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Supersonic Flight Without The Sonic Boom 311

Posted by timothy
from the and-half-the-fat dept.
fname writes "Here's a story from Spaceflight Now about a new test aircraft that can travel at supersonic speeds without triggering a sonic boom. The technology works by modifying the shape of the plane. Although it's been believed to be possible for a long time, this is the first actual flight test, barring black box projects I suppose."
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Supersonic Flight Without The Sonic Boom

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  • by Anonymous Coward on Sunday September 07, 2003 @02:47PM (#6894409)
    What does Guile think about these developments?
  • by Raybies (223750) on Sunday September 07, 2003 @02:49PM (#6894421)
    There's supposed to an Earth shattering kaboom?!?!
  • Summary misleading (Score:5, Informative)

    by prestomation (583502) on Sunday September 07, 2003 @02:51PM (#6894428)
    It seems it merely muffles the sonic boom. The technology doesn't completely silence it.
    • by timeOday (582209) on Sunday September 07, 2003 @06:47PM (#6895698)
      Airplanes make plenty of noise even without the boom, so silience it isn't necessary. If it's enough to make supersonic flight over populated areas acceptable to people, the mission is accomplished. Noise is what really prevents supersonic passenger planes.
      • by joggle (594025)
        Noise is only a factor for intra-national flights. The real problem is fuel economy. Supersonic flight causes much more drag than subsonic flight. So even with a very well designed aircraft like the Concord, the amount of fuel per passanger-mile is about 3-4 times as much as for a Boeing 747.

        At best, this will allow corporate execs to travel in small jets supersonically as they'll be the only ones who can afford it.

  • by Kedisar (705040) on Sunday September 07, 2003 @02:52PM (#6894440) Journal
    Wh00t! Now I can run outside and not have to worry about being blown through my house by a sonic boom! Now if we can just do something about those G5s...
  • by Daniel_Staal (609844) <DStaal@usa.net> on Sunday September 07, 2003 @02:53PM (#6894450)
    It just modifies it so it isn't as annoying. (Spreading the force over a larger area.)

    Very useful, yes, but you would still hear it going overhead. (Though I suppose the 'boom' fades as you move away from the plane, and this could speed that up...)
  • I happened to notice a show (On The Edge [discovery.com]) on the Discovery Wings [discovery.com] channel covering a lot of this. Not as in depth, of course, but interesting nonetheless.
  • Guns? (Score:3, Funny)

    by t_allardyce (48447) on Sunday September 07, 2003 @02:55PM (#6894469) Journal
    Now all i need is a way to reshape the bullet in-flight for my high powered rifle and presto, the perfect assasination ;)
    • Now all i need is a way to reshape the bullet in-flight for my high powered rifle and presto, the perfect assasination ;)
      Use a silencer bud.
  • So, when can we throw out the Concord and whatnot and get transcontinental supersonic flight to boot?
    • no. (Score:5, Insightful)

      by twitter (104583) on Sunday September 07, 2003 @03:50PM (#6894743) Homepage Journal
      So, when can we throw out the Concord and whatnot and get transcontinental supersonic flight to boot?

      You don't need to throw it out, it just needs a nose job. Witness:

      Honk, honk!

      You only want to throw the thing out when maintaining it costs more than developing and buying a new one. While it might be hard to modify the concord's swiveling nose this way, it's worth looking into.

      The next modification needed is to the law, so that flights that don't make too much noise can fly over the contenetal US. If you can get from New York to California supersonically, people will want to do it and will pay for the above mentioned development and building.

    • Re:Concord (Score:4, Informative)

      by Jetson (176002) on Sunday September 07, 2003 @07:29PM (#6895907) Homepage
      So, when can we throw out the Concord and whatnot and get transcontinental supersonic flight to boot?

      For starters, you don't have to "throw out" the Concorde as BA/AF are doing that for you. They even refused to sell one to Virgin Airways as Branson might find a way to make the flight profitable and would thereby kill BA/AF's hopes of pushing all of the Concorde folks into the 747 first class section.

