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More On Silent Supersonic Planes
Reverberant writes "Popular Science describes the latest attempt at developing a supersonic plane designed to minimize sonic booms. The article describes some of the history behind the research, and recent attempts at validating the theory. Also note that researcher Ken Plotkin is a frequent contributer to alt.sci.physics.acoustics."
Where is that Hedgehog when you need him? Can't we tell him just to be quiet?
Friends help you move...
REAL Friends help you move dead bodies... ^_^
Conjugate much?
is it just me being paranoid, or is not having any windows and having cameras send external images to the cockpit a "bad thing." obviously, without computer systems, the planes are almost useless, but if anything happens to the camera, the pilot can't even *see* outside the plane.
BSD is for people who love UNIX. Linux is for those who hate Microsoft.
If it's been published on the prestigious trade journal 'alt.sci.physics.acoustics', it must be true!
Since when has this country used intellectual elite as a pejorative term?
Pilots rely on more than just being able to see outside. They have literally dozens of instruments that they have to monitor in addition to the view outside. During the night and over the ocean, you have nothing but your insturments to rely on, so it's not like this is a new thing for pilots. Still, if it were ME I would want a window :)
As I grew up I watched so many programs like "Beyond 2000" on discovery channel and felt excited about being in the years beyond 2000. This is 2004 and none of the promises came true. We are at about the same level as we were in 1999 technologically. Or even worse as concorde is gone. Somebody, move us into the future!
If you lost your job today, don't despair. You may die tomorrow anyway.
"Popular Science." No such thing, man. More like, "nerdular nerdance."
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If you don't get it, don't moderate!
if a plane breaks the sound barrier and no one is around to hear it, does it make a boom?
...can be found here.
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I've never heard a sonic boom... so I'm not really sure how loud they are, but a co-worker described it as "pretty much sounds like thunder".
Is that really a big problem? It seems kind of dumb to me to ban supersonic flight over cities.
What the fuck kind of idiocy is this? First of all, we already have stealth technology so we're already catching our opponents by surprise. Second, sonic booms are detected AFTER the aircraft flies overhead -- not before! The whole phenomenon of a sonic boom is that the aircraft is racing ahead of the "information" of its arrival (in the form of sound waves).
I'm not saying that a sonic-boom-free aircraft is of no military use. The shockwaves responsible for sonic booms cause drag to increase signficantly, thus requiring much more fuel. But the motivation certainly isn't one of trying to catch someone off guard.
GMD
watch this
That's very interesting, but would not it make more sense to make the normal, subsonic planes more silent? They are much more in use, and the noise causes a lot of grief near airports, especially at night. Here in Brussels, this problem is already for years on the political agenda, being a very difficult problem to solve (economics vs. health...), so silent planes are really a must!
I've never heard a sonic boom... so I'm not really sure how loud they are, but a co-worker described it as "pretty much sounds like thunder".
EVERYONE has heard a sonic boom at one point: the crack of a whip. That sound you hear is not the tip of the whip hitting anything. It's the sound of the tip accelerating beyond the speed of sound and creating a mini-sonic boom. That little flick at the end causes the tip to snap out at incredible speed.
Now as far as a big sonic boom, I haven't heard one either. I'm sure there are some pretty strict regulations about not creating sonic booms in civilian areas.
GMD
watch this
I am almost certain that people wont want it flying over their neighborhoods. I can remember watching a show about all of the hubub people made about the Concord landing at their local airport. You would have thought the world was going to end!
Then, once they heard the landing (which wasn't any louder than a regular plane landing), they went back to their caves and silently watched the news for another issue to get their panties in a bunch about. *sigh*
It seems that they are doing this using the traditional method of changing the shape of the aircraft. What about more novel methods such as striation, the same way tha dolphins achieve much higher efficiency than their shape would suggest. I'm surprised I never hear about this being applied to aircraft because it seems like such a simple thing to do.
Or an interesting method I heard about involving many tiny flaps on the surface which can dynamically shape the airflow to minimize turbulence?
so they finaly resolved the secret of those nazi ufos? was about time!
