back to article Japan's aerospace agency hooks up with Boeing to make planes quieter when they land

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 …

  1. SkippyBing

    Interesting, I remember reading a piece in the RAeS journal years ago where they estimated the noise from some of the proposed super-jumbo aircraft would exceed the limits even with the engines turned off. Surprised it's taken so long to tackle it as it least some must be from inefficiencies, a lot though is presumably required if you're turning a few hundred tonnes of air through 90 degrees to generate lift.

    1. Richard 12 Silver badge

      Well, you are trying to slow down and descend, and all that energy has to go *somewhere*.

      It's not practicable to use regenerative airbrakes just yet...

    2. anothercynic Silver badge

      The easiest has been tackling the most obvious source of noise - the engines.

      Now that turbofans are at the point where they are arguably quieter than the latent noise generated by all other parts of the plane but the engines (and even unducted fans à la the GE36 UDF or the Safran RISE), the hard work begins. After all, the wing is meant to be ultra-efficient (with few vortexes, with laminar flow etc) for flight, and now we're having to make the wing less efficient and in fact be a piece of resistance to slow the plane down and to make it drop but not in a way that makes it go "boom" or leave a crater at the end of the runway, all whilst being *quiet* to avoid noise on approach and finals.

      The aerospace engineers have their work cut out for them.

      1. Snapper

        Well, at least it isn't rocket-science!

        1. anothercynic Silver badge

          Gets pretty close to it though. Aerodynamics and all their ilk are a magic all to their own...

  2. G R Goslin

    Why not go the whole hog

    I'd have thought it obvious that the engine noise would reduce when throttling back to descend. Why not go the whole hog and turn them off totally. Then you'd only have the wind noise to worry about. And perhaps the screams of the passengers.

    1. John Robson Silver badge

      Re: Why not go the whole hog

      I assume you're not being serious - the engines are required for stopping (thrust reversal) and for aborting in case of issues (go around)

      1. The Man Who Fell To Earth Silver badge
        Joke

        Re: Why not go the whole hog

        Why land at all? Just drop the passengers out the back by parachute at altitude, and land the plane at some airport out in the sticks.

        1. ChrisC Silver badge

          Re: Why not go the whole hog

          Mr O'Leary, gentleman on line 2 says he's got an idea to stop our customers complaining about how far away we land from our alleged destinations...

        2. bombastic bob Silver badge
          Coat

          Re: Why not go the whole hog

          that might work if the people compartment has the general shape of a shipping container. Roll it out the back like a C-130 dropping supplies...

      2. An0n C0w4rd

        Re: Why not go the whole hog

        Not to mention the small issue of hydraulic and electrical power needed for the flight instruments and control surfaces. As ably proved by the 737MAX debacle, muscle power alone is not enough to move control surfaces on a modern aircraft

        I guess you could point to the RAT (Ram Air Turbine), but that only provides power for very basic instruments and controls.

        1. John Robson Silver badge

          Re: Why not go the whole hog

          I reckon the APU is probably orders of magnitude quieter than the exposed engines, power shouldn't be an issue (or even a small stash of something less flammable than jet fuel - Lithium? :p

    2. I ain't Spartacus Gold badge

      Re: Why not go the whole hog

      G R Goslin,

      The aircraft is insulated - so I doubt passenger screamage will be externally audible. So that's not a problem.

      The problem is clearly operating engines at low level. So I think the solutions should borrow from existing, well understood, technology. I suggest we consider aircraft carriers.

      In order not to have to slow the plane so much, we can dispense with slats and flaps, simply have a few arrestor wires - and that will slow the plane down nicely. You'd get some problem with tyre noise, carrier landings can be have significant tyre squeal. Maybe oil the runways, to make them extra-slippery?

      Or another, long forgotten, piece of carrier tech as tested by Eric Brown. Simply remove the undercarriage entirely and have a rubber trampoline thingy fitted above the runway. Simply stall the aircraft above that - and have a nice bouncy landing. Extends aircraft range by saving weight as well - actually tested by the Royal Navy due to the pathetically short range of early jets.

