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Air Force Builds Quiet Mach 6 Wind Tunnel

ScuttleMonkey posted more than 8 years ago | from the hold-on-to-your-hat dept.

Technology 153

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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153 comments

whee! (1)

gcnaddict (841664) | more than 8 years ago | (#14417811)

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! (5, Informative)

Anonymous Coward | more than 8 years ago | (#14417825)

Wikipedia on Scramjets [wikipedia.org] . AC to avoid karma whoring..

ScramJet takeoffs (1)

robgamble (925419) | more than 8 years ago | (#14418260)

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?

Re:ScramJet takeoffs (2, Informative)

MichaelSmith (789609) | more than 8 years ago | (#14418322)

(2) give it two types of engines?

Yep.

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

wind tunnel? (-1, Offtopic)

Anonymous Coward | more than 8 years ago | (#14417821)

can i make a wind tunnel from us down to china below?

"After four years of debugging"... (-1, Offtopic)

Paperghost (942699) | more than 8 years ago | (#14417822)

...wow, I thought I was reading another story about a Windows exploit!

"Quiet"? (3, Interesting)

timeOday (582209) | more than 8 years ago | (#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"? (5, Funny)

slashdotnickname (882178) | more than 8 years ago | (#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.

Cultural Reference (1)

turgid (580780) | more than 8 years ago | (#14418138)

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?

Re:Cultural Reference (1)

mspohr (589790) | more than 8 years ago | (#14418171)

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.

Re:Cultural Reference (0)

Anonymous Coward | more than 8 years ago | (#14418177)

Holiday inn is running (ran?) a series of commercials where lay people perform extraordinay acts, then when asked about their background, the 'hero' replies 'I stayed at a Holiday Inn last night.'

For example, one commercial shows a man in the desert being bitten by a poisonous snake. As the victim and his friends stand by helplessly, a cowboy comes by, examines the wound, then directs the victim's friends to suck out the poison and start a fire so he can cauterize the wound. When the victim asks if he's ever done this before, the cowboy says "no, but I stayed at a Holiday Inn last night." At that point, a movie director comes by and directs the 'cowboy' (really an actor) to get back to his set.

Re:Cultural Reference (0)

Anonymous Coward | more than 8 years ago | (#14418187)

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?

It's just another way of saying "IANA(blank)".

In a series of Holiday Inn commericals awhile back, they had ordinary "nobodies" leading others in dramatic situations. For example, in one a nuclear reactor was malfunctioning and the operators couldn't fix it. Suddenly some guy walks in, makes a suggestion and saves the day. When the operators ask if he's the new technician, he says: "No, I'm just part of the tour group. But I did stay at a Holiday Inn Express last night." Other commercials included skydiving and surgery. All the commercials ended with the slogan: "It won't make you smarter. But you'll feel smarter."

Re:Cultural Reference (2, Informative)

afidel (530433) | more than 8 years ago | (#14418263)

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.

Re:Cultural Reference (1)

Fulcrum of Evil (560260) | more than 8 years ago | (#14418722)

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?

Re:"Quiet"? (1)

Reverberant (303566) | more than 8 years ago | (#14418095)

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 be sure that the only noise is from the air flow, and not from something else.

As far as my background, I haven't stayed at a Holiday Inn for a while, but I did spend a year and a half working with MIT's subsonic anechoic wind tunnel [dtic.mil] before it was crated off to Wilmington to make room for the Pappalardo Labs. [mit.edu]

Re:"Quiet"? (1)

Jozer99 (693146) | more than 8 years ago | (#14418145)

Shouldn't this article be called "NASA sits around while a poor graduate student builds quiet Mach 6 wind tunnel."

Re:"Quiet"? (1)

nietsch (112711) | more than 8 years ago | (#14418262)

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"? (2, Informative)

joeljkp (254783) | more than 8 years ago | (#14418421)

"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.

Re:"Quiet"? (0)

Anonymous Coward | more than 8 years ago | (#14418329)

You could just read the god damned article...

18 inches (2, Insightful)

Janek Kozicki (722688) | more than 8 years ago | (#14417837)

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 (5, Insightful)

mickyflynn (842205) | more than 8 years ago | (#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 (2, Informative)

bluelip (123578) | more than 8 years ago | (#14418218)

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.

Re:18 inches (2, Insightful)

Anonymous Coward | more than 8 years ago | (#14417862)

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 millions more.

Re:18 inches (2, Funny)

thatshortkid (808634) | more than 8 years ago | (#14417954)

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?

Re:18 inches (0)

Anonymous Coward | more than 8 years ago | (#14417989)

Well, it isn't to that say the size of the pipe doesn't matter. A larger pipe is never a bad thing. However, a small pipe, when used right, can be better than a larger pipe used incorrectly. In addition, Air Force engineers are looking to clean up the edges of the pipe in order to make it look a bit larger than it is. No word yet on whether or not this will help the scramjet experiments.

