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| The main reason supersonic flight is dead is the sonic boom Is it? The Concorde would fly at subsonic speeds over land and move to supersonic over the Atlant

by af78 2y ago

| The main reason supersonic flight is dead is the sonic boom Is it? The Concorde would fly at subsonic speeds over land and move to supersonic over the Atlantic. Given the reduced flight time at supersonic speeds I thought economic considerations prevailed.

rsynnott 2y ago
The sonic boom made Concorde's economics harder, but they'd have been hard anyway. It confined it to largely only being useful for that transatlantic route, and that was borderline economically viable for airlines. However, as there was really only one route where it was useful, there were not many Concordes flying and the fixed costs were considerable. Eventually Airbus pulled the plug, and ended maintenance, and that was the end of that. It was probably spurred on by a high-profile disaster, but even without that, the writing was on the wall; if you were an airline Concorde looked economically viable, but without subsidy by the state or by Airbus or both, it never had been. In a world where there had been many viable Concorde routes, this could all have worked out a lot differently, Concorde B might have happened (which would have allowed a Pacific crossing), and maybe we'd still see supersonic airliners.
- lstodd 2y ago
  This I agree with. There were not enough viable routes. Same thing happened with TU-144 - no destinations.
  - twelve40 2y ago
    Sad for both. Saw Concorde at Le Bourget. Both were miracles of engineering in their day.
- filereaper 2y ago
  Genuinely trying to understand. Didn't the SR71 fly between LA and NY at above supersonic speeds? Don't military jets fly at supersonic speeds above land? What makes this allowable in terms of sonic booms? Is it that they're much smaller and the their booms don't cause as much of a "wake" on the ground?
  - adgjlsfhk1 2y ago
    a couple things: 1. smaller lighter, and higher flying reduce the sonic boom size 2. way fewer planes 3. the military gets some latitude to ignore the rules that everyone else has to follow
  - twelve40 2y ago
    smaller, and SR71 could cruise at 85000 feet
  - rsynnott 2y ago
    > Didn't the SR71 fly between LA and NY at above supersonic speeds? Don't military jets fly at supersonic speeds above land? I think not routinely in either case? Most supersonic aircraft can't actually sustain supersonic speeds for a significant period; the Concorde and Tu-144 are, as far as I know, the only aircraft ever designed with supersonic flight as the effective _default_ mode of operation. For both planes, _getting_ to supersonic was rather expensive, and required the use of afterburners, so an ideal flight profile would involve ramping up to supersonic once, and then staying that way for the rest of the flight. The SR71 was, unusually, _capable_ of sustained long-range supersonic flight, but I can't imagine it was routinely used above land when not actually on missions; why would it be?
    - ceejayoz 2y ago
      The F-22 can also cruise at supersonic speeds without afterburners. https://en.wikipedia.org/wiki/Supercruise https://en.wikipedia.org/wiki/Supercruise.
      - rsynnott 2y ago
        _Can_, but does it routinely outside of training/deployment situations? Like if you're just moving one from one side of the US to the other, you're probably going subsonic.
    - kube-system 2y ago
