Author Topic: The Hyperloop: BUSTED  (Read 77305 times)

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Online nctnico

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Re: The Hyperloop: BUSTED
« Reply #225 on: January 16, 2018, 11:16:48 am »
Since some revived this old thread I watched the video in the first post. I find it cringeworthy. Commercial airliners are made of aluminium composite material and they deal with similar pressures safely so why is that suddenly a problem for the hyperloop?
I'm not a mechanical engineer, yet I can think of many show-stopper problems and why this comparison with planes is not meaningful.
The airplane is just an example of a pressure vessel made as light as possible and yet it withstands similar pressure differences like the hyperloop is supposed to do. Actually an oil or gas pipeline is pretty much comparable to the build scale of a hyperloop tube (and oil and gas pipeline use much higher pressures). It is not like they are building something completely new. For once don't ignore the fact a lot of very smart people are working on building hyperloops allover the world and have working prototypes. Now it all comes down to whether it makes sense economically or not (which intrinsically means getting it safe to operate).
« Last Edit: January 16, 2018, 11:18:57 am by nctnico »
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Offline orion242

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Re: The Hyperloop: BUSTED
« Reply #226 on: January 16, 2018, 12:19:41 pm »
How are you getting up to his speeds if you deal with expansion like oil pipelines as you suggest??  Gonna be one wild as hell ride!



https://www.quora.com/Why-do-oil-pipelines-that-transfer-oil-long-distances-run-in-a-zigzag-manner
 
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Online wraper

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Re: The Hyperloop: BUSTED
« Reply #227 on: January 16, 2018, 12:46:43 pm »
Junctions for thermal expansion compensation are completely possible. They need to hold only 1 bar of pressure, therefore could be made even from soft polymer.
 

Offline hayatepilot

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Re: The Hyperloop: BUSTED
« Reply #228 on: January 16, 2018, 01:53:15 pm »
Since some revived this old thread I watched the video in the first post. I find it cringeworthy. Commercial airliners are made of aluminium composite material and they deal with similar pressures safely so why is that suddenly a problem for the hyperloop?
I'm not a mechanical engineer, yet I can think of many show-stopper problems and why this comparison with planes is not meaningful.
The airplane is just an example of a pressure vessel made as light as possible and yet it withstands similar pressure differences like the hyperloop is supposed to do. Actually an oil or gas pipeline is pretty much comparable to the build scale of a hyperloop tube (and oil and gas pipeline use much higher pressures). It is not like they are building something completely new. For once don't ignore the fact a lot of very smart people are working on building hyperloops allover the world and have working prototypes. Now it all comes down to whether it makes sense economically or not (which intrinsically means getting it safe to operate).
The problem with the pressure difference is not with the pod but with the tube!
It is very important whether the pressure differential is positive or negative. If you have a vacuum inside a tube the walls must be very thick to prevent buckling. And if the tube gets kinked enough then the whole tube collapses in on itself.
If the pressure is on the inside then the tube can withstand much higher pressure differentials.
 

Online nctnico

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Re: The Hyperloop: BUSTED
« Reply #229 on: January 16, 2018, 03:00:36 pm »
Still it is not undoable.
My point is that all these 'debunking', 'busted', etc videos about big projects are just scaremongering, FUD and fake news (as it is called nowadays). IMHO a video which goes into the technical challenges and possible solutions is much more interesting. I hate the 'can't do /can't be done' attitude because it stops progress. FFS people have walked on the moon so how hard can it be to run a pod through a vacuum tube? Try it at least!
« Last Edit: January 16, 2018, 03:02:33 pm by nctnico »
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Offline ebastler

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Re: The Hyperloop: BUSTED
« Reply #230 on: January 16, 2018, 03:28:50 pm »
The problem with the pressure difference is not with the pod but with the tube!
It is very important whether the pressure differential is positive or negative. If you have a vacuum inside a tube the walls must be very thick to prevent buckling. And if the tube gets kinked enough then the whole tube collapses in on itself.
If the pressure is on the inside then the tube can withstand much higher pressure differentials.

OK, I'll offer submarines as an example then. Correct direction of the pressure differential there. Yes, they are built much sturdier than airplanes, and are rather short for a hyperloop tube... But they also withstand quite a bit more pressure than one atmoshpere.
 

