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Hyperloop One Becomes ‘Virgin Hyperloop One’

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Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#311

Post by gaius »

detritus wrote: post #102
biznickman wrote: post #94

The viability of Hyperloop One should not be the focus in the context of this article. That's not what this is about at all. It's that Hyperloop One needed Richard Branson on board because Elon Musk is creating his own competitor now. This is an incredibly smart move to ensure the survivability of the business from a publicity perspective. Branson has a history of doing things that people thought impossible or just a…

Branson's missing a d from his almost nominatively-determining name — the guy's got a talent for self publicity over challenging the incumbency, which for the most part he hasn't since launching Virgin Airlines and Megastores, which were both back in the 80s.

he hasn't since launching Virgin Airlines and Megastores, which were both back in the 80s.

There's a jar of Branson Pickle in every home in England!

But his moves into healthcare are looking extremely dodgy and of course he lives offshore in a tax haven.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#312

Post by hwillis »

JumpCrisscross wrote: post #288
sbierwagen wrote: post #277

Earlier quoted context omitted.

>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_SpacePowe…

> I am not sure what your objection is here. Are you saying vacuum chambers can't be built on Earth? No, I specifically linked to the Space Power Facility in my original comment! The "materials science" problem I call out is in the tube's lateral thermal expansion. The best solution I've come up with for that is to take a regenerative rocket engine [1] and make it a tube. Pumping fluid in spirals along kilometers of…

How about wrapping the tube in insulating foam and using peltier modules to regulate temperature. Or even using double walled tubes. It would not be challenging to regulate the temperature, but nobody talks about it because it doesn't even seem necessary.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#313

Post by KGIII »

aswanson wrote: post #298
KGIII wrote: post #194

Earlier quoted context omitted.

One of my favorites is on Slashdot. If you go there and search for 'VMware' then you can find it. When VMware was first announced and demoed, the commenters at Slashdot declared things like it was fake, it was stupid, it was a waste, it would never work, or that dual booting was a better solution. They largely concluded that virtual machines weren't a thing and happily congratulated themselves for their brilliant ins…

Thanks, I really need to check that one out.

I never tell people that they 'need' to do something, so I'll say I highly suggest you do.

So, to make it easier for you - I've grabbed a laptop and dug out the link:

https://tech.slashdot.org/story/99/02/11/0939233/multiple-os...

I absolutely encourage anyone/everyone to read the linked comments. It's one of my favorite examples when a number of discussions come up.

My preferred time to reference it is when people say things like, "Slashdot used to be so much better!" Or when they say things like, "We had much better commentary back in the day!"

No, no they did not. In fact, it was never as good as people recall it being. That is kind of what makes it so wonderful and why I love discussion sites.

I am, by no means, innocent or superior. ;-)

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#314

Post by DanBC »

gaius wrote: post #311
detritus wrote: post #102

Earlier quoted context omitted.

Branson's missing a d from his almost nominatively-determining name — the guy's got a talent for self publicity over challenging the incumbency, which for the most part he hasn't since launching Virgin Airlines and Megastores, which were both back in the 80s.

he hasn't since launching Virgin Airlines and Megastores, which were both back in the 80s. There's a jar of Branson Pickle in every home in England! But his moves into healthcare are looking extremely dodgy and of course he lives offshore in a tax haven.

> There's a jar of Branson Pickle in every home in England!

Is this humour? The pickle, and beans, are Branston.

https://en.wikipedia.org/wiki/Branston_(brand)

> But his moves into healthcare are looking extremely dodgy

His healthcare stuff is really dodgy. There are already serious concerns about care and treatment at his places.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#315

Post by KGIII »

aswanson wrote: post #302
KGIII wrote: post #194

Earlier quoted context omitted.

One of my favorites is on Slashdot. If you go there and search for 'VMware' then you can find it. When VMware was first announced and demoed, the commenters at Slashdot declared things like it was fake, it was stupid, it was a waste, it would never work, or that dual booting was a better solution. They largely concluded that virtual machines weren't a thing and happily congratulated themselves for their brilliant ins…

Reminds me, Im just as guilty. Check out my insights on Amazon introducing the Kindle: https://news.ycombinator.com/item?id=81804

Yeah, we've all got comments from our past that we wish we'd not made. Our seemingly brilliant insights aren't so brilliant after all.

