Concorde without the cacophony: NASA thinks it's cracked quiet supersonic flight NASA says the preliminary design review of its Quiet Supersonic Transport (QueSST) project suggests it is possible to create a supersonic aircraft that doesn't produce a sonic boom. We've been able to build supersonic passenger planes for decades, but they're tricky things. Russia's Tupolev Tu-144 proved highly unreliable. …
I'm sure they'll fly it over somewhere deserted first - not least because they need to get confidence that it won't crash into the city! They will also want to measure enough to ensure that the sonic boom/thump is not going to break glass or do other damage. There are lots of windows in a city and breaking even a few percent of them would be very very expensive!
But once they've done that, the real goal has to be to get public support for supersonic travel. To do that they'll want to demonstrate the "sonic thump" to people, by flying over them, so people know what it sounds like and don't have the fear of the unknown that was a problem for Concorde. They will also want to be able to say to regulators and the press that they have really flown over real US cities without problems (no broken glass, no excessive complaints, etc).
Also note that the impact of a sonic boom on a city is going to be different from a cornfield - there are buildings to block or reflect the sound, and there's a higher level of background noise.
...."But once they've done that, the real goal has to be to get public support for supersonic travel. To do that they'll want to demonstrate the "sonic thump" to people, by flying over them, so people know what it sounds like and don't have the fear of the unknown that was a problem for Concorde."...
The only reason Concorde wasn't certified to fly over the mainland United States is because it wasn't built by an American company; had it been built by Boeing or MacDonald Douglas it would have had no trouble getting cerification.
The only reason Concorde wasn't certified to fly over the mainland United States is because it wasn't built by an American company
and of course the only reason it got to fly into Washington at all was that despite of
Even when flying below the speed of sound, it was often noisier than always-subsonic aircraft
It was quieter than the President's jet, so they couldn't ban it without also banning El'Presidenty
"It was quieter than the President's jet, so they couldn't ban it without also banning El'Presidenty"
Well, that's certainly within the realms of possibility. The original article states:
"Even when flying below the speed of sound, it was often noisier than always-subsonic aircraft and generated plenty of complaints around airports, [...]"
Noise complaints were certainly made about Concorde, yes - but the truth is that Concorde wasn't a serious noise problem on take off or landing when it first came into service: Concorde proved itself quieter than much of the subsonic competition.
The thing about airliners back when Concorde came into service is that an awful lot of them were very noisy. Notwithstanding that, the Concorde people knew perfectly well that they were going to have an issue with noise, so they developed methods of managing speed, altitude, and throttle on take-off and landing to mitigate the noise experienced by populations on the ground near airports.
The procedures are described in the Concorde Haynes manual, pages 113 and 114, if you want to read up on it.
The result was that Concorde was, as far as airport neighbours were concerned, quieter than many airliners when it came into service. The Haynes book says in the context of take off:
"Concorde was [...] quieter, certainly, than a number of aircraft then in service including the [Boeing] 707 and 727"
The Wikipedia Concorde article states:
"In 1971, BAC's technical director was quoted as saying, "It is certain on present evidence and calculations that in the airport context, production Concordes will be no worse than aircraft now in service and will in fact be better than many of them."
"In spite of complaints about noise, the noise report noted that Air Force One, at the time a Boeing VC-137 [derived from the Boeing 707], was louder than Concorde at subsonic speeds and during take-off and landing [...]"
Of course, once Concorde operations proved quieter than typical subsonic airliner operations near airports at least (there's not much you can say to excuse the sonic boom), the subsonic laddies had to follow suit and aim for lower noise themselves - first by adapting Concorde's reduced noise departure and landing procedures, and then by developing inherently quieter designs; so by the time Concorde left service, it was indeed comparatively noisy on take off and landing - but it was never as bad as its harshest critics claimed.
The Haynes book says "One result of the Concorde noise abatement procedure was that other aircraft were forced to tighten up theirs, because ours was producing less noise. Therefore, Concorde made New York a little quieter!"
When Concorde flew overhead you knew it was Concorde - certainly by the 1990s it was much, much louder than anything else in the sky as it descended over SE London on its way to Heathrow. It was a regular sight when I lived there and sounded like a real monster. Nothing else came close.
Now I live in rural France. Occasionally French air force jets have flown over at supersonic speeds. You know they're supersonic because the impact on the house, while it's never broken windows, feels like an oil tanker must have crashed into the living room at speed. It's truly terrifying.
Wouldn't it make more sense to fly it over Kansas cornfields first?
A supersonic test over inhabited areas is done less for the physics and more to quantify the legal aspects of the aircraft, i.e., how many lawsuits and insurance claims a "sonic thump" generates. See Operation Bongo II, a 1964 equivalent test series.
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That's what I thought. I don't wish to be personal, but your aeroplane has a big nose. A really honking great hooter. A positively protuberant proboscis.
Why it almost reminds me of this kids TV classic.
Yes.
The downside of such cargo is that it places a minimum size on the whole vehicle, and with that form factor it's going to be biiiig.
Concorde, at 100 seats, was finally accepted by the French as the minimum size for an SST. Most people who've looked at this since have said you need at least 300 passengers (plus baggage) to make this viable. You also need a minimum range from day one of roughly Frankfurt to New York.
