• goatsarah@thegoatery.dyndns.org
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    10 days ago

    @yogthos No, just someone who can smell obvious bullshit. SCRAMjets basically don’t work for any real world application, and can’t. They inherently have utterly useless power to weight performance.

    None of this shit works on anything that’s not a scale model.

    • ☆ Yσɠƚԋσʂ ☆@lemmy.mlOP
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      10 days ago

      I guess we’ll see won’t we. Pretty much same thing was confidently said about lots of technology in modern use, like the high speed train network in China. Plenty of western geniuses derided it as not being cost effective.

      • geneva_convenience@lemmy.ml
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        9 days ago

        High speed rail can be cost effective. High speed planes however cannot.

        The amount of air resistance at higher speeds is insane. Instead of relying on wing lift for efficiency the entire aircraft has to remove all wings and it literally becomes a missile.

        Efficient planes have long wings to create lift and cruise at lower speeds. This is the opposite where all lift is generated from the fuel.

        • ☆ Yσɠƚԋσʂ ☆@lemmy.mlOP
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          9 days ago

          Given that China has high speed rail all across the country, I suspect that there’s going to be little market for short flights. I would expect this sort of a plane would go all the way to the edge of space where it doesn’t need to worry about air density.

          • geneva_convenience@lemmy.ml
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            9 days ago

            That’s going to cost a lot of fuel, maintenance and spare parts. Rebranding an ICBM as a passenger plane is not that big an invention.

            The high spees rail is much more impressive as it can be used by the general population. Whereas these top speed planes will only be for the elites.

            • ☆ Yσɠƚԋσʂ ☆@lemmy.mlOP
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              8 days ago

              It’s not really an ICBM, it’s likely a hypersonic glide vehicle. I imagine people building this stuff have thought of obvious things like cost of fuel and parts before trying to build it. Maybe it will work or maybe it won’t, I think we’ll learn something interesting one way or another.

              I also don’t think it’ll just be for elites. All successful technology becomes cheaper over time, and it sounds like they’re explicitly building a large capacity vehicle here. I imagine it’s going to be a long haul vehicle that could go anywhere in the world in about an hour.

          • goatsarah@thegoatery.dyndns.org
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            10 days ago

            @yogthos plenty of published stuff on why scramjets aren’t practical and air breathing hypersonic transport is basically a white elephant even if you’re able to do it.

            I’m not your butler

            • goatsarah@thegoatery.dyndns.org
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              10 days ago

              @yogthos the tl;dr is that you basically have super high energy air coming in at Mach 5. You then have to take all that energy away to get your fuel to burn in it, which barely gets you past break even. They create massive amounts of drag too and in order to function need to stay in the part of the atmosphere that’s thick enough to breathe, thus prolonging the drag and problematic heat generation.

              Given the point of a scramjet is to get you into a suborbital trajectory for a rapid glide to your destination, the fact that they have inherently terrible thrust performance and only work when you’re in the bit of the atmosphere you desperately don’t want to be in, they’re uniquely terrible at it.

              Turborockets solve these problems. Get up to Mach 5 on air, close the intakes, run on liquid oxygen, and CLIMB.

              They’re lighter, more efficient, and faster than hypersonic air breathers. You wanna go that fast, use a rocket, and get away from the nasty draggy burny stuff. As enticing as the idea of “free oxidiser” is, it’s a sucker bet.

              • ☆ Yσɠƚԋσʂ ☆@lemmy.mlOP
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                10 days ago

                Again, go ahead and explain what the paper about this specific jet gets wrong. Also, nobody is asking your to be anybody’s butler. You made a claim, so now it’s up to you to substantiate it.

                I find it absolutely hilarious how arm chair aeronautics engineers such as yourself just assume that people building this stuff aren’t aware of obvious arguments that even a layman such as yourself understands. Like it took your galaxy brain to figure this out, but the people actually making the jet aren’t aware of this.

                • goatsarah@thegoatery.dyndns.org
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                  10 days ago

                  @yogthos I did.

                  Scramjets are fundamentally fighting Newton’s 3rd law. Slow air down by Mach 5 only to speed if back up to Mach 5 again. You’re burning tonnes of fuel to accomplish almost nothing.

                  If they have a practical scramjet vehicle (they don’t), then they should feel free to show the world, rather than posting vacuous bullshit on the Internet.

                  • ☆ Yσɠƚԋσʂ ☆@lemmy.mlOP
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                    10 days ago

                    Nowhere in the paper does it say that this is a scramjet. Meanwhile, obvious solution for a hypersonic vehicle would be to go to upper atmosphere at a lower speed, and then achieve speeds over Mach 5 where there is low atmospheric density. You really think that you’re smarter than literally everybody working on this project, and it’s absolutely hilarious.

                    Maybe take your own advice and stop posting vacuous bullshit on the internet pretending that you’re an expert on things you have little understanding of.

      • FleetingTit@feddit.org
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        9 days ago

        Their high speed train network is impressive, but none of it was new technology when they built it. The first train sets they bought were Siemens Velaro D, a mature high speed train system that has been around in Europe for almost a decade prior.

        It ISN’T cost effective, but in China that doesn’t matter: what the state wants the state gets. No matter the cost. And I’m willing to bet that in 10 years time a lot of the stuff just doesn’t work anymore, line speeds get reduced and stops cancelled due to infrastructure not being maintained.

        We have seen chinese prestige projects fall into disrepair time and again, and their extensive transport network will see the same fate.

        • ☆ Yσɠƚԋσʂ ☆@lemmy.mlOP
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          9 days ago

          China absolutely has done a lot of innovation in HSR tech. Building stuff is how we develop and improve technology. It’s absolutely incredible that you think China hasn’t innovated in this area.

          It ISN’T cost effective, but in China that doesn’t matter: what the state wants the state gets. No matter the cost. And I’m willing to bet that in 10 years time a lot of the stuff just doesn’t work anymore, line speeds get reduced and stops cancelled due to infrastructure not being maintained.

          That shows just how utterly clueless you are. The reason China wants to have the whole country connected by rail is because it stimulates the economy. It makes it easy to transport goods across the country, and for people to move around. To suggest that China would abandon its rail network is sheer idiocy.

          We have seen chinese prestige projects fall into disrepair time and again, and their extensive transport network will see the same fate.

          It’s not a prestige project, it’s critical infrastructure. You’re gonna be doing a lot seething and coping in your future.