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More On Silent Supersonic Planes 297

Posted by timothy from the more-of-a-phhhhffftt dept.
Reverberant writes "Popular Science describes the latest attempt at developing a supersonic plane designed to minimize sonic booms. The article describes some of the history behind the research, and recent attempts at validating the theory. Also note that researcher Ken Plotkin is a frequent contributer to alt.sci.physics.acoustics."
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More On Silent Supersonic Planes More

More On Silent Supersonic Planes

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  • Sonic booms... (Score:5, Funny)

    by XaviorPenguin ( 789745 ) on Sunday August 01, 2004 @02:41PM (#9859007) Homepage Journal
    Where is that Hedgehog when you need him? Can't we tell him just to be quiet?

  • Towards A Silent Sonic Booms (Score:5, Funny)

    by NitsujTPU ( 19263 ) on Sunday August 01, 2004 @02:43PM (#9859019)
    Conjugate much?

  • windows (Score:5, Interesting)

    by dollargonzo ( 519030 ) on Sunday August 01, 2004 @02:43PM (#9859020) Homepage
    is it just me being paranoid, or is not having any windows and having cameras send external images to the cockpit a "bad thing." obviously, without computer systems, the planes are almost useless, but if anything happens to the camera, the pilot can't even *see* outside the plane.

    • Re:windows (Score:4, Funny)

      by Exiler ( 589908 ) on Sunday August 01, 2004 @02:45PM (#9859031)
      Not to mention, you can't stick your arm out the window when you're cruisin'.

    • So? (Score:5, Insightful)

      by Anonymous Coward on Sunday August 01, 2004 @02:49PM (#9859050)
      Pilots rely on more than just being able to see outside. They have literally dozens of instruments that they have to monitor in addition to the view outside. During the night and over the ocean, you have nothing but your insturments to rely on, so it's not like this is a new thing for pilots. Still, if it were ME I would want a window :)

    • Re:windows (Score:5, Informative)

      by Tyler Eaves ( 344284 ) on Sunday August 01, 2004 @02:56PM (#9859079)
      It's just you being paranoid.

      A modern airliner with all the latest gadgets (GPS, EFIS, ILS) can be flown without any sort of external vision at all. Heck, the modern autopilots can take off, fly to the destination, fly the approach, and do all but about the last 50ft onto the runway.

      • Re:windows (Score:4, Interesting)

        by pjt33 ( 739471 ) on Sunday August 01, 2004 @03:06PM (#9859128)
        I beg to differ. Instruments can fail, sometimes for unexpected reasons [wikipedia.org].

        • Re:windows (Score:4, Insightful)

          by Tyler Eaves ( 344284 ) on Sunday August 01, 2004 @03:55PM (#9859360)
          Well, of course. That's why you have backups, and backups for the backups. Likely backups for THOSE. If all those levels of redundency fail, odds are not being able to see is the least of your worries.
        • He didn't say that airliners could do all that, perfectly and without fail, he just said they COULD do it. It's as if I said, "People can drive cars from one destination to another," and you replied, "I beg to differ. People can get in accidents, sometimes for unexpected reasons."

          Yeah, it's a nitpick, but so what?

      • Re:windows (Score:5, Interesting)

        by the pickle ( 261584 ) on Sunday August 01, 2004 @04:09PM (#9859429) Homepage
        Assuming all hydraulic systems are fully operative, a 777 or 747 can actually do the last 50 feet, too.

        We pilots are there in case something goes wrong, and because ATC doesn't issue the exact same route every single time. Someone has to input the proper arrival procedure for the destination, since weather changes a LOT. ;)

        p
        • ...is nothing new. The Tridents, BAC 1-11s and VC10s (all British!) of the early 1960s had it. Don't try and pretend Boeing invented everything - they are the Microsoft of the skies - not much invented here....

          • I never meant to imply that Boeing invented the system. The 747 and 777 are two common FAA-certified examples that I can think of. I'm sure there are plenty of others, although I doubt the FAA certified any such systems in the US as early as the 1960s.

            p
    • I happen to think that instruments are FAR more important and relavant and visual flying. Windows are nice for those clear, blue days, but what about when it's dark and rainy? No help there from the view!

