Supersonic Flight Without The Sonic Boom 311
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."
What does... (Score:5, Funny)
Where's the Earth Shattering Kaboom!?!? (Score:5, Funny)
Re:Where's the Earth Shattering Kaboom!?!? (Score:4, Funny)
Re:Where's the Earth Shattering Kaboom!?!? (Score:3, Informative)
Re:Where's the Earth Shattering Kaboom!?!? (Score:2, Funny)
Bill
Summary misleading (Score:5, Informative)
Re:Summary misleading (Score:4, Insightful)
Re:Summary misleading (Score:3, Informative)
At best, this will allow corporate execs to travel in small jets supersonically as they'll be the only ones who can afford it.
Proud day for you and your family! (Score:4, Funny)
It doesn't elimanate the boom... (Score:5, Interesting)
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...)
offtopic: gay (Score:4, Insightful)
Gay. Gay. Gay.
Was it entirely necessary to bring your rebuttal down to a middle-school level, by including that last line?
Re:offtopic: gay (Score:3, Funny)
Nope, didn't work.
Discovery Wings channel show touches on this (Score:5, Informative)
Guns? (Score:3, Funny)
Re:Guns? (Score:2)
Re:Guns? (Score:2, Interesting)
Re:Guns? (Score:2)
Concord (Score:2)
no. (Score:5, Insightful)
You don't need to throw it out, it just needs a nose job. Witness:
Honk, honk!
You only want to throw the thing out when maintaining it costs more than developing and buying a new one. While it might be hard to modify the concord's swiveling nose this way, it's worth looking into.
The next modification needed is to the law, so that flights that don't make too much noise can fly over the contenetal US. If you can get from New York to California supersonically, people will want to do it and will pay for the above mentioned development and building.
Re:no. (Score:2)
Re:no. (Score:5, Informative)
Re:no. (Score:2)
And if we can build planes that go fast enough, the average flier will spend less time in the air than waiting in line for pointless intrusive security checks. Now that's progress!
Re:Concord (Score:4, Informative)
For starters, you don't have to "throw out" the Concorde as BA/AF are doing that for you. They even refused to sell one to Virgin Airways as Branson might find a way to make the flight profitable and would thereby kill BA/AF's hopes of pushing all of the Concorde folks into the 747 first class section.
There are two other reasons why you won't see the Concorde flying supersonic over the continental USA, with or without a sonic boom:
1) There are far too many other slow aircraft flying at or near Concorde altitudes. Considering the fuel costs involved in getting to supersonic speeds (max drag between 0.97M and 1.4M), the economics of trans-continental supersonic flight would require sterile airspace for end-to-end clearance. The lobby group for bizjet owners would never let that happen at their expense.
2) Even a reduced shock wave will have destructive powers if the aircraft is required to turn at supersonic speeds - the waves on the inside of the turn are concentrated toward a single point at which the N-wave would be amplified to an unacceptable level. Although it would be possible to structure straight-line routes between city pairs, the odds are pretty good that the flight would be unmanageable in terms of communication and coordination among ATC units.
Re:Concord vs. U2, G5, Lr55 (Score:3, Informative)
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 f
Re:Concord (Score:4, Informative)
That's because you fly commercial like me, prole. OTOH, Gulfstreams and other long range bizjets cruise in the 50k' range. Check out 'specifications' at thus URL: http://www.gulfstream.com/g550/
And while the Concorde ends its flight at 60K, it starts at 50 and gradually climbs as the weight of used fuel is lost. So not only is it ripping along at high speed but also constantly changing altitude. Not the kind of wild behavior you want over the continental US where there are a lot of the aforementioned bizjets puttering around at less than half the speed.
Real Estate Bargains (Score:3, Funny)
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.
Re:Real Estate Bargains (Score:4, Insightful)
SST possibilities (Score:3, Insightful)
But, this could be great for supersonic transports if the design technolgy is used in future designs. It would mean that we could have supersonic flights from NY to LA lasting only a couple hours! If the noise was reduced enough, the FAA would let them fly over populated areas (like the continental US)
Yes, but how? (Score:2, Interesting)
But then again, it is a government project, can't expect much in the way of information.
