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Supersonic Flight Without The Sonic Boom
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."
Why is this important? The article seems to leave that important bit out.
Does this somehow preserve the energy better?
How small a thought it takes to fill a whole life
What does Guile think about these developments?
There's supposed to an Earth shattering kaboom?!?!
It seems it merely muffles the sonic boom. The technology doesn't completely silence it.
The article states that the boom is reduced because the merging of the pressure waves does not combine into a shock wave(s) as readily.
There is still a sonic boom.
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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...
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...)
'Sensible' is a curse word.
Ever wonder why the Concord only flew at supersonic speeds over water, and not land? Because they couldn't - it's too disruptive. A supersonic craft without a sonic boom would enable flight over land.
This is early 1990s technology.
Aurora has had this incorporated since the beginning.
But then again, I'm drunk and saying too much. So ignore all this.
I live near the airbase, and I'm talking on the telephone to you (miles away). You'll hear the boom before you see the plane!
I happened to notice a show (On The Edge) on the Discovery Wings channel covering a lot of this. Not as in depth, of course, but interesting nonetheless.
Now all i need is a way to reshape the bullet in-flight for my high powered rifle and presto, the perfect assasination ;)
This comment does not represent the views or opinions of the user.
... that the vision of supersonic flying cars didn't float through your mind when you read the article :)
So, when can we throw out the Concord and whatnot and get transcontinental supersonic flight to boot?
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.
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)
har har _____
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.
___________
"Build a man a fire warm him for a day, set a man on fire and warm him for the rest of his life."
surely you meant "black ops", no?
Because we all know how annoying those sonic booms are that keep us up all night.
Hmmmm. That must be how the UFO's do it.
Submited on september 6, 2003:
Northrop, working with the Pentagon and NASA sucessfully tested a "quiet" supersonic flight wednesday at California's Edwards Air Force Base. In the tests, an F-5E aircraft with a modified nose section flew supersonically through the test range, shortly thereafter, an unmodified F-5E 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.
You can't take the sky from me...
oh brave new world, that has such people in it!
Sonic booms can be a helluva lot more than just "loud" or "annoying." They can implode outbuildings, knock shit off shelves, break windows... and toss around house trailers like a blast from a hurricane.
No boom today, boom tomorrow, there is always a boom tomorrow. What?! Look somebody got to have some damn perspective around here. Boom! Sooner or later...BOOM!"
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.
looks like new use for the old flying boats...
SCO claims to have the copyright on SCOnic...oh wait.
Note to self: get smarter troll to guard door.
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
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.
Invalid Checksum. Retrying.
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.
I hate how petty and arbitrary the editors can seem to be... Your summary is better than the one they accepted...
The article didn't say exactly how great the reduction was. If they didn't explicitly mention the magnitude of the reduction then it couldn't have been that spectacular. Looks like they want publicity that they've had some (small) initial success so they can get more funding.
Anyways, jet engines with the thrust to get these craft supersonic have supersonic exhaust and are extremely loud anyways. A jet engine is a standard measurement when discussing/teaching what sound decibels are. A jet engine is way louder than the loudest rock concert. It's usually the loudest thing on such comparitive decibel scales. Even if the aircraft could be made silent, the engine couldn't.
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.
Friends don't help friends install M$ junk.
Please please enlighten me on how reducing loudness = no sonic boom?
Gay. Gay. Gay.
Was it entirely necessary to bring your rebuttal down to a middle-school level, by including that last line?
Win dain a lotica, en vai tu ri silota
That can serve as my wallpaper for a bit.
Your science is crazy!
"If you are a dreamer, a wisher, a liar, A hope-er, a pray-er, a magic bean buyer
...how are people supposed to admire the speed of a plane when there is no sonic boom? All the sensation is lost :(
You know, for some reason or another, the plane reminds me of Richard Nixon.
how loud is a sonic boom? And how much less with this new tech?