      Other conditions can contribute to being totally disoriented (like the cause of JFK Jr.'s crash). In his case, he wasn't authorized to fly at night due to the fact that he wasn't instrument-only rated.

    • Re:windows (Score:4, Informative)

      by dj245 ( 732906 ) on Sunday August 01, 2004 @04:03PM (#9859392)
      The earliest subway cars had no windows either, since there was nothing worthwhile to see. Windows were added later since they made people more at ease and helped with claustrophobia, even if what is outside isn't that pretty.
    • As long as it doesn't run Windows things should be okay.

  • phew (Score:5, Funny)

    by c0dedude ( 587568 ) on Sunday August 01, 2004 @02:48PM (#9859045)
    If it's been published on the prestigious trade journal 'alt.sci.physics.acoustics', it must be true!

  • It's about time! (Score:2, Interesting)

    by stroustrup ( 712004 )
    As I grew up I watched so many programs like "Beyond 2000" on discovery channel and felt excited about being in the years beyond 2000. This is 2004 and none of the promises came true. We are at about the same level as we were in 1999 technologically. Or even worse as concorde is gone. Somebody, move us into the future!

    • That's not really true, it's just that most of the changes are more subtle than the flamboyant extravaganza that was Concorde. The newer planes are doing much the same job they did back in '99, but much more efficiently and safely. There's little "Gee Whiz" factor, but technology is sure marching on.

      There's more than just technology involved too. I remember an article on Beyond 2000 about BMW's Hydrogen powered 7 series. The technology has been around for decades, but we don't have this stuff on the road d

  • 'Popular Science' (Score:4, Funny)

    by shobadobs ( 264600 ) on Sunday August 01, 2004 @02:50PM (#9859057)
    "Popular Science." No such thing, man. More like, "nerdular nerdance."

    --
    If you don't get it, don't moderate!

    • Actually, on a serious note, I got pretty frustrated with the article. Actually, I only read the first page and then got bored. I'll never understand why science writers always clutter up their articles with crap like that turtle in the story. We want to read about advanced aerodynamics, not wildlife. Then they go on and on talking in detail about the test. Just tell us what happened at the test; we don't need a blow-by-blow account.

      Extra clutter like that really makes the article seem amateurish. Yo

      • The general feeling in any kind of journalism that tries to take a complex subject people know little about (e.g., just about any kind of science or engineering) is that it's necessary to inject some everyday, human-interest details into the story to keep people reading. And I have the feeling, readers like you aside, that overall they're right. If you want Just The Facts, read the journals where the more detailed descriptions are published.

        As someone who reads journals all the time, I enjoy the breezy,
      • You are "frustrated" because an article in Popular Mechanics seems amateurish?

        Newsflash: PM is not a scientific or engineering magazine, it's basically the nerdy guy/Redneck mechanic version of supermarket tabloids like News Of The World, or the Star. Try looking at some back issues and you'll figure out pretty soon that this rag is just recycling the same badly written, factually wrong and unrepentantly gush-y articles every year. (Oh, it's June--let's do the supersonic plane again. July--the Navy's next

        • PM was once a serious and useful publication, but that must have been more than 15 years ago.

          Way more than that. As early as the late 60's (the oldest issues in my memory) PS was pretty much a gee-whiz magazine not intended for actual practitioners of science or engineering. But if you look at pre-WWII reprints, it has the flavor of a trade rag, with actual practical knowlege for projects (homebuilt radio sets were common, I think this was before a separate Popular Electronics) The premiere ussue was

      • I'll never understand why science writers always clutter up their articles with crap like that turtle in the story.

        that's because the magazine is Popular Science, and not Hardcore, Adless, Emotionless & Subject-Verb-Object-Only-Sentences Science. ;)

  • I'd like to know... (Score:3, Funny)

    by xpccx ( 247431 ) on Sunday August 01, 2004 @02:57PM (#9859081)
    if a plane breaks the sound barrier and no one is around to hear it, does it make a boom?

