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Hyperloop

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Re: Hyperloop

#341

Post by bbatsell »

julian37 wrote: post #287
axus wrote: post #176

Earlier quoted context omitted.

It's also scary that the passengers would suffocate if the life support system failed.

Isn't that the case with planes also? As far as I know, at 35,000 feet altitude you'd die, too, if cabin pressure drops and the plane's life support system fails. And I don't recall ever hearing of an air plane accident that involved suffocation.

There have been a few, but they're quite rare. Two of the more prominent:

https://en.wikipedia.org/wiki/Helios_Airways_Flight_522

https://en.wikipedia.org/wiki/1999_South_Dakota_Learjet_cras...

Re: Hyperloop

#342

Post by dragonwriter »

MBCook wrote: post #269
Osmium wrote: post #199

Reading the entire PDF is highly recommended; it contains a surprising amount of answers already (including many to comments below). I think, if anything, safety aspects haven't been sufficiently explored in the pdf. I'm quite happy to believe it's safer than other modes of transport, but I wouldn't be too quick to overstate it. Also, if anyone can explain what "Tubes located on pylons would limit access to the criti…

I'm really impressed to see the entire thing out in the public. They showed the designs, proposed routes, stress analysis, cost analysis... It's quire clear that this isn't just some "Hey I thought of an idea", they really put a lot of work into this. I was worried this was going to be some pie-in-the-sky idea that was nebulous on a lot of basic details with quite a bit of "we can figure that out later".

> I was worried this was going to be some pie-in-the-sky idea

Sure, they put a lot of theoretical analysis into it, but its still pretty pie-in-the-sky. From the last page, note that

  The authors recognize the need for additional work,   
  including but not limited to:
    1. More expansion on the control mechanism for 
       Hyperloop capsules, including attitude thruster or 
       control moment gyros.
    2. Detailed station designs with loading and unloading 
       of both passenger and passenger plus vehicle 
       versions of the Hyperloop capsules.
    3. Trades comparing the costs and benefits of 
       Hyperloop with more conventional magnetic 
       levitation systems.
    4. Sub-scale testing based on a further optimized  
       design to demonstrate the physics of Hyperloop.
It's not a current competitor to high-speed rail, its more in the position that high-speed rail was in in the 1930s.

Re: Hyperloop

#343

Post by pxtang »

jeffasinger wrote: post #248
trafficlight wrote: post #187

Earlier quoted context omitted.

And at a cost of ~$20. That's pretty good.

That cost is the infrastructure cost, amortized over a long time, not counting R&D, maintenance, marketing, ticketing, and various personnel costs, assuming it's near capacity. Translation, it's going to cost more than $20.

Even if it costs $100 for one way, it's still cheaper than plane, and you save an hour on travel time.

Re: Hyperloop

#344

Post by rinon »

dragonwriter wrote: post #250
LekkoscPiwa wrote: post #206

Earlier quoted context omitted.

but why to ask California State for subsidy? Why not to build it using private funds? I'd imagine that if this is economically sound idea there must be potential investors lining up to have their share in the Project? The estimated cost is $7B. Now, Musk just needs to make a few calls to his friends at Google, Amazon, etc. Can't these guys just form a company together just to build it? Maybe I'm naive... or maybe Mus…

> but why to ask California State for subsidy? Why not to build it using private funds? Because you can't, in practice, acquire the rights of way necessary to build a substantial railroad/hyperloop/freeway or other major infrastructure project of that type without government (specifically, without use of eminent domain).

But as I recall, the gov't can use eminent domain to give land to a private entity if they're in favor of the idea for the "public good." Or am I way off base here...?

Re: Hyperloop

#345

Post by asmithmd1 »

Turing_Machine wrote: post #337
asmithmd1 wrote: post #306

Earlier quoted context omitted.

The output of the compressor is at 1000 deg. F and 300 psi. That is pretty scary.

The combustion temperature of JP-4 is 3,688 °C.

Sure - but that is happening dozens of feet away inside a can designed to contain it. This extremely high temperature and pressure air will be flowing right under your butt. Serious question, Is any kind of breakthrough in insulation needed?

