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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."
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
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.
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
They're not modifying the shape in flight. So all you'd need is a modified bullet before you fired it.
But you'd probably run into many problems, hence they haven't done it?
Also, I'm not clear on this, but I suspect a silencer would slow a bullet enough that it wouldn't be supersonic, so that wouldn't be viable.
Plus using a coke bottle filled with anything to silence a gun would probably result in it exploding, most cobbled together silencers do so.
This was also covered in Flight International (subscribers - I read the paper version in the library), in a bit more depth. The classic sonic boom was described as "N-shaped" and gives a crack-crack effect. This modified it to more of a "table-top", and was said to sound like a long rumble.
Consciousness is an illusion caused by an excess of self consciousness.
I don't think Boeing worried at all about the Russian programme. The Russians were not about the buy Boeing planes, nor were about to sell SST to American carriers for the NY-LA route. Boeing's only worry was the English/French Concorde concertium (sp?).
"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!
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.
What you need is one of these http://world.guns.ru/sniper/sn20-e.htm
I believe it can also use silenced ammunition
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
Quite possibly, fluid dynamics applies to both liquids and gasses.
0x0D 0x0A
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.
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.
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