    • Re:I'd like to know... (Score:2, Funny)

      by Anonymous Coward
      If someone posts a joke on /. and no one reads it, is it still funny?

    • Re:I'd like to know... (Score:2, Funny)

      by Anonymous Coward
      if a plane breaks the sound barrier and no one is around to hear it, does it make a boom?

      If I'm in the middle of the woods and cannot hear my wife, am I still wrong?

  • A picture of the modified plane... (Score:5, Informative)

    by pldms ( 136522 ) on Sunday August 01, 2004 @02:58PM (#9859085)
    ...can be found here [rotor.com].

  • really a problem? (Score:3, Interesting)

    by prockcore ( 543967 ) on Sunday August 01, 2004 @03:11PM (#9859144)
    I've never heard a sonic boom... so I'm not really sure how loud they are, but a co-worker described it as "pretty much sounds like thunder".

    Is that really a big problem? It seems kind of dumb to me to ban supersonic flight over cities.

    • EVERYONE has heard a sonic boom (Score:5, Interesting)

      by GuyMannDude ( 574364 ) on Sunday August 01, 2004 @03:14PM (#9859161) Journal

      I've never heard a sonic boom... so I'm not really sure how loud they are, but a co-worker described it as "pretty much sounds like thunder".

      EVERYONE has heard a sonic boom at one point: the crack of a whip. That sound you hear is not the tip of the whip hitting anything. It's the sound of the tip accelerating beyond the speed of sound and creating a mini-sonic boom. That little flick at the end causes the tip to snap out at incredible speed.

      Now as far as a big sonic boom, I haven't heard one either. I'm sure there are some pretty strict regulations about not creating sonic booms in civilian areas.

      GMD

      • In Michigan, we usually have the Blue Angels or the Thunderbirds fly over Traverse City during the 4th of July. I can't say they do it every year, but I know that last year, the Thunderbirds broke the sound barrier right out over Lake Michigan near shore (you could actually see the shockwave); you could feel it in your stomach. It wasn't exactly shattering windows and setting off car alarms, but it was far from subtle.

        Think of standing in front of a *really* powerful subwoofer, but without any crappy booty

      • Re:EVERYONE has heard a sonic boom (Score:4, Interesting)

        by CvD ( 94050 ) on Sunday August 01, 2004 @03:54PM (#9859355) Homepage Journal
        Here in the Netherlands about two months ago a bunch of cities were subjected to sonic booms of 2 F16's scrambling to intercept a commercial airliner that wouldn't respond to any sort of radio contact. It was some sort of charter from Scandinavia to Spain if I remember right (I can't find any news article about it any more). Later turned out to be a huge misunderstanding, but I guess they didn't take any chances and had the jets intercept.

        It was pretty cool... a very low boom as if someone had set off explosives somewhere a distance away. The windows rattled in their frames. I didn't know it was a sonic boom at the time, but it was mentioned on the news later.

        • I can't find any news article about it any more

          The incident occurred on June 17. There's a brief reference to it here [f-16.net].

          Generally, the military restricts supersonic speed over land to altitudes above 30,000 feet to limit the intensity of the sonic boom. It is probably a measure of the urgency of that mission that the F-16s broke the sound barrier so soon after take off.

      • Re:EVERYONE has heard a sonic boom (Score:5, Informative)

        by swatoa ( 743331 ) on Sunday August 01, 2004 @04:27PM (#9859526)
        Here's an F-14 creating a sonic boom overhead in some type of airshow.

        http://users.wpi.edu/~jbendor/F-14%20Sonic%20Boom. mpg [wpi.edu]
        • Nice vid.

          I think I see the tel-tale signs of an aircraft carrier as the camera pans left.

          So that's probably out to sea.

          There's another of an F-14 doing the same thing floating about the internet, only the air is moist so the shockwave cone shows visibly in a cloud-like mist.

