Slashdot Mirror

← Back to Stories (view on slashdot.org)

JAXA Successfully Tests Its D-SEND Low-Noise Supersonic Aircraft

Posted by timothy on from the not-quite-free-fall dept.

AmiMoJo writes: JAXA, the Japanese space agency, has successfully tested its low sonic boom demonstration aircraft D-SEND#2. The unmanned aircraft is floated up to 30,000m by balloon and released, falling back to earth and breaking the sound barrier in the process. The sonic boom created is measured on the ground. The project aims to halve the noise created by sonic booms, paving the way for future supersonic aircraft.

31 comments

  1. Less boom by invictusvoyd · · Score: 1

    My window pane is so happy to hear that .

    1. Re:Less boom by invictusvoyd · · Score: 1

      Anonymous coward

    2. Re:Less boom by Anonymous Coward · · Score: 0

      Why does it matter? Have your mom slept around so much that you have problems figuring out who it was?

    3. Re:Less boom by invictusvoyd · · Score: 1

      Anonymous idiot

    4. Re:Less boom by Anonymous Coward · · Score: 0

      Still doesn't narrow it down, does it?

    5. Re:Less boom by Anonymous Coward · · Score: 0

      I know Dad, my room is right next to yours!

  2. Hmmmmmmm by NoNonAlphaCharsHere · · Score: 1

    Ya know, I'll bet that if we didn't have so many science haters and pork barrelers in Congress playing games with the budget, that the National Aeronautics and Space Administration could do similar research.

    1. Re:Hmmmmmmm by thinkwaitfast · · Score: 1

      They do and there was a demonstration of this about ten years ago.

    2. Re:Hmmmmmmm by Gravis+Zero · · Score: 0

      Ya know, I'll bet that if we didn't have so many science haters and pork barrelers in Congress playing games with the budget, that the National Aeronautics and Space Administration could do similar research.

      do you really think NASA should be wasting any brainpower on this corporate horseshit? if companies want to make supersonic jets quiet, let them do/pay for the research. frankly, i would prefer NASA stay on the task of helping humanity, not corporations.

      --
      Anons need not reply. Questions end with a question mark.
    3. Re:Hmmmmmmm by NoNonAlphaCharsHere · · Score: 1

      I'm just gonna take your sig at face value.

    4. Re:Hmmmmmmm by AmiMoJo · · Score: 1, Insightful

      Actually this is exactly the kind of research governments should be doing. Stuff that is commercially risky but could have massive pay-offs. If Japan can build a reasonably quiet and efficient supersonic passenger jet they could really boost their aircraft industry. Currently they focus on smaller regional jets, but this could be a big new opportunity.

      It's similar to how they developed their high speed trains. The government did the basic research and development, and then it grew into a huge business where Japan lead the world for over 50 years.

      --
      const int one = 65536; (Silvermoon, Texture.cs)
      SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
    5. Re:Hmmmmmmm by serviscope_minor · · Score: 2

      It's similar to how they developed their high speed trains. The government did the basic research and development, and then it grew into a huge business where Japan lead the world for over 50 years.

      Interestingly that's the exact opposite to the way the UK works. You see we put in all the risky research money to develop tilting trains. Then because "reasons"[1] it was shut down and sold off and we're now buying tilting trains from Pendolino (a foreign company which bought the rights cheap) at great expense. The original tilting train still holds the speed record on the relevant routes.

      Which is a better investment, I shall leave as an exercise to the reader.

      [1]The reasons were bogus. Some people claimed it made people feel ill. There was an early problem because the tilting compensation was too good. Dialling it back a bit solved the problem and the trains became no worse than the modern ones in that regard. Basically the reason is that no matter who is in power, parliament hates local industry for some reason.

      --
      SJW n. One who posts facts.
    6. Re:Hmmmmmmm by Anonymous Coward · · Score: 0

      I see your point about politicians either being corrupt or having no ball or no vision or some combination of or all of the above.
      But No-one really buys the Japanese bullet trains outside Japan, and Japan is deeply indebted so shouldn't be buying them either.
      Fantasy economics aside, they're not essential. They do make sense in a mountainous country like Japan that is xenophobic and doesn't want oil dependence but otherwise, they're overly expensive. Also, the best market for them to export to would be America and everyone flies there. Europe makes its own high speed trains, and though not as fast, they at least don't break the bank. China does too.