      There are two other reasons why you won't see the Concorde flying supersonic over the continental USA, with or without a sonic boom:
      1) There are far too many other slow aircraft flying at or near Concorde altitudes. Considering the fuel costs involved in getting to supersonic speeds (max drag between 0.97M and 1.4M), the economics of trans-continental supersonic flight would require sterile airspace for end-to-end clearance. The lobby group for bizjet owners would never let that happen at their expense.
      2) Even a reduced shock wave will have destructive powers if the aircraft is required to turn at supersonic speeds - the waves on the inside of the turn are concentrated toward a single point at which the N-wave would be amplified to an unacceptable level. Although it would be possible to structure straight-line routes between city pairs, the odds are pretty good that the flight would be unmanageable in terms of communication and coordination among ATC units.

  • by sssmashy (612587) on Sunday September 07, 2003 @02:59PM (#6894491)

    In related news, real estate prices for residential property located near military airbases just jumped by 10%.

    It then plummeted by 20% as investors realized that this technology was just in the prototype phase and unlikely to be implemented on a large scale for decades.

  • SST possibilities (Score:3, Insightful)

    by n3xup (411763) on Sunday September 07, 2003 @02:59PM (#6894495)
    Unfortunately, the article never reveals how much they have reduced the sonic boom.

    But, this could be great for supersonic transports if the design technolgy is used in future designs. It would mean that we could have supersonic flights from NY to LA lasting only a couple hours! If the noise was reduced enough, the FAA would let them fly over populated areas (like the continental US)
  • Yes, but how? (Score:2, Interesting)

    I would really like more infomation on this, that article was incredibly short and left me with many questions. Mostly, how are the shock waves being broken up, and how would it affect the drag (ie, would it be a better design for watercraft also?)

    But then again, it is a government project, can't expect much in the way of information.
    ___________
    • Re:Yes, but how? (Score:5, Informative)

      by AlecC (512609) <aleccawley@gmail.com> on Sunday September 07, 2003 @03:21PM (#6894613)
      This was also covered in Flight International (subscribers - I read the paper version in the library), in a bit more depth. The classic sonic boom was described as "N-shaped" and gives a crack-crack effect. This modified it to more of a "table-top", and was said to sound like a long rumble.
    • Watercraft (Score:5, Interesting)

      by FreeLinux (555387) on Sunday September 07, 2003 @03:26PM (#6894636)
      would it be a better design for watercraft also?

      Judging from the picture, the design borrows heavily from that of watercraft. The bottom of the aircraft has been modified to the point that it resembles the hull of a boat of personal watercraft.

      I suspect that it works very similarly to the way that planing hulls(no pun intended) work. Just as a boat's hull spreads its wake outwards from the sides of the hull, this aircraft design likely spreads the aircraft's wake out to the sides more than straight down. This would reduce the pressure wave below the aircraft. I am confident that if the sonic boom was measured from the side on the same plane with the aircrafts altitude the sonic boom would be the same as normal and possibly more intense.
      • Re:Watercraft (Score:3, Interesting)

        by droleary (47999)

        Judging from the picture, the design borrows heavily from that of watercraft. The bottom of the aircraft has been modified to the point that it resembles the hull of a boat of personal watercraft.

        Out of curiosity, does anyone know what speeds aircraft could see supercavitation at? I mean, given fluid dynamic apply to both air and water, shouldn't it be possible for planes as well as submarines? Anyone know what that would do to the shape/strength of a sonic boom?

        • Re:Watercraft (Score:3, Interesting)

          by aXis100 (690904)
          I briefly thought about supercavitation, but I dont think it is relevant in air.

          Water is not elastic - low pressure regions cause the waster to cavitate (vaporise), thereby reducing drag. Air is elastic, and AfAIK cant cavitate.