Today's thread about Musk's "Hyperloop" is good fodder to bookmark and look back at in a decade. I have to wonder how many of the posters will admit they were wrong, should this reach fruition?

I dug the link out for another person who replied. You may want to take a look?

https://tech.slashdot.org/story/99/02/11/0939233/multiple-os...

There was a database glitch that messed up usernames (I think that was after they'd added accounts, my memory isn't that good so I'm not certain) but it's still an amusing read. It really is a good example for a variety of discussions. It's my favorite example, actually.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#316

Post by JumpCrisscross »

schiffern wrote: post #307
JumpCrisscross wrote: post #266

Earlier quoted context omitted.

> You're just describing a usual vacuum pump Scaling is hard. The largest vacuum chamber we've built is a fraction of the size of the proposed Hyperloop. It was a very, very hard problem [1]. It's expensive, sucks up loads and loads of power and needs lots of thermal management, structural reinforcement and vacuum-off maintenance. > Keep in mind that the absolute pressure difference is far less for Hyperloop than for…

> The largest vacuum chamber we've built is a fraction of the size of the proposed Hyperloop. It was a very, very hard problem [1]. Do we really have to say that a long extruded tube that only has to maintain low vacuum is a lot simpler than the SPS? SPS: big thing made up of many custom one-off parts that runs at 1/380,000,000ths of an atmosphere and can blast test articles with intense simulated sunlight. Hyperloop…

> I think they know that, don't you?

Who's they? Hyperloop One? No--they've just punted the "hard" stuff to the end. (Kind of like the Wright Brothers designing the seats of their plane before getting it flying. Oh look! [1])

Elon Musk? Yes--I do. That's why he's waiting.

> what specific problem do you see?

The top heats up and the bottom doesn't.

> The paper calls for 0.8-1.0 inch thick steel, which my math says is more than adequate

Adding mass adds strength while increasing the time the structure takes to reach thermal equilibrium. The thermal gradient isn't itself a problem. But if you look at the forces necessary for the materials in question to tear themselves apart, and then consider their thermal coefficients of linear thermal expansion, you can derive a maximum tolerable thermal gradient given the size of each tube segment (we'll assume the problem of reticulating vacuum seals is solved).

When you solve for strength, you get too much material for the system to reach equilibrium before inclement weather either causes (a) the structure to buckle, laterally or (b) the outside of the tube to start shearing itself from the cooler inside.

When you solve for thermal stresses, you lose your strength. Microbuckling and microfracturing may not seem like a big deal, but it is when you're talking about 1 standard atmosphere bearing down from the outside with a capsule swinging about on the inside.

We need a strong material that either (a) conducts heat really well or (b) doesn't change shape when asymmetrically heated. We don't have something that meets those requirements yet that we can manufacture at scale.

[1] http://www.stacksmag.net/2013/10/space-virgin-galactics-rich...

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#317

Post by yahna »

hwillis wrote: post #290
yahna wrote: post #269

Earlier quoted context omitted.

But I thought this all came to our god king in a dream.

oh stop. People are excited about reusable rockets, a mainstay of science fiction since the beginning. Why do you have to be a wet blanket? "Elon Musk didn't think of reusing rockets, and he didn't personally build them, and he doesn't have a degree in rocketry!" You're fighting a Quixotic battle against a strawman.

I think reusable rockets are cool, and I think musk is impressive.

I'm just not a member of the cult of Elon. I think he follows a path of aim impossibly high, be happy with getting pretty far. People instead take it as "he's literally going to do everything".

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#318

Post by hwillis »

JumpCrisscross wrote: post #301
hwillis wrote: post #292

Earlier quoted context omitted.

