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Hyperloop One Becomes ‘Virgin Hyperloop One’

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Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#271

Post by JumpCrisscross »

schiffern wrote: post #257
JumpCrisscross wrote: post #241

Earlier quoted context omitted.

> Some colleagues of mine also did a short feasibility assessment of the original white paper, and came to some similar conclusions Likewise. It sounds like above-surface (on Earth) is probably unfeasible given (a) security and (b) thermal concerns. For security, we just contemplated debris from the track (or a bullet from an errant rifle) puncturing the tube. Hyperloop One is testing an 3.3m diameter and 500m long t…

sigh another "deadly wall of air" theory ala Thunderf00t? Hasn't this been debunked already? "A little bit of physics is a dangerous thing." * A bullet or piece of debris would likely leave a hole much smaller than the diameter of the tube. A breach 1/10th the diameter of the tube will admit 1/100ths as much the air. * Even if there was a whole-tube breach, the "wall of air" will rapidly slow down and smear out into…

> ala Thunderf00t

Just watched one of his videos on this--interesting and thank you for the pointer. Agree with you on his overstating the deadliness of pressure pulses. 30 kg of TNT is a lot of energy, certainly enough to knock your infrastructure out of commission for a couple days. The "everyone dies if the tube is punctured" argument is hyperbolic, though.

The materials science problem is the thermal expansion. And not the longitudinal one that Thunderf00t mentions. It's the transverse expansion. If these are above ground, the top will heat up relative to the bottom. That's a nasty problem to solve while maintaining the structural integrity to keep a giant vacuum with speeding capsules in place.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#272

Post by the8472 »

JumpCrisscross wrote: post #250
hwillis wrote: post #231

Earlier quoted context omitted.

> The Hyperloop’s thermal issues are a hard enough problem that they alone put this in the domain of materials science. That’s the same category of problems separating us from a space elevator. What? What are you even talking about?? That's a completely ridiculous statement. The pressure inside and outside the lunar landing module was 1,000,000,000,000,000x. 100 kPa to 10^-10 Pa. It makes zero sense to apply this kin…

> The pressure inside and outside the lunar landing module was 1,000,000,000,000,000x. 100 kPa to 10^-10 Pa We didn't pump air into the lunar module from the Moon. We carried it from Earth pre-pressurized. Unless you're proposing we build and seal the Hyperloop tubes in space before bringing them down, the analogy isn't appropriate. Also, consider a soda can. It's stronger when pressurized from the inside. Modern nuc…

The force exerted by the atmosphere on an evacuated tube is the same as the force exerted on a standard-atmosphere filled submarine diving 10m beneath the surface. A 100kPa difference.

And since they explicitly do not want a high vacuum - some residual air inside the tube is necessary for the hyperloop concept! - they don't have to deal with advanced tech like turbomolecular pumps. Simple displacement pumps will do.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#273

Post by kbenson »

nradov wrote: post #226
valas wrote: post #219

Earlier quoted context omitted.

"it would be as slow as conventional rail" - citation? Even Reason Foundation (which is as biased as it gets - it's funded by Koch brothers and ideological critic of almost any government investment) claim SF to LA times will be 3:30 to 4:40, which is faster than any train today.

That's barely faster than driving, once you account for the time spent moving between your origin/destination and the train station as well as transferring luggage.

And taking the light rail north of SF to the ferry and then the Embarcadero in SF takes longer than driving when my brother commutes, but he still chooses that method. Perhaps there are factors other than time that go into his calculation.

People would take HSR even if it took the same time as driving. They would likely take it if it took an extra 20%, as the time has more utility to them when used for a train ride. That it's actually faster than driving just makes it more attractive.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#274

Post by manigandham »

sigmar wrote: post #259
manigandham wrote: post #152

Earlier quoted context omitted.

Yes it's possible to build, but no it's not cheap enough to make money on = not worth building. We can build lots of fantastic things today but they would cost trillions so clearly are not a good idea. You also missed the ending about construction + maintenance, those will be the real costs and aren't likely to become radically cheaper.

To the generations that traveled the world on boats, constructing flying machines that move faster (and required more tech/maintenance) also probably seemed like an unknown of whether it would be prohibitively expensive or not. I'm grateful that they didn't wait long to explore the possibility, which is what Virgin is doing here.

Maybe I'm communicating poorly here but the tech is not the problem. We don't need to invent anything new, we know how to do it. It does need to get cheaper but the construction and maintenance costs are gigantic and that hasn't changed for any big project over the last century.

Jetliners are complex machines but it's the entire infrastructure of airports and traffic control that actually make it possible, which is only viable because people choose to pay for it. Massive infrastructure does not build or take care of itself, and if it did, that would be a far bigger revolution than just building a train.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#275

Post by kbenson »

detritus wrote: post #173
adventured wrote: post #160

Earlier quoted context omitted.

He's worth $5 billion. He's a high-school drop-out dyslexic that started from nothing. He built a successful airline and record label, along with countless successful branded companies whose success partially rides on the vast effort he has put into building his own well-known brand - a substantial feat unto itself. Yes, golly gee, what HAS he done.

I trust my respone to 'waegawegawe' pads out where I'm coming from. He has a certain reputation here in Britain, however we here in Britain also have a certain reputation of shitting on people's success - I sincerely hope that's not how I'm coming across here. Anyway, this is tangential nonsense, I'm sorry for diluting discourse!

> however we here in Britain also have a certain reputation of shitting on people's success

That's okay, I appreciate you loaning us John Oliver. ;)

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#276

Post by yahna »

Pxtl wrote: post #147
martinald wrote: post #77

Earlier quoted context omitted.