  • must be (Score:2, Funny)

    by falsification (644190)
    Hmmmm. That must be how the UFO's do it.
  • Rejected (Score:4, Informative)

    by Scrameustache (459504) on Sunday September 07, 2003 @03:06PM (#6894543) Homepage Journal
    Submited on september 6, 2003:

    Northrop [northgrum.com], working with the Pentagon [defenselink.mil] and NASA [nasa.gov] sucessfully tested a "quiet" supersonic flight [cnn.com] wednesday at California's Edwards Air Force Base [af.mil]. In the tests, an F-5E aircraft [primezone.com] with a modified nose section flew supersonically through the test range, shortly thereafter, an unmodified F-5E [af.mil] flew supersonically through the same airspace, with the sensors showing a clear reduction in the intensity of the sonic boom produced by the F-5E modified fuselage [primezone.com].
    • you didn't mention the conspiracy theory though. Didn't you know that you have to post a link from the NYT, the Register, mention how Bill Gates is the anti-christ, or that there was some conspiracy going on?

      Jesus, shame on you.
    • Reason why it was rejected: Article referenced was from MONEY.cnn.com and more than a week old ;-(
    • Submited on september 6, 2003

      Sure, but you only submitted one with links from NASA, the Pentagon, and a military contractor. I mean, if you aren't going to take the time to submit it with a real and reputable source linked, like Spaceflight Now, then how can we take you seriously?!?

      Sheesh! Some people expect too much.

      -Tom
    • Your submission is more informative, but honestly, my bet is it was rejected because you went overboard on your links. For example, you had 3 different links on the F5E, when one would have more than sufficed. I think the article that was actually accepted is on the opposite extreme of the spectrum (one link?), but with your's, you have to play the "Guess which one's the story that you actually want to read" game. Note, this isn't a flame. I'm just trying to give you constructive criticism that might help
    • That's why I don't won't to submit anything to /. anymore - they approve badly written, "grammer-prone" dupes from their friends, but never from unknown people, even if submitted material were good for reading.

      It doesn't matter, a geek forum or a fortune-500. People are the same. They love their friends. No matter that it may sacrafice the quality of their business.

  • Old science (Score:3, Informative)

    by LiftOp (637065) on Sunday September 07, 2003 @03:19PM (#6894593) Homepage
    Seabass-George worked out a figure of merit (FM) quite some time ago, relating a sonic boom's relative strength to factors such as the aircraft's height, width, and weight.

    • Re:Old science (Score:5, Informative)

      by arivanov (12034) on Sunday September 07, 2003 @04:38PM (#6894973) Homepage
      That is differnt. It is for a single shockwave. What this article deals with is multiple shockwaves.

      The examples are ATF, Eurofighter, Viggen, Suhoy S27 and later, so on so forth. All of these have shapes designed specifically to split the shockwave into a series of shockwaves to improve lift and maneuvrability at hypersonic speeds. As a result the noise is muffled as a side effect. From there to muffling it completely is just one step.

      In btw, I am glad that it was done on the F5. It is the only US bird that has some resemblance of grace and beauty in the air.
  • hmmm.... (Score:2, Offtopic)

    by temojen (678985)
    looks like new use for the old flying boats...
  • by Superfreaker (581067) on Sunday September 07, 2003 @03:35PM (#6894680) Homepage Journal
    I love the headline posted here at /.:
    "Supersonic Flight Without The Sonic Boom"

    Which is a complete lie when you read the first paragraph of the article stating that they simply reduced the boom created, not eliminated. Fox News' web site does this too.

    There is NO way to eliminate a sonic boom as long as the aircraft has either mass or creates friction. It is very doubtful that they are close to creating a massless, frictionless airplane ;-)

    • Are you implying that Fox News isn't 100% fair, balanced, and fact-driven? Next you'll try to tell me that Saddam wasn't behind 9/11. ;)
    • I believe it's possible to eliminate the major side effect of a sonic boom, to the point that in lay parlance we will have aircraft that do not generate a sonic boom.