      We can also think further into this. Why must people put up with low level engine noise? Simply have catapult launch. With a decent length of runway, I'm sure you could get the plane up to takeoff speed, and with a nice ramp get the aircraft launched, and only turn the engines on, once above a certain height.

      It all seems very sensible to me...

      1. Electronics'R'Us Silver badge
        Go

        Arrestor wires

        In order not to have to slow the plane so much, we can dispense with slats and flaps, simply have a few arrestor wires - and that will slow the plane down nicely.

        Already available!

        Simply have catapult launch.

        Here you go. Available for both land and sea.

        1. JamesTGrant
          Thumb Up

          Re: Arrestor wires

          Can’t see any down side to this - you could even make the landing runway 30deg steep and the aircraft wouldn’t have to slow down before getting snagged. Big fuel saving - could turn the engine off and coast the last little bit.

          If it went wrong it’d be in slow motion anyway so no damage would be done…

        2. Snapper

          Re: Arrestor wires

          Ohhhh, just thinking how that would work with your usual boozed-up Brit coming back from a holiday. 4-G would work wonders in keeping the blubbers in their seats.

          Then there is landing with arrestor hooks, and a tsunami of vomit hitting the seats at the front!

    3. Anonymous Coward
      Anonymous Coward

      Re: Why not go the whole hog

      >I'd have thought it obvious that the engine noise would reduce when throttling back to descend

      Joking aside it's a big part of our flight path planning.

      Decrease engine power slowly and descend slowly you have slightly less engine noise - BUT you spend a lot more time at low level above houses.

      Fly at full power for longer and then approach the airport like a dive bomber you are only at low level inside the airport perimeter - BUT it annoys passengers who don't enjoy roller coasters and occasionally you experience lithobraking

      1. werdsmith Silver badge

        Re: Why not go the whole hog

        I live under an approach and I love the noises. The flaps deploying, the undercarriage going down all make noises I recognise and I can tell plane types apart purely by their sound now (I miss the distinct flap howl of BAE 146 / RJ180).

        This morning one plane made a loud rattling noise that had me running out to see what was up.

        The engines do make a whine on approach, you can hear it throttling up and down adjusting slope.

        The old planes that do freight very early in the morning are very loud.

        1. John Robson Silver badge

          Re: Why not go the whole hog

          Interesting, when I lived in about that location for Heathrow it wasn't long before the only plane I ever heard was Concorde. Home video from that time is useless, it's just constant jet noise, but we didn't hear it.

      2. anothercynic Silver badge

        Re: Why not go the whole hog

        And of course there's a *lot* of work done by Eurocontrol, NATS and others to reduce the amount of 'loiter' by jets in holding stacks, which also adds to the noise profile, and going for other, alternate approach and landing profiles.

        I understand London City (LCY) uses the latter, with a steeper approach angle to not only get through the housing estate jungle but also to reduce the noise in the area. Embraer, Bombardier and Airbus all have specific configurations for such approaches that they developed in cooperation with LCY because it's useful elsewhere. :-)

    4. bombastic bob Silver badge
      Thumb Up

      Re: Why not go the whole hog

      And perhaps the screams of the passengers

      have an upvote

      1. Imhotep Silver badge

        Re: Why not go the whole hog

        From all his downvotes, I think a lot of people are missing the humor.

        But he got an upvote from me too.

  3. Mike 137 Silver badge
    Joke

    Others use ...

    Outside broadcasters find fur fabric very good as reducng surface turbulence. It would make planes look nice too.

    1. I ain't Spartacus Gold badge

      Re: Others use ...

      Hmmm. I like the idea of a nice leopardskin print airliner. Fly the kinky skies...

      1. Neil Barnes Silver badge

        Fly the kinky skies...