Is this not an attempt to just derail CAHSR, or HSR in general? Nearly every anti-HSR comment is now 'we should build hyperloop instead!'.

That's impressively cynical, but Musk obviously stands to gain a lot if people keep California using roads. California wants to go green and he sells the best technology for green road-based transportation.

heh.

Reminds me of when an actual AI expert pointed out that by making dire predictions about smart AI, that we are nowhere near having, keeps eyes off the autopilot system and the issues with that.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#277

Post by sbierwagen »

JumpCrisscross wrote: post #250
hwillis wrote: post #231

Earlier quoted context omitted.

> The Hyperloop’s thermal issues are a hard enough problem that they alone put this in the domain of materials science. That’s the same category of problems separating us from a space elevator. What? What are you even talking about?? That's a completely ridiculous statement. The pressure inside and outside the lunar landing module was 1,000,000,000,000,000x. 100 kPa to 10^-10 Pa. It makes zero sense to apply this kin…

> The pressure inside and outside the lunar landing module was 1,000,000,000,000,000x. 100 kPa to 10^-10 Pa We didn't pump air into the lunar module from the Moon. We carried it from Earth pre-pressurized. Unless you're proposing we build and seal the Hyperloop tubes in space before bringing them down, the analogy isn't appropriate. Also, consider a soda can. It's stronger when pressurized from the inside. Modern nuc…

>Unless you're proposing we build and seal the Hyperloop tubes in space before bringing them down, the analogy isn't appropriate.

I am not sure what your objection is here. Are you saying vacuum chambers can't be built on Earth? There are quite a few examples of large vacuum chambers, like the NASA Space Power Facility (23,400 m^3) or the Large Hadron Collider (9,000 m^3) https://scap.hq.nasa.gov/docs/Glenn_SpacePower.pdf https://lhc-machine-outreach.web.cern.ch/lhc-machine-outreac...

Both are pumped down to very high vacuum, not required for the Musk Hyperloop, (low pressure electric jet in a tube) but probably needed for the Hyperloop One. (maglev vactrain) And, obviously, both chambers were built terrestrially, and evacuated using conventional vacuum pumps.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#278

Post by schiffern »

the8472 wrote: post #272
JumpCrisscross wrote: post #250

Earlier quoted context omitted.

> The pressure inside and outside the lunar landing module was 1,000,000,000,000,000x. 100 kPa to 10^-10 Pa We didn't pump air into the lunar module from the Moon. We carried it from Earth pre-pressurized. Unless you're proposing we build and seal the Hyperloop tubes in space before bringing them down, the analogy isn't appropriate. Also, consider a soda can. It's stronger when pressurized from the inside. Modern nuc…

The force exerted by the atmosphere on an evacuated tube is the same as the force exerted on a standard-atmosphere filled submarine diving 10m beneath the surface. A 100kPa difference. And since they explicitly do not want a high vacuum - some residual air inside the tube is necessary for the hyperloop concept! - they don't have to deal with advanced tech like turbomolecular pumps. Simple displacement pumps will do.

Note that downthread, they've already moved the goalpost from "these pumps are technologically impossible" to "but they'll need a lot of them!"

https://news.ycombinator.com/item?id=15459820

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#279

Post by hwillis »

JumpCrisscross wrote: post #250
hwillis wrote: post #231

Earlier quoted context omitted.

> The Hyperloop’s thermal issues are a hard enough problem that they alone put this in the domain of materials science. That’s the same category of problems separating us from a space elevator. What? What are you even talking about?? That's a completely ridiculous statement. The pressure inside and outside the lunar landing module was 1,000,000,000,000,000x. 100 kPa to 10^-10 Pa. It makes zero sense to apply this kin…

> The pressure inside and outside the lunar landing module was 1,000,000,000,000,000x. 100 kPa to 10^-10 Pa We didn't pump air into the lunar module from the Moon. We carried it from Earth pre-pressurized. Unless you're proposing we build and seal the Hyperloop tubes in space before bringing them down, the analogy isn't appropriate. Also, consider a soda can. It's stronger when pressurized from the inside. Modern nuc…

> We didn't pump air into the lunar module from the Moon. We carried it from Earth pre-pressurized. Unless you're proposing we build and seal the Hyperloop tubes in space before bringing them down, the analogy isn't appropriate.

It absolutely is appropriate, since the module was emptied and filled each time the astronauts left.

> Modern nuclear attack submarines collapse around 730m. Since for "every 33 feet (10.06 meters) you go down, the pressure increases by 14.5 psi," we're talking about water pressure of about 1,000 psi or about 72 atm.

Yeah- so building a hyperloop is structurally as complicated as building a tube that sits 33 feet under water. Hardly sounds complicated when put like that.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#280

Post by always_good »

ravenstine wrote: post #91
batrat wrote: post #16

I see so many negative comments about this, but in my opinion everything has to start somewhere. It doesn't matter how crazy and impossible it looks, it will be done eventually (and we have plenty of examples). Maybe we will not teleport in 2 seconds across the globe or this project will die, who knows if we don't try. A little bit of optimism doesn't hurt. Just saying. And for Virgin, it's not my money, if they want…

My instinct tells me negative comments aren't actually coming from the direction of "stupid idea! can't be done!". This isn't to say there aren't significant engineering roadblocks to the Hyperloop, but I don't think that's the root of the negativity. People are pointing out the glaring flaws in the Hyperloop idea, not because they can't or won't believe that crazy ideas are possible, but in reaction to the media's r…

Let's be honest. People criticize because it's easy, makes them feel good, and because they have no skin in the game.

You might like the idea that it's some sort of reasoned rejection of Elon PR, but it's not. Just make a Show HN sometime.

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