      > The SR71 was, unusually, _capable_ of sustained long-range supersonic flight, but I can't imagine it was routinely used above land when not actually on missions; why would it be? Everything a military plane does is a mission, and the SR-71 absolutely did supersonic training missions over the US. And as I understand, the military can and still does do supersonic training missions over land, but they do it at higher altitudes and in locations where it isn't disruptive to population centers.
- dghughes 2y ago
  >The sonic boom made Concorde's economics harder... I live in south-east Canada in the province of PEI and I hope no supersonic aircraft are made. Right now all commercial air traffic from NA flies right over my house. Especially every evening the rumble of high flying jets can he heard. It's not loud but it's certainly noticeable for something 10,000m above me.
- kitd 2y ago
  Even without the sonic boom, it was painfully loud on takeoff and final approach. It used to fly over us near Heathrow and the ground would shake as it went over at a few thousand feet.
  - rsynnott 2y ago
    Concorde B, apparently, would’ve fixed that (though not the sonic boom, of course).
    - bobthepanda 2y ago
      Concorde B allowed a Pacific crossing in a technical sense, if you did a technical stop in Anchorage or Honolulu. And then only to Japan, but not to Korea or China. In the 90s and 2000s you would have had 747s and a340s doing that nonstop without Anchorage or Honolulu, so if anything that would have made concorde B have an even shorter shelf life.
lstodd 2y ago
Green and nimby bullshit as usual. I lived at a summer home in 80s which was near a (soviet) air force base for many summers, and listened to sonic booms daily. In no way it was even disturbing.
jjk166 2y ago
It's a little more complicated then that. The main impetus for the development of the Concorde was actually fuel efficiency - once you get high enough above the sound barrier supersonic flight is more fuel efficient than subsonic flight, all else being equal. Back in the 50s, as fuel costs became more and more of a concern for airlines, this seemed like the obvious future: you get your passengers to their destinations faster, you spend less on fuel, and you can make more flights per day. So Super Sonic Transports (SSTs) looked great on paper. SSTs need to use turbojet engines, which all passenger jets in the 50s were using anyways. But shortly after Concorde's design was locked in high bypass turbofan engines were developed whose fuel efficiency was way higher than turbojets, and indeed much higher than the jump to supersonic flight could achieve. Now it was a choice between speed and fuel efficiency. This really could have gone either way, but when Boeing got out of the SST game they lobbied for overland supersonic flight to be restricted because of sonic booms, which eliminated the potential domestic market. Concorde was reduced from the future of air travel to an offshoot for a niche market. Still it was profitable. People were willing to pay a premium for faster travel, it just wasn't a big enough success to warrant further development. The aircraft aged, unable to take advantage of many of the improvements that came to subsonic jets, and there was no replacement in sight. The Concorde was increasingly expensive to operate compared to more modern aircraft, not because of fuel but because of maintenance and staffing. Between a high profile Concorde crash in 2000, then the reduction in aircraft travel after 9/11, and the security increases which essentially tacked on 2 hours to every trip by air, the Concorde ceased to be viable.

