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All of these supersonic passenger craft have solved the issue with the noise. Nobody wants planes sending sonic booms over them, so the routes for these planes

All of these supersonic passenger craft have solved the issue with the noise. Nobody wants planes sending sonic booms over them, so the routes for these planes will be quite limited.

jakeinspace 4y ago
Cruising at 50km of altitude is one way to solve it. The problem I’ve always had with the idea of rocket-powered rapid aircraft like this is that, presumably, only the very wealthy could afford this. But what billionaire is going to risk the much higher risk of death compared to regular aircraft? Especially if they’re taking 10 long flights per year, I don’t see how you can engineer a rocket plane that doesn’t shorten life expectancy for frequent flyers by several years.
- popcalc 4y ago
  Airliners were at one time reserved for the rich. And they crashed, a lot. When you get to know a lot of ultra wealthy people you can sense a lot of these guys are pathological gamblers and have intimidatingly low risk aversion.
- masklinn 4y ago
  > Cruising at 50km of altitude is one way to solve it. The problem I’ve always had with the idea of rocket-powered rapid aircraft like this is that, presumably, only the very wealthy could afford this. Surely the primary issues are that the efficiency would be dreadful and that the price would be ridiculous even for “the very wealthy”? This would only be accessible to double if not triple digit millionaires, and is the gain in time really worth the hassle versus the comfort of a long-range business jet?
  - avmich 4y ago
    I hope not. I believe energy costs are historically falling, so not only for upper middle class. Efficiency is usually sacrificed for the effect, so yes, it will spend joules - but that's what the human race does since birth.
  - credit_guy 4y ago
    > Surely the primary issues are that the efficiency would be dreadful and that the price would be ridiculous even for “the very wealthy”? I guess you're thinking that drag increases with the square of the speed, and so for very high speed the fuel consumption should be horrendous. This is only if all things are equal. And they are not. Two things change when you increase speed: you decrease the cross-section (via decreased angle of attack, and shorter wings) and decrease the air density (because you fly higher). A regular commercial jet flies at about 10 km height, where the air density is about 3-4 times lower than on the ground. The airplane discussed here is supposed to fly at 50km where the air density is more than 1000 times lower than at ground level [1]. By the way, I don't think this particular project has any chance of ever becoming reality. The main problem with hypersonic vehicles is the aerodynamics, not the propulsion. These guys are simply working on the wrong problem. [1] https://www.engineeringtoolbox.com/standard-atmosphere-d_604.html https://www.engineeringtoolbox.com/standard-atmosphere-d_604...

All of these supersonic passenger craft have solved the issue with the noise. Nobody wants planes sending sonic booms over them, so the routes for these planes will be quite limited.

jakeinspace 4y ago

Cruising at 50km of altitude is one way to solve it. The problem I’ve always had with the idea of rocket-powered rapid aircraft like this is that, presumably, only the very wealthy could afford this. But what billionaire is going to risk the much higher risk of death compared to regular aircraft? Especially if they’re taking 10 long flights per year, I don’t see how you can engineer a rocket plane that doesn’t shorten life expectancy for frequent flyers by several years.

popcalc 4y ago
Airliners were at one time reserved for the rich. And they crashed, a lot. When you get to know a lot of ultra wealthy people you can sense a lot of these guys are pathological gamblers and have intimidatingly low risk aversion.
masklinn 4y ago
> Cruising at 50km of altitude is one way to solve it. The problem I’ve always had with the idea of rocket-powered rapid aircraft like this is that, presumably, only the very wealthy could afford this. Surely the primary issues are that the efficiency would be dreadful and that the price would be ridiculous even for “the very wealthy”? This would only be accessible to double if not triple digit millionaires, and is the gain in time really worth the hassle versus the comfort of a long-range business jet?
- avmich 4y ago
  I hope not. I believe energy costs are historically falling, so not only for upper middle class. Efficiency is usually sacrificed for the effect, so yes, it will spend joules - but that's what the human race does since birth.
- credit_guy 4y ago
  > Surely the primary issues are that the efficiency would be dreadful and that the price would be ridiculous even for “the very wealthy”? I guess you're thinking that drag increases with the square of the speed, and so for very high speed the fuel consumption should be horrendous. This is only if all things are equal. And they are not. Two things change when you increase speed: you decrease the cross-section (via decreased angle of attack, and shorter wings) and decrease the air density (because you fly higher). A regular commercial jet flies at about 10 km height, where the air density is about 3-4 times lower than on the ground. The airplane discussed here is supposed to fly at 50km where the air density is more than 1000 times lower than at ground level [1]. By the way, I don't think this particular project has any chance of ever becoming reality. The main problem with hypersonic vehicles is the aerodynamics, not the propulsion. These guys are simply working on the wrong problem. [1] https://www.engineeringtoolbox.com/standard-atmosphere-d_604.html https://www.engineeringtoolbox.com/standard-atmosphere-d_604...