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Air Force Builds Quiet Mach 6 Wind Tunnel 153

Posted by ScuttleMonkey
from the hold-on-to-your-hat dept.
An anonymous reader writes "To help design 'scramjets' -- vehicles that'll travel thousands of miles per hour as they leave the atmosphere and zip around the globe -- the U.S. Air Force has just funded a wind tunnel that operates quietly at Mach 6. To get a quiet flow, the throat of the Mach 6 nozzle must be polished to a near-perfect mirror finish, eliminating roughness that would trip the flow."
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Air Force Builds Quiet Mach 6 Wind Tunnel

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  • Scramjets are one of the more interesting types of aircraft in research. I wouldn't mind seeing a link describing how it works :)

    (Watch it ed up as an unmanned payload delivery system -_-;;)
    • Re:whee! (Score:5, Informative)

      by Anonymous Coward on Saturday January 07, 2006 @04:06PM (#14417825)
      Wikipedia on Scramjets [wikipedia.org]. AC to avoid karma whoring..
      • I read the Wikipedia article but didn't get something. If the engine only works at a minimum speed, how will we get a craft up to that speed? (1) Tow it or (2) give it two types of engines?
        • (2) give it two types of engines?

          Yep.

          Current test models use standard rocket boosters to get speed and altitude.

        • Re:ScramJet takeoffs (Score:3, Informative)

          by ddopson (940155)
          (crap, no formatting... reposting) Yes, there is one of the major challenges of both RAMjets and SCRAMjets. There is actually a whole range of technologies designed for different speed and air density regimes

          Turbo-Props (propeller driven by jet like turbine power) is good up to a few hundred mph. Then the tips of the prop start going supersonic and cavitating. Highest efficiency

          Turbo-Fan (same turbo jet power like a turbo-prop, but with an enclosed fan rather than a prop. Most of thrust still comes

          • Turbo-Jet (same turbo jet power as turbo-prop, but little or no "bypass" air. The main purpose of the intake fan is now to pressurize air at intake for combustion with jet fuel. Thrust comes from) can provide substantial power at high velocites. TurboJets are the big muscular loud as hell engines used on fighter planes.

            Turbojet engines don't have any fans, so there is no bypass at all. They only have compressors and turbines. Probably the only aircraft the Air Force still flies with turbojets are T-38

  • "Quiet"? (Score:4, Interesting)

    by timeOday (582209) on Saturday January 07, 2006 @04:09PM (#14417836)
    From reading the article, I gather "quiet" is being used here as a technical term which is roughly synonymous with laminar, or lack of turbulence (rather than "gee I wish my vacuum cleaner were quiet").

    Can anybody with the right background tell me whether that's the case?

    • Re:"Quiet"? (Score:5, Funny)

      by slashdotnickname (882178) on Saturday January 07, 2006 @04:33PM (#14417951)
      From reading the article, I gather "quiet" is being used here as a technical term which is roughly synonymous with laminar, or lack of turbulence (rather than "gee I wish my vacuum cleaner were quiet").

      Can anybody with the right background tell me whether that's the case?


      You're correct, they mean "quiet" in a laminar sense. Mach 6 wind will sound pretty loud to human ears regardless of how turbulance-free it is, just because of the immense air pressure... but it won't be "noisy" loud.

      As far as my background, I stayed at a Holiday Inn Express last night.
      • As far as my background, I stayed at a Holiday Inn Express last night.

        I assume that this is a USA-specific cultural reference intended as a joke. Can anyone please explain for those of us who are foreigners?

        • I believe this reference is to a Holiday Inn TV commercial where people who were famous/ highly skilled/ special stayed at Holiday Inn and then did amazing things the next day.
        • by afidel (530433)
          Here [advertisementave.com] is an example of a line of commercials that Holiday Inn Express did. The best one is a guy who saves a nuclear power plant from a three mile island style nuclear disaster.
          • The best one is a guy who saves a nuclear power plant from a three mile island style nuclear disaster.