          Way cool. (I'd upload my copy, but I have no servers capbable of a pseudo-slashdotting.)
      • I've never heard a whip crack- but up here at the lake [collinslake.com] we used to hear sonic booms from SR71s about one day every 4 months or so. One boom was strong enough to shake the spoon out of my Lucky Charms on a Sunday morning in our mobile home. (all those happy memories)
    • One f4 or tornado (dont remember which) pilot went a BIT to fast at 35000 feet, he didnt actually fly over my city, so the actuall distace was 20-30 km (my room-plane).

      It sounded like an bomb explosion a few 100m away. No high pitch noises, but a solid "whooop" that made me check if any window had cracks. In fact the window need my desk vibrated visibly. Even through the windows it could be felt in the belly like an effect in a thx theatre.

      To make it short, its not a sound, its more like a shockwave. Bein
    • Just hearing one once in awhile may not be bad. But if you had one for every flight that passed over head you would get tired of it pretty quickly.

      When the shuttle was flying and they landed at Cape Canaveral I would hear the sonic booms as they would pass over Orlando. Was woken up a few time in the early morning hours as they went over at 30000 or 40000 feet and it was enough to make the windows rattle. In that case it was a double sonic boom, like two claps of thunder. BOOM BOOM!

      Multiply that b
    • You don't hear a sonic boom so much as feel it.

      A few years back I was sitting in my car near Orlando and there was a very big thump. I quick made sure none of the idiot lights on the dash had gone on and then I looked around wondering if some crane somewhere had just dropped an I-beam. Then I remembered: "Oh yeah, the shuttle is landing today."

      The best analogy I can think of is a small, sharp earthquake. There's a reason why seismographs pick them up.
    • depends on how close you are. i once lived in utah, and fighter jets often cracked the barrier above. Its like very loud, window rattling, house shaking thunder.

      It would get old fast if it happened regularly.
    • It sounds like a fucking bomb went off. When there are sonic booms over civillian areas people panic. And they're loud enough that you wouldn't want them over your house, plus they travel a lood way out so the entire city hears them.
    • I've never heard a sonic boom... so I'm not really sure how loud they are, but a co-worker described it as "pretty much sounds like thunder".

      Is that really a big problem? It seems kind of dumb to me to ban supersonic flight over cities.

      There are certainly very important military implications to being able to go supersonic without a boom. If you have a plane capable of going supersonic, but is indistinguishable from noise on radar thanks to stealth technology, a sonic boom is one thing that could give you

    • Re:really a problem? (Score:3, Informative)

      by j_w_d ( 114171 )
      It is a matter of what is making the "boom" and how far off it is. As another poster notes, the crack of a whip is a tiny sonic "boom." The kind caused by jets vary in intensity depending on distance. From a distance of a mile or more they sound like thunder, which oin a sense is a sonic boom as well. The sound is caused by the abrupt displacement of surrounding air by intensely heated air along the course of the lightening. Close up they can be painful and structurally damaging. I think the Israelis

  • Let's rather make subsonic planes silent (Score:5, Interesting)

    by Anonymous Coward on Sunday August 01, 2004 @03:12PM (#9859154)
    That's very interesting, but would not it make more sense to make the normal, subsonic planes more silent? They are much more in use, and the noise causes a lot of grief near airports, especially at night. Here in Brussels, this problem is already for years on the political agenda, being a very difficult problem to solve (economics vs. health...), so silent planes are really a must!
    • Heck, I'd be happy with someone making Honda Civics more silent...

  • There will still be protests (Score:4, Interesting)

    by SteakandcheeseUm ( 191173 ) on Sunday August 01, 2004 @03:19PM (#9859190) Homepage
    I am almost certain that people wont want it flying over their neighborhoods. I can remember watching a show about all of the hubub people made about the Concord landing at their local airport. You would have thought the world was going to end!

    Then, once they heard the landing (which wasn't any louder than a regular plane landing), they went back to their caves and silently watched the news for another issue to get their panties in a bunch about. *sigh*

    • Re:There will still be protests (Score:5, Informative)

      by Rob Riggs ( 6418 ) on Sunday August 01, 2004 @03:43PM (#9859290) Homepage Journal
      I beg to differ. The Concord's landings may not be any louder than a regular commercial jet. I don't recall it being particularly loud. But take-off is another thing altogether.

