- cross-posted to:
- hackernews@lemmy.smeargle.fans
- hackernews@derp.foo
- cross-posted to:
- hackernews@lemmy.smeargle.fans
- hackernews@derp.foo
It’s time to be honest about Musk’s vacuum tube to nowhere
It’s time to be honest about Musk’s vacuum tube to nowhere
There wasn’t going to be any air resistance. They were just going to build a vacuum chamber 1000 times larger than the biggest one ever engineered, then contain it in a thin metal tube snaking hundreds of miles across the heat of the California desert. So simple. /s
Good thing California is geological stable, otherwise it would never have worked… /s
Right, that was the whole point. I think folks arent appreciating air resistance. The ISS is an example of what vehicles are capable of without it. Speeds incomparable to anything on earth, with little fuel usage. Its the largest source of inefficiency in travel. And the engineering science of reducing it is wholesale a scam for people.
The ISS travels at a constant speed in relation to the earth. People have to get on and off a train
Yes, acceleration is a thing, but trains a)reach a top speed and spend a lot of fuel maintaining it, and b)reaches much, much lower top speeds, with any effort to increase it requiring exponentially more fuel to reach and maintain. Air resistance is an absurdly important factor to travel efficiency.
Whoooosh
No, without air resistance , you don’t get that sound.
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Yeah i seen the rest of it, i was short on time. Thats not how engineering tubes works, we use them because you can add as much length as you want, the balancing of pressure forces occurs cross sectionally. A 2 foot pipe carrying 100 psi is experiencing the same stresses as a 2 mile pipe at 100 psi. You might as well be adding a /s to the idea of distributing water through pipes.
Very long pipes use expansion/contraction sections that may not be possible for a vacuum sealed system that has to be incredibly straight to allow the passage of a train, and can flex pretty significantly for earthquakes, seasonal temperature changes, etc.
Earthquakes keep getting brought up as if they’re not devastating to absolutely everything we already use. What if an earthquake hits a regular train? Or a bridge, or a house. only a vacuum tube is susceptible to earthquakes.
I really don’t think they want actual science or logic, this is the five minute hate for the day.
I think it really boils down to capitalism being really bad at things like this, look at the UKs high-speed rail project - hugely over budget and behind schedule AND not getting any of the important bits that actually make it usable. There’s no way we could do anything actually cool like a passenger vacuum tube.
I was actually a little excited by some of the stuff musk was saying back in the boring company days because it briefly sounded like he was investing money in technologies that would be huge, narrow bore vaccum tunnels especially… Sadly I think he didn’t really understand the science fiction he was reading, or rather he didn’t get the importance of intermediary steps. Or he remembered me owns a car company.
What would make a huge difference in reducing vehicles on the road is rapid hands free cargo delivery through automated vacuum tunnels - but he wanted to skip micro tunnels and instead just go to ever so slightly smaller tunnels which is basically pointless. We needed a totally new boring technology not a slightly shrunk one, it should be doing city infrastructure and micro cargo transit then when we’ve perfected the mechanisms we can scale up into passenger sized networks to complement the developing passenger rail system (which rapid micro transit would really help as the need for cargo transit is the main reason that stops the subway being feasible for certain people)
Even with public support this isnt something I’d expect to see in my lifetime, this would be a huge undertaking, a milestone for a more advanced civilization in the future. I’d compare it to space travel, something that was figured as theoretically possible long before it was even attempted. It was a massive effort, but it was possible and was achieved and now many many decades later its having practical applications for things like satellites. But Musk has put it into a bit of a dark age, where its disregarded as a meme and so wont be seeing any advancement for quite some time.
If any part of the hundreds of miles of tube suddenly stops being a vacuum chamber, every train all along the tube is going to be hit by air rushing in, at the speed of sound, with all the turbulence that implies, while its already moving at full speed. It might be possible to engineer a capsule that will keep the people inside alive when that happens, but it is not at all the same as e.g. rail, where “stop moving fowards” depletes essentially all the energy in the system.
You deal with thermal expansion the same way you do with continuous welded rail.
The major strategy on CWR is pretensioning, but there are also multiple kinds of expansion joints used in different circumstances. I’m not saying it’s impossible to do the same with a vacuum chamber, but I am saying there’s no simple reliable answer, and certainly no answer so obvious and bulletproof that it doesn’t even require testing before you could start construction.
Elon Musk either didn’t know or didn’t care that his company wasn’t doing the required engineering and testing to make a real functioning hyperloop.
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I think a better example is airplanes. You run at high altitudes to increase efficiency due to reduced atmosphere.