        Old enough to remember 'I'm Mandy, Fly Me'?

    2. Timbo Bronze badge

      Re: Others use ...

      "Outside broadcasters find fur fabric very good as reducing surface turbulence. It would make planes look nice too."

      Two problems:

      1) The fur would absorb water so flying through a rain shower, would cause the weight of the plane to increase significantly, resulting in either a need for bigger wings and/or more engines.

      2) You'd need a lot of fur...the animal rights activists would not be pleased and thefts/kidnappings of domestic animals might increase as the criminal trade in fur would increase.

      A better idea might be to put dimples on planes (as it works for golf balls), or maybe design the body of the plane with flutes (like the rifling inside a gun barrel) - both of these supposedly make for less air resistance and better directivity....

      1. Mike 137 Silver badge

        Re: Others use ...

        "animal rights activists would not be pleased

        Actually it's fur fabric that's used, so no animal rights issues. It's used as the outer layer on microphone wind shields to eliminate turbulence at the surface of the shield, so it has to have an open weave to avoid blocking the sound. Some folks who don't understand the principle have tried real fur, but of course the impervious leather stops the sound getting to the microphone.

        1. Anonymous Coward
          Anonymous Coward

          Re: Others use ...

          >Actually it's fur fabric that's used, so no animal rights issues

          Can't you use cat fur to ensure the plane always lands the right way up ?

          1. Anonymous Coward
            Anonymous Coward

            Re: Others use ...

            "Can't you use cat fur to ensure the plane always lands the right way up ?"

            Oh please, no!

            Remember how there was a rash of incidents where pilots were blinded by laser pointers? Just think how much worse it would be if the entire plane chased after the laser!

          2. Gotno iShit Wantno iShit

            Re: Others use ...

            "Ladies and gentlemen, this is your captain speaking. There will be a short delay before we push back and taxi for takeoff while the underside of our aircraft is buttered. We'll be under way in a few minutes.

            Thank you"

          3. Snapper

            Re: Others use ...

            Yes, but it would want to show everyone a close-up of its arse-hole within a very short space of time.

      2. Mike 137 Silver badge

        Re: Others use ...

        "design the body of the plane with flutes"

        It's not the flutes on a bullet that make it fly straight - it's the spin imparted by the spiral flutes of the gun barrel. I don't think most passengers would appreciate a plane that revolved at high speed on its longitudinal axis.

      3. anothercynic Silver badge

        Re: Others use ...

        It would only absorb water if it wasn't hydrophobic... ;-)

    3. Denarius Silver badge

      Re: Others use ...

      Fur ?

      Considered in the 1970s IRCC. Like owl feathers at reducing surface vortices. Cant recall magazine, probably not Flight but more research. It was only about 50 years ago

    4. Def Silver badge

      Re: Others use ...

      Norwegian Air Shuttle planes look enough like used flying tampons as it is. I don't think making them furry would help in any way.

  4. Timbo Bronze badge

    Take a cue for the Shuttle?

    Why not deploy a large (re-useable) parachute from the rear end of the plane?

    It worked for the shuttle...

    Then you don't need to extend the noise-producing "flaps" from the wings and can keep them smooth.

    1. Mike 137 Silver badge

      Re: Take a cue for the Shuttle?

      I've never flown an airliner, but my impression is that flaps are engaged quite a long time before any parachute could be used effectively and safely. Military planes deploy the parachute after touchdown, not while in the air. If they did the latter they'd probably just fall out of the sky.

      1. Yet Another Anonymous coward Silver badge

        Re: Take a cue for the Shuttle?

        > If they did the latter they'd probably just fall out of the sky.

        But that would be ok cos they have a parachute

        1. werdsmith Silver badge

          Re: Take a cue for the Shuttle?

          Ballistic Recovery Systems parachutes and planes like Cirrus SR22 do occasionally deploy in the air.

      2. Denarius Silver badge

        Re: Take a cue for the Shuttle?