> 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. Right... you can probably solve that with a bucket of white paint. Worst case you cover it with an aluminum shield- aluminum does not absorb infrared radiation and will reflect 99.9% o…

> you can probably solve that with a bucket of white paint. Worst case you cover it with an aluminum shield- aluminum does not absorb infrared radiation and will reflect 99.9% of ambient heat It's, unfortunately, harder than this. It's a similar problem to the ones we dealt with regarding rockets, standing fueled, on a pad. Both methods you propose were tried. The solution is to (a) paint it and (b) launch before the…

Dude, what. That's bullshit, and the size difference will be on the order of dozens or low hundreds of microns. Not only that, but the distortion will be spread evenly across the tube because it's a tube. You're just asserting that putting the tube in shadow will somehow not block heat from the sun.

I'm also not sure you understand what I'm saying about an aluminum shield? Aluminum has an emissivity coefficient of .04. Thermal conductivity has nothing to do with it since it isn't touching the tube. It's purpose is just to not re-radiate infrared onto the tube.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#319

Post by scott_karana »

dmix wrote: post #15
sschueller wrote: post #3

When are we going to address the elephants in the room? Just the tube alone: - largest pressure vessel in the world. How do you keep it at near vacuum? - Thermal expansion over such a large distance, especially if the top of the tube is warmer than the bottom. - Safety, how does an evacuation look like if the tubes are sealed?. There are many more. Some how I feel like this is a "pipe" dream. Lots of marketing, very…

> Lots of marketing, very little engineering. It started as a technical whitepaper, not a marketing campaign, and multiple companies are building experimental models. I don't think this critique is accurate or fair. There have been far worse vapourware and hype-only concepts that haven't gotten close to hyperloop's tangible progress. No tech can be perfected from the planning stage either, it takes talent, money, and…

No, the whitepaper came after the start, which was Musk publicly bragged about how he and his engineers could do the rail project better.

"More marketing than engineering" seems accurate to me.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#320

Post by sbierwagen »

JumpCrisscross wrote: post #288
sbierwagen wrote: post #277

Earlier quoted context omitted.

>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_SpacePowe…

> I am not sure what your objection is here. Are you saying vacuum chambers can't be built on Earth? No, I specifically linked to the Space Power Facility in my original comment! The "materials science" problem I call out is in the tube's lateral thermal expansion. The best solution I've come up with for that is to take a regenerative rocket engine [1] and make it a tube. Pumping fluid in spirals along kilometers of…

>The "materials science" problem I call out is in the tube's lateral thermal expansion.

I admire your method of argumentation.

The comment I replied to said nothing at all about thermal expansion. Your original comment, which I wasn't replying to, was mostly strange references to pressure ratios, and a single line about thermal problems, with no numbers cited. In that comment you did link to the Space Power Facility... as an argument against Hyperloop One! You did something similar downthread: https://news.ycombinator.com/item?id=15459777 But by asserting that you addressed the problem in your original comment, you make the person you're arguing with look like a bully, without having to actually address their points. Very efficient.

>The best solution I've come up with for that is to take a regenerative rocket engine [1] and make it a tube. Pumping fluid in spirals along kilometers of a vacuum tube isn't easy, but it isn't as hard as trying to invent a material that won't deform when the top gets hotter than the bottom, or the east side gets hotter than the west.

Using the phrase "regenerative cooling" in this context is another headscratcher. Regenerative cooling in rocketry is running propellant through channels in the nozzle, then either dumping it overboard, using it to power a gas generator, or burning it in the rocket. It's a great way to get rid of megawatts of heat.

None of these things would be useful for a hyperloop tube? You don't want to run kerosene/liquid oxygen/hydrazine/whatever through a cooling jacket then dump it on the ground, you don't need a gas generator for anything, and there's no way to feed the heated propellant to the actual hyperloop car. And if you could, you wouldn't want to, since if you combusted it in the car it would just dump the exhaust in the tube, killing the vacuum.

Presumably active cooling of a hyperloop tube would use a closed refrigerant cycle, which has little to do with regenerative cooling, besides the idea of cooling channels.

Talking about regenerative cooling in this context isn't wrong, exactly, it just betrays a rather shallow understanding of the problem at hand, as seen in your first comment.

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