Offline jonovid

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Re: The Hyperloop: BUSTED
« Reply #231 on: January 16, 2018, 04:11:40 pm »
this 285 mph - 500km/h  japanese maglev train looks like a lot safer way to travel.
 
as for Hyper loop
until we see a full working prototype that elon musk himself must ride, addressing all safety concerns.
Hyperloop will remain a billionaires toy train set.
Hobby of evil genius      basic knowledge of electronics
 

Offline HalFET

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Re: The Hyperloop: BUSTED
« Reply #232 on: January 16, 2018, 05:02:45 pm »
Since some revived this old thread I watched the video in the first post. I find it cringeworthy. Commercial airliners are made of aluminium composite material and they deal with similar pressures safely so why is that suddenly a problem for the hyperloop?
I'm not a mechanical engineer, yet I can think of many show-stopper problems and why this comparison with planes is not meaningful.
The airplane is just an example of a pressure vessel made as light as possible and yet it withstands similar pressure differences like the hyperloop is supposed to do. Actually an oil or gas pipeline is pretty much comparable to the build scale of a hyperloop tube (and oil and gas pipeline use much higher pressures). It is not like they are building something completely new. For once don't ignore the fact a lot of very smart people are working on building hyperloops allover the world and have working prototypes. Now it all comes down to whether it makes sense economically or not (which intrinsically means getting it safe to operate).
The problem with the pressure difference is not with the pod but with the tube!
It is very important whether the pressure differential is positive or negative. If you have a vacuum inside a tube the walls must be very thick to prevent buckling. And if the tube gets kinked enough then the whole tube collapses in on itself.
If the pressure is on the inside then the tube can withstand much higher pressure differentials.

Heh, these assumptions are a bit of a fallacy in some ways. You could design around this to prevent catastrophic failure by taking for example a double walled tube with sections which fail in a controlled manner. (e.g. perforated inner tube with foam and reinforcement rings around it inside the tube that acts as the "pressure vessel") That way the failure would be a lot more gradual and a lot safer. Keep in mind folks, we're engineers and not nay-sayers, which isn't to say this is very ambitious, but to outright shoot it down based on simplistic assumptions seems a bit low. The math on this points at it being a lot more feasible than solar roadways for example... I've seen more questionable things than this succeed before.
 
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Online wraper

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Re: The Hyperloop: BUSTED
« Reply #233 on: January 16, 2018, 06:06:04 pm »
The problem with the pressure difference is not with the pod but with the tube!
It is very important whether the pressure differential is positive or negative. If you have a vacuum inside a tube the walls must be very thick to prevent buckling. And if the tube gets kinked enough then the whole tube collapses in on itself.
If the pressure is on the inside then the tube can withstand much higher pressure differentials.
FWIW, usual tunnel tubes must withstand much higher outside pressure than miserable 1 bar in case of hyperloop.
http://www.cowi.com/menu/service/bridgetunnelandmarinestructures/tunnels/documents/021-1700-020e-10b_tunnelengineering.pdf
Quote
Great Belt
The Great Belt tunnel is to date the world’s
deepest tunnel in soft soil conditions and under
the sea.
The challenge was to design the tunnel lining
for extraordinary conditions with regard to
outside pressure and chemical aggressivity and
also to design joints to be resistant to the ambient
water pressure (8 bar).

Quote
The TBM is required to operate in open or
closed mode in extremely variable geological
and hydrogeological conditions with water
pressures corresponding to 130 metres head of
water. As such, the TBM was designed to be
able to excavate short distances at up to 13 bar
pressure.
 

Online wraper

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Re: The Hyperloop: BUSTED
« Reply #234 on: January 16, 2018, 06:09:25 pm »
this 285 mph - 500km/h  japanese maglev train looks like a lot safer way to travel.\
Expensive as hell, and not nearly as fast.
 

Offline technix

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Re: The Hyperloop: BUSTED
« Reply #235 on: January 16, 2018, 06:15:41 pm »
I've been on a MagLev train at 430kmh.
There is a single city with a 430km/h maglev... when did you visit Shanghai?
 

Offline orion242

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Re: The Hyperloop: BUSTED
« Reply #236 on: January 16, 2018, 08:00:51 pm »
FWIW, usual tunnel tubes must withstand much higher outside pressure than miserable 1 bar in case of hyperloop.

All underground where expansion is less of an issue since temps remain constant and they are not steel.  Nothing stopping them from taking the hyperpoop underground.  Might take a few generations before we see a cross country underground tube network.

I also don't think TBMs can work in all soil types either.
« Last Edit: January 16, 2018, 08:04:29 pm by orion242 »
 

Offline EEVblog

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Re: The Hyperloop: BUSTED
« Reply #237 on: January 16, 2018, 09:44:56 pm »
Still it is not undoable.

