[{"command":"openDialog","selector":"#drupal-modal","settings":null,"data":"\u003Cdiv id=\u0022republish_modal_form\u0022\u003E\u003Cform class=\u0022modal-form-example-modal-form ecl-form\u0022 data-drupal-selector=\u0022modal-form-example-modal-form\u0022 action=\u0022\/en\/article\/modal\/11285\u0022 method=\u0022post\u0022 id=\u0022modal-form-example-modal-form\u0022 accept-charset=\u0022UTF-8\u0022\u003E\u003Cp\u003EHorizon articles can be republished for free under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence.\u003C\/p\u003E\n \u003Cp\u003EYou must give appropriate credit. We ask you to do this by:\u003Cbr \/\u003E\n 1) Using the original journalist\u0027s byline\u003Cbr \/\u003E\n 2) Linking back to our original story\u003Cbr \/\u003E\n 3) Using the following text in the footer: This article was originally published in \u003Ca href=\u0027#\u0027\u003EHorizon, the EU Research and Innovation magazine\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003ESee our full republication guidelines \u003Ca href=\u0027\/horizon-magazine\/republish-our-stories\u0027\u003Ehere\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003EHTML for this article, including the attribution and page view counter, is below:\u003C\/p\u003E\u003Cdiv class=\u0022js-form-item form-item js-form-type-textarea form-item-body-content js-form-item-body-content ecl-form-group ecl-form-group--text-area form-no-label ecl-u-mv-m\u0022\u003E\n \n\u003Cdiv\u003E\n \u003Ctextarea data-drupal-selector=\u0022edit-body-content\u0022 aria-describedby=\u0022edit-body-content--description\u0022 id=\u0022edit-body-content\u0022 name=\u0022body_content\u0022 rows=\u00225\u0022 cols=\u002260\u0022 class=\u0022form-textarea ecl-text-area\u0022\u003E\u003Ch2\u003EReducing aircraft noise \u2013 one decibel at a time\u003C\/h2\u003E\u003Cp\u003EIn mid-December 2023, a demonstration in Ireland revealed the strength of public concerns about noise caused by commercial aeroplanes. Protesters gathered outside the county offices where the Dublin Airport Authority was discussing a planned expansion.\u003C\/p\u003E\u003Cp\u003E\u2018Wrong way DAA!\u2019 the people\u0026nbsp;\u003Ca href=\u0022https:\/\/www.98fm.com\/news\/residents-protest-plans-to-increase-dublin-airport-capacity-1623613\u0022\u003Echanted\u003C\/a\u003E.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ETesty times\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003ESuch reactions are common across Europe as airports strive for more business and residents under the flightpath seek relief from the sound of jetliners when they take off and land. In September, Schiphol Airport in the Netherlands capped its flights because of noise concerns, dismaying airlines as their bottom lines were hit.\u003C\/p\u003E\u003Cp\u003EThis tension between commercial and public interests has prompted researchers to seek ways for planes to fly more quietly. With around 30 000 flights a day in Europe, preventing ill health has been a prime driver of the research efforts.\u003C\/p\u003E\u003Cp\u003E\u2018At takeoff in particular, but also at landing, aircraft make a lot of noise,\u2019 said Dr Werner Haase, a German aeronautics consultant and aerodynamics expert with a doctorate from the Technical University of Berlin. \u2018If you\u2019re sleeping and a plane flies over your home, that\u2019s very disruptive. The social impact of that kind of noise is quite high.\u2019\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EWhile individual planes have become around\u0026nbsp;\u003Ca href=\u0022https:\/\/transport.ec.europa.eu\/transport-modes\/air\/environment\/aircraft-noise_en\u0022\u003E75% quieter\u003C\/a\u003E over the past three decades and \u003Ca href=\u0022https:\/\/eur-lex.europa.eu\/legal-content\/EN\/TXT\/HTML\/?uri=CELEX:52023DC0139\u0022\u003Eroad transport\u003C\/a\u003E causes significantly more noise than aviation, increases in air traffic have resulted in noise disturbances for great numbers of people.\u003C\/p\u003E\u003Cp\u003EIn Europe, 22 million people have \u201cchronic high annoyance\u201d as a result of environmental noise including from planes, according to the\u0026nbsp;\u003Ca href=\u0022https:\/\/environment.ec.europa.eu\/topics\/noise_en\u0022\u003EEuropean Commission\u003C\/a\u003E, which cites related illnesses such as cardiovascular diseases, stress and tinnitus.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EIt says that 12\u0026nbsp;000 premature deaths are caused each year by long-term exposure to environmental noise and that 12 500 school children face learning impairment from aircraft noise alone.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003ENoise pollution is the second-biggest environmental cause of health troubles after air contamination, according to the World Health Organization.