Re:18 inches (1)

trewornan (608722) | more than 8 years ago | (#14418156)

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.

8 seconds is really a lot of time (1)

dbIII (701233) | more than 8 years ago | (#14418258)

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 do a lot more, like the effect of moving control surfaces on an aircraft model instead of just a scramjet engine test - the engine has no moving parts.

Re:18 inches (0)

Anonymous Coward | more than 8 years ago | (#14417923)

It'd still make a hell of CPU fan!

Re:18 inches (1)

Yaotzin (827566) | more than 8 years ago | (#14418052)

Nah, I'm guessing it would blow pretty hard.

Re:18 inches (0)

Anonymous Coward | more than 8 years ago | (#14418840)

Nope, he said he has a wife. No blowing after marriage.

Re:18 inches (1)

wernercd (837757) | more than 8 years ago | (#14418251)

Probably needed for Dell's Quad SLI System [slashdot.org]

These two stories released days apart... coincidence? I think not!

Re:18 inches (1)

dbIII (701233) | more than 8 years ago | (#14418219)

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.

Re:18 inches (0)

Anonymous Coward | more than 8 years ago | (#14418378)

Your wife talks in typoes?

Re:18 inches (1)

james_marsh (147079) | more than 8 years ago | (#14418382)

[...] my realistic wife said [...]

Cool, so those dolls talk now as well?

Re:18 inches (0)

Anonymous Coward | more than 8 years ago | (#14418713)

It's not really the size of the pipe that counts...

Quiet windtunnel needed? (1)

jurt1235 (834677) | more than 8 years ago | (#14417840)

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.

Re:Quiet windtunnel needed? (2, Informative)

User 956 (568564) | more than 8 years ago | (#14417859)

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.

Re:Quiet windtunnel needed? (1)

Moofie (22272) | more than 8 years ago | (#14418114)

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.

Quiet? (1)

Falconpro10k (602396) | more than 8 years ago | (#14417843)

do they mean quiet as in 130db compared to so loud it can set your hair on fire? thats the thing im wondering...

Re:Quiet? (0)

Anonymous Coward | more than 8 years ago | (#14417915)

Quiet has more than one term. I suppose it should have been more clearly defined in the article - as on first glance it does give the impression that it means that it is of low noise creation - but in this case, it is about the air and its "ease" of motion. When air is moving at speeds as high as Mach 6, even the slightest aberation in a contact surface can cause the air to ripple and refract (for lack of a better word). This would make the air tunnel unusable for testing purposes, as it would either destroy the model from frictional forces or make the scramjet (which requires a "quiet" stream of air to work properly) not work.

In short, I'm sure the damn thing is loud as hell in terms of dB. But in terms of air flow, it's supposed to be quite quiet.

ooo.. (5, Informative)

User 956 (568564) | more than 8 years ago | (#14417846)

neat scramjet pictures here [bbc.co.uk] .

And a reason for MPAA to rejoice... or not (1)

ZoomieDood (778915) | more than 8 years ago | (#14418364)

From the end of the article with the picture:

"Eventually, scramjets may revolutionise air travel, allowing passenger aircraft to fly to London from Sydney in just two hours, making in-flight movies obsolete."

I love being an undergrad... (5, Funny)

metaomni (667105) | more than 8 years ago | (#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!

Re:I love being an undergrad... (5, Funny)

Hal_Porter (817932) | more than 8 years ago | (#14417889)

Could be worse though, the lecturers at my Uni would have turned on the airflow if it would have saved them twenty bucks.

Re:I love being an undergrad... (1)

fanblade (863089) | more than 8 years ago | (#14417952)

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. Then a valve is opened between the tank and the wind tunnel, sucking a burst of air through the wind tunnel at high velocity.

Re:I love being an undergrad... (1)

joeljkp (254783) | more than 8 years ago | (#14418454)

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.

Re:I love being an undergrad... (1)

heavy snowfall (847023) | more than 8 years ago | (#14418029)

My first thought when I saw this story was 'poor undergrad who had to polish it'. Too obvious :)

A Job that Really Sucks. Safety First! (1)

twitter (104583) | more than 8 years ago | (#14418501)

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 do it with elbow grease. Remember that scene from the movie Heavy Metal, where aliens suck up two people from the Pentagon? That's one hell of a ride that ends with a bang.

It's nice to see them saving money, but we can only hope they don't send anyone in when the thing is primed.

Re:I love being an undergrad... (1)

Guppy06 (410832) | more than 8 years ago | (#14418736)

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!

I loved the part where... (1)

Schlemphfer (556732) | more than 8 years ago | (#14417857)

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.