            Based on my recollection, does that mean he stopped people from doing anything about it, thus allowing the automatics to do their job?

            • by afidel (530433)
              No, something needed to be done, the valve that stuck open needed to be closed. They were incorrectly acting because the system was not responding as they expected based on their inputs. Btw TMI pisses me off. People whine about the dangers of nuclear power, yet TMI which was about the worst possible scenario for a US nuclear power plant released less radiation than a MUCH smaller coal plant would in a year.
              • They were incorrectly acting because the system was not responding as they expected based on their inputs.

                IIRC, part of the problem was that the sensors measured inputs rather than outputs. The example I heard was measuring a servo being activaated and assuming that that meant the valve was closed, rather than measuring the valve directly.

                People whine about the dangers of nuclear power, yet TMI which was about the worst possible scenario for a US nuclear power plant released less radiation than a MUCH

      • Mach 6 wind will sound pretty loud to human ears regardless of how turbulance-free it is, just because of the immense air pressure

        The air pressure is of the magnitude found in explosions. The hypersonic windtunnel at Imperial College in London is in an annex with blast doors and a flimsy roof so, if there was a catastrophe, the roof could rupture to release the pressure, rather than demolishing the neighbouring buildings.

    • From reading the article, I gather "quiet" is being used here as a technical term which is roughly synonymous with laminar, or lack of turbulence (rather than "gee I wish my vacuum cleaner were quiet").

      As slashdotnickname said, that is at least part of it. But another part of it may mean (I fully admit I haven't RTFA, I just skimmed it), quiet may also mean that steps were taken to isolate the test chember from external noise sources (tunnel motor, lab equipment, students, etc) so that experimenters can b

    • Shouldn't this article be called "NASA sits around while a poor graduate student builds quiet Mach 6 wind tunnel."
    • I don't have the right background, but I have read the article :-)
      "A quiet wind tunnel more closely simulates flight," he said.
      [...]
      Quiet wind tunnel operation requires laminar flow on the walls of a tunnel segment called the nozzle. Turbulent flow in this segment radiates noise onto the test model, interfering with experiments.


      So that is why, probably. The post title was a bit misleading as always. And it runs only for 8 seconds.
      • Re:"Quiet"? (Score:3, Informative)

        by joeljkp (254783)
        "And it runs only for 8 seconds."

        This is typical for high-speed wind tunnels. The runs are captured on high-speed cameras, then examined frame-by-frame or in slow motion to pick out the details of what actually happened. Supersonic flow in a nozzle develops very quickly, and there's no real benefit to running it for long periods of time.

    • After all, they're trying not to trip the flow, yo.
  • 18 inches (Score:3, Insightful)

    by Janek Kozicki (722688) on Saturday January 07, 2006 @04:09PM (#14417837) Journal
    Initially I thought, wow! they will be able to test new aeroplanes in real conditions! No more depending on computer simulations of air flow. That's groundbreaking. But my realistic wife said: 'no way, thwy will not put REAL planes there'. So I checked in TFA:

    The pipe is only 18 inches in diameter

    So long, and thanks for the fish.
    • Re:18 inches (Score:5, Insightful)

      by mickyflynn (842205) on Saturday January 07, 2006 @04:13PM (#14417858)
      they'll use a model, just like the used to before computers. Duh. a model is still "real" unless you take real to mean 1:1 scale with the final production model, or a "real" working aircraft. And they are not going to put all the work and money into building a fullsize or working one without having proven that the basic design is sound. and that can be done with a model.
      • Re:18 inches (Score:2, Informative)

        by bluelip (123578)
        No matter how accurate the model resembles the larger craft the data collected won't be 100% accurate for many reasons. One of the main concerns is Reynold's Number [wikipedia.org].

        This number, basically, relates the size of air molecules to the size of the object. The size of the air molecules are the same in the airtunnel as in the atmosphere. The model, oviously, differs in size from the actual craft.