___________
Re:Yes, but how? (Score:5, Informative)
Watercraft (Score:5, Interesting)
Judging from the picture, the design borrows heavily from that of watercraft. The bottom of the aircraft has been modified to the point that it resembles the hull of a boat of personal watercraft.
I suspect that it works very similarly to the way that planing hulls(no pun intended) work. Just as a boat's hull spreads its wake outwards from the sides of the hull, this aircraft design likely spreads the aircraft's wake out to the sides more than straight down. This would reduce the pressure wave below the aircraft. I am confident that if the sonic boom was measured from the side on the same plane with the aircrafts altitude the sonic boom would be the same as normal and possibly more intense.
Re:Watercraft (Score:3, Interesting)
Judging from the picture, the design borrows heavily from that of watercraft. The bottom of the aircraft has been modified to the point that it resembles the hull of a boat of personal watercraft.
Out of curiosity, does anyone know what speeds aircraft could see supercavitation at? I mean, given fluid dynamic apply to both air and water, shouldn't it be possible for planes as well as submarines? Anyone know what that would do to the shape/strength of a sonic boom?
Re:Watercraft (Score:3, Interesting)
Water is not elastic - low pressure regions cause the waster to cavitate (vaporise), thereby reducing drag. Air is elastic, and AfAIK cant cavitate.
must be (Score:2, Funny)
Rejected (Score:4, Informative)
Northrop [northgrum.com], working with the Pentagon [defenselink.mil] and NASA [nasa.gov] sucessfully tested a "quiet" supersonic flight [cnn.com] wednesday at California's Edwards Air Force Base [af.mil]. In the tests, an F-5E aircraft [primezone.com] with a modified nose section flew supersonically through the test range, shortly thereafter, an unmodified F-5E [af.mil] flew supersonically through the same airspace, with the sensors showing a clear reduction in the intensity of the sonic boom produced by the F-5E modified fuselage [primezone.com].
Re:Rejected (Score:2)
Jesus, shame on you.
Re:Rejected (Score:2)
Re:Rejected (Score:2)
Basic English, people. =)
Re:Rejected (Score:2)
Sure, but you only submitted one with links from NASA, the Pentagon, and a military contractor. I mean, if you aren't going to take the time to submit it with a real and reputable source linked, like Spaceflight Now, then how can we take you seriously?!?
Sheesh! Some people expect too much.
-Tom
Re:Rejected (Score:2)
It will be rejected again (Score:2)
It doesn't matter, a geek forum or a fortune-500. People are the same. They love their friends. No matter that it may sacrafice the quality of their business.
Old science (Score:3, Informative)
Re:Old science (Score:5, Informative)
The examples are ATF, Eurofighter, Viggen, Suhoy S27 and later, so on so forth. All of these have shapes designed specifically to split the shockwave into a series of shockwaves to improve lift and maneuvrability at hypersonic speeds. As a result the noise is muffled as a side effect. From there to muffling it completely is just one step.
In btw, I am glad that it was done on the F5. It is the only US bird that has some resemblance of grace and beauty in the air.
hmmm.... (Score:2, Offtopic)
/. Sensationalism? (Score:5, Funny)
"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
Re:/. Sensationalism? (Score:2)
Eliminate sonic 'boom' (Score:2)
If you can manipulate the shockwaves and bowfronts trailing a plane in such a way that they interfere, essentially producing low energy zones at the appropriate distance, and then redirect the rest of the sonic energy to disperse and spread out along a larger surface area and upwards into empty space, you can create supersonic craft with subso
Re:/. Sensationalism? (Score:3, Funny)
Fans (Score:2, Offtopic)
Long time comming (Score:5, Interesting)
In numbers... (Score:2)
Re:In numbers... (Score:2)
2) Well, according to the Northrop Grumman site [northgrum.com], they used sensors to measure the difference in loudness and they hoped that with further study, they could "produce a noticeably quieter sonic boom." Therefore, I'm guessing it wasn't reduced by a large factor, but the very fact that they *can* reduce it via aircraft design is rather significant.
dont want to post again... (Score:2)
It is LOUD. Its not like the long fading sound a subsonic jet creates, but a short "hit" of sound, like a gunshot, but with lower frequences.