Re:I loved the part where... (1)

maynard (3337) | more than 8 years ago | (#14417912)

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...

Re:I loved the part where... (3, Insightful)

ultranova (717540) | more than 8 years ago | (#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.

Re:I loved the part where... (1)

maynard (3337) | more than 8 years ago | (#14418354)

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.

Re:I loved the part where... (5, Funny)

AndroidCat (229562) | more than 8 years ago | (#14417941)

Even if it didn't kill you, you'd certainly be exhausted.

Re:I loved the part where... (1)

whopis (465819) | more than 8 years ago | (#14418208)

bravo.

Re:I loved the part where... (1)

AndroidCat (229562) | more than 8 years ago | (#14418807)

To add insult, he'll also be fired.

Re:I loved the part where... (1)

ultranova (717540) | more than 8 years ago | (#14417977)

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...

Re:I loved the part where... (3, Informative)

green1 (322787) | more than 8 years ago | (#14418022)

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 comes along and puts it back together (the same idiot who first tried the switch and found it didn't work) always LOCK it out.

ok... so there's always some moron with bolt-cutters... but I'd love to see him claim THAT was an accident when he goes to trial...

Re:I loved the part where... (1)

ScentCone (795499) | more than 8 years ago | (#14418513)

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 inside the unit under some risk that it might be turned on raises the question of whether or not there's a better way to incapacitate the hardware while it's being maintained. I won't even bother coming up with an example of how you could ask a question about this thing that involves actually begging the question. Since you're just wondering about something (rather than using question-begging as rhetorical device), it's just not even the right context.

Which doesn't change the value of your underlying question (answered well alread by someone else).

Re:I loved the part where... (1)

Gandalf_the_Beardy (894476) | more than 8 years ago | (#14418190)

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....

Re:I loved the part where... (1)

Azreal (147961) | more than 8 years ago | (#14418327)

Then they'd have to send in another undergrad to clean up that mess...

Re:I loved the part where... (1)

Skynyrd (25155) | more than 8 years ago | (#14418358)

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, nobody can turn the power (or whatever) back on until you unlock the control. If everybody going in has locked out the power source, nobody dies.

You have to do it every time you enter a dangerous space.

My company, a large beverage manufacturing plant that is full of deadly threats, has gone almost two years without a serious (no days away from work) injury.

There's no need for meat grinders to kill people. Sadly, the employees of slaughterhouses tend to be illegal/undocumented and have no voice. There's money to be made, an dthe owners look the other way. LOTO is slower than just jumping into a threatening environment, so it costs a company a bit of down time to follow procedures.

Fortunately, I work in a good union shop, and my boss cannot force me to skip safety procedures, unlike the slaughterhouse industy. Read "Fast Food Nation" for an interesting look at the fast food industry, as well as slaughterhouses, in the US.

Re:I loved the part where... (1)

Gandalf_the_Beardy (894476) | more than 8 years ago | (#14418533)

Sounds like the devices used on the electrified railways here. Padlocks with as many as fifteen keys - all are needed to unlock it. Let's a lot of men work on a large section of rail safely as everyone working has a key with them so it cannot be unlocked.

Another old one... (5, Funny)

isny (681711) | more than 8 years ago | (#14417879)

Grad student 1: This job sucks.
Grad student 2 (turning on wind tunnel): No, it blows!

Thank you, I'll be here all day.

Re:Another old one... (0)

Anonymous Coward | more than 8 years ago | (#14417924)

actually, from tfa, this tunnel does suck

Re:Another old one... (2, Interesting)

james_shoemaker (12459) | more than 8 years ago | (#14417996)

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. (3, Informative)

Short Circuit (52384) | more than 8 years ago | (#14418113)

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.

Re:No, it sucks. (1)

solitas (916005) | more than 8 years ago | (#14418606)

Mach 6, in an 18" diameter tube, for 8 seconds, by venting a pumped-out tank. Howinhell BIG is a tank that can pull that kind of volume over that length of time? And I wonder how long pumpdown takes.

PC Modding... (0, Offtopic)

creimer (824291) | more than 8 years ago | (#14417929)

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.

Hooray for the quiet Boilermakers (1)

thatshortkid (808634) | more than 8 years ago | (#14417930)

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.

Re:Hooray for the quiet Boilermakers (1)

Short Circuit (52384) | more than 8 years ago | (#14418132)

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.

Re:Hooray for the quiet Boilermakers (0)

Anonymous Coward | more than 8 years ago | (#14418221)

How they did it? That's easy: a really powerful and large fan that pushes air through a constricted channel: Bernoulli's principle. From an engineering perspective, they probably also have polished surfaces to minimize the turbulence of the air in contact with the surfaces. It's also probably pretty long to allow air to stabilize into a nice laminar form. At the end, there is probably a muffler system (such as parallel tubes with holes drilled along the cylindrical walls) to dissipate the energy (like what you have for discharging high pressure air reservoirs).