        • Its ok if the reynolds number (which is merely a ratio of the inertial forces to the viscous forces) is off a little bit... since the size of the model compared to the real craft is probably only an order of magnitude smaller, compared to many orders of magnitude larger than an atom, its inconsequential ... And actually it won't be off at all, in a modern wind tunnel it is calculated as a function of dynamic pressure , which will not vary.

          Using the Pi theorem [wolfram.com] we can find nondimensional quantities. The quan

        • The size of the air molecules are the same in the airtunnel as in the atmosphere

          I was about to post a similar comment, but I'm reading late (Sunday) and you pegged it good.

          Any science fiction movie fan can point out the obvious flaws when film makers try to represent water (in submarine movies, as an example) because of the dynamics of full-sized molecules hitting 1/4 scale models.

          Using CG to simulate the appearance of fluids to trick a viewer is not the same thing as true understanding of fluid b
          • I don't think that it is the size of the molecules that matter. After all even a 1:1000 scale model is pretty big compared to a N2 molecule... In general, I suspect that there are other reasons for concern other than the size of N2 and O2 molecules...

            However, a lot of things are dependant on the scale that people don't think of. Surface area to volume increases as you get smaller, which means you get different effects. If you are trying to measure lifting capacity, for example, you could be off unless y
      • My memory is a bit fuzzy on this, but from what I recall of wind tunnel dynamics, unless you are using a 1:1 scale model, you need to adjust either the speed of the tunnel or the viscosity of the tunnel medium in order to still get meaningful results. For example, in order to test a half scale model in "real" conditions, you either need to double the speed of the tunnel, or use something more viscous than air in the tunnel.

        If that is actually the case, this tunnel would only be useful for testing a full sc
    • Re:18 inches (Score:2, Insightful)

      by Anonymous Coward
      It's called scale models. Do you think that they have "conventional" wind tunnels to test Boeing 777's aerodynamics in true size? I didn't think so. Certainly, it would be nice to have an 18 meter instead of an 18 inch tunnel, but an 18 inch tunnel is much better than nothing. It will still allow for the scramjets to be tested on a limited scale in real life conditions without creating a multimillion dollar delivery package that costs millions per launch and could (crash|explode|burn up) and cost tens of mi
      • It will still allow for the scramjets to be tested on a limited scale in real life conditions without creating a multimillion dollar delivery package that costs millions per launch and could (crash|explode|burn up) and cost tens of millions more.

        so you're saying it's not the size of the pipe, but how you use it?
      • It will still allow for the scramjets to be tested on a limited scale in real life conditions

        I know the article says that they can now get lots of data in 8 seconds but I'd question whether you could test a scramjet in any realistic sense in that amount of time. It's got to take at least that long just to fire one up, let alone get it up to normal operating temp.

        • I know the article says that they can now get lots of data in 8 seconds but I'd question whether you could test a scramjet in any realistic sense in that amount of time.

          Scramjets were tested in shock tunnels with test durations in microseconds. Since you are dealing with a simple nozzle which compresses gasses to the point where they combust at hypersonic speeds a microsecond or two is enough for them to start up - they get hit with gas at mach 6 or more at the start of the test.

          With 8 seconds they could d

    • No more depending on computer simulations of air flow
      We don't have good enough equations for air flow in many conditions to completely rely on computer simulations.
  • That doesn't bode much good for the final airplane. I do not want to live near the (military) airport where that thing will take off.
    • I do not want to live near the (military) airport where that thing will take off.

