,15.2,8,15.2z\"\/><path d=\"M5.6,12c0.8-0.8,1.6-1.6,2.4-2.4c0.8,0.8,1.6,1.6,2.4,2.4c0-2.7,0-5.3,0-8C8.8,4,7.2,4,5.6,4 C5.6,6.7,5.6,9.3,5.6,12z\"\/><\/g><\/g><\/svg>\n\t\t\t\t\t\t\t\t\t\t<span>Article<\/span>\n\t\t\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<span class=\"\">\n\t\t\t\t\t\t\t\t\t\t2 days ago\t\t\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/a>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<div class=\"grid-col-12 desktop:grid-col-4 margin-bottom-4 desktop:margin-bottom-0 desktop:padding-right-3\">\n\t\t\t\t\t\t<a href=\"https:\/\/www.nasa.gov\/centers-and-facilities\/johnson\/nasa-showcases-innovations-at-the-2024-first-robotics-world-championships\/\" class=\"color-carbon-black\">\n\t\t\t\t\t\t\t<div class=\"margin-bottom-2\">\n\t\t\t\t\t\t\t\t<div class=\"hds-cover-wrapper cover-hover-zoom bg-carbon-black minh-mobile\">\n\t\t\t\t\t\t\t\t<figure class=\"hds-media-background  \"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"225\" src=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?w=300\" class=\"attachment-medium size-medium\" alt=\"\" style=\"transform: scale(1); transform-origin: 50% 50%; object-position: 50% 50%; object-fit: cover;\" block_context=\"nasa-block\" srcset=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg 2776w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?resize=300,225 300w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?resize=768,576 768w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?resize=1024,768 1024w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?resize=1536,1152 1536w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?resize=2048,1536 2048w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?resize=400,300 400w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?resize=600,450 600w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?resize=900,675 900w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?resize=1200,900 1200w, https:\/\/www.nasa.gov\/wp-content\/uploads\/2024\/04\/microsoftteams-image-2024-04-24t090305-316.jpg?resize=2000,1500 2000w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/figure>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<div class=\"padding-right-0 desktop:padding-right-10\">\n\t\t\t\t\t\t\t\t<div class=\"subheading margin-bottom-1\">2 min read<\/div>\n\t\t\t\t\t\t\t\t<div class=\"margin-bottom-1\"><h3 class=\"related-article-title\">NASA Showcases Innovations at the 2024 FIRST Robotics World Championships<\/h3><\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"display-flex flex-align-center label related-article-label margin-bottom-1 color-carbon-60\">\n\t\t\t\t\t\t\t\t\t<span class=\"display-flex flex-align-center margin-right-2\">\n\t\t\t\t\t\t\t\t\t\t<svg version=\"1.1\" class=\"square-2 margin-right-1\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" x=\"0px\" y=\"0px\" width=\"16px\" height=\"16px\" viewBox=\"0 0 16 16\" style=\"enable-background:new 0 0 16 16;\" xml:space=\"preserve\"><g><g><path d=\"M8,0C3.5,0-0.1,3.7,0,8.2C0.1,12.5,3.6,16,8,16c4.4,0,8-3.6,8-8C16,3.5,12.4,0,8,0z M8,15.2 C4,15.2,0.8,12,0.8,8C0.8,4,4,0.8,8,0.8c3.9,0,7.2,3.2,7.2,7.1C15.2,11.9,12,15.2,8,15.2z\"\/><path d=\"M5.6,12c0.8-0.8,1.6-1.6,2.4-2.4c0.8,0.8,1.6,1.6,2.4,2.4c0-2.7,0-5.3,0-8C8.8,4,7.2,4,5.6,4 C5.6,6.7,5.6,9.3,5.6,12z\"\/><\/g><\/g><\/svg>\n\t\t\t\t\t\t\t\t\t\t<span>Article<\/span>\n\t\t\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<span class=\"\">\n\t\t\t\t\t\t\t\t\t\t4 days ago\t\t\t\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/a>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t<\/div>","protected":false},"excerpt":{"rendered":"<p>NASA Has Helped Hush Aircraft Engine Noise for