The research airplane in this experiment failed to reduce the sound of the sonic boom as much as hoped.
In fact, this research is primarily intended for the next generation business jets , not the military. The future of such planes is up in the air in the moment, because not only do they have to reduce the wake of sonic booms (they shatter windows and suprise people), the regulations have to change. I for one know that the FAA is slow at that.
Regarding the need for windows in airliners: A Boeing 777 pilot today needs to be able to see a few hundred feet ahead of him on takeoff, but after rotating off the runway, he doesn't need to see anything at all. Modern airliners can land and auto-flare... that is, land themselves in ZERO visibility conditions. The pilots undergo extra training for this, of course.
FAA Certified Flight Instructor
Actually, on a serious note, I got pretty frustrated with the article. Actually, I only read the first page and then got bored. I'll never understand why science writers always clutter up their articles with crap like that turtle in the story. We want to read about advanced aerodynamics, not wildlife. Then they go on and on talking in detail about the test. Just tell us what happened at the test; we don't need a blow-by-blow account.
Extra clutter like that really makes the article seem amateurish. You have to be really damn interested in the topic to wade through all that extraneous crap at the beginning of the article no less! Maybe they think they are humanizing the dry science. But do you think people who buy a magazine that has Science in the title really find science boring? Or that they need this high-school-like prose at the beginning?
And don't even get me started on when an article tries to make an analogy with something real-life. I read an article in Scientific American some years ago that was using the swordfight between Zhang Ziyi and Michelle Yeoh in Crouching Tiger, Hidden Dragon as an example of how the new technology can better the "old standbys". The whole point of that scene was that Yeoh could have killed Ziyi even with that fancy Green Destiny in her hands. What a terrible analogy! And this is the way you start off a science article?
Sorry, just had to rant,
GMD
watch this
This won't solve anything. This won't make anything better for anyone.
I agree. Faster, cheaper travel never benefitted mankind in any way. Only fat, rich, white men could possibly want to travel the world in a timely, affordable manner.
Mod down posts with a "Free Mac Mini/iPod" sig, they're spam!
a sonic "boom" isn't a one time event. The shockwave is continuous, so long as the aircraft is flying at supersonic speeds. Therefore, people on the ground for the entire flight corridor will hear/feel the boom as the plane flies overhead.
In fact, no kidding the people at the airport the plane lands at dont hear a boom! Obviously, the plane slows down to subsonic speeds prior to landing. But for everyone in between the takeoff and landing airport that the plane flies over, will be subjected to it.
Hence the reason the concorde was banned from flying over the US, but landing on coastal airports isnt a big deal.
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As the very first paragraph of the article mentioned, one use is for supersonic business jets. Just because the researchers are using a heavily modifed F-15 as a test vehicle doesn't mean it's all for killing things. NASA still uses Titans for launching spaceprobes, even though they were originally designed for launching nuclear warheads. The planes that fly through hurricanes to gather wind speed data probably save lives every time a big one approaches land, but they are still modifed military aircraft.
Yes, this has military applications as well. Lots of things do. The medical resarch you mention has been perverted to war before, for just one example. If you would like to see this knowledge focused on peaceful persuits and shared for the benefit of all, more power to you. It is not going to be possible to share it with businesses across the country and still keep it a military secret. All you have to do to help mankind here is pressure the people talking about applying it to silencing commercial aircraft to keep that promise, and it will make things better for lots of people.
Who is John Cabal?
While you're right, Kennedy shouldn't have been flying under VFR in IMC. He wasn't instrument rated, although he had had lots of instrument training, and with passengers on board, doing it was just horribly irresponsible.
A related side note: commercial pilots are required to have an instrument rating to fly for hire at night. This doesn't apply in this case because Kennedy wasn't flying for hire.
p
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What I'm going to say is nothing new, totally unoriginal, but...
I find it paradoxal that the bleeding hearts will criticise the US military to no end, when there very right to express those opinions has been secured by the technological edge that allowed the US and its allies to win both WWII and the Cold War.
