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They predicted us traveling by rocket much quicker across the globe. I see this mentioned now and then with disappointment that the one thing close to a rocket

They predicted us traveling by rocket much quicker across the globe. I see this mentioned now and then with disappointment that the one thing close to a rocket - the Concorde - was discontinued. But what happened in the aerospace industry is that we instead focused on fuel efficiency and lower noise, which lead to the high bypass turbofan engine. Instead of accelerating a small amount of air to supersonic speeds, which is both extremely noisy and fuel inefficient, we moved to a system that takes that small amount of air and uses it to drive a much larger fan which then takes a large volume of air and accelerates it to subsonic speeds. That's why 'jet engines' of the old days were much thinner and noisier than the really fat engines we have today. This led to much cheaper and quieter air travel. This is a huge benefit - just not quite as spectacularly "space age" as the sci fi authors of the 1950s envisioned.

cwmma 7y ago
Charles Stross wrote a whole thing on why we point to point rockets weren't a thing that would work https://www.antipope.org/charlie/blog-static/2015/01/why-were-not-going-to-see-sub-.html https://www.antipope.org/charlie/blog-static/2015/01/why-wer...
- martythemaniak 7y ago
  Let me try to break it down: 1. Expensive. For sure, it inherently uses a lot more energy. There's not going to be an economy class on these and they'll never replace jets en masse. 2. Security. Not really. He talks about hijacking/terrorism, but these things won't have pilots or free movement on board. Everybody's going to be strapped into their seat for 45 minutes to withstand the forces and the rocket's gonna do all the flying. 3. Spaceports. See my sibling comment, these will have to be build on water far away from cities. 4. Inconvenient. No, these will be massively convenient if you can afford them. It takes 90 minutes to complete an orbit around the earth, so any two points will be at most 45 minutes away. Spending a bit over an 1hr flying New York-Sydney downtown-to-downtown is incomparable to the slog that exists today.
  - FlyMoreRockets 7y ago
    > 2. Security. Not really. He talks about hijacking/terrorism, but these things won't have pilots or free movement on board. Everybody's going to be strapped into their seat for 45 minutes to withstand the forces and the rocket's gonna do all the flying. It isn't just the cabin that is a potential terror threat, but a huge part of the supply chain and operations/management. If these are built on water, a distance from land, it should be possible to construct a nearby floating rectenna to crack and cryocool hydrogen and oxygen for propellant via beamed energy from a solar sat. Granted, there is a fair bit of infrastructure requirement, but with interest rates so low, compounding interest isn't a big deal, like it was in the original SPS calculations.
    - outworlder 7y ago
      > If these are built on water, a distance from land, it should be possible to construct a nearby floating rectenna to crack and cryocool hydrogen and oxygen for propellant via beamed energy from a solar sat. That's such an enormous undertaking that it dwarfs the rockets themselves. SpaceX, which is the only company that's even close to achieving this, prefers kerolox. So what threat are we trying to mitigate? Liquid oxygen is not very problematic. We transport large amounts of the stuff on roads with no issue. Kerosene is used everywhere.
      - njarboe 7y ago
        The Raptor engine for SpaceX's next rocket that would do these orbital/sub-orbital flights is fueled by liquid methane and LOX. A better fuel in many ways and much easier to make on Mars.
  - outworlder 7y ago
