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Hyperloop One Becomes ‘Virgin Hyperloop One’

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Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#381

Post by greglindahl »

nkoren wrote: post #371
Rebelgecko wrote: post #261

Earlier quoted context omitted.

Where are you pulling those numbers from? On ULA's website [1] they say you can launch an Atlas V for less than half the $/kg you listed [1] I went to rocketbuilder.com and both LEO configurations I tried were around $8,000/kg (and I didn't count the 20% deduction for "ULA added value" since the numbers there are debatable)

ULA has abruptly gotten way more competitive in their pricing. A few years ago they were not. Their "Best deal" for the Atlas V was a 36-rocket "bulk buy" priced the lowest-tier Atlas V 401 at $164M/launch[1]. That does 9,797kg to LEO[2], or $16,740/kg. The GAO cites $164M/launch as the price for the cheapest Delta V[3] (is there some kind of threshold at $165M?), which when the Falcon 9 was introduced could put 8,50…

For the "block buy", that price includes building the rocket but not the launch.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#382

Post by daurnimator »

mrguyorama wrote: post #157
drzaiusapelord wrote: post #35

Earlier quoted context omitted.

Musk has addressed this: Similarly, the proposal briefly discusses thermal expansion: as the steel of the tubes heats in the hot California sun, the metal expands. That expansion needs somewhere to go. In high-speed railways, rails are allowed to overlap at the ends, but that’s not possible in the Hyperloop, and so Musk has a different solution: “Specially designed slip joints at stations will be able to take any tub…

Does he not realize that you can't just take up all the slack at the ends? That would mean the pylons nearest the station would be pushed over around 300 feet. How would the hyperloop stay elevated without pylons?

Why would the pylons need to move? You can essentially have tube sitting on top of the pylons (which I expect could have ~50 degrees of contact area). You could even have it sitting on rollers between the pylons and the tube.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#383

Post by jcranmer »

hbosch wrote: post #86
Analemma_ wrote: post #21

Earlier quoted context omitted.

When Musk first said that an LA SF Hyperloop could be built for 1/8th the cost of the equivalent HSR, I chuckled and then waited for the punchline, which still hasn’t arrived. It’s a cool idea and I do want to see more prototypes and feasibility studies, but people need to get off the hype train (no pun intended) and be realistic about the cost.

Okay, we'll bookmark this for the future. Amtrak estimated a HSR/"bullet train" from D.C. to Boston would cost ~$151 billion. Since LA to SF will only be two stops, and we can assume Amtrak estimated at least 4 (Philly and NYC) let's bring the number down closer to $100 billion to make it even. Do we think the Hyperloop costs are more or less than that? 1/8 of a theoretical $100b is $12.5b -- is $12.5billion for Hype…

> Okay, we'll bookmark this for the future. Amtrak estimated a HSR/"bullet train" from D.C. to Boston would cost ~$151 billion. Since LA to SF will only be two stops, and we can assume Amtrak estimated at least 4 (Philly and NYC) let's bring the number down closer to $100 billion to make it even.

You're starting with the wrong number. The $151B number is Amtrak's estimated cost for it's "shoot for the stars" plan. Its basic NEC stretch plan is effectively 4-track corridor (shared with commuter rail) from DC to Boston, with new stations and new inner city track being laid in Philly and Baltimore, two new Hudson River tubes and a new station annex in NYC, among other less notable improvements. I don't recall if the "abandon current Connecticut track and instead go from NYC along Long Island and tunnel under the sound" plan is in that tier or the next one. The stretch tier is somewhere in the region of $70B.

The reach for the stars tier is "do all that, and then build a parallel 2-track dedicated HSR track from DC to Boston." That's $150B. Which means building dedicated track from DC to Boston is only $80B. The estimated full buildout for CAHSR (including San Diego and Sacremento) is around $80B, as I recall.

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#384

Post by marssaxman »

doingmything wrote: post #362
kbenson wrote: post #273

Earlier quoted context omitted.