Computer Simulation (1)

michelcultivo (524114) | more than 8 years ago | (#14417934)

Computer Simulation can't help the project?

Re:Computer Simulation (1)

starbird (409793) | more than 8 years ago | (#14417985)

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.

Re:Computer Simulation (1)

kryten_nl (863119) | more than 8 years ago | (#14417991)

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.

Re:Computer Simulation (1)

Moofie (22272) | more than 8 years ago | (#14418015)

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

sounds cool (1, Funny)

icepick72 (834363) | more than 8 years ago | (#14417939)

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.

Re:sounds cool (1, Offtopic)

demmer (623592) | more than 8 years ago | (#14417990)

how do posts liek this get score 2?
he has absolutely no idea what he is talking about and it is not funny.

Re:sounds cool (0, Offtopic)

icepick72 (834363) | more than 8 years ago | (#14418355)

C'mon man, I was going for three in a row. Oh well, can't win them all.

Re:sounds cool (1)

19thNervousBreakdown (768619) | more than 8 years ago | (#14418593)

The “mirror finish” is on the other side of the glass.

Xbox 360 (-1, Troll)

Anonymous Coward | more than 8 years ago | (#14417961)

no more over heating with this bad boy, i wonder if microsofts interested

Some further comments (3, Insightful)

Xeirxes (908329) | more than 8 years ago | (#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.

Re:Some further comments (3, Interesting)

Moofie (22272) | more than 8 years ago | (#14418024)

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.

Re:Some further comments (4, Funny)

YrWrstNtmr (564987) | more than 8 years ago | (#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.

Re:Some further comments (1)

Short Circuit (52384) | more than 8 years ago | (#14418159)

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.

Re:Some further comments (2, Informative)

Moofie (22272) | more than 8 years ago | (#14418650)

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 control of the airplane at speed. Yes, the pilot could absolutely command the airplane to change course, but that would happen mediated by the computer, which will have full and exclusive authority to change the airplane's attitude.

Re:Some further comments (3, Informative)

Forbman (794277) | more than 8 years ago | (#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.

Sure, but.... (1, Funny)

Anonymous Coward | more than 8 years ago | (#14417973)

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.)

Gillette announces the Mach 7 (5, Funny)

SuperBanana (662181) | more than 8 years ago | (#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."

Re:Gillette announces the Mach 7 (1)

che.kai-jei (686930) | more than 8 years ago | (#14418212)

you sir, are a mammal, king amongst them!

trendy vaccum cleaners (0)

Anonymous Coward | more than 8 years ago | (#14418070)

HA! And that dyson guy spent millions on his vaccum cleaner- and can it suck air at 4000mph+, NO!

Awsome! Yet... (1)

inphizzible_friend (942173) | more than 8 years ago | (#14418131)

And I quote, " Scramjet technology is challenging because only limited testing can be performed in ground facilities." So, incredibly awsome. As it is operated by subsonic combustion of fuel in a stream of air compressed by the forward speed of the aircraft itself, as opposed to conventional turbojet engines, in which the compressor section (the fan blades) compresses the air. In comparison to turbojets, ramjets have no moving parts. And since this is a scramjet (supersonic-combustion ramjet) it would be double awsome to see them up, and running soonly.

Cleaning the pipe and you get stuck... (1)

ZoomieDood (778915) | more than 8 years ago | (#14418343)

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. :-)

Ahh, the life of a grad student (2, Funny)

jaxon6 (104115) | more than 8 years ago | (#14418430)

Remember, it's not a job, it's an indenture.

In other words... (1)

Efrat Regev (935278) | more than 8 years ago | (#14418452)

They're working on breaking wind quietly? What else is new?

Super Smooth vs. Dimples... (1)

skogs (628589) | more than 8 years ago | (#14418509)

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?

Re:Super Smooth vs. Dimples... (1)

dsci (658278) | more than 8 years ago | (#14418599)

Different flow regime. A (quite) subsonic golf ball spins in flight, and the dimples are there to keep adjacent air attached as it spins.

Regulations (1)

Mateorabi (108522) | more than 8 years ago | (#14418634)

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 you hit the dirt and loose distance.

Re:Super Smooth vs. Dimples... (3, Interesting)

penguin121 (804920) | more than 8 years ago | (#14418669)

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 flow along the walls would generate noise that would interfere with the experiments, so they want as smooth a surface as possible to minimize turbulence at the tunnel walls, thereby minimizing the background noise.

a million? (2, Insightful)

Loconut1389 (455297) | more than 8 years ago | (#14418780)

I read and thought "A million bucks? Is that all?" then I read it was 18" in diameter. Oh well.
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