You needn't be an avid fan of the current government's decisions to realise that many *many* people have benefited enormously from the security and technological advances that were pioneered by this "war machine".
To add my own anecdote, this is very similar to the discussions that I have with fellow French Canadians. We've got a big collective chip on our shoulder against the English. However, the reality is that the English system of government, instituted here in Canada and the United States, has spared us from the sort of upheaval that our blood-thirsty European ancestors have inflicted on themselves. Bloodthirsty, yes, because before Europe decided to "remake" its virginity, it was one of the most war-torn shitholes on the planet. And I don't think that will ever change because people there remain as naïfs as before.
Writing from Norway, eh?
Probably a country that benefited enormously from the protection guaranteed by the US and its allies. So much so that you had no need to invest in a real military to defend yourselves. So shut the fuck up.
Flamebait, yes, but it needs to be said.
correct, but the Concorde didn't ordinarily use afterburners; it had them only for the greater thrust demands at take-off and during acceleration, not for cruise. it was an expensive plane to run largely because of its low seating capacity and short range, which barred it from many of the lucrative trans-Pacific routes.
(some have also argued that the low-to-nil bypass ratio of the Concorde's Olympus engines made it more expensive to run. that may be true; i don't have any really convincing evidence either way.)
that would have had to depend on what the plane was doing. during landing, i can well believe the difference might have been small; during take-off (under afterburners, natch!) that would very much surprise me; and while supersonic, absolutely not.
Concordes were politically acceptable so long as they stayed subsonic over land, so nobody would complain about the boom. they were also hideously expensive to run, which in a more rational world might have shut them down all by itself, but apparently there were enough eccentric ultra-rich people to keep them flying for decades in spite of that fault. no amount of money, however, would let them reamin at their designed cruise speed above anyplace people lived, and that was as much a political shortcoming as a technical one.
Yah and the two damn supersonic planes did nothing to frighten the poor little tortoise?
Oh well, what the hell...
Well now, nothing prevents the poor from getting a good education and becoming rich beyond measure: http://www.universityofnigeria.com
Oh well, what the hell...
Sending 'stealth' planes into airspace that has no defending air force is not exactly a 'proof of the concept'. Coulda flown into iraq using a concorde, complete with it's huge sonic trail, would not have made any difference, there was no air force to defend anyways.
Stealth planes are not undetectable, they are just more difficult to detect than traditional aircraft. Countries with the will, and the technology, have long since built better detection systems, so flying into thier airspace with a 'stealth' machine will be no different than flying in with a traditional airplane. they are gonna see it coming well in advance, and the only surprise will be to the american taxpayer, those billion dollar airplanes are not nearly as sneaky as the military would have you believe.
...is nothing new. The Tridents, BAC 1-11s and VC10s (all British!) of the early 1960s had it. Don't try and pretend Boeing invented everything - they are the Microsoft of the skies - not much invented here....
I may be incorrect about this, but I seem to recall that the mathematician Paul Garabedian independently developed the mathematical theory for shockless supersonic flight at the same time that people in AE developed a theory. The Popular Science article does not mention Garabedian.
The review by N. Geffen of "Analysis of Transonic Airfoils", Comm. Pure Appl. Math. 24 (1971), 841--851 by Garabedian, P. R.; Korn, D. G.
"Calculation of inviscid, subsonic-supercritical flow around prescribed airfoils is described. This supplements the authors' previous design of a shockless transonic wing using real and complex characteristics in the hodograph plane. The flow about the designed wing is calculated for a range of off-design conditions.
"Neumann's problem for the flow-potential equation is solved numerically in a plane where the exterior of the airfoil is conformally (also numerically) mapped onto the interior of the unit circle. Following E. M. Murman and J. D. Cole [AIAA J. 9 (1971), 114--121], a second-order finite-difference scheme is used in the subsonic region, while an implicit second-order scheme is used in the hyperbolic zone, introducing artificial viscosity of the right sign. The Kutta condition is satisfied by an iterative scheme. Results with relatively narrow shocks (i.e., steep gradients) are given and compared with wind-tunnel experiments."