      The scramjet engine only starts to work at speeds above Mach 5. Average takeoff speed for a regular plane is about 150mph.
    • Yeah, because it's TOTALLY going to be going Mach 6 at 400 feet above your house. It better watch out for flying pigs, and monkeys that have flown out of my butt.
  • do they mean quiet as in 130db compared to so loud it can set your hair on fire? thats the thing im wondering...
  • ooo.. (Score:5, Informative)

    by User 956 (568564) on Saturday January 07, 2006 @04:11PM (#14417846) Homepage
    neat scramjet pictures here [bbc.co.uk].
  • by metaomni (667105) on Saturday January 07, 2006 @04:11PM (#14417848)
    To help ensure this ultra-clean condition, engineers enlisted the help of an undergraduate student who is a spelunker. The slender student crawled through a 120-foot section of the wind tunnel, wearing a suit like those worn by technicians in clean rooms, and wiped down the inside of the stainless-steel pipe. The pipe is only 18 inches in diameter.

    We undergrads are the guineapigs of science, the people who do the things no one else wants to... all in exchange for $20. And we LIKE IT!

    • by Hal_Porter (817932) on Saturday January 07, 2006 @04:19PM (#14417889)
      Could be worse though, the lecturers at my Uni would have turned on the airflow if it would have saved them twenty bucks.
    • Yeah, the more I read, the more low-tech this actually sounds!

      The quiet Mach 6 wind tunnel is not the first of its kind. The National Aeronautics and Space Administration previously operated a wind tunnel capable of similar performance, but that wind tunnel is not currently in operation.

      The tunnel is relatively inexpensive to operate because each "run" is only about eight seconds. First, air is pumped out of a large tank that is connected to one end of the wind tunnel, creating a vacuum inside the tank. The
      • Much notable science occurs by tinkering around in labs, even though it appears low-tech from the outside. The notion that everyone in science runs around in bunny suits and fears single particles of dust was put there my movies and stories of quantum physicists.

        By the way, 8 seconds is pretty typical for high-speed tunnels. The results are looked at by examining slow-motion video.
    • My first thought when I saw this story was 'poor undergrad who had to polish it'. Too obvious :)
    • TFA on how it works:

      First, air is pumped out of a large tank that is connected to one end of the wind tunnel, creating a vacuum inside the tank. Then a valve is opened between the tank and the wind tunnel, sucking a burst of air through the wind tunnel at high velocity. The short run time requires less expensive equipment, unlike the large compressors needed for other wind tunnels that pump air continuously.

      I would have thought they could clean and polish by simply operating the thing, but no they have to

    • But consider: how many male undergraduates would fit into an 18 in pipe? Personally, I'd have to have an arm chopped off.

      Build a hypersonic wind tunnel and meet female undergrads!
  • They said they send some poor undergrad into the 120-foot wind shaft to polish the thing. Every once in a while you read about some slaughterhouse worker in the middle of cleaning out a meat grinder when somebody turns the damned thing on. Until now, I thought that was pretty much the grisliest way a person could die, but this looks infinitely more messy. You couldn't get me to crawl in there.

    • At mach 6 at least it would be a *very* fast death. Doubtful that the undergrad would feel a thing, he'd be blender juice before he knew it. OTOH: getting caught in a commercial meat grinder might be slow enough not only to notice, but to scream in agony as his legs are turned to hamburger.

      Hmmmm... hamburger...

      • by ultranova (717540) on Saturday January 07, 2006 @04:44PM (#14417994)

        At mach 6 at least it would be a *very* fast death.

        At Mach 6, yes. But if the thing is turned on when the undergrad is inside, the air doesn't just suddenly jump to Mach 6 - no, it accelerates, and that takes time. It takes an especially long time if the pipe is clogged by a human body.

        What will happen is that the undergrad will get an overpressure against her feet or head, likely strong enough to eject her from the pipe. The pressure itself is unlikely to kill her, but injuries sustained when thrown out of the pipe might.

        • Sigh. I guess you're right. The undergrad *would* know death was coming before being blown out the windtunnel. Then... *SPLAT!* Oh well, just another undergrad.
        • The pressure itself is unlikely to kill her, but injuries sustained when thrown out of the pipe might.