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.…

Agreed. Many people underestimate the aversion of a large swath of the population to driving. Driving basically monopolizes your time and focus and exposes you to accidents. I don’t know if I know anyone who would rather drive if they could get to their destination in the same relative time, unless they’d need a car on the other end.

Oh goodness. Monopolizing your time is part of the value of driving, for me - it gives me something to do while I'm waiting to arrive at my destination!

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#385

Post by caf »

Twirrim wrote: post #248
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…

All Branson has left is a partial holding of Virgin Atlantic on the flying business side of things. Virgin is in the train business, and has 100% holdings there, so if anything he has more business interest in seeing high speed rail come about.

They also have a small stake in Virgin Australia (not that this in any way contradicts your point).

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#387

Post by BRAlNlAC »

sbierwagen wrote: post #330
JumpCrisscross wrote: post #324

Earlier quoted context omitted.

> 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 compressi…

>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.

Just want to point out a facet of such a project that you probably haven't considered. The EPA puts strict requirements on the operators of refrigerant systems, the way they categorize operator class is based on pounds of refrigerant. Thus even though a COTS phase change refrigerant system seems like the obvious choice for Hyperloop One, because of regulatory burden it would almost certainly unfeasible. A refrigeration system big enough to cool a hyperloop would have to have every inch of refrigerant line spray tested every 3 months or an insanely expensive monitoring system.

https://www.arb.ca.gov/cc/rmp/rmpcomply.htm#large

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#388

Post by ellyagg »

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…

Musk literally wants to colonize Mars in his lifetime. Do you think that claim is a clever strategy too? Why is the hyperloop where people draw the line at credulity?

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#389

Post by microcolonel »

Frondo wrote: post #374
dkersten wrote: post #360

Earlier quoted context omitted.

On top of that, my experience of (southern) Californian roads is that they are muuuuuch wider and take up much more space than the coaster/amtrak train tracks take up, so roads have been much more damaging to historic sentimental land than rail is or would be.

What really irks me with that particular sentiment (the land is historic/already in use) is how the federal highway system absolutely decimated communities of color in a lot of major cities. They'd put a highway right through where the black folk live, and who cares? Well, all the people in that neighborhood care, but they're poor minorities--they have no political power, no ability to push back. If you want to start…

Who says I agree with either?

Re: Hyperloop One Becomes ‘Virgin Hyperloop One’

#390

Post by schiffern »

JumpCrisscross wrote: post #353
schiffern wrote: post #345

Earlier quoted context omitted.

>At that point why not just bury it? Because foam is cheaper? A nice K.I.S.S. solution. Having seemingly solved this thermal expansion problem "in the same category of problems separating us from a space elevator," I'll be expecting The Fountains of Paradise to come true soon. ;)

> We seem to have solved this thermal expansion problem I guess I'll have to telegraph my buddies in Hawthorne and at NASA :). Joking aside, no, foam doesn't solve the problem. You'll still have flexing. This is one of the limits on how long you can have a launch tank on the pad. Imperceptibly small flexing, but of the kind that weakens every metal we know.

>Joking aside, no, foam doesn't solve the problem. You'll still have flexing.

Of course the flexing isn't zero, but by adjusting the thickness of the foam you can drive the diurnal/solar heating thermal gradient arbitrarily low without compromising strength by making the steel walls thinner. That was your material science objection,[1] right?

>but of the kind that weakens every metal we know.

That's true, but misleading. It's true that every metal gets weaker, but in steel and titanium this weakening levels off (all other metals continue to get weaker until failure). Once these two metals are at the fatigue limit they stop weakening and have unlimited flexing cycles.[2] So you can set that as your final material strength and size the tube thickness accordingly.

So repeated flexing is fine, and flexing can be made arbitrarily small with insulation. Foam solves the problem.

[1] https://news.ycombinator.com/item?id=15460617

[2] https://en.wikipedia.org/wiki/Fatigue_limit

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