Solar roads, uBeam and Energous are not "undoable" either.

Quote
My point is that all these 'debunking', 'busted', etc videos about big projects are just scaremongering, FUD and fake news (as it is called nowadays).

No, they are calling out obvious impractical bullshit.

Quote
so how hard can it be to run a pod through a vacuum tube? Try it at least!

You'll see...
 

Offline GeorgeOfTheJungle

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Re: The Hyperloop: BUSTED
« Reply #238 on: January 16, 2018, 10:09:34 pm »
Anybody knows how much was the US deficit and debt in the sixties during the "space race" ? Isn't it now over eighteen million millions (108% of GDP)? Is it ok to increase both (deficit and debt) to spend in this, now? Is this experiment being private or publicly funded? And, do you even have a say on this matter?
i= i++;
 

Online nctnico

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Re: The Hyperloop: BUSTED
« Reply #239 on: January 16, 2018, 11:15:11 pm »
Still it is not undoable.
Solar roads, uBeam and Energous are not "undoable" either.
Quote
My point is that all these 'debunking', 'busted', etc videos about big projects are just scaremongering, FUD and fake news (as it is called nowadays).
No, they are calling out obvious impractical bullshit.
Perhaps but without doing some real research into the subject, the project itself and the people behind the project a debunking video quickly becomes unfounded FUD. A first simple check is to see if a project is done by multiple companies (in parallel) or just one and where the funding is coming from.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Online nctnico

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Re: The Hyperloop: BUSTED
« Reply #240 on: January 16, 2018, 11:16:39 pm »
Still it is not undoable.
Solar roads, uBeam and Energous are not "undoable" either.
Quote
My point is that all these 'debunking', 'busted', etc videos about big projects are just scaremongering, FUD and fake news (as it is called nowadays).
No, they are calling out obvious impractical bullshit.
Perhaps but without doing some real research into the subject, the project itself and the people behind the project a debunking video quickly becomes unfounded FUD. A first simple check is to see if a project is done by multiple companies (in parallel) or just one and where the funding is coming from.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Online ogden

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Re: The Hyperloop: BUSTED
« Reply #241 on: January 16, 2018, 11:52:24 pm »
No, they are calling out obvious impractical bullshit.

NASA and France space agency (CNES) both were skeptical about reusable rocket booster. Wording was not "impractical bullshit", but close. Yet SpaceX prove them wrong, in surprisingly short time BTW. All those who "debunked" rocket landing as obviously impractical bullshit, failed as well. So... you never know :)

With current knowledge and technology we most likely will not travel in vacuum tube, but maybe in 100 years our descendants or at least their postage - will.
 

Offline james_s

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Re: The Hyperloop: BUSTED
« Reply #242 on: January 17, 2018, 01:36:56 am »
I have not looked into the hyperloop in detail but it doesn't immediately jump out at me as bullshit, I see no over-unity claims, no magic required. Given unlimited resources I have little doubt it could be made a reality. Unlike aircraft, capsule weight is of relatively little importance, the thing could be incredibly stout and sturdy

Now whether or not it ever becomes feasible to actually build the thing I don't know but the safety aspect doesn't worry me too much. Somewhere between 100-150 people die every single day in car accidents just in the US, rapid transportation has inherent risks. Yes a hyperloop accident could be spectacular with a lot of deaths but so is an airliner crash and that doesn't stop us from flying. I suspect the barrier is going to be almost purely financial rather than engineering. Building an entire new infrastructure of this sort is incredibly expensive, it pretty much has to blast straight through to be practical.
 
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Offline mtdoc

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Re: The Hyperloop: BUSTED
« Reply #243 on: January 17, 2018, 03:26:21 am »
Is it ok to increase both (deficit and debt) to spend in this, now?

Perhaps not, but better this than spend $700 Billion on the military .

I I suspect the barrier is going to be almost purely financial rather than engineering. Building an entire new infrastructure of this sort is incredibly expensive, it pretty much has to blast straight through to be practical.

Exactly! It  is the financial and political realities that will likely prevent long distance hyperloop transport in the USA, not the engineering.  While there are certainly engineering challenges, I’ve read enough back and forth between the “busted!” proponents and real Engineers with experience and expertise in the relevant areas to convincingly debunk the “debunkers” IMHO.
 
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Offline EEVblog

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Re: The