Apart from the supersonic Concorde, the fastest commercial way to fly is in a Boeing 747 at around 885 kph - about 85% of the speed of sound. Supersonic flight would get you there very much faster. But everybody thinks that destructive sonic booms are an essential part of supersonic travel. However, there are many factors that influence the loudness of the sonic boom down on the ground. They include the weight, shape and size of the aircraft, as well the plane's altitude, attitude (nose-up or nose-down), flight path and the local weather conditions. Fooling around with some of these could make a supersonic plane acceptably quiet.
For example, back in the 1970s, Richard Seebass from the University of Colorado in Boulder, worked out that you could virtually eliminate the sonic boom by making the nose of the plane blunt. This blunt nose would heat up the air in front of the plane, and would also stretch the bow shock wave out a long way in front of the plane. So there wouldn't be a sudden jump in pressure, that would give the offensive shock wave down on the ground. But H. K Cheng, a retired Aeronautical Engineer formerly with the Department of Aerospace Engineering at the University of Southern California, has a modern Star Wars version of this - it uses a laser to heat up the air in front of the plane.
In 2001, the United States Defence Advanced Research Projects Agency allotted some $70 million to three manufacturers to work out how to make supersonic planes more quiet. The companies (Boeing, Lockheed Martin and Northrop Grumman) are each trying different approaches.
John Morgenstern, an Aeronautical Engineer and expert in sonic booms from the Lockheed Martin Skunk Works in California, has come up with a very neat way of effectively blunting the nose of a plane. His design has a little flap that pushes forward from the nose of the aeroplane. Not only does it stretch out the shock wave coming from the nose, it also creates an extra bit of lift, which cuts the fuel consumption. In 1999, he published a patent with an even more daring design, which has a longer nose and a V-shaped tail.
Domenic Maglieri from Eagle Aerospace in Hampton Virginia has an even wilder design - a supersonic biplane. This would spread the lift over more surface area of wing, and so reduce the sonic boom. Heinz Gerhardt, an aeronautical engineer from Northrop Grumman in Los Angeles likes this idea so much that he has designed a family of supersonic biplanes.
At this stage, all the big companies are keeping quiet. But Gulfstream (which is funding its own research) reckons its supersonic business jet will be flying in around six years time, while the Russian Sukhoi Company reckons their supersonic bizjet will fly in 2010.
And of course, in the backs of their minds, the companies are all thinking of big supersonic jets that can carry a big number of people a big distance, and so generate big bucks. You see, for all of its speed, the Concorde has only a short range, which is fine for flying across the Atlantic, but hopeless for flying across the Pacific or around the Pacific Rim.
The new supersonic designs aim for a maximum overpressure of just 0.3 pounds per square foot.
But as well as new shapes, the new supersonic planes will need radically new engines. The Concorde engine is fine at Mach 2.2, but it's very thirsty and noisy on take-off and landing.
Rolls Royce, on the other hand, has decided to modify the existing giant engine that powers the Boeing 777 with 95,000 pounds of thrust. This enormous engine is bigger in diameter than the body of a Boeing 737. Rolls Royce want to remove the huge fan off the front, and in this form, it should just meet take-off and landing noise requirements.
These supersonic bizjets will still burn up a lot of fuel. But if you can afford a$160 million plane, the cost of a few extra tonnes of fuel will be no worry at all.
So once the supersonic flight industry loses the boom, business should start to bloom.
Now they'll have to use old planes in the movies, or fake the sonic boom through sound fx.
home
now under special conditions the sound waves all pile up making one giant pressure sheer, the shock front.
to the extent that you can disperse the shock front then the boom is indeed disperesed. You have not however eliminated the energy dumped into the air. But the "boom" is gone.
that's what this article is saying I beleive.
The really cool part of this is that its like to old adage about genius taking many steps. first everyone believes that something cannot be done. then some fool shows it might be not be impossible. then a scientist shows it is theoretically possible, and finally some engineer shows how to do it. Then it seems obvious
now that we have crossed the threshold of knowing that its possible to break the sound barrier without a sonic boom we can now get on with wondering if maybe the remaining waves could be modified in other ways, like directing all the sonic energy up and not down, minimizing it or maximally dispersing it. its now on the table.
