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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.
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.
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.
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.
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.
@yogthos Oh, their rail network is impressive and I wish it was being copied elsewhere.
But this ... is not credible.
Well since you obviously must be an aeronautics engineering expert, perhaps you can explain what aspects of the paper aren't credible for a dumdum like me
https://www.researchgate.net/publication/321943882_Hypersonic_I-shaped_aerodynamic_configurations/link/5a9933c5a6fdccecff0e4504/download
@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
@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.
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.
@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.
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.
@yogthos “The paper”.
This isn’t a paper. It’s a blog post.
It’s no more a “paper” that is subject to any kind of scientific debate than some rando who said they made cold fusion in their microwave.
“Jumbo jet prototype”. Bless.
The "paper" that OP is referring to is the one they posted a few levels up. It links to a researchgate paper that I believe is associated with the article. Just from a quick look at the paper, which is only 3 pages, they are talking about the design the aircraft uses to mitigate the negative effects that occur at hypersonic speeds. They refer to the Waverider design and modified it by including a High-Pressure Capturing Wing to improve lift. Waveriders are designed to conform to the shockwaves the vehicle produces at hypersonic speeds to reduce the drag from those shockwaves. When designing high speed aircraft you have to design around the shockwaves it will produce. This enhancement seems to improve the lift the vehicle creates at those speeds.
Also you aren't getting everything right in your arguments. Earlier you stated that scramjets are fighting Newton's 3rd law which states, "For every action, there is an equal and opposite reaction". You do understand that all air-breathing engines slows the air down before it gets to the engine. This is usually done during a compression cycle to increase the pressure and density of the air. Turbojet and Turbofan engines do this using compression fans, Ramjets uses a normal shockwave, and scramjets uses a series of oblique shockwaves called a "shock train". The difference between a scramjet and the other engines is the airflow is subsonic in Turbojet, Turbofan, Ramjet, etc while the air enters the engine at supersonic speeds for scramjets. That's why its called a SCRamjet, Supersonic Combustion Ramjet. But like OP said the paper doesn't mention what type of engine was used, only that it was a hypersonic vehicle so it could be a rocket.
How do I understand this? I actually have a degree in aerospace engineering, I've worked on scramjets (X-51) for the USAF, and I designed engines for GE Aviation. Your arguments are all wrong.
Nothing more adorable than internet randos acting like they're bonafied rocket scientists. Bless.
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.
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.
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.
It's not a prestige project, it's critical infrastructure. You're gonna be doing a lot seething and coping in your future.