this post was submitted on 14 Jul 2023
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[–] [email protected] 4 points 1 year ago

The Hyperloop was never meant to be built. Elon Musk admitted it was all about fueling opposition to California’s high-speed rail project so it would get canceled. He never planned to improve transportation;

he just wants to keep people trapped in cars.

https://mastodon.online/@parismarx/110715154031130002

[–] [email protected] 4 points 1 year ago

Leave it to Musk to be so full of himself that he thinks he's invented trains.

[–] [email protected] 3 points 1 year ago

"It'll be complete in 2 years"

-some idiot emerald baron 8 years ago

[–] [email protected] 3 points 1 year ago (2 children)

I think there needs to be some disambiguation.

Richard Branson’s Virgin Hyperloop One is literally a train. They themselves call it a train. I guess the idea is that they're small individual cars (called pods) instead of a chain of train cars connected together, which seems really energy inefficient.

Elon Musk's Hyperloop is a train for automobiles, which has all the inefficient downsides of a personal car, with none of the energy benefits of a train. It is the worst of both worlds. And it relies on car infrastructure at both ends, so it will bottleneck just like a highway on/off ramp. Completely nonsensical.

[–] [email protected] 2 points 1 year ago

Musk "invented" the hyperloop and said he didn't want to develop it and others should. One of the companies that picked it up was virgin. The car tunnels are the "loop".

[–] [email protected] 1 points 1 year ago (1 children)

That sounds like a very Muskrat idea. Don't worry though, he never builds his own ideas. When someone smarter comes along and invents something better, Elongated will buy it and claim to have invented it, just like every single one of his other accomplishments.

[–] [email protected] 1 points 1 year ago

Elongated 😂

[–] [email protected] 1 points 1 year ago

The Hyperloop is just a fancy train. Or a very large vacuum tube document transfer system, whichever description you like best.

[–] [email protected] 0 points 1 year ago (1 children)

So I have a question for anyone who might know.

Is there any reason to go with low-pressure tunnels at all? For example, having a plexiglass tunnel at .5 atm doesn’t sound that dangerous to me, and it should be easier to build and maintain, but does it actually provide any irl benefit? Like what’s the production costs/train speed/energy savings relation here? What’s the highest low pressure that starts to make sense? Like, do you have to go down to .01 atm, or can .1 or .5 provide enough of a benefit? If not now, what kind of material advances might help?

Just curious about long-term feasibility of that whole thing.

[–] [email protected] 0 points 1 year ago* (last edited 1 year ago) (1 children)

Hi, aerospace engineer here. As far as benefits go it depends.

If we assume the tube is constant volume and constant temperature. The ideal gas law says that in this case, the pressure would change proportionally with density. So if you lower the pressure by 50% the density should lower by about 50%.

Drag force is also proportional to density. So a 50% decrease in density will result in a 50% decrease in drag. This is true for subsonic speeds. The speed of sound is 343 m/s or 770 mph.

Drag also has a square relationship with velocity. So drag gets extremely high when there is an increase in velocity.

If we take the speed of the shinkansen(90 m/s or 200mph) as a baseline and lower the pressure by half. The new speed the Hyperloop would be able to travel with the new speed is 127m/s or 284 mph. That is faster 40% for the same amount the trains will have to work, but to build all of that infrastructure, spend all the money creating a lower pressure environment and maintain that pressure for thousands of miles is just not worth it. The vacuum tube is just not practical to make.

Edit: If you maintain a reduced pressure and increase speeds about 30% of the speed of sound, the subsonic equations I used start to be less accurate. But in that case drag increases dramatically in transonic and supersonic regimes.

[–] [email protected] 1 points 1 year ago (2 children)

This is the kind of actual discussion that I hope for in these discussions. While many people focus on the dangers of the vacuum tube proposed for the Hyperloop infrastructure, I always wondered about the benefits. It's not like putting a train in a vacuum will suddenly make it go infinitely fast.

So, the question is how much faster would it go? Once you have that number, you can adjust the car vs plane vs train chart that CityNerd showed off. All it would do is deepen and lengthen the railed transit curve some amount. It would potentially increase the distance two cities could be and still provide a benefit over airplane travel. It's just a question of how many city pairs it would help to include as a rail option.

