JAXA and Boeing to try to make landing aircraft quieter
The Japan Aerospace Exploration Agency (JAXA) has teamed with Boeing on a joint research project to make quieter mid-sized passenger planes – by figuring out how to cut the noise generated by their airframes.
Aircraft noise is an issue around the world, and the aviation industry is keenly aware that its social licence depends on operating as quietly as possible – especially at urban airports that travellers prefer because they’re closer to big city centres.
One such airport is Tokyo’s Haneda, which in 2020 opened new routes. Although the numbers of flights arriving were suppressed by unexpected subsequent travel bans, pre-COVID the new routes would have increased Haneda’s annual international arrivals and departures from 60,000 to 99,000. The result would be many aircraft flying at low altitudes over Tokyo.
Any city dweller, city planner or unfortunate person living along a flight path can see this plan’s inherent noise pollution problem.
Japan’s Transport Ministry has tried different methods to combat the acoustic by-product of international travel. It has even ordered planes to descend at steeper angles – a tactic which can lead to an increase in hard landings and has caused some planes to divert to Narita, 70km outside Tokyo.
Aircraft and engine manufacturers have worked on the problem for a while, too. Turbojet and turbofan engine designs have helped by increasing bypass ratios, thereby improving efficiency and dramatically reducing sound.
But ballooning volumes of air travel has made such progress insufficient.
All this puts the aviation industry in a bit of a tricky spot as it strives to meet future passenger traffic demands and, in the case of Haneda airport, maintain an internationally competitive facility.
JAXA worked with Japanese aircraft industries, universities, and NASA to further quiet aircraft by tackling airframe noise for six years starting in 2013 through the Flight Demonstration of Quiet Technology to Reduce Noise from High-lift Configurations (FQUROH) project.
FQUROH researchers have largely considered noise coming from flaps, slats and landing gear – all indispensable equipment that slow the aircraft while descending without thwarting lift. Aerodynamic noise caused by turbulent airflow from these sources at times exceeds engine noise as the pilot closes the engine throttle during approach procedures.
Probable solutions determined by FQUROH to reduce the noise-causing turbulent flow are practical flap-edge configuration devices, serrated lower parts of the slat to break down large-scale vortices, and perforated fairings on the landing gear.
Testing such designs with wind tunnels and computer simulations only gets you so far, hence JAXA’s partnership with Boeing to build on the FQUROH research and their development of a plan for validating designs in flight tests.
JAXA said it will continue working with Japanese manufacturers on the noise-reduction design concepts in the meantime.
The agency also said it will finalise design concepts by March 2022 and that these would be ready for flight test in 2023 “or later.”
See more here: theregister.com
Header image: JAXA
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D. Boss
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What a load of drivel! That airframe noise exceeds engine noise is utter nonsense!
To be fair, I am a pilot and have lived under the approach/departure path of runways at major airports.
This study is nothing more than the scientific industrial complex drumming up funding for moot or nonsense things to “study”.
First off the airports are almost always in place well before development puts homes around them. So the onus is on the buyer as to whether they want to accept the noise of living near an airport.
Next a landing jetliner does NOT have engine throttles at idle! A B737 on final will have N1 at 60% to 70% depending on flap setting and wind conditions. Idle has N1 speed at 35%. That same B737 only retards the throttles to idle at 20 feet above the runway during the flare!
Next EVERY landing jetliner and even a turboprop uses reverse thrust for slowing down after touchdown – and that noise can be as loud as a full power takeoff.
Finally the major noise pollution from airports is not from landing aircraft – when you live under an approach/departure path for a major airport, you barely notice the landing craft – it’s the planes taking off that make all the noise – duh!!! (and landing gear and flaps are retracted very shortly after takeoff – but to suggest aerodynamic noise from gear and flaps is anything but a teensy proportion of engine noise is laughable)
See/hear for yourselves – plane spotting at Princess Juliana:
https://www.youtube.com/watch?v=k1ozzD7aUL4
Do you hear any wind noise from the flaps and gear? No you hear engines screaming on approach.
Here is Frankfurt in high crosswind:
Now at 2:40 to 3:20 an Airbus A320 approaches but decides to go around – applying takeoff thrust at about 50 feet above ground – can you hear any flap and gear noise with takeoff thrust applied?
The article is a joke as is the “study”.
“Science” is doomed with this kind of crap passing off as legitimate.
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Joseph Olson
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Why reinvent the wheel (flaps, spoilers) with weight and drag to solve a problem that was corrected in 1930s using ANTI-SOUND. Active Noise Canceling systems have been in aircraft cockpits since the 1950s and popularized in headphones by Bose since the 1980s. College lab rats trolling for government grants is NON SCIENCE nonsense.
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