      If you can manipulate the shockwaves and bowfronts trailing a plane in such a way that they interfere, essentially producing low energy zones at the appropriate distance, and then redirect the rest of the sonic energy to disperse and spread out along a larger surface area and upwards into empty space, you can create supersonic craft with subso
    • What if the plane was covered with Crisco, or maybe KY Jelly. Wouldn't be fictionless then? ;-)
  • Fans (Score:2, Offtopic)

    by kmahan (80459)
    Now if they could just make some computer fans that were quiet. I really hate the sonic booms that come out of them when I power up my machine.
  • Long time comming (Score:5, Interesting)

    by Izago909 (637084) <tauisgod AT gmail DOT com> on Sunday September 07, 2003 @03:41PM (#6894705)
    The future of ultra fast transit isn't in airplanes gliding along, masking their sonic wake. It's with things like multi stage trans-orbital aircraft. A plane could take off using standard jets until it got to the maximum height the jets could support. Then switch over to SCRAM jets and break for the outer atmosphere. Even the prototype SCRAM jets today are capable of flying at many multiples of mach. It just takes the energy to get a plane beyond mach 2 (or so) to begin with. If you stay at the edge of the atmosphere, the very low pressures create little drag compared to today's cruising altitudes. Also, the higher you are, the faster you must go in order to create that critical pressure point. You don't need to totally leave the atmosphere; in fact it's easier that you don't. You won't have nearly as much heat to deal with as reentry, and you won't have to add rockets or thrusters to maneuver in low orbit. Imagine flying form New York to Tokyo so fast that food service isn't needed.
  • how loud is a sonic boom? And how much less with this new tech?

    • 1) Usually similiar to window-rattling thunder.

      2) Well, according to the Northrop Grumman site [northgrum.com], they used sensors to measure the difference in loudness and they hoped that with further study, they could "produce a noticeably quieter sonic boom." Therefore, I'm guessing it wasn't reduced by a large factor, but the very fact that they *can* reduce it via aircraft design is rather significant.
    • http://science.slashdot.org/comments.pl?sid=77565 & cid=6895042

      It is LOUD. Its not like the long fading sound a subsonic jet creates, but a short "hit" of sound, like a gunshot, but with lower frequences.
      Thing of a bomb detonating 200 meters away or a single bass beat from love-parade class speakers inserted into silence.

      A story i cannot verify is that in the early 80s a pair of tornados practives ultra low altitude "vallay crawling" and something went wrong.
      One pilot needed to gain altitude fast beca
  • by dpbsmith (263124) on Sunday September 07, 2003 @04:19PM (#6894891) Homepage
    "When you can measure what you are speaking about and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of the meager and unsatisfactory kind."--Lord Kelvin

    The article doesn't give one single blessed number that would enable anyone to judge how effective the experiment was.

    I'm not sure what the right measurement would be... decibels? sones? psi? pascal-seconds? Or average blood pressure increase in human subjects in Hgmm? But the article doesn't say.

    Not even the usual marketing claim, like "42% less boom than traditional aircraft, yet still has that same great NASA 'look'"

    Something about "We were all blown away by the clarity of what we measured" just doesn't do it for me.
  • That's why pelicans are so fast!!!!
  • Fuel Efficiency (Score:5, Interesting)

    by Yartrebo (690383) on Sunday September 07, 2003 @04:31PM (#6894940)
    On the contrary, my guess is these low-noise jets will be even bigger gas guzzlers than normal supersonic jets, for three reasons.

    1 - Fuel efficiency wasn't mentioned in the article. If it were better, I figure they'd be bragging about it.

    2 - Apparantly the main advancement that they did was to have the air heat up near the nose of the aircraft, to make a smooth pressure gradient. Now that heating must come from friction, which takes energy (quite a bit when the air is rushing by at Mach 2).

    3 - Current aircraft are designed with loads of computer aerodynamics modelling, with the main design goal being low drag (ie., high fuel efficiency), so if reducing the sonic boom reduced drag, it already would have been discovered and implemented long ago. In subsonic aircraft, design improvements of 0.01% are fairly typical and worth going after, as this is a very mature field of engineering.