One interesting idea is that the maximum use temperature of plastics has been gradually rising. In principle CFC would be viable up to about 250C today. Likewise stainless steel could be an option up to 300c with laser welding or diffusion bonding.
By the time this actually gets off the ground, I wouldn't think it would be flown by humans at all! Turn around time on a new commercial airliner can be a couple of decades. The Airbus A380 took first flight in 2005. Design began seventeen years before in 1988. And we've still only built about two-hundred of them.
This isn't even an actual plane design, is it? If a real plane based on these ideas launches in 2037, I can well imagine you wont need a pilot at all let alone need to fly it visually!
Concorde could dip the nose down so the pilot could see the ground during landing. Does anyone know why they didn't add a window near the pilot's feet?
(This project hit the news over a year ago. It probably started well before that so a chunk of development time has already happened.)
I practice in my back yard with subsonic .22s, and .45ACP. However, nearly all ammunition is supersonic unless specifically loaded as subsonic. Even using Remington Subsonic ammo (1050 fps), fired from a 24 inch barrel, you'll hear the supersonic (1100+ fps) crack on occasion.
Actually IIRC the very early work on development shaping was done using bullets.
Essentially firing differently shaped bullets to get a rough idea of what (at the same mass) sounded quieter.
Obviously you needed a reload bench to do this but that's still pretty cheap compared to a supersonic wind tunnel.
They should do a tie-in with Reaction Engines:- bolt on a couple of their Sabre engines, and you've got a very high speed, very high altitude passenger jet, which will hopefully be allowed to cross above most major land masses and therefore link all major airports. No need to go orbital. The US and UK could come to an agreement on sharing the engineering work. We'll have to call the jet something like "arrangement", or "treaty"...
Look further. Up and back.
Ben Bova, Asimov, Clarke, Lemm had this figured out.
Increasing the speed of an aircraft is diminishing returns. The true solution for high speed travel beyond 3000 km or thereabouts is going ballistic via suborbital trajectory.
The main issue there is not so much technology. Wwe are going in that direction with Space X and ReactionEngines and will be there in a couple of decades well before quiet supersonic aircraft is productized. It is the fact that with the current level of paranoya and militarization nobody will allow you to lob a payload the size of an airliner cabin on a ballistic suborbital trajectory to LA, NY, Moscow or Berlin.
More precisely it was due to the use of reheat for take-off (or "afterburners" as the Yanks call it) which is normally only used by the military since (1) it is fuel-inefficient and (2) it is damn noisy.
More detailed reason is you get more thrust from heating the existing mass-flow of engine exhaust to increase the speed and hence the momentum-rate. Down side is noise is approximately related to the 8th power of exhaust speed so 25% extra thrust comes with about 6000% extra noise.
A major reason why most modern aircraft are cheaper to fly and quieter is the use of the wide "high bypass" engines where much of the thrust comes from a large volume of air at lower speed from the part that goes past the actual engine.
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"high bypass" engines where much of the thrust comes from a large volume of air at lower speed from the part that goes past the actual engine
They'll have a huge challenge making supersonic capable engines anything near compliant with current noise rules for aircraft design. As proven by Concorde, there's a small, high wealth customer base willing to pay the high fuel and operating cost of an SST, but I suspect that there's no economic case when the development costs are combined with the small passenger numbers. And because fuel consumption and costs will always be high, it will be impossible to take the technology into the mainstream, and then recover development costs across a much greater production volume.
Sadly, I think this is a rich man's toy, and it is sad to see NASA wanting to spend taxpayer's money on a technology that will only ever benefit the ultra wealthy. Britain and France did this, and funnily enough seem in no hurry to repeat the adventure. If Boeing (or Musk, or Branson) wanted to develop their own aircraft at their own risk and cost, that's different. Evidently NASA haven't realised that The UK and France don't appear to be in a hurry to repeat the experiment.
I disagree that they wouldn't take a chance. The A380 has lost money on every unit. It may break even per unit but the total program is a huge loss. The 787 is $33 billion in the hole so far. Taking a chance on an innovative plane that addresses an untapped market (getting somewhere a hell of a lot faster) might be interesting to Boeing and Airbus since other than 737s and A320s they haven't a lot of new ideas in the pipe. [The 797 is simply a 757/767 replacement that has a narrow market segment with 737 MAX10 and A321 encroaching in the medium single aisle category and 787, et al right above it in wide body.]
They both need a new winner.
Your points about reheat are true, but it was still a noisy bugger without it. I remember it sitting in the Heathrow queue a few times (normally they had priority, but sometimes they got stuck in it) over south London. From Hyde Park it was still loud enough to make everyone notice.
"A major reason why most modern aircraft are cheaper to fly and quieter is the use of the wide "high bypass" engines where much of the thrust comes from a large volume of air at lower speed from the part that goes past the actual engine."
Yes, it will be tough to fit high bypass with large frontal intake into a slippery supersonic shape, I think Concorde Olympus was pure turbojet.
The subsonic noise of Concorde during take off and climb went on for a while and is a greater problem than the very quick b-boom from the supersonic pressure wave.
So fixing the boom is only part of the problem, if the aircraft must maintain a slippery shape.
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