      My company's UK office is very close to the flight paths into and out of Heathrow. Work comes to a stop when the Concord flies anywhere near on take off. No one notices the other commercial jets. I didn't notice it until last summer. Most of my time in the UK office was spent while those beasties were grounded. It was quite noticible when they were allowed back in the air.

      • I beg to differ. The Concord[e]'s landings may not be any louder than a regular commercial jet. I don't recall it being particularly loud. But take-off is another thing altogether.

        And by God, what a noise. Especially when you're standing right by the fence and she's low enough for the wake vortices to kick up a dust storm. Hooyeh. (I'd just washed the car, too.)

        I feel I have to point out that the God-awful roar of those lovely, lovely engines is not the sonic boom. It always made me smile when some cant

    • its not the landing (Score:3, Informative)

      by rebelcool ( 247749 )
      a sonic "boom" isn't a one time event. The shockwave is continuous, so long as the aircraft is flying at supersonic speeds. Therefore, people on the ground for the entire flight corridor will hear/feel the boom as the plane flies overhead.

      In fact, no kidding the people at the airport the plane lands at dont hear a boom! Obviously, the plane slows down to subsonic speeds prior to landing. But for everyone in between the takeoff and landing airport that the plane flies over, will be subjected to it.

      Henc
    • I thought half the fuss over the noise levels of Concorde were due to politics rather than reality. If it had been an American invention you can bet that the story would have been quite different.

  • Just more of the same? (Score:2, Interesting)

    by Anonymous Coward
    It seems that they are doing this using the traditional method of changing the shape of the aircraft. What about more novel methods such as striation, the same way tha dolphins achieve much higher efficiency than their shape would suggest. I'm surprised I never hear about this being applied to aircraft because it seems like such a simple thing to do.

    Or an interesting method I heard about involving many tiny flaps on the surface which can dynamically shape the airflow to minimize turbulence?

  • wow (Score:2, Funny)

    by Anonymous Coward
    so they finaly resolved the secret of those nazi ufos? was about time!

  • Dissapointing... (Score:3, Interesting)

    by iawix ( 802099 ) on Sunday August 01, 2004 @03:44PM (#9859293)
    The research airplane in this experiment failed to reduce the sound of the sonic boom as much as hoped.

    In fact, this research is primarily intended for the next generation business jets , not the military. The future of such planes is up in the air in the moment, because not only do they have to reduce the wake of sonic booms (they shatter windows and suprise people), the regulations have to change. I for one know that the FAA is slow at that.

    Regarding the need for windows in airliners: A Boeing 777 pilot today needs to be able to see a few hundred feet ahead of him on takeoff, but after rotating off the runway, he doesn't need to see anything at all. Modern airliners can land and auto-flare... that is, land themselves in ZERO visibility conditions. The pilots undergo extra training for this, of course.
    • but after rotating off the runway, he doesn't need to see anything at all.

      I beg to differ. Unless the plane is in controlled airspace, there will be aneed to look out for other traffic (actually not a bad idea even in controlled airspace). The 1978 crash in San Diego took place between two aircraft that were both in contact with air traffic control.

      • Here's a hint: the vast majority of airline traffic is in controlled airspace for the entire time the engines are running.

        While it is the responsibility of all pilots to "see and avoid" other traffic, if instrument meteorological conditions (IMC) exist, that's not possible. But if IMC exists, then pilots who aren't instrument-rated had damn well better not be flying in it.

        Now, if a controller fucks up and vectors two planes into each other, well, how, exactly were the pilots supposed to see that coming in

      • Re:Dissapointing... (Score:2, Informative)

        by iawix ( 802099 )
        As a pilot, it is my responsibility to see-and-avoid other traffic during my entire flight. But it becomes the controller's responsibility to maintain seperation in controlled airspace.