    I guess we can forget about those 4 hour NYC to Tokyo flights for the time being.
  • by fygment (444210) on Sunday September 07, 2003 @04:34PM (#6894949)
    ... my CPU fan? Now that's a silencing challenge that will make money.
  • by imsabbel (611519) on Sunday September 07, 2003 @04:51PM (#6895042)
    A month ago a F4 went supersonic in 11000m height in the area i live. Actually, it traveled 200km west to east through north bavaria.
    I can tell you "boom" is a light understatement...

    I grew up near an infantry test area and im quite used to RPG explosions in the distance ect.

    I was standing near an open window and could feel the pressure. It was like back in the army if someone detonated a practice handgranate and your earplugs filter out the high frequency noise.

    I read in the paper the next day that hundereds of people called the police believing there was some kind of bombing...

  • "Here's a story from Spaceflight Now about a new test aircraft that can travel at supersonic speeds [with a lessened sonic boom]. The technology works by modifying the shape of the [sonic boom]. Although it's been believed to be possible for a long time, this is the first actual flight test, barring black projects I suppose."

  • A reduced sonic boom has obvious civil purposes, but the aim of this program is to improve the designs of military aircraft. A reduced sonic boom would make supersonic aircraft in enemy airspace less noticeable.

    Of course aircraft cannot be tracked using aural emissions, but it only takes sound to wake up an airbase full of sleeping pilots or snoozing radar operators...
  • by afidel (530433) on Sunday September 07, 2003 @05:50PM (#6895377)
    This is simply the most amazing thing I have ever seen. A bunch of civi's were on a naval ship when a hotshot pilot buzzed the ship at supersonic speed. One of them happened to get some amazing video [rmwc.edu] of the pressure wave.
  • hey... (Score:3, Interesting)

    by ShadowRage (678728) on Sunday September 07, 2003 @06:17PM (#6895511) Homepage Journal
    I just noticed something with the nose.. it looks a LOT like the front of a boat. that's probably how it disperses sound waves.. I'm probably wrong, but it looks that way.
  • by WolfWithoutAClause (162946) on Sunday September 07, 2003 @06:25PM (#6895546) Homepage
    The boom is merely reduced, as others have noted.

    Supersonic vehicles actually generate two booms- one for the nose and one from the tail- that's why this has the nose glove and the modified tail.

    Incidentally, the size of the boom is related to the size of the aircraft, military planes are much smaller and hence give much less problems.

    Interestingly, Concorde's nose is sharp- this is aerodynamically efficient, but generates bad sonic booms- it would be much better to use a rounded nose from that respect. Detailed changes to the tail section (other than the ones shown here) can also greatly reduce the shockwave. If you've seen Thunderbirds, some of the airliners shown there are strongly reminiscent of the kinds of shapes that probably help out, (strangely enough, that's probably because they got fairly good advice when designing their models.)

    I think that the vehicle shown in the photo has a compromise nose shape- it's sharp on top to give better aerodynamics, but rounded underneath to project a weaker sonic boom downwards. Atleast that's my take on what they've done- IANAA. (I Am Not An Aerodynamicist).

  • by thompson42 (668043) on Sunday September 07, 2003 @06:57PM (#6895760)
    For those who have asked how much of a reduction in sonic boom was achieved:

    The following URL says the peak pressure was reduced by one third, but there was very little difference in the sound of the boom on the ground. This was a better result than expected, since they did not expect to hear _any_ difference.

    After all, this was _not_ an attempt to fly supersonically without generating a sonic boom, despite the misleading title of this thread. Instead, it was a (very successful) attempt to valid the CFD models used to design the aircraft nose modifications and predict the reduction of the pressure wave on the ground.

    Now that they have proved that their method works, they can work on more noticeable reductions.

    http://209.157.64.200/focus/f-news/973267/posts
  • by RealErmine (621439) <commerce&wordhole,net> on Monday September 08, 2003 @08:58AM (#6898856)
    From the article:
    In flights conducted Aug. 27 on the same test range where Chuck Yeager first broke the sound barrier nearly 56 years ago...

    Of course it works here. They admit themselves that the sound barrier is already broken at this location. Did anyone ever bother to FIX it in 56 years? Nooooooo. Maybe if it works at another location I will be impressed.

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