It reminds me of discovery of negaitve index of refraction or of "optical bullets". At a certain optical power density the plasma of electrons stripped from air creates a non-linear lens that focuses a light beam in both time and space down to a stable optical pulse that neither diffracts nor diverges for macroscopic distances (hundred of meters till it runs out of energy). Now that is pretty weird since if you ask anyone who knows anything about light they will tell you that the two most fundamental proerties of waves propagation in media are dispersion and diffraction. Thus optical bullets are a form of electormagnetic farfield propagation that is not like a light wave. Negative index of refraction destroys another myth that light cant be focused smaller than a wavelength without non-linear methods.
so now we have yet another wave propagation myth falling, that when the speed of an aobject passes the wave speed in the media that a shock front is created.
just to go off on wacky extrapolation for a moment, I will point out that there is a close connection between the idea of a shock front and the idea that faster than light travel is impossible. Perhaps we can disperse that "light cone" and bend time some day.
Some drink at the fountain of knowledge. Others just gargle.
"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.
"How to Do Nothing," kids activities, back in print!
I just travelled back in time to make the parent of your post! Ha.
G5 too fast? just run Bochs and emulate windows.
That's why pelicans are so fast!!!!
You are not the customer.
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.
... my CPU fan? Now that's a silencing challenge that will make money.
"Consensus" in science is _always_ a political construct.
A sonic boom isn't a one time deal when you crack the sound barrier. after you break it, the boom is continous as you fly over the ground. Thus if you travel supersonically over the entire width of texas, then the entire width of texas for that corridor your plane passes over will hear/feel the shockwave.
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Wow, you sure put a lot of effort into that reply. It must burn you to know that Karl S. Kruszelnicki Pty Ltd had the gall to blatantly plagiarise it and copyright it, no less.
It all goes downhill from first post
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...
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
On planes such as the 747, this is offset by the large load of passengers you can carry. In a supersonic jet however, you are limited by the shape of the plane. The concorde carries very few passengers as its fuselage is VERY narrow. At this point in time, its simply much too expensive to fly a fleet of supersonic passenger jets.
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"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."
Or they could use any of the current or still in development aircraft that still produce significant sonic booms.
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 because he left the cloud layer facing a hill slope.
He used the afterburner and broke the sonic wall only a few hunderd meters above a village.
They hadn't got much unbroken windows after that and the church had suffered cracks a few centimeter wide in its ceiling.
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
After reading just the first paragraph I could tell it was taken from somewhere else, no one writes like that in a damn slashdot post. It's always gratifying when someone knows where it came from and links to it though... makes the original poster look like that much more of a fucker. :)
Joseph?
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...
Article says " the loudness of the sonic boom is greatly reduced" (my emphasis), "We were all blown away by the clarity of what we measured", "Comparison of the data confirmed the modified shape of the test aircraft altered the sonic boom as expected" ... and, in case you are thick: "Repeated tests verified these results".
But it never says what the results were! Did it reduce the "loudness" by 10%? 50%? 90%? Using what kind of weighting?
Don't moderate it, if you don't think it's funny, but in any case don't moderate it the wrong way!
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 of the pressure wave.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
Simple. You install a larger diameter fan at lower RPM to move the same CFM with less noise. The big problem inside a computer is how to mount it.
Your description of smoothing out the N is just another way of saying the pressure sheer of the boom is dispersed. which is what I said in other terms.
Kids these days just don't seem to realize that my internet is just as powerful as theirs ;)
If they find something to plagiarize from Google, searching for nearly any unique phrase will find it just as quickly.
It all goes downhill from first post
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.
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 subsonic noise signatures.
IE, the noise the craft generates is self canceled at exactly ground level: Fly higher, and you hear a supersonic rumble, fly lower, and you hear the supersonic rumble; bank, turn, or make any maneuvers, and you hear the supersonic rumble. The rest of the shockwave will necessarily get quieter as it travels farther from the plane such that by the time they reach ground level they are essentially 'quiet'.
GPL Deconstructed
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).
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"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.
Less is more !