\u003C\/p\u003E\u003Cp\u003EThrough a\u0026nbsp;\u003Ca href=\u0022https:\/\/environment.ec.europa.eu\/strategy\/zero-pollution-action-plan_en\u0022\u003E\u201czero pollution action plan\u201d\u003C\/a\u003E dating to 2021, the Commission aims to decrease the share of people chronically disturbed by transport noise by 30% this decade.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWing flaps and slats\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EAn EU-funded project called\u0026nbsp;\u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/860538\u0022\u003EINVENTOR\u003C\/a\u003E wants to make landings in particular less intrusive for the inhabitants below. The focus is on the landing gear, the flaps at the back of the wings and the slats at the wing fronts.\u003C\/p\u003E\u003Cp\u003E\u003Cblockquote class=\u0022tw-text-center tw-text-blue tw-font-bold tw-text-2xl lg:tw-w-1\/2 tw-border-2 tw-border-blue tw-p-12 tw-my-8 lg:tw-m-12 lg:tw--ml-16 tw-float-left\u0022\u003E\n \u003Cspan class=\u0022tw-text-5xl tw-rotate-180\u0022\u003E\u201c\u003C\/span\u003E\n \u003Cp class=\u0022tw-font-serif tw-italic\u0022\u003EThe social impact of that kind of noise is quite high.\u003C\/p\u003E\n \u003Cfooter\u003E\n \u003Ccite class=\u0022tw-not-italic tw-font-normal tw-text-sm tw-text-black\u0022\u003EDr Werner Haase, DJINN\u003C\/cite\u003E\n \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\u003Cp\u003EWhen an aircraft approaches an airport, the landing gear is down and the flaps and slats are deployed to increase the lift at low speed, according to Dr Eric Manoha, head of the Computational Aeroacoustics Research Unit at French aerospace research centre ONERA.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u2018The aircraft follows a gentle descent along a standardised route,\u2019 he said. \u2018This means that aircraft are constantly flying at low altitude over the homes of the same group of people.\u2019\u003C\/p\u003E\u003Cp\u003EManoha leads INVENTOR, which began in May 2020 and runs until the end of October 2024.\u003C\/p\u003E\u003Cp\u003EBringing together major European aircraft makers Airbus and Dassault and landing-gear manufacturer Safran Landing Systems, it is homing in on the noise that emanates from wing flaps and slats and from the landing gear.\u003C\/p\u003E\u003Cp\u003EWhile plane engines are a major source of noise at takeoff, making flaps and slats as well as the landing gear quieter can produce a big overall improvement during approaches and landings when engines are less noisy.\u003C\/p\u003E\u003Cp\u003E\u2018Roughly 30% to 50% of the noise caused by an aircraft in these stages of the flight comes from the airframe, not the engine,\u2019 said Manoha.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EAir flows\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EThe INVENTOR team is testing \u2013 and planning to propose to the aviation industry \u2013 a range of design changes to lower decibel levels.\u003C\/p\u003E\u003Cp\u003EOne is to place a passive porous structure in front of the landing gear so that the surrounding airflow interacting with the structure is altered and noise is muffled.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EAnother is to install an active device on the landing gear that blows air out. This would create an \u201cair curtain\u201d that, again, cuts noise by diverting the airflow.\u003C\/p\u003E\u003Cp\u003EThe landing gear also has to be considered when trying to reduce noise from wing flaps, which are extended during landing and takeoff to provide more lift and drag.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u2018The wake of the landing gear impacts the flaps,\u2019 said Manoha. \u2018This causes noise.\u2019\u003C\/p\u003E\u003Cp\u003EThe project team is placing a porous material on the flap to reduce the noise generated by the flow around the flap. It\u2019s also examining options to reduce slat noise with porous materials and the noise generated by mechanical devices used to deploy the slats. \u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EDecibel decline\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cblockquote class=\u0022tw-text-center tw-text-blue tw-font-bold tw-text-2xl lg:tw-w-1\/2 tw-border-2 tw-border-blue tw-p-12 tw-my-8 lg:tw-m-12 lg:tw--ml-16 tw-float-left\u0022\u003E\n \u003Cspan class=\u0022tw-text-5xl tw-rotate-180\u0022\u003E\u201c\u003C\/span\u003E\n \u003Cp class=\u0022tw-font-serif tw-italic\u0022\u003EEach step forward is progress.\u003C\/p\u003E\n \u003Cfooter\u003E\n \u003Ccite class=\u0022tw-not-italic tw-font-normal tw-text-sm tw-text-black\u0022\u003EDr Eric Manoha, INVENTOR\u003C\/cite\u003E\n \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\u003Cp\u003EQuieter planes will emerge mainly from the cumulative effects of such design improvements rather than from any single one of them.\u003C\/p\u003E\u003Cp\u003EFor example, the latest generation of single-aisle aircraft generates around 75-80 decibels of noise during landing.