          No worries, then. I thus conclude my fear of heights to be totally irrational because it's not the falling that will kill me, but the hitting the ground part.
    • by AndroidCat (229562) on Saturday January 07, 2006 @04:31PM (#14417941) Homepage
      Even if it didn't kill you, you'd certainly be exhausted.
    • Every once in a while you read about some slaughterhouse worker in the middle of cleaning out a meat grinder when somebody turns the damned thing on.

      Which begs the question (oh yes it does, you grammar nazis I just know have their response fingers twitching): why do they simply turn it off, as opposed to removing fuses or otherwise rendering it incapable of operating ? I mean, that's what I'd do...

      • proper lockout/tagout procedures would involve the person doing the work personally putting a padlock on the circuit breaker (in the off position), one to which the only key is in the posession of the person working inside the device, along with a tag stating who he is, what he's working on, and when he expects to be done, after which he would personally test that the equipment is not capable of powering on before climbing inside.

        Removing a fuse is no more effective then turning off the switch if some idiot
      • Which begs the question (oh yes it does, you grammar nazis I just know have their response fingers twitching): why do they simply turn it off, as opposed to removing fuses or otherwise rendering it incapable of operating?

        *sigh* Normally I wouldn't respond to yet another blatant misuse of "begging the question," but since you come right out and assert that you're not using it wrong, it's worth pointing out that you are, in fact, using it exactly the wrong way.

        Talking about being worried about being i
        • Look up the word beg. Now look up the word question. Now, admittingly, it might be more grammatically correct to say "begs for the question," but is not that a valid interpretation of the words "begs the question?" That there happens to be another meaning of that phrase which originates from an archaic translation of a latin phrase should be irrelevant. When I talk about a slippery slope, I am not always referring to a hasty generalization, sometimes I'm talking about inclined surfaces with minimal friction
    • Falling into a vat of molten bronze is also pretty bad. Not only do you not go much deeper than your knees, but you flail about for a long time before you finally sink into it. Not only that but you also screw the batch up as you leave excess carbon and calcium behind. At least you have some satisfaction of revenge....
    • Then they'd have to send in another undergrad to clean up that mess...
    • Acyually, it should be safe. If, and only if, all the proper "lock-out tag-out" procedures are followed.
      http://en.wikipedia.org/wiki/Lock_and_tag [wikipedia.org]

      In short:
      All sources of energy (electric, hydraulic, pneumatic, gravity, steam...) are identified and marked
      Anything that can move, or harm is isolated and marked.

      As a person entering a dangerous area for maintenance, you'd have a lock, or set of locks. Each marked item is locked by your lock (or the locks of everybody entereing). You keep the key.

      In the end, nobod
    • At least it would be fast. If I was going to go, I'd rather die quick but messy than trapped in a mine, or like this [bbc.co.uk].
  • by isny (681711) on Saturday January 07, 2006 @04:18PM (#14417879) Homepage
    Grad student 1: This job sucks.
    Grad student 2 (turning on wind tunnel): No, it blows!

    Thank you, I'll be here all day.
    • Grad student 1: This job sucks.
      Grad student 2 (turning on wind tunnel): No, it blows!


            All wind tunnels suck, the flow off of a fan is to turbulent to get good readings.

      James
    • No, it sucks. (Score:3, Informative)

      by Short Circuit (52384) *
      This tunnel works in a fashion opposite most wind tunnels. Instead of pressurizing one end, they create a vacuum at the other. That means they only get a run time of 8 seconds, but they use computers to get all the data they need in that short of a time frame.