        I'm a low time pilot, but I can tell you that most of the time in controlled airspace, the controllers do their job well. The problem is on the weekends at uncontrolled airports...
    • not only do they have to reduce the wake of sonic booms (they shatter windows and suprise people)

      Therefore, if we can train people to expect shattered windows, we have won half the battle.
  • Well, hopefully, since it will be invented by the yankees (unlike the Concorde), the technology will not be sunk down...
  • I may be incorrect about this, but I seem to recall that the mathematician Paul Garabedian [nyu.edu] independently developed the mathematical theory for shockless supersonic flight at the same time that people in AE developed a theory. The Popular Science article does not mention Garabedian.

    • a 1971 paper (Score:2, Informative)

      by Phragmen-Lindelof ( 246056 )
      The review [ams.org] by N. Geffen of "Analysis of Transonic Airfoils", Comm. Pure Appl. Math. 24 (1971), 841--851 by Garabedian, P. R.; Korn, D. G.

      "Calculation of inviscid, subsonic-supercritical flow around prescribed airfoils is described. This supplements the authors' previous design of a shockless transonic wing using real and complex characteristics in the hodograph plane. The flow about the designed wing is calculated for a range of off-design conditions.

      "Neumann's problem for the flow-potential equa
  • I used to live directly under the Concorde's flight path a little west of Heathrow. Yes, it was loud. But, I'd trade loud for cheap seats any time.

    BTW, the loudest aircraft I've heard is a water-injected C-141 taking off about 3 miles away. Most have been painful for the crew.

    • Ouch, my worst was C-5's doing "touch and go" tests back in the 80's, drop in at something close to stall speed and then throttle up to maximum as soon as the cargo fell out the back, climbing as fast as possible, never mind the fact that the each cargo drop weighed 50+ tons (M60 tanks, I found out later). Shame I didn't have a camera when they did the "missle evade" section, the C-5 starting dumping flares as soon as it started climbing. Pretty fireworks show, but given some of our enemies tastes in shou
  • ... they call it the "Dutch oven" effect.

  • Not me! (Score:3, Insightful)

    by evilviper ( 135110 ) on Sunday August 01, 2004 @09:54PM (#9860896) Journal
    Don't be alarmed by the lack of windows: Cameras will send exterior images to the cockpit and cabin.

    Don't be alarmed... MY ASS!

    If you watch cable TV shows much, no doubt you've seen your share of close-calls in airplanes.

    Yes, there are plenty of occasions where all the instruments fail, the power goes out, the hydraulics go out, etc. People still survive because, despite the high-tech systems, there is still JUST ENOUGH under manual control that a very good pilot in decent weather can land such a crippled plane.

    Good luck doing that when they can't even see! And don't bother telling me that they're going to have multiple cameras, with backup systems and all that, I've already heard of plenty of cases where all 3 computer systems on 747s have failed. That's not one case, but MANY independant cases.

    As you can probably assume, I'm not afraid of technology in the slightest. However, I do know that even the most advanced and well-tested technology in the real world can fail. If you aren't willing to trust electronic voting machines, are you really ready to give technology 100% control over matters of life and death?
  • The concept of a $100 million executive jet is a bit much. For comparison, a Grumman Gulfstream IV, considered the top-of-the-line executive jet, costs about $18 million.

    And note that this boom-diffuser approach increases drag, which means more fuel consumption. As a rule of thumb, supersonic flight uses 3x as much fuel per unit distance as subsonic flight already. This is worse. And it still produces an 0.5psi overpressure, which is above what the FAA allows now.

    It can probably be made to work, but a

  • I have this feeling that with Northrop's validation of the research that shows reshaping a plane's profile CAN dramatically reduce the effects of the sonic boom, Boeing may be seriously looking at the possibility of a supersonic airliner again.

    Imagine something derived from the shelved Sonic Cruiser design, but carefully shaped to eliminate the pressure wave buildup that causes the sonic boom in the first place. The result could be a Mach 1.7 airliner that could:

    1. Fly at 55,000 feet with just about no so

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