Re: Hyperloop

#346

Post by [deleted] »

Turing_Machine wrote: post #312
goodcanadian wrote: post #270

Earlier quoted context omitted.

Can you elevate rail as easily? The short answer is, "yes." I've ridden on it. The slightly longer answer (as another commenter has pointed out) is that it depends on the weight of the train versus the weight of the hyperloop. I see no fundamental reason to assume that the hyperloop is lighter than the train. It could be so, but then, we could make smaller and lighter trains, too (light rail). Plus you don't get the…

"I see no fundamental reason to assume that the hyperloop is lighter than the train." Did you actually read the PDF? It doesn't carry its motor with it. That's a pretty big reason. Nor does it need the heavy-duty (and heavy!) trucks of a standard rail car.

[deleted]

Re: Hyperloop

#347

Post by Turing_Machine »

asmithmd1 wrote: post #345
Turing_Machine wrote: post #337

Earlier quoted context omitted.

The combustion temperature of JP-4 is 3,688 °C.

Sure - but that is happening dozens of feet away inside a can designed to contain it. This extremely high temperature and pressure air will be flowing right under your butt. Serious question, Is any kind of breakthrough in insulation needed?

Well, if the can fails you're toast either way. :-)

The pressure ratio for the compressors in the CFM56 engines in current model 737-800 models is 32.8:1, so somewhere in the neighborhood of 400-500 psi (will depend a lot on altitude).

Seriously, we've been building machinery to operate safely in this pressure and temperature range for a long time.

Re: Hyperloop

#349

Post by marshray »

sitharus wrote: post #265
marshray wrote: post #203

Earlier quoted context omitted.

Well, there's a low grade vacuum outside so you probably don't want to. It's a failure of the onboard steam tanks that scares me. ("The steam is stored onboard until reaching the station. Water and steam tanks are changed automatically at each stop") I don't want to think about what the result of that would look like for the cleanup crew. Eeeewww.

I really doubt the steam tank will be inside the pressurised volume. If they fail they would vent overboard. While an explosive failure would probably cause problems it wouldn't expose the passengers to high pressure steam. The failure mode for composite overwrap pressure vessels is a slow leak, due to the overwrap containing the metal.

A vehicle near the end of its ride will be carrying up to 818 kg (1800 lb) of superheated steam (127 C, 260 F). The 4000 kg (8,900 lb) of onboard batteries and 1800 kg compressor will be dumping heat too. This is 6600 kg of "hot stuff", whereas the entire capsule is projected to have a mass of 15000 kg.

The current design has the passengers in an enclosed capsule in between the compressors and the batteries, with a pressurized air channel running right down the center isle.

Keeping the cabin cool will be a challenge. If that emergency braking is activated, it could get a little warm in there before they are rescued.

I think they may have to quickly repressurize the loop if a car ever gets stuck.

Re: Hyperloop

#350

Post by apendleton »

goodcanadian wrote: post #270
cma wrote: post #238

Earlier quoted context omitted.

Can you elevate rail as easily? We're talking a lot more weight being carried by the pillars in that case. Plus you don't get the same natural banking off the walls he talks about, which is relevant at these speeds. While rail could bank, you better be going at the right speed when doing so, too slow and you just fall laterally off the tracks.

Can you elevate rail as easily? The short answer is, "yes." I've ridden on it. The slightly longer answer (as another commenter has pointed out) is that it depends on the weight of the train versus the weight of the hyperloop. I see no fundamental reason to assume that the hyperloop is lighter than the train. It could be so, but then, we could make smaller and lighter trains, too (light rail). Plus you don't get the…

You can't just make lighter trains; heavy rail is heavy because it has high capacity. These vehicles can be much lower-capacity per vehicle because the speed is very high, which means you get equivalent throughput even with much smaller per-vehicle capacity. It's just like how you can get the same amount of water through a high-pressure, low-diameter pipe as through a low-pressure, high-diameter pipe.

So yes, you could make the rail lighter, but in order to match the proposed passenger throughput, it would have to go 700mph. Good luck with that.

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