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u2018We\u2019re aiming for a one to three decibel reduction per airframe element,\u2019 said Manoha. \u2018Each step forward is progress.\u2019\u003C\/p\u003E\u003Cp\u003EIn any case, residents near European airports will have to remain patient. Although some technologies might be retrofitted on existing aircraft, significant relief from air-traffic sounds may come only with the next generation of passenger jets.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EMotoring along\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EA separate EU-funded project that has just ended \u2013 and that Haase led \u2013 took a broader approach to the whole challenge.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003ECalled\u0026nbsp;\u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/861438\u0022\u003EDJINN\u003C\/a\u003E, the project improved the simulation methods used by aircraft manufacturers to predict how loud their planes will be. It ran from June 2020 through November 2023 and used advanced numerical methods and high-performance computing to predict fluid flows and improve the aerodynamic and acoustic performance of aircraft.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EIts findings will help plane manufacturers experiment with design options to reduce noise.\u003C\/p\u003E\u003Cp\u003E\u2018These methods became more accurate than what industry uses today to calculate noise,\u2019 said Haase. \u2018This is something the industry is looking for because they want to improve their designs.\u2019\u003C\/p\u003E\u003Cp\u003EIn contrast to INVENTOR, DJINN looked at the noise generated by both the engines and the airframe and included plane-engine manufacturers Rolls-Royce and Safran Aircraft Engines as project participants.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EEngine covers\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EOne possible design change that the DJINN team examined is a jagged shape of the engine outlet. Serrated engine covers have been shown in certain tests to reduce noise from aircraft engines and already feature in some Boeing models.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003ESo far Airbus has opted against serrated engine covers, citing a lack of gains in tackling noise.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EOther options, including the use of porous flaps, exist to reduce noise.\u003C\/p\u003E\u003Cp\u003E\u2018They all have their pros and cons,\u2019 Haase said. \u2018The question of which is the preferable approach remains open.\u2019\u003C\/p\u003E\u003Cp\u003EIn any case, while changes to planes themselves may not come immediately, both Haase and Manoha are optimistic about the prospects for reducing aircraft noise given the research advances taking place.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003EIn that context, the airline industry has an incentive to accelerate change because airports in Europe increasingly modulate landing and takeoff fees on the basis of planes\u2019 noise levels.\u003C\/p\u003E\u003Cp\u003EThis practice reflects growing environmental concerns and public outcries like the one in Ireland last month.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u2018Aircraft noise is disrupting the lives of certain people every single day,\u2019 said Manoha. \u2018New technology can help us reduce this burden.\u2019\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EResearch in this article was funded by the EU\u2019s Horizon Programme. The views of the interviewees don\u2019t necessarily reflect those of the European Commission. If you liked this article, please consider sharing it on social media.\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWatch the video\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Ciframe allow=\u0022accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture\u0022 allowfullscreen=\u0022\u0022 frameborder=\u00220\u0022 height=\u0022315\u0022 src=\u0022https:\/\/europa.eu\/webtools\/crs\/iframe\/?oriurl=https%3A%2F%2Fwww.youtube.com%2Fembed%2FEr5aBmSZEWA\u0022 title=\u0022YouTube video player\u0022 width=\u0022560\u0022\u003E\u003C\/iframe\u003E\u003C\/p\u003E\u003C\/textarea\u003E\n\u003C\/div\u003E\n\n \u003Cdiv id=\u0022edit-body-content--description\u0022 class=\u0022ecl-help-block description\u0022\u003E\n Please copy the above code and embed it onto your website to republish.\n \u003C\/div\u003E\n \u003C\/div\u003E\n\u003Cinput autocomplete=\u0022off\u0022 data-drupal-selector=\u0022form-lvo7mbszsgy6qth9w6ixeuhsibyigxwjbmgbycix7eo\u0022 type=\u0022hidden\u0022 name=\u0022form_build_id\u0022 value=\u0022form-lvo7mbSZSgY6qtH9W6iXeuhSIbYiGxwjBmgBycix7eo\u0022 \/\u003E\n\u003Cinput data-drupal-selector=\u0022edit-modal-form-example-modal-form\u0022 type=\u0022hidden\u0022 name=\u0022form_id\u0022 value=\u0022modal_form_example_modal_form\u0022 \/\u003E\n\u003C\/form\u003E\n\u003C\/div\u003E","dialogOptions":{"width":"800","modal":true,"title":"Republish this content"}}]