    7. Re:Hmmmmmmm by MoarSauce123 · · Score: 1

      Parliaments pay attention to those who write the biggest checks. Research labs rarely do that unless they are convinced that their 'research' will gain a lot of commercial success and they just need the tax payer for initial funding rather than go through the trouble of seeking private investment.

  3. TGIF by Anonymous Coward · · Score: 0

    Rebecca Black hopes you had a happy Friday!

  4. Helium by Anonymous Coward · · Score: 0

    I wonder how much of our limited supply of helium gets lost every time they do this.

  5. Less noise by rossdee · · Score: 1

    "falling back to earth and breaking the sound barrier in the process."

    So it wasn't powered by a jet engine, meaning less noise to begin with.

    1. Re:Less noise by Gravis+Zero · · Score: 1

      "falling back to earth and breaking the sound barrier in the process."

      So it wasn't powered by a jet engine, meaning less noise to begin with.

      the point is to reduce the sound from a sonic boom, not the engine, genius.

      --
      Anons need not reply. Questions end with a question mark.
    2. Re:Less noise by wonkey_monkey · · Score: 1

      Yeees. And?

      --
      systemd is Roko's Basilisk.
  6. Sonic Booms by Trax3001BBS · · Score: 1

    With my Dad in the Air Force sonic booms were common place, the SST (Super Sonic Transport) battle made them stop entirely (only certain situations are they allowed anymore). It's rare to hear them anymore. I've even a story that shows one can even be accused of firing a weapon when one happens, people just aren't used to them, or never heard one before.

  7. Re:I see problems by Anonymous Coward · · Score: 1

    Of course, Mr. Coward! You should write those dumb fucks at JAXA explaining their glaring mistake in simple terms. Don't forget to attach your contact information since they'll need you to step in after they're done smacking their foreheads and resigning in shame.

  8. Wow by rsilvergun · · Score: 1

    And with those robot arms he'll be able to go even faster! (looks) Oh, _JAXA_. Drat. Well then. Carry on I suppose.

    --
    Hi! I make Firefox Plug-ins. Check 'em out @ https://addons.mozilla.org/en-US/firefox/addon/youtube-mp3-podcaster/
  9. Measured how? by ChrisMaple · · Score: 1

    Halving the noise is not a scientific description. Half the noise power? Half the peak pressure? Half the average pressure? Half the perceived noise?

    Half the noise power (3 dB) is so small a difference that an untrained listener couldn't reliably tell the difference between tests performed a day apart.

    --
    Contribute to civilization: ari.aynrand.org/donate
    1. Re:Measured how? by arielCo · · Score: 1

      It's in TFA (2nd link). The peak positive pressure of the N-shaped waveform was reduced to less than half and the peak underpressure to about 2/3 compared to a conventional cone.

      --
      This post contains no rudeness or derision of any kind. All arguments are friendly. Terms and exclusions may apply.
    2. Re:Measured how? by PhloppyPhallus · · Score: 2

      i.e. a 6 dB reduction in overall Sound Pressure Level. Just enough to be noticeable, but not really a huge change.

      The real issue is that no one has reliably determined what noise levels are "acceptable" for sonic booms. A lot of recent work by NASA and JAXA has focused on which types of noise metrics correlate best with annoyance (in short, Perceived Noise Level seems to do about as well as anything), but it's the politicians who have to decide what levels are allowable for overland flight. For that, you have to identify their constituents that care. Quite honestly, the big boys in the aviation industry aren't that interested in supersonic flight--few will pay much more for their airplane ticket to save a few minutes of flight time, especially with so much extra time now spent in security. In fact, airliners have slowed down in recent years to save fuel and lower ticket prices. The guys pushing for a rules change are the business jet manufacturers, like Gulfstream, who do have customers who care about speed (and can skip the lines at the airports). How much noise are people in "flyover country" willing to accept so that rich CEOs can get from NY to LA an hour sooner?

  10. factor of 2 is nothing logarithmically by Anonymous Coward · · Score: 0

    Sound is perceived and measured logarithmically, so they're going to have to do much better than that.

  11. Terminated by rh2600 · · Score: 1

    TFA mentions that the craft was successfully terminated after the test, which I assume means it was somehow destroyed in-flight or directed to the ground/sea in a fatal fashion.

    It's incidents like these that we will regret when SKYNET finally rises and calls us to account.