      So, yeah, it really does suck.
  • PC Modding... (Score:1, Offtopic)

    by creimer (824291)
    The Air Force is designing a quieter PC case? Replacing the 60mm or 80mm fans with 120mm fans should fix the fan noise problem. I think polishing the fan casing to mirror-like quality to reduce air drag is a bit of an overkill unless you like the polished chrome look.
  • TFA: that is the only one of its kind... and not the first of its kind....

    nitpicking aside, my favorite part was that it's pricetag was under $1 million. if they're sharing their "how we did it" information (a big if since it's the USAF and boeing), scramjet research should take off in leaps and bounds given the cheapness of testing in a controlled environment, sans crashes [google.com], accidental or on-purpose.
    • TFA: The National Aeronautics and Space Administration previously operated a wind tunnel capable of similar performance, but that wind tunnel is not currently in operation.

      Also according to the article, big savings came from using vacuum at one end, instead of expensive compressors at the other. They only get short runs of about 8 seconds, but their computers can take all the readings they need.
    • I like the bit where they talk about scramjets leaving the atmosphere as if they are going to remain in operation without air. How exactly does this work again? I thought scramjets required air to operate...
  • Computer Simulation can't help the project?
    • Computer simulation only takes you so far. You can't simulate something if you have no idea what the numbers should be to start with. At some point you have to test real hardware in real conditions.

      Its a lot easier and more cost effective to test in a wind tunnel than build a full scale testbed everytime you change something in your design.
    • It can and it will, you always need (/want) an experimental reference for your models. Especially in a relatively new field, like hypersonic aero(thermo)dynamics.
    • Computer simulation of hypersonic flows is not ready for prime-time, "it's time to bend metal now" engineering.

      • Computer simulation of hypersonic flows is not ready for prime-time, "it's time to bend metal now" engineering.

        Aw, crap, please tell me that Jesse James' way skillz bending the pipes will save us all. He makes cars go faster, is a tough SOB and is a multi-millionaire, right?
  • sounds cool (Score:2, Funny)

    by icepick72 (834363)
    the Mach 6 nozzle must be polished to a near-perfect mirror finish, eliminating roughness that would trip the flow

    Thank goodness this "mirror" technology is all around us! I've always been an early tech adopter and there's even one on my bathroom wall. It's so smooth (almost has a "mirror finish") that I can actually rub my hand across it without detecting any roughness. It's exciting to know this is the same stuff the U.S. Air Force is using.

  • by Xeirxes (908329) <xeirxes@gm[ ].com ['ail' in gap]> on Saturday January 07, 2006 @04:36PM (#14417963)
    It said in the article that having these surfaces would greatly reduce the amount of heat that an aircraft recieves when returning to the atmosphere. And I was thinking, does that mean that one small tear could rip the aircraft apart, like the Columbia? It seems like it might be more beneficial to build craft that don't rip up like the space shuttle did, than craft that are even lighter.
    • by Moofie (22272)
      Columbia broke up somewhere north of Mach 12, I believe.

      I'd be much, MUCH more concerned about an engine unstart than about a mechanical problem with the heat shielding system. So much so, that I'd be totally unwilling to fly aboard a scramjet-powered aircraft that had a pilot with a joystick in his hand.
      • by YrWrstNtmr (564987) on Saturday January 07, 2006 @05:13PM (#14418109)
        There will be two occupants in the cockpit of the future. A man and a dog. The man is there to feed the dog, and the dog is there to bite the man if he tries to touch anything.
      • With a mechanical control system? Sure. But if you slowly deaden the controls at higher speeds, the capability of the pilot to overstress the aircraft can be controlled.

        Also, what's the plane doing before it goes hypersonic? Depending on how it gets up to speed, and what it does while not hypersonic, I could still see pilot control as important.
        • by Moofie (22272)
          If you pitch the aircraft at hypersonic speeds, you will disrupt the shock wave system that is compressing the air going into your engine. You will probably create a normal shock wave in the throat of the engine, and if that happens, everybody aboard will die. Maneuvering just does not happen at those sorts of speeds.