        Was an issue with early fiberglass gliders. Some had a tail chute to get a decent descent rate. Big problem if pulled too early. Fences are fatal. The chute could be released but then risks being lost. Chute was way too small to be a ballistic recovery device, unlike the ones used in some ultralites

  5. CoffeeBlackest

    Japan has a space agency? Next thing you know you'll tell me Canada has a navy... ;-)

    1. TeeCee Gold badge
      WTF?

      I did hear that Luxembourg has (or had?) a Grand AdmiraL

      Presumably the job came with a little fleet for the chap's bath...

    2. Lars Silver badge
      Thumb Down

      Oh dear

      @CoffeeBlackest

      The ugly voice of English exceptionalism speaking again and again.

      Japan is a bigger richer country than Britain with a stronger currency too.

      The Japanese space agency JAXA is doing/has done more than the "British space agency" alone ever.

      This repulsive idiotic attitude is killing you from inside, rightfully so.

      https://en.wikipedia.org/wiki/JAXA

      1. JamesTGrant
        Happy

        Re: Oh dear

        Jaxa little harsh don’t’cha think?

      2. Steve K Silver badge
        WTF?

        Re: Oh dear

        I don’t see anything to suggest that Coffblackest is British/English?

        The Canada reference suggests he/she may be left-pondian.

  6. JDPower666

    I'm not sure Boeing is the ideal partner for this - their solution will probably be to crash further away.

    1. Yet Another Anonymous coward Silver badge

      But quietly

    2. Imhotep Silver badge

      If Boeing is involved, the safest and quietest solution might be not to takeoff in the first place

  7. Totally not a Cylon
    Joke

    Simple fix

    Either arrange for a pair of F-111s to do 'touch & goes' for a couple of hours......

    or announce your airport is going to host Starship.

    Nobody will complain about civil airliner noise again.....

    1. werdsmith Silver badge

      Re: Simple fix

      F1-11s transiting to Upper Heyford would roar over my junior school daily and are part of the soundtrack of my childhood. Glorious, often in pairs, lessons would have to stop for 30 seconds while they passed over.

      1. I ain't Spartacus Gold badge

        Re: Simple fix

        I worked at the end of the runway at Heathrow. It wasn't Concorde landing that caused us to have to stop work for a minute twice a day. It wasn't all that noisy. Takeoff on the other hand... As you say though, it did mean that you didn't tend to notice the other planes so much.

        1. Anonymous Coward
          Anonymous Coward

          Re: Simple fix

          I used to work at Heathrow. I remember Concorde taking off used to set off all the car alarms in the car-parks. For a good few minutes after Concore had gone all its all you could hear. :)

  8. DS999 Silver badge

    That landing pic is nothing

    When I was a kid my family and I went to Hong Kong. Now that was an interesting landing in the original airport!

    1. John R. Macdonald
      Pint

      Re: That landing pic is nothing

      @DS999

      Ah yes, I remember landings at Kai Tak Airport in the 1980-90s, plane flying between the Kowloon high-rise buildings and the passengers peering into the living rooms of the locals.

      a.k.a. Kai Tak Heart Attack

  9. bombastic bob Silver badge
    Devil

    golf ball exterior

    there is some evidence that the appearance of the skin of a golf ball not only reduces the air drag during the ball's flight, but the noise it would generate as well.

    I have to wonder what effect this would have on airplane parts...

    (parts of the article already allude to existing features that might behave similarly, like lots of small holes in a control surface, which could also reduce weight)

    1. Denarius Silver badge

      Re: golf ball exterior

      Mythbusters found dimpling worked for cars, scaled up. Noise they did nt measure but suspect at the speeds they used would have been swamped by engine and type noise.

    2. DS999 Silver badge

      Re: golf ball exterior

      That works for golf balls because they are rotating at thousands of rpm. If you shoot a golf ball out of an air cannon with little or no spin, it actually performs worse than a smooth ball due to INCREASED drag. If dimples worked on a wing, we'd have dimpled wings. It isn't like golf balls are a secret to aerodynamic engineers.