    > Security. Not really. He talks about hijacking/terrorism, but these things won't have pilots or free movement on board. Everybody's going to be strapped into their seat for 45 minutes to withstand the forces and the rocket's gonna do all the flying. Superpowers already have the capability to intercept things that travel faster and are smaller than these. > It takes 90 minutes to complete an orbit around the earth Except these are suborbital. And 90 minutes is for a full orbit around ISS altitudes. For most routes, it would be around 30 minutes (https://www.youtube.com/watch?v=zqE-ultsWt0 https://www.youtube.com/watch?v=zqE-ultsWt0)
- outworlder 7y ago
  That piece is talking about suborbital Spaceplanes I agree with the article. But we may have suborbital rockets. Which are much more feasible.
martythemaniak 7y ago
That might not be too far away - SpaceX does want to use their Starship to fly point-to-point across the globe. I suspect the noise, will make it infeasible for all but a few major destinations. They'd likely have to have a sea-based platform 20-30km away from the city, then use a floating tunnel with Tesla/BoringCo pods the rest of the way to actually get downtown. Still, it would be pretty sweet. Go downtown, check in, take a 10 minute pod ride, get strapped into your seat (there's no washrooms, or moving around), blast off and 45 minutes later you're on the other side of the world, another 10 minute pod ride away from downtown.
- deleted 7y ago
  [deleted]
- sneak 7y ago
  > I suspect the noise, will make it infeasible for all but a few major destinations. I think the issue will be more geopolitical than anything. Few national defense organizations will trust an ICBM heading toward "just next to (no seriously, it's fine)" one of their largest population centers, even if it is from someone they consider friendly. Not insurmountable, but definitely an uphill battle.
  - derekp7 7y ago
    And yet they are perfectly content with thousands of inbound jet planes flying into all their major cities. Which could just as easily have any payload they want.
    - njarboe 7y ago
      Or trucks.
      - TheOtherHobbes 7y ago
        Or - in some areas at least - ships.
    - deleted 7y ago
jdsully 7y ago
At cruising speed the Concorde was as efficient as a commercial jetliner of the day. The issue was they had to be subsonic near land due to noise and in that mode of operation they were extremely inefficient.
- outworlder 7y ago
  Almost(not quite) as efficient as a 747 or business jet. On a per-passenger basis, it was vastly less efficient. But that's the Concorde. That's not the upper bound on what physics allows.
gok 7y ago
High bypass turbofans can be used for supersonic transport, as can even more sophisticated efficiency wins, like geared turbofans. SST was killed by noise regulations in North America, which in turn were largely protectionism that Boeing demanded because their own SST project was a failure. It's not a coincidence that somehow no other country in the world had problems being overflow by supersonic jets.
- bluGill 7y ago
  India and Malaysia both banned over flights because of noise. It wasn't just Boeing.
mdorazio 7y ago
I would argue that the market demanded lower cost travel rather than higher speed, so the technical development followed suit. Fuel efficiency and lower cruising speeds were simply a result of that demand.
verelo 7y ago
Also by looking at the raw number of flights to accidents, its probably the most dangerous plane ever invented. We also optimized for safety.
elevenoh 7y ago
>This led to much cheaper and quieter air travel. This is a huge benefit - just not quite as spectacularly "space age" as the sci fi authors of the 1950s envisioned. A moral here: align tech predictions w/ what most people want, don't assuming a kind of linear progression in advancement?