by af78 2y ago

rsynnott 2y ago

The sonic boom made Concorde's economics harder, but they'd have been hard anyway. It confined it to largely only being useful for that transatlantic route, and that was borderline economically viable for airlines. However, as there was really only one route where it was useful, there were not many Concordes flying and the fixed costs were considerable. Eventually Airbus pulled the plug, and ended maintenance, and that was the end of that. It was probably spurred on by a high-profile disaster, but even without that, the writing was on the wall; if you were an airline Concorde looked economically viable, but without subsidy by the state or by Airbus or both, it never had been. In a world where there had been many viable Concorde routes, this could all have worked out a lot differently, Concorde B might have happened (which would have allowed a Pacific crossing), and maybe we'd still see supersonic airliners.

lstodd 2y ago
This I agree with. There were not enough viable routes. Same thing happened with TU-144 - no destinations.
- twelve40 2y ago
  Sad for both. Saw Concorde at Le Bourget. Both were miracles of engineering in their day.
filereaper 2y ago
Genuinely trying to understand. Didn't the SR71 fly between LA and NY at above supersonic speeds? Don't military jets fly at supersonic speeds above land? What makes this allowable in terms of sonic booms? Is it that they're much smaller and the their booms don't cause as much of a "wake" on the ground?
- adgjlsfhk1 2y ago
  a couple things: 1. smaller lighter, and higher flying reduce the sonic boom size 2. way fewer planes 3. the military gets some latitude to ignore the rules that everyone else has to follow
- twelve40 2y ago
  smaller, and SR71 could cruise at 85000 feet
- rsynnott 2y ago
  > Didn't the SR71 fly between LA and NY at above supersonic speeds? Don't military jets fly at supersonic speeds above land? I think not routinely in either case? Most supersonic aircraft can't actually sustain supersonic speeds for a significant period; the Concorde and Tu-144 are, as far as I know, the only aircraft ever designed with supersonic flight as the effective _default_ mode of operation. For both planes, _getting_ to supersonic was rather expensive, and required the use of afterburners, so an ideal flight profile would involve ramping up to supersonic once, and then staying that way for the rest of the flight. The SR71 was, unusually, _capable_ of sustained long-range supersonic flight, but I can't imagine it was routinely used above land when not actually on missions; why would it be?
  - ceejayoz 2y ago
    The F-22 can also cruise at supersonic speeds without afterburners. https://en.wikipedia.org/wiki/Supercruise https://en.wikipedia.org/wiki/Supercruise.
    - rsynnott 2y ago
      _Can_, but does it routinely outside of training/deployment situations? Like if you're just moving one from one side of the US to the other, you're probably going subsonic.
  - kube-system 2y ago
    > The SR71 was, unusually, _capable_ of sustained long-range supersonic flight, but I can't imagine it was routinely used above land when not actually on missions; why would it be? Everything a military plane does is a mission, and the SR-71 absolutely did supersonic training missions over the US. And as I understand, the military can and still does do supersonic training missions over land, but they do it at higher altitudes and in locations where it isn't disruptive to population centers.
dghughes 2y ago
>The sonic boom made Concorde's economics harder... I live in south-east Canada in the province of PEI and I hope no supersonic aircraft are made. Right now all commercial air traffic from NA flies right over my house. Especially every evening the rumble of high flying jets can he heard. It's not loud but it's certainly noticeable for something 10,000m above me.
kitd 2y ago
Even without the sonic boom, it was painfully loud on takeoff and final approach. It used to fly over us near Heathrow and the ground would shake as it went over at a few thousand feet.
- rsynnott 2y ago
  Concorde B, apparently, would’ve fixed that (though not the sonic boom, of course).
  - bobthepanda 2y ago
    Concorde B allowed a Pacific crossing in a technical sense, if you did a technical stop in Anchorage or Honolulu. And then only to Japan, but not to Korea or China. In the 90s and 2000s you would have had 747s and a340s doing that nonstop without Anchorage or Honolulu, so if anything that would have made concorde B have an even shorter shelf life.

lstodd 2y ago

Green and nimby bullshit as usual. I lived at a summer home in 80s which was near a (soviet) air force base for many summers, and listened to sonic booms daily. In no way it was even disturbing.

jjk166 2y ago

It's a little more complicated then that. The main impetus for the development of the Concorde was actually fuel efficiency - once you get high enough above the sound barrier supersonic flight is more fuel efficient than subsonic flight, all else being equal. Back in the 50s, as fuel costs became more and more of a concern for airlines, this seemed like the obvious future: you get your passengers to their destinations faster, you spend less on fuel, and you can make more flights per day. So Super Sonic Transports (SSTs) looked great on paper. SSTs need to use turbojet engines, which all passenger jets in the 50s were using anyways. But shortly after Concorde's design was locked in high bypass turbofan engines were developed whose fuel efficiency was way higher than turbojets, and indeed much higher than the jump to supersonic flight could achieve. Now it was a choice between speed and fuel efficiency. This really could have gone either way, but when Boeing got out of the SST game they lobbied for overland supersonic flight to be restricted because of sonic booms, which eliminated the potential domestic market. Concorde was reduced from the future of air travel to an offshoot for a niche market. Still it was profitable. People were willing to pay a premium for faster travel, it just wasn't a big enough success to warrant further development. The aircraft aged, unable to take advantage of many of the improvements that came to subsonic jets, and there was no replacement in sight. The Concorde was increasingly expensive to operate compared to more modern aircraft, not because of fuel but because of maintenance and staffing. Between a high profile Concorde crash in 2000, then the reduction in aircraft travel after 9/11, and the security increases which essentially tacked on 2 hours to every trip by air, the Concorde ceased to be viable.