      1. Lars Silver badge
        Happy

        Re: golf ball exterior

        There is what is called shark skin tried on yacht hulls, as a paint, to decrease drag and that is because it's not completely smooth.

        This is not to rebuff your comment.

        1. DS999 Silver badge

          Re: golf ball exterior

          Interesting, so dimpled wings won't help but maybe sharkskin wings will!

          1. Lars Silver badge
            Happy

            Re: golf ball exterior

            Perhaps water sticks to a surface in a different way than air, not to mention that the speeds are very different.

  10. Anonymous Coward
    Anonymous Coward

    "Turbojet and turbofan engine designs have helped by increasing bypass ratios,"

    Isn't that basically the differentiation between a turbojet and a turbofan? Aren't they essentially the same, except the turbofan has a higher bypass ratio, so most of the thrust comes from the fan part, not the jet part?

    Asking because I'm sure a few Reg readers will know for certain.

    1. Denarius Silver badge

      right enough. Turbojets have most air go through engine. A bit of air bled off for cooling. A turbofan has up to 20 times air going thru fan as engine. In short, a modern turbofan is a shrouded propeller in effect. Corrections ?

  11. Anonymous Coward
    Anonymous Coward

    Owls

    I think the project acronym is a play on fukuroh, Japanese for owl, I.e. silent flight.

    Less joyously, this sort of nonsense comes round every ten years. Last time it was Cambridge with some big aerospace boondoggle to develop silent flight. I think results so far are nil.

    1. Anonymous Coward
      Anonymous Coward

      Re: Owls

      In my corner of the world, which is under the flight path of our friendly neighborhood military base, one could deduce how to pronounce the first part of the FQUROH acronym from how little care or respect the military seems to have for the residents (and schools and churches and businesses and parks/playgrounds) over whom they fly. Honestly, if one MUST learn how to race in at full throttle (which I am sure pilots do need to learn to do safely), can not that be done at a base that is NOT totally encircled by built-out residential development (much of which pre-existed the base)?

      1. Denarius Silver badge
        Mushroom

        Re: Owls

        infinite regression problem added to stupid/corrupt (but I repeat myself) local government. For airports good access is required. So airport built in scrub away from all and sundry. Developers see great road, make donations, and build suburb next to and eventually around airport. Cue noise from locals demanding airport goes away. Jandacot in Perth WA is a classic case. Miles from anywhere, used to trail bike in empty scrub disturbing only kangaroos. Now it is surrounded by suburbs, which whine about aircraft noise and is on top of a major underground water supply for city, now being polluted by garden waste, leaking pipes etc.

      2. Trigonoceps occipitalis Silver badge

        Re: Owls

        Jet-wash, the sound of freedom!

    2. John Brown (no body) Silver badge

      Re: Owls

      "Less joyously, this sort of nonsense comes round every ten years. Last time it was Cambridge with some big aerospace boondoggle to develop silent flight. I think results so far are nil."

      I suspect the problem is no one is really building new planes. A new plane takes many years from concept to service-ready, so most new planes are adaptions and improvements on older models, thus seriously reducing the development and certification phases.

      The research ideally needs to come up with simple adaptions that can be retrofitted to existing planes which then must be mandated in at least some jurisdictions, forcing the manufactures, owners and operators to take it seriously. They won't spend money they don't have to unless there are savings to be made in one opr more of fuel economy, lifting capacity or fine avoidance.

    3. rg287 Silver badge

      Re: Owls

      Less joyously, this sort of nonsense comes round every ten years. Last time it was Cambridge with some big aerospace boondoggle to develop silent flight. I think results so far are nil.

      Nonsense? Boondoggle?