cwmma 7y ago

Charles Stross wrote a whole thing on why we point to point rockets weren't a thing that would work https://www.antipope.org/charlie/blog-static/2015/01/why-were-not-going-to-see-sub-.html https://www.antipope.org/charlie/blog-static/2015/01/why-wer...

martythemaniak 7y ago
Let me try to break it down: 1. Expensive. For sure, it inherently uses a lot more energy. There's not going to be an economy class on these and they'll never replace jets en masse. 2. Security. Not really. He talks about hijacking/terrorism, but these things won't have pilots or free movement on board. Everybody's going to be strapped into their seat for 45 minutes to withstand the forces and the rocket's gonna do all the flying. 3. Spaceports. See my sibling comment, these will have to be build on water far away from cities. 4. Inconvenient. No, these will be massively convenient if you can afford them. It takes 90 minutes to complete an orbit around the earth, so any two points will be at most 45 minutes away. Spending a bit over an 1hr flying New York-Sydney downtown-to-downtown is incomparable to the slog that exists today.
- FlyMoreRockets 7y ago
  > 2. Security. Not really. He talks about hijacking/terrorism, but these things won't have pilots or free movement on board. Everybody's going to be strapped into their seat for 45 minutes to withstand the forces and the rocket's gonna do all the flying. It isn't just the cabin that is a potential terror threat, but a huge part of the supply chain and operations/management. If these are built on water, a distance from land, it should be possible to construct a nearby floating rectenna to crack and cryocool hydrogen and oxygen for propellant via beamed energy from a solar sat. Granted, there is a fair bit of infrastructure requirement, but with interest rates so low, compounding interest isn't a big deal, like it was in the original SPS calculations.
  - outworlder 7y ago
    > If these are built on water, a distance from land, it should be possible to construct a nearby floating rectenna to crack and cryocool hydrogen and oxygen for propellant via beamed energy from a solar sat. That's such an enormous undertaking that it dwarfs the rockets themselves. SpaceX, which is the only company that's even close to achieving this, prefers kerolox. So what threat are we trying to mitigate? Liquid oxygen is not very problematic. We transport large amounts of the stuff on roads with no issue. Kerosene is used everywhere.
    - njarboe 7y ago
      The Raptor engine for SpaceX's next rocket that would do these orbital/sub-orbital flights is fueled by liquid methane and LOX. A better fuel in many ways and much easier to make on Mars.
- outworlder 7y ago
  > Security. Not really. He talks about hijacking/terrorism, but these things won't have pilots or free movement on board. Everybody's going to be strapped into their seat for 45 minutes to withstand the forces and the rocket's gonna do all the flying. Superpowers already have the capability to intercept things that travel faster and are smaller than these. > It takes 90 minutes to complete an orbit around the earth Except these are suborbital. And 90 minutes is for a full orbit around ISS altitudes. For most routes, it would be around 30 minutes (https://www.youtube.com/watch?v=zqE-ultsWt0 https://www.youtube.com/watch?v=zqE-ultsWt0)
outworlder 7y ago
That piece is talking about suborbital Spaceplanes I agree with the article. But we may have suborbital rockets. Which are much more feasible.

martythemaniak 7y ago

That might not be too far away - SpaceX does want to use their Starship to fly point-to-point across the globe. I suspect the noise, will make it infeasible for all but a few major destinations. They'd likely have to have a sea-based platform 20-30km away from the city, then use a floating tunnel with Tesla/BoringCo pods the rest of the way to actually get downtown. Still, it would be pretty sweet. Go downtown, check in, take a 10 minute pod ride, get strapped into your seat (there's no washrooms, or moving around), blast off and 45 minutes later you're on the other side of the world, another 10 minute pod ride away from downtown.

deleted 7y ago
[deleted]
sneak 7y ago
> I suspect the noise, will make it infeasible for all but a few major destinations. I think the issue will be more geopolitical than anything. Few national defense organizations will trust an ICBM heading toward "just next to (no seriously, it's fine)" one of their largest population centers, even if it is from someone they consider friendly. Not insurmountable, but definitely an uphill battle.
- derekp7 7y ago
  And yet they are perfectly content with thousands of inbound jet planes flying into all their major cities. Which could just as easily have any payload they want.
  - njarboe 7y ago
    Or trucks.
    - TheOtherHobbes 7y ago
      Or - in some areas at least - ships.
  - deleted 7y ago

jdsully 7y ago

At cruising speed the Concorde was as efficient as a commercial jetliner of the day. The issue was they had to be subsonic near land due to noise and in that mode of operation they were extremely inefficient.

outworlder 7y ago
Almost(not quite) as efficient as a 747 or business jet. On a per-passenger basis, it was vastly less efficient. But that's the Concorde. That's not the upper bound on what physics allows.

gok 7y ago

High bypass turbofans can be used for supersonic transport, as can even more sophisticated efficiency wins, like geared turbofans. SST was killed by noise regulations in North America, which in turn were largely protectionism that Boeing demanded because their own SST project was a failure. It's not a coincidence that somehow no other country in the world had problems being overflow by supersonic jets.

bluGill 7y ago
India and Malaysia both banned over flights because of noise. It wasn't just Boeing.

mdorazio 7y ago

I would argue that the market demanded lower cost travel rather than higher speed, so the technical development followed suit. Fuel efficiency and lower cruising speeds were simply a result of that demand.

verelo 7y ago

Also by looking at the raw number of flights to accidents, its probably the most dangerous plane ever invented. We also optimized for safety.

elevenoh 7y ago

>This led to much cheaper and quieter air travel. This is a huge benefit - just not quite as spectacularly "space age" as the sci fi authors of the 1950s envisioned. A moral here: align tech predictions w/ what most people want, don't assuming a kind of linear progression in advancement?