          Mechanical control systems on high-performance aircraft are a thing of the past. The system would CERTAINLY be fly-by-wire, and the pilot would be rendered pretty much incapable of direct co
      • by Forbman (794277) on Saturday January 07, 2006 @06:49PM (#14418488)
        Yep. For those that don't know, there hopefully are archives of teh Skunkworks-L mail digest on the net, where several people who were associated with the SR-71 programs (USAF and NASA) have some great stories about this incredible aircraft, and how bad engine unstarts were when zipping along at Mach 3, with the typical reason being that the shock wave entered into the engine inlet faster than the inlet spike system could respond to it. IIRC, more than one SR71 was lost operationally because the restart didn't go well or the plane broke because of the violence of the yaw caused by the unstart.
        • Indeed, unstarts were a huge problem with the early SR-71's. They never really "solved" the problem of unstarts, they just mitigated the problem by having the flight control system control engine restarts at high speed.
  • by Anonymous Coward

    Sure, but can it cool a Pentium 4?

    (yes guys, we've still got a good three or four years of Intel bashing ahead of us seeing how the AMD socket-A bashing is still in progress.)

  • by SuperBanana (662181) on Saturday January 07, 2006 @04:54PM (#14418034)
    'Quiet' Mach 6 wind tunnel helps shape future aircraft

    Executives at Gillette have announced the Mach 7 in response to Purdue's Mach 6 wind tunnel. "We simply cannot be outdone on Mach numbers."

    When asked what the commercial for the Mach 7 will feature, the unnammed executive replied, "jet fighters, women, racecars, women, missiles, women, bullets...it will be more spectacular than watching the entire French airforce crash into a fireworks factory."

  • With an 18" diameter pipe for such air to go through, and the student intern needed to enter it to clean/polish it, what first came to mind was someone turning it on to pull a more circumferentially challenged intern out.

    And then I remembered the same scene in Charlie and the Chocolate factory (with Gene Wilder) and knew that it wasn't such a bad way to go. :-)
  • by jaxon6 (104115) on Saturday January 07, 2006 @06:36PM (#14418430)
    Remember, it's not a job, it's an indenture.
  • Does it really need to be super smooth and mirror like?

    I'm sure if it gave it a huge bonus in range, they would make golf balls with mirror finishes.

    Perhaps we could dimple the surfaces of the tube...and achieve warp 1.

    Really...or do dimples only work on spherical objects?

    • Different flow regime. A (quite) subsonic golf ball spins in flight, and the dimples are there to keep adjacent air attached as it spins.
    • I believe the ball has dimples due to the rules of golf. There's all sorts of rules about how the ball is made, shape of the clubs, etc.

      Also, the dimples mean that the ball reacts the opposite way to spin than a smooth ball would react. A smooth ball spinning clockwise will hook left due to lower pressure on it's left side due to the bernouli (sp?) effect. A dimpled ball will actualy experience higher pressure on that side and slice right.

      This is why topspin is bad (on a drive) for a golfball cause y

    • The reason that dimples work for a golf ball is exactly the same reason they would be counter productive for the wind tunnel. Basically the dimples induce a turbulent flow around the golf ball, which reduces the flow seperation at the rear of the ball as compared to that resulting from laminar flow over a smooth ball. By reducing the size of the flow separation region, the pressure drag on the ball is significantly reduced, allowing the ball to travel farther. Now in the case of the wind tunnel turbulent
  • a million? (Score:2, Insightful)

    by Loconut1389 (455297)
    I read and thought "A million bucks? Is that all?" then I read it was 18" in diameter. Oh well.
  • They build a multi million dollar device and forget to build a gawddamn pipe cleaner...
  • NASA Ames (Score:2, Informative)

    As I recall, there are already some very high power and large wind tunnels at the NASA Ames research center in Mountain View California. http://windtunnels.arc.nasa.gov/ [nasa.gov]. For those of you that live in Silicon Valley, I'm sure you are all familiar with the gigantic wind tunnel that is large enouph to handle a complete mid-sized airliner.
  • Anywhere the wind blows ...

Don't sweat it -- it's only ones and zeros. -- P. Skelly

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