Decades<\/p>\n","protected":false},"author":9,"featured_media":498436,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"nasa_hds_core_meta_l10n":"en-US","nasa_hds_core_meta_article_editor":"","nasa_hds_core_meta_article_contacts":[],"nasa_hds_core_meta_article_topic":"","nasa_hds_core_meta_linked_locations":[],"nasa_hds_core_meta_article_related_articles":[],"hds_migrate_meta_pr_release_id":"","hds_migrate_meta_pr_release_type":"","nasa_hds_core_meta_location_x":"","nasa_hds_core_meta_location_y":"","nasa_hds_core_meta_gallery_images":[],"footnotes":""},"categories":[1,2660,10843,2856],"news-tags":[],"internal-terms":[],"coauthors":[12636],"parsely":{"version":"1.1.0","meta":{"@context":"https:\/\/schema.org","@type":"NewsArticle","headline":"NASA Has Helped Hush Aircraft Engine Noise for Decades","url":"https:\/\/www.nasa.gov\/general\/nasa-has-helped-hush-aircraft-engine-noise-for-decades\/","mainEntityOfPage":{"@type":"WebPage","@id":"https:\/\/www.nasa.gov\/general\/nasa-has-helped-hush-aircraft-engine-noise-for-decades\/"},"thumbnailUrl":"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg?w=150&h=150&crop=1","image":{"@type":"ImageObject","url":"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg"},"articleSection":"General","author":[{"@type":"Person","name":"Glenn Communications"}],"creator":["Glenn Communications"],"publisher":{"@type":"Organization","name":"NASA","logo":"https:\/\/www.nasa.gov\/wp-content\/themes\/nasa\/assets\/images\/nasa-logo.svg"},"keywords":["NASA Centers & Facilities","Glenn Research Center","General","Aeronautics","Aeronautics Technology"],"dateCreated":"2023-08-24T12:00:00Z","datePublished":"2023-08-24T12:00:00Z","dateModified":"2023-10-18T19:06:25Z"},"rendered":"<meta name=\"parsely-title\" content=\"NASA Has Helped Hush Aircraft Engine Noise for Decades\" \/>\n<meta name=\"parsely-link\" content=\"https:\/\/www.nasa.gov\/general\/nasa-has-helped-hush-aircraft-engine-noise-for-decades\/\" \/>\n<meta name=\"parsely-type\" content=\"post\" \/>\n<meta name=\"parsely-image-url\" content=\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg?w=150&h=150&crop=1\" \/>\n<meta name=\"parsely-pub-date\" content=\"2023-08-24T12:00:00Z\" \/>\n<meta name=\"parsely-section\" content=\"General\" \/>\n<meta name=\"parsely-tags\" content=\"NASA Centers & Facilities,Glenn Research Center,General,Aeronautics,Aeronautics Technology\" \/>\n<meta name=\"parsely-author\" content=\"Glenn Communications\" \/>","tracker_url":"https:\/\/cdn.parsely.com\/keys\/nasa.gov\/p.js"},"read_time":4,"time_ago":"8 months","featured_image":{"id":498436,"file":"https:\/\/www.nasa.gov\/wp-content\/uploads\/2023\/08\/dome_1.jpg","title":"POWERED LIFT FACILITY PLF WITH MODEL MOUNTED ON IT.","alt":"A white, half-dome 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Through the facilitys open door, test rigs can be seen inside.","caption":""},"_links":{"self":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/posts\/498354"}],"collection":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/comments?post=498354"}],"version-history":[{"count":6,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/posts\/498354\/revisions"}],"predecessor-version":[{"id":551327,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/posts\/498354\/revisions\/551327"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/media\/498436"}],"wp:attachment":[{"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/media?parent=498354"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/categories?post=498354"},{"taxonomy":"news-tags","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/news-tags?post=498354"},{"taxonomy":"internal-terms","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/internal-terms?post=498354"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.nasa.gov\/wp-json\/wp\/v2\/coauthors?post=498354"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}