The real question here is, how can we turn this into some sort of weapon! Boo-yah!
Proverbs 21:19
Funny you should mention that. When I was a kid I saw the movie Firefox. Briefly, an American agent steals a Soviet Mach 5 plane. While escaping said agent flies low over the ocean, producing such an effect. This article reminded me of this film. I recall, when I saw the spray, thinking "Jeeze Louise, that's friggin' awesome." That's the only part I remember about the movie all these years later. It wasn't so good otherwise. If you don't mind B acting and vintage 1982 special effects though, it may be worth a look.
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
Had sex whenever I wanted it.
Suck it, babydoll...
It seems to me that this is the way that ultrasonic planes should have been built in the first place. The concept is so simple that I knew what the whole article would be about after I read the title of the summary.
The power of Christ compiles you.
A Random Blog
The "N" wave is caused by a high-pressure spike at the nose and a low-pressure spike at the tail. A shorter aircraft would have the two extremes of pressure happening much closer together, increasing the effects of the sonic boom. A longer aircraft such as Concorde results in a small but important delay between the two pressure extremes, to the point that they are usually distinguishable as two separate and somewhat reduced booms instead of one large one.
99, Can we combine this with the "hush" bomb?
I am the unwilling control for my Origin.
You actually CAN remove the supersonic boom, by using what is called "Magnetohydrodynamic". By surrounding an object with a fluid conductor (like a plasma), you can induce movement to an object without making him break the sound barrier, even if it fly way over it. This would be a good explanation of some "UFO" sight (American testing this theory), since plasma gives an multi-colored shape around the object. This could also be used in salted water, to move submarine to unprecedented speed, even more than in the air! You can find some of the experiment and the actual theory if you search for "Jean-Pierre Petit" and magnetohydrodynamic (MHD), and probably many others sites.
Here is the link where you can find information about what I just say before : http://www.jp-petit.com/science/mhd/m_mhd_e/m_mhd_ e.htm
Well, the 767/777 routinely fly as high as 41,000'. Lear and Gulfstream both reach into the mid-50's.
Concorde didn't actually spend much time at 60,000. A typical trans-Atlantic flight would start at 45,000 and then slowly climb as fuel weight was reduced, with only the last hour of supersonic flight above 55,000'. In the first half of any transcontinental flight it would be in the way of quite a few aircraft.
FWIW, the U2 is really the least of Concorde's problems as they generally fly between 65,000 and 70,000', well out of reach of Concorde.
This design will likely have higher drag than traditional supersonic aircraft. The designers cannot get around the fact that the air cannot move out of the way as quickly as the oucoming aircraft passes through it. Its just that instead of all the air piling up into a massive shockwave, it is distributed into a more gradual shock front that will be less perceptible.
The supersonic area rule tells designers how to minimize drag by shaping the profile of cross-sections (creating the right curve to the cross-sectional area). By inference, this invention does not minimize drag because it uses a different-from-optimal profile of cross-sectional areas. High drag = high fuel consumption and that will limit it's application to non-military aircraft.
Two wrongs don't make a right, but three lefts do.
The B-70 prototype was supposed to benefit from "compression lift" and get high lift-to-drag ratios to give it intercontinental range. The B-70 had all (six) engines clustered in a single pod underneath a delta wing, and the outer segments of the delta wing drooped down. The whole thing was supposed to get lift from the resulting shock wave bubble under the aircraft, generated by the engine pod and herded together by the down-drooped wing tips.
The word is that it didn't get the same low drag as the wind tunnel models, and the SST design that followed it didn't seem to go for clustered engines and drooped wing tips to get compression lift. On the other hand, in the high-altitude hypersonic regime you are proposing, various types of "wave riders" have been proposed.
Another concept along the lines you are suggesting came out of Lawrence-Livermore Labs (I guess they are looking for stuff to do with the end of the Cold War) where they went back to Eugen Sanger's idea of atmospheric "skip" -- you would boost something into space with a rocket and then let it skip across the upper atmosphere like a stone sent skimming across a pond. The claim for that was improved energy efficiency (over subsonic travel?), although I wonder if the reentry heating problem is worse when you have these multiple partial reentries, and I wonder how popular these skip trajectories would be with passengers apart from those passengers who want a roller coaster type ride (Vomit Comet anyone?).