Thing of a bomb detonating 200 meters away or a single bass beat from love-parade class speakers inserted into silence.
A story i cannot verify is that in the early 80s a pair of tornados practives ultra low altitude "vallay crawling" and something went wrong.
One pilot needed to gain altitude fast beca
No QUANTITATIVE information at all. (Score:4, Informative)
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.
Wow! (Score:2)
Fuel Efficiency (Score:5, Interesting)
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.
Fine. Silence a plane but what about ... (Score:3, Funny)
Re:Fine. Silence a plane but what about ... (Score:2)
Sonic boom in reality... (Score:5, Interesting)
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...
Corrections (Score:2)
Military advantages (Score:2)
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...
If you want to see a sonic boom (Score:5, Interesting)
Re:If you want to see a sonic boom (Score:3)
Here [apk.net] you go.
hey... (Score:3, Interesting)
It doesn't remove boom/New Scientist covered this (Score:5, Informative)
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).
Quantifying the reduction in the sonic boom (Score:4, Informative)
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
I found a flaw (Score:4, Funny)
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.
Re:Why? (Score:4, Insightful)
Besides, would you want your military aircraft alerting everyone for miles of your presence?
Re:Why? (Score:5, Insightful)
Oh, and there are likely military applications, as well. Anything to reduce chances of someone hearing you coming can help (although, most times, these planes take off far from their mission).
Re:Why? (Score:3, Insightful)
Hmmm, I think the likelyhood of someone hearing you coming is already pretty small IF YOU'RE TRAVELLING FASTER THAN THE SPEED OF SOUND.
booms are continuous (Score:3, Informative)
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.
Re:Why? (Score:3, Informative)
"They foresaw a way to solve the sonic boom problem, and to enable a generation of supersonic aircraft that do not disturb people on the ground."
Re:Why? (Score:2, Informative)
First paragraph:
Re:Why? (Score:4, Informative)
if a SST can go supersonic without the boom, then development of new craft could take place, because new markets could open up...
Re:Why? (Score:5, Interesting)
The big barrier to SST success has always been economics. It's incredibly expensive to fly faster than sound. Boeing had a quite successful SST program, but cancelled it when it became clear that SSTs would not be economical. Concorde never made money for either of its parent airlines, despite the incredibly expensive tickets for the flights for which it made any sense at all.
Re:Why? (Score:3, Informative)
Your logic is refuted by the fact that Concorde was in service for almost 30 years -- it carried its first passengers in 1976. The technical failures of the Russian project have no bearing on Concorde.
in fact the original poster has a good point. Concorde failed to flourish economically largely because the US authorities refused it pe
Re:Why? (Score:2)
I suggest that it was because the Concorde was a fuel-guzzling white elephant.
Re:Why? (Score:3, Insightful)
I'll give you a hint. What else travels supersonically and flies over the pole?
Give up? [fas.org]
No commercial flights went over the pole until 2000 [cnn.com].
Re:Why? (Score:3, Informative)
No, not even close. Try 1954 [boeing.com]. I know I've seen on TV why they stopped but I cannot find the reason now. Fear of ballistic missiles or bombers doesn't fly (pardon the pun) since telling missiles bombers and civilian airplanes apart was the main reason there even is a NORAD. It was their main operational task. Even built huge analog machines, complete with PPI:s and light pens in the fifties to cope with the burden.
Re:Why? What REALLY Killed the TU-146 (Score:3, Informative)
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 p
Re:Why? (Score:5, Interesting)
Getting 1/4 of the MPG per passenger compared to a subsonic plane also had something to do with it. The extra cost for fuel alone is going to double the price of most airline tickets.