I've never heard a sonic boom... so I'm not really sure how loud they are, but a co-worker described it as "pretty much sounds like thunder".
Is that really a big problem? It seems kind of dumb to me to ban supersonic flight over cities.
There are certainly very important military implications to being able to go supersonic without a boom. If you have a plane capable of going supersonic, but is indistinguishable from noise on radar thanks to stealth technology, a sonic boom is one thing that could give you away in enemy territory. If you can't be heard on the ground, or easily seen on radar, that makes your mission that much easier.
A lot of rookies think they're better at IFR (Instrument Flight Rules) than they really are. They fixate too much on a single dial or meter, and end up augering in (with perhaps perfect speed) in a sim. Skilled IFR is mostly actually flying by the seat of one's pants; looking at all those instruments eventually gives a pilot an almost intuitive knowledge of how the aircraft behaves. He need only glance down a few times per several seconds to have a fair idea of what the plane's doing, using his experience to connect the pieces of data.
Don't be alarmed... MY ASS!
If you watch cable TV shows much, no doubt you've seen your share of close-calls in airplanes.
Yes, there are plenty of occasions where all the instruments fail, the power goes out, the hydraulics go out, etc. People still survive because, despite the high-tech systems, there is still JUST ENOUGH under manual control that a very good pilot in decent weather can land such a crippled plane.
Good luck doing that when they can't even see! And don't bother telling me that they're going to have multiple cameras, with backup systems and all that, I've already heard of plenty of cases where all 3 computer systems on 747s have failed. That's not one case, but MANY independant cases.
As you can probably assume, I'm not afraid of technology in the slightest. However, I do know that even the most advanced and well-tested technology in the real world can fail. If you aren't willing to trust electronic voting machines, are you really ready to give technology 100% control over matters of life and death?
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A better analogy is armor. Whatever armor you have, the enemy can make ordnance to penetrate it. But is still better to defend against an armor brigade with $2 million Abrahms tanks, rather than a fleet of $20,000 jeeps.
Actually, jet engine manufacturers have done a very commendable job reducing engine noise, thanks to high-bypass turbofan engines that use mostly the front fan to generate thrust and the use of acoustically-treated and tuned jet engine nacelles.
A less-known problem is that of the noise rushing around the airframe at flight speeds, which can also generate a lot of noise that could be heard from the ground. Fortunately, modern computational fluid dynamic research has reduced this problem, even on the upcoming Airbus A380 super jumbo airliner.
Point 1: Barriers to trade
You know, you're absolutely right. I am totally against the difficulties that we create for developing nations, that keep them from putting their goods (usually agricultural) on our markets.
The fact is, both the United States *and* Europe are guilty, one as much as the other.
That said, many African governments have adopted protectionist policies of Marxist inspiration. Mugabe is only the latest and most flagrant example; it's been happening for decades. So you can't expect Country A to allow Country B's goods into their domestic market if there is no reciprocity. Reciprocity is essential for free trade. However, this is done in a bilateral fashion on a category-by-category basis, so reciprocity would apply to, say, all raw agricultural products. The fact that they don't want to drop tarifs on your heavy equipment is not a mitigating factor related to the said agricultural products, as far as I understand.
Point 2: Natural resources
I'm growing very wear of the argument that we are raping all those poor countries' natural resources. The fundamental nature of economic exchange is the fact that someone places a higher value on your good or service than you do. This is how wealth is generated, *this* is the basis of true economic development.
This is silly, I shouldn't even have to illustrate it, but let's take the example of diamonds. African Country is rich in diamonds. The country really doesn't know what to do with them -- it doesn't have experienced jewellers to cut them or industries to use them in other products. However, African Country has people with families to feed, and these people need jobs. That means that a demand exists for a domestic product that will create a net inflow of cash if exploited.
Basically, I suppose that it comes down to an ideological preference. Do you prefer free commerce that generates new wealth, or are you stuck in the sclerotic mindset that prefers to give away millions of dollars in the form of "aid" that will never encourage these countries to take the steps necessary to improve their well being? If your dream is to create a global welfare state, we have nothing further to say to each other.