Slashdot Mirror
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."
What does Guile think about these developments?
Never lived near an airbase, eh?
Besides, would you want your military aircraft alerting everyone for miles of your presence?
It makes it more practical to have supersonic travel in and around cities, which are notoriously noise sensitive. In the past, the routes for such planes were quite limited. Now, if the cost drops, perhaps we'll see them more in the mainstream.
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).
There's supposed to an Earth shattering kaboom?!?!
evidently, you can't read...
"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."
It seems it merely muffles the sonic boom. The technology doesn't completely silence it.
First paragraph:
My Karma: ran over your Dogma
StrawberryFrog
It is felt that the SST movement (i.e. concorde) was derailed by the american plane maker (i.e. Boeing) which got enough lawmakers to say that the concorde could not fly over the USA (i.e NY to LA) because of the sonic boom.
if a SST can go supersonic without the boom, then development of new craft could take place, because new markets could open up...
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.
"There is no teacher but the enemy."-Mazer Rackham
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.
The reason to do this is to allow supersonic transports to fly over inhabited areas. The sonic boom from the Concorde, for example, is shockingly loud, it would never be tolerated.
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
I love Mondays. On a Monday, anything is possible.
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.
> Just think. Los Angeles to New York in 3 hours.
What!? I've been getting about 120ms average.
The unofficial
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)
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."
Uhh...no. Your story is refuted by the fact that the Russian program (which would have suffered none of the enivronmental concerns of the Boeing and Concorde efforts) failed as well, despite being hugely helped by data stolen from the Concorde's testing. The Russian SST died when their test plane crashed horribly at the Paris Air Show. Despite the Russian air fleet's total lack of interest in passenger safety, the Air Ministry decided to kill the project.
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.
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...
The Concorde was also removed from service because of its limited availability, due to ticket costs, its aging fleet, and its travelling through the Ozone layer. The first two would have to be fixed before SSTs became mainstream aircraft.
More than enough BS
Not every technical advancement needs to be in better energy conversation. This will greatly help with noise pollution and lead to faster commercial plains in the future. Running a subsonic airplane will on the average will use less fuel then an supersonic one and supersonic plains will increase air pollution. But at least it is not making every bison in the midwest going deaf after a bunch of booms that break their eardrums. Sometimes the need for speed is more important then fuel consumption. (Think about an ability to quickly transport a Heart of Liver from a downer in CA to NY much quicker. Heck if I was that Guy In NY I would love to have it flying to me at supersonic speeds compared to subsonic.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
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.
Anything to reduce chances of someone hearing you coming can help
Hmmm, I think the likelyhood of someone hearing you coming is already pretty small IF YOU'RE TRAVELLING FASTER THAN THE SPEED OF SOUND.
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.
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
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.
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.
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
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!
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.
Your story is refuted by the fact that the Russian program (which would have suffered none of the enivronmental concerns of the Boeing and Concorde efforts) failed as wel
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 permission to fly supersonically over the continental USA. That meant it was automatically excluded from the longer routes, such as London-LA, where the timne difference from supersonic speeds would have made a revolution in business travel possible.
Even on regular jets it's possible to make it to NY and back on business in 24hr (leave London 9am, arrive NY around 11am, afternoon meeting, leave NY 10pm, arrive London 9am...) Concorde's extra speed on that route is basically just adding convenience and glamour. But London-LA in 3 hours instead of 10 would revolutionise business travel between Europe and the west coast. That's what BA and Air France were counting on to make the numbers work. Another result of the FAA ban on supersonic travel was that US airlines, naturally, would never buy the airline.
So basically, the FAA ban on supersonic travel in the US meant that Concorde was barred from its most profitable routes, and so was unattractive to most airlines. That's why it never made any money, either for its makers or for BA and Air France. And there's little doubt that the FAA ban -- while partly based on genuine concerns about noise -- was also in part a response to protect the US aircraft industry.
It's just ironic that the long-term effects of this strategy were to kill of Boeing's Sonic Cruiser, which it had pinned its hopes on as the airplane to beat Airbus (the descendant of the consortium that built Concorde). As a result, Boeing is reduced to relying on the 747 -- first flown in 1969 -- to compete with Airbus's new superjumbo.
The author of this post asserts his moral rights.
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.
-
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?
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.
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.
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.
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!"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
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.
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
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.
Most planes I fly on cruise at about 35000'
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.
The Concords noise problems had more to do with takeoff and not supersonic flight.
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 does not make too much moise or pollute too much.
Good luck.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
The great circle route from Seattle to London passes over the North Pole, and need never cross land. Why didn't Concorde ever fly that route?
I'll give you a hint. What else travels supersonically and flies over the pole?
Give up?
No commercial flights went over the pole until 2000.
A legparnasom tele van angolnaval.
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."
No, not even close. Try 1954. 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.
Stefan Axelsson
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!
Eeep. I sure hope no Concorde flight I'm ever on ends at 60K. I prefer my flights to end on the ground, preferably at an airport!
-T