That means you're in a niche market, which reduces the number of customers and impacts economy of scale. This increases maintenence costs and R&D and manufacturing overhead to very high levels. That's how you get $10,000 one-way fares across the Atlantic on the Concorde.
To compound the problem, most domestic flights just aren't that long. If you take a 1500-mile trip that needs a connection (as many do with the hub-and-spoke system), it can easily take you 9 hours to get from your home to your destination address, and only about 3 of those hours is in the air. An SST would cut that trip down to 7-1/2 or 8 hours at the cost of 4X the fuel usage. It just doesn't make any sense on the vast majority of flights.
Re:Why? (Score:2)
Re:Why? (Score:3, Insightful)
People who would pay this price are already saving more time end-to-end than an SST airliner would save. They do it by flying private business jets on their own schedule between small airports which are uncongested and near their destinations.
Re:Why? (Score:2)
not terribly likely for awhile (Score:2)
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
Re:Why? (Score:5, Informative)
This is important because the main reason super sonic airplanes are not used more often for civils is because of the sonic boom. The sonic booms can be very loud and disturbs urban areas. The Concord, for example, had to wait to be very far away from populated areas before getting into super sonic speeds. This rwas costly, since the Concord was design to have optimal fuel efficiency at super sonic speeds.
Re:Why? (Score:3, Informative)
Very LOUD? (Score:4, Interesting)
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.
Re:Why? (Score:2)
1.) Military people can have fast jest (read "attack planes") that don't alert the person on the ground (read "those who aren't killed by the bomb that will be dropped on them") as to whether there is a jet above them.
2.) One of the biggest problems with commercial super-sonic airlines is that people didn't want them flying over their house (the major reason such flights were primarily only over the Atlantic Ocean). If the sonic boom didn't
Re:Why? (Score:2)
Yes, it's called "having a control". They measured them both to see the difference. It's common sense.
Re:Why? (Score:5, Informative)
What the article doesn't say, but was reported in Aviation Week a few weeks ago, is that this technique (and certainly this airplane) only reduces sonic booms -- it doesn't eliminate them. This demonstration is to show people that the math is right; that the sonic booms can be reduced through shaping. It is still unclear whether it is possible to build a practical airplane with a tolerable (negligible) sonic boom. Perhaps this could be combined with other techniques (the Russians have been working with exciting a plasma in front of the airplane, for instance) and together you could get a minimal boom.
Probably the parent article was questioning the need for supersonic travel at all -- whether it's worth the cost. It will almost certainly be less fuel efficient than subsonic travel. Travel in general is less fuel efficient than staying home. Living is less fuel efficient than dying.
thad
Re:Why? (Score:3, Insightful)
Re:Why? (Score:5, Funny)
What!? I've been getting about 120ms average.
Re:Why? (Score:3, Informative)
The engines that the Concord used where turbojets not the turbofans that airliners use now. To make matters worse the Concord used afterburners for take off. The amount of noise that that an afterburning tubojet makes compaired to tubofan of the same thurst is huge.
To not make a sonic boom over land is easy. Just do not fly supersonic. THe trick is to make an engine that is efficent at supersonic and subsonic speeds and that d
Re:Now *that* is one ugly aircraft (Score:2)
My sister, I thought it looked like a boat...
Re:Now *that* is one ugly aircraft (Score:2)
A Naval Architect once told me that the speed of a boat is limited not by its motor so much as by it's hull length. This had somet
Yes it does prevent the boom. time travel too! (Score:5, Interesting)
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.
Re:Yes it does prevent the boom. time travel too! (Score:2)
Or maybe modulating it? How much would Intel pay to have the sound pressure waves reproduce their jingle as the airplanes fly by?
Re: Blatant Plagiarism Whore (Score:4, Informative)
Wow, you sure put a lot of effort into that reply. It must burn you to know that Karl S. Kruszelnicki Pty Ltd [abc.net.au] had the gall to blatantly plagiarise it and copyright it, no less.
Re:Google, my friend :) (Score:2)
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 [google.com] will find it just as quickly.