Going from 200 mph to 284 mph won't make that much of a difference. Yes, it'll open up more city pairs for high speed rail, but when comparing those benefits against the cost of the massive tube construction it's not going to seriously pencil out as a net benefit.

Here's the video where CityNerd lays out their reasoning and charts a rough model of where high speed rail is going to be a more reasonable choice for travel based on the distance needed to go: https://youtu.be/pwgZfZxzuQU?t=477

[–] [email protected] 2 points 1 year ago (1 children)

@azimir @Erismi14 I'd be interested in seeing "the cost of building a massive tube" compared to "the cost of building a massive highway".

DOTs across the country have been using phony math to justify ludicrously expensive highway projects for decades -- given a train in a tube would be higher speed and higher throughout, I feel like using their same logic we'd see huge "economic benefits" from connecting two new business centers with a transport mode that allows workers to work in-transit.

[–] [email protected] 1 points 1 year ago (1 children)

I think if we had an economy already built around these tubes it would be much cheaper, but I think that it would still be similar if not more in price as the building of highways.

  1. It is not as easy as building a "bigger oil pipeline and running trains through it. The train moving at high speeds will need a complex and robust system that is continuous inside and outside the tube. The tube will also need ground foundation to handle those forces.

  2. Curves and elevation changes will need to happen at even flatter grades than highways. The higher speeds mean higher acceleration around curves or up inclines. The less sharp turns means more of a reliance on raised structures and tunneling. Good luck on convincing thousands of farmers to put a tube through their property

  3. Maintenance. A highway with a crack in it still works. A highway with a pothole in it still works. Maintenance on that pothole costs $10k USD and the highway is still usable through maintenance. Hyperloop maintenance would not be as cheap, the tube would be shut down before and during maintenance due to repressuring. The tube would need to be vacuumed again.

I'm sure there are other things undiscovered that would be costs as well.

I think the Hyperloop is a cool and shiny idea. In the US I would much prefer reliable and cheap, normal speed rail first, then highspeed, then Hyperloop if we ever get there. I don't think we should be able to eat our pudding before we eat our meat if that makes sense.

[–] [email protected] 1 points 1 year ago

Add to that that the Hyperloop is incompatible with regular rail.

If you build a highspeed rail connection between two cities, you can start by just building highspeed tracks on the straight, empty areas of the connection where you get the biggest benefits, while letting the train run on regular rails in between. So while building the track, the travel time will be gradually reduced as more and more of the track is completed. In the cities themselves, the train can use regular tracks (since highspeed travel probably won't be a thing there anyway due to space restrictions), and it can also use the regular railway stations. This allows you to directly connect the rail service to other trains without having to build separate stations with potential shuttle services in between.

[–] [email protected] 1 points 1 year ago

I think if they are doing a vacuum tube, they should get as close to a vacuum as possible.

I think if the USA is going to spend trillions on rail infrastructure, I think we should start with doubling or tripling the amount of trains on Amtrak first. It's not as sexy as the Hyperloop, but it would get people riding trains more often

[–] [email protected] 0 points 1 year ago (1 children)

It's basically much more expensive slightly faster trains right?

[–] [email protected] 2 points 1 year ago* (last edited 1 year ago) (2 children)

More like a pipe dream with no practical thought put into it that was sold by a conman entirely to derail the planned high speed rail that would have connected SoCal to Seattle.

The end result is a tiny quarter mile tube in a convention centre where you can drive your Tesla in a loop but only like 10 mph and god forbid there's an emergency like a fire because there's no emergency exits if you're stuck behind a burning Tesla.

[–] [email protected] 2 points 1 year ago

FWIW the hyperloop ("pods" in vacuum tubes) and the loop (teslas in tunnels) are separate grifts.

[–] [email protected] 1 points 1 year ago (1 children)

you can drive your Tesla

Incorrect. You don't even get to drive your own car. Someone else drives a Tesla for you. Basically an underground Uber car.

[–] [email protected] 1 points 1 year ago

And underground taxi with only one destination option. It defeats the purpose of using individual cars for travel in almost every category.

[–] [email protected] 0 points 1 year ago (1 children)
[–] [email protected] 3 points 1 year ago

Lol what a clown