      Nobody is trying to develop silent flight. that would be stupid and impossible. Any aircraft will move air out the way and generate some sound. They are simply seeking to minimise that. This is extremely useful research in the general sense since it furthers understanding of fluid dynamics, turbulence, vortices, etc which have broad ranging applications in many sectors.

      Previous projects have improved things like the design of landing gear, which makes a measurable difference to landing noise.

      Nobody is going to announce a new (magic) "silent" airliner. But the results of this sort of work feeds back into existing designs to incrementally improve certain components as you go from (say) the 737NG to 737MAX or A330 to A330neo. Older planes were louder than newer planes, and it isn't just down to the engines.

  12. Gene Cash Silver badge

    Boeing

    Well, Boeings these days just make one loud thump when they land, and sometimes a boom afterwards.

    1. Kevin McMurtrie Silver badge

      Re: Boeing

      The first step of noise reduction is making sure all landings remain on the tires.

      1. FILE_ID.DIZ Bronze badge
        Trollface

        Re: Boeing

        Rubber side down then, eh?

  13. Tony W

    Owls

    Owls have extremely quiet low speed gliding flight. Unfortunately their feathers are not waterproof so you can't simply fit owl feathers to an aircraft; however I'm sure someone is working on it.

    1. Lars Silver badge
      Coat

      Re: Owls

      I don't think they use raincoats though.

  14. martinusher Silver badge

    Overlooking the obvious

    The turbulence from the control surfaces is all part of the process of destroying energy as the plane lands. You've got anything up to a couple of hundred tons of metal and stuff that's descending from several miles up so all that potential energy has to go somewhere. You're also trying to slow the plane to a reasonable landing speed so there's no use converting that potential energy into forward motion. So you deploy flaps, slats and what-have-you to change the aerodynamic properties of the wing from ultra-efficient to 'not quite a metal parachute'. All the inefficiencies result in turbulence, and so noise.

    I'm surprised that nobody's thought of this before, its obvious. (Its unfortunate that we can't recover all that energy we spent lifting and accelerating the plane for the flight. Flying was always going to be a relatively inefficient way of getting about.)

  15. Delta Oscar

    "....to hold....."

    ...I thought it was called Continuous Descent Approaches...???

  16. xformer

    Well, I strongly disagree with the sentence "Turbojet and turbofan engine designs have helped by increasing bypass ratios, thereby improving efficiency and dramatically reducing sound". That is simply not true.

    I live near an airport and I know the sounds of all the airplanes that buzz around here. Take for example the GE90 used by the Boeing 777 airplane. This is a high-bypass turbofan aircraft engine and it is much louder than than other engines. The high-bypass reduces the rumbling of the engines a bit and certainly not dramatically. Unfortunately it generates and extremly loud high-pitched whistling sound, making the noise even more unbearable than those of engines with a lower bypass value.

    The Boeing 737-800, which uses CFM56 engines (high-bypass ratio, you guessed it) is *extremely* loud. It is one of the most annoying planes that are in use. It is even louder than some 4 engine planes.The noise is much louder than the one Airbus A320 classic engine planes. It is the loudest small plane that I know of.

    The same holds true for the much-praised Airbus "neo" engines (PW1100G-JM and LEAP-1A). They are a bit less-noisy than the "ceo" engines but also have this extremely annoying whistling sound which make them even harder to bear, especially shortly after take off.

    Even the Airbus 350 with it's Trent XWB with a "reduced acoustic mode scattering engine duct system (RAMSES)", a quieting engine and "zero splice" is quite loud.

    I know of only two planes that are dramatically less noisy: Boeing 787 and Bombardier CS-100/-300 (now called Airbus 220). The Boeing 787 uses GEnx-1B and Rolls-Royce Trent 1000 engines. The CS-100/-300 uses PW-1500G engines. All of them are also high-bypass engines. So what is the difference? The B787 uses engine nacelles with chevrons. I do not know what makes the PW-1500G less noisy.

    All-in-all it is not the high-bypass ratio that makes plane engines less noisy. That is simply not true.

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