Is that how they deliver all the books, then?
Damn, what a cunt. Oh well, at least it was still informative.
CAn'T CompreHend SARcaSm?
I've /used/ magnetohydrodynamics, have you? (Cambridge University Engineering Labs, 1980)
At some point, whatever magical properties the plasma has (not much) it has to move air out of the way of the vehicle+plasma field. At some point, typically directly in front of the plasma bubble the air has to move faster than it can react, so (crudely) it creates a sonic boom.
Even if there were no friction between the air and the bubble it would stll have to move out of the way.
Well, if they are 180 degrees out of phase they could be said to be in antiphase. Personally I think dictionary.com is wrong really.
For instance, if one signal is exactly 90 degrees behind another it is out of phase, but could still be perfectly synchronized, or correlated, or (technically) coherent with the first signal.
Perhaps it depends on the field of use.
IANAABIAANAVE
A=aerodynamicist,B=But, NAVE = noise and vibration engineer
I am a banana.
Can't wait. . .
Hmm, I wonder if you'd still get Peanuts and Coke budget carriers?
GENERAL PUBLIC SIGNATURE (GPS) Any replies (derivatives) of this post must also use the GPS
You can't silence a super-sonic bullet, but you can change the sound coming from the muzzle.
... your out of luck! Bullets spin ... try archery.
As for bullet shape
please tell me you are not so ignorant to honestly wonder why this is a big deal. lol
That isn't what killed the TU-146. It was their inability to get modern digital fuel controls that doomed that plane. The engines were also used on a major Russian bomber and no way in hell did the West plan to help that program.
And, btw, what caused the SST crash at the Paris airshow was the TU-146 pilot having to suddenly dodge a French fighter plane that was playing hide-and-seek in the clouds trying to get some spy photos of the SST. (Why they just didn't go back and use Concorde photos escapes me.) The Russian pilot had been assured that he had clear airspace for 10 miles. Dodging the French plane broke the spine of the TU-146. The French and Russians together covered this up for a long time -- each for their own reasons.
And yes, the French copped to this finally a few years ago.
"It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
Im surprised they let this information out, it seems exactly like the kind of top secret thing the government would want to keep secret.
One of the other non-political problems with polar flight is the fact that cosmic radiation is much stronger at the poles due to the earth's magnetic field. The FAA was worried that this might interfere with navigation and flight control systems.
retrorocket.o not found, launch anyway?
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.
Dewey, you fool! Your decimal system has played right into my hands!
The people who ONLY want to go from NY to LA is a SMALL subset of the people who normally travel between those airports.
And let's not forget the hassles of check-in and such. Thanks to current security measures, even if you "just" want to go from NY to LA, you will probably get their faster if you go to Teterboro from NY and then take a private jet to Sacremento and then take a train/cab to L.A.
retrorocket.o not found, launch anyway?
get there faster, not get "their" faster.
Exactly! Stealth= life for the Air Force. Moreover, the military does not care about fuel consumption -- its only an issue of ensuring a reasonable operating range with a reasonable payload of big cans of whoopass.
Civilian applications are much more fuel economy sensitive - if the airplane is not economical, no airline will buy it. Plus, the more fuel it consumes, the more pollution it dumps into the upper atmosphere, the less likely it will ever be permitted to get off the ground. Noise is not the only reason the SST never made it into production.
Two wrongs don't make a right, but three lefts do.
Your sig:
Loose the type A personality. Become an under-clocker.
Sure... Turn off your CPU fan and you'll get two birds with one stone - nice silent computer, and it'll be waaaay underclocked. ;)
-T
You might get a 747 or 777 up to the mid 30K range, but not much higher than that considering fuel, passengers, and cargo. It's just not going that high. Ask any pilot of an Airbus A330. They'll jump to 39K and stay there to be out of traffic since the Boeings can't make it up there.
Plant a tree in a developing country.