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Hyperloop One Becomes ‘Virgin Hyperloop One’

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Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#321

Post by hwillis »

yahna wrote: post #317
hwillis wrote: post #290

Earlier quoted context omitted.

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".

I see many more people talking about "the cult of Elon" than people who actually think he's literally going to do everything.

It reminds me way more of the nickelback is terrible thing. It's more of a meme than the actual subject. It's fun to feel like a member of the enlightened in-group that doesn't follow Elon Musk like sheep. All those dumb people that think GM will go bankrupt next year.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#322

Post by Robotbeat »

evanlivingston wrote: post #300
Robotbeat wrote: post #296

The biggest problem people have with Hyperloop is because it certainly seems like Elon Musk just waltzed into the high speed rail debate and Dunning-Krugered some crazy scheme that doesn't look anything at all like conventional approaches to the problem and thus doesn't jive with any common sense we might have built up around different transport methods. But that's kind of what Elon Musk does: he Dunning-Krugers hims…

The moral might be that hubris along with billions in cash can accomplish the things the person with hubris set out to do.

Elon Musk didn't start out with billions of dollars, and he has almost no liquid assets (he borrows against his stock when he needs cash).

But this is a good point. Lots of talented people have good ideas that end up going nowhere because of lack of capital for implementation.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#323

Post by Robotbeat »

JumpCrisscross wrote: post #305
Robotbeat wrote: post #296

The biggest problem people have with Hyperloop is because it certainly seems like Elon Musk just waltzed into the high speed rail debate and Dunning-Krugered some crazy scheme that doesn't look anything at all like conventional approaches to the problem and thus doesn't jive with any common sense we might have built up around different transport methods. But that's kind of what Elon Musk does: he Dunning-Krugers hims…

> Elon Musk just waltzed into the high speed rail debate and Dunning-Krugered some crazy scheme I think it's incredibly important to segregate Musk's work, i.e. SpaceX and Tesla, from his proposals, e.g. the Hyperloop, modular infrastructure and other things.

Nah, the Dunning-Kruger thing applies equally well to Tesla and SpaceX. He had no experience in either field before starting those companies. It's just that he has, in spite of all probability, succeeded and so you see them in a different light.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#324

Post by JumpCrisscross »

sbierwagen wrote: post #320
JumpCrisscross wrote: post #288

Earlier quoted context omitted.

> 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…

> 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

"Regenerative cooling" is a rocket term. It came to mind because I used to be an aerospace engineer. There's no requirement in the definition of regenerative cooling for the coolant to be dumped.

> Presumably active cooling of a hyperloop tube would use a closed refrigerant cycle

I don't think one can just presume that. You've already got lots of pumps for pumping air. Given (a) the seal on the tube will be periodically broken (for entry, exit and maintenance) and (b) a safety factor, you'll have more pump capacity than you'll need. Filtering and then compressing atmosphere, running it through a heat exchanger, and then letting it expand through the cooling channels before dumping it doesn't seem obviously worse than having kilometers of refrigerant running around.

> which has little to do with regenerative cooling, besides the idea of cooling channels

See above. Also, I assumed if you did this you'd use it to boost SpaceX's nozzles' economies of scale.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#325

Post by sgt101 »

gaius wrote: post #308
Brakenshire wrote: post #249

Earlier quoted context omitted.

> a significantly better argument against HS2 is that it's an impossibly expensive boondoggle. Nah, it connects most of England's largest cities, and will be 2/3rds of the network which will connect all of the cities of the North of England into something approaching a single labour market. Liverpool, Leeds, Sheffield, Manchester, Birmingham will be all be within 30-50 minutes of each other, with London within an hou…

It would have been politically a LOT easier of they'd built a Birmingham-Newcastle leg first

and probably better for the long term economy as well; the last thing Birmingham needs is a reason why London is a good base for doing business in Birmingham.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#326

Post by gsnedders »

gaius wrote: post #308
Brakenshire wrote: post #249

Earlier quoted context omitted.

> a significantly better argument against HS2 is that it's an impossibly expensive boondoggle. Nah, it connects most of England's largest cities, and will be 2/3rds of the network which will connect all of the cities of the North of England into something approaching a single labour market. Liverpool, Leeds, Sheffield, Manchester, Birmingham will be all be within 30-50 minutes of each other, with London within an hou…

It would have been politically a LOT easier of they'd built a Birmingham-Newcastle leg first

Perhaps. There would also have been political costs incurred due to the overcrowding on the southern end of the WCML and that then being apparently a lower priority than providing a quicker link between two cities.

And yes, I realise the XC trains around Birmingham (inc. to Newcastle) are frequently overcrowded, but there's a comparatively cheap solution to this: buy more trains.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#327

Post by JumpCrisscross »

hwillis wrote: post #312
JumpCrisscross wrote: post #288

Earlier quoted context omitted.

> 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.

> How about wrapping the tube in insulating foam

At that point why not just bury it? It swaps the thermal problem for the water problem, but we know how to build tunnels.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#329

Post by aerovistae »

jaredhansen wrote: post #185
daemin wrote: post #165

Just as a thought experiment, could the promotion of these "hyperloop" projects be a clever political ploy to misdirect/divert attention and prevent a viable high speed rail network from being built? Elon's main business is electric cars and (one of) Branson's is airlines. So a reasonable competitor to both is fast and cheap(er) public transport along a major travel corridor in the USA. This means that by promoting t…

Of all the problems facing construction of "viable high speed rail" in the US (they already exist in many other places), I don't think Hyperloop competition is among ... the top 50. Practically anything could be "a clever political ploy", but where's the evidence for this? Any in the absence of such evidence, why speculate? Just as a thought experiment, could HN user daemin's comments be part of a clever ploy to inve…

Exactly.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#330

Post by sbierwagen »

JumpCrisscross wrote: post #324
sbierwagen wrote: post #320

Earlier quoted context omitted.

> 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…

> 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 "Regenerative cooling" is a rocket term. It came to mind because I used to be an aerospace engineer. There's no requirement in the definition of regenerative cooling for the coolant to be dumped. > Presumably active cooling of a hyper…

>"Regenerative cooling" is a rocket term. It came to mind because I used to be an aerospace engineer. There's no requirement in the definition of regenerative cooling for the coolant to be dumped.

?

Regenerative cooling in rocketry uses propellant. Propellant is always dumped overboard, because it's propellant.

Please show me a rocket that uses closed loop cooling of the rocket nozzle.

>Filtering and then compressing atmosphere, running it through a heat exchanger, and then letting it expand through the cooling channels before dumping it doesn't seem obviously worse than having kilometers of refrigerant running around.

My turn to be pedantic about definitions: this sure sounds like closed loop cooling to me! The working fluid is air, you draw it from a big reservoir, (the atmosphere) cool something with it, then return it to the reservoir. (Something you can't do with open-loop regenerative cooling of a rocket nozzle, since the coolant gets burned at the end of the cycle)

However, maintaining the air dryers and replacing the filters sounds like it wouldn't be any cheaper than conventional phase-change cooling, and having to build custom vacuum/compressor pumps for the hyperloop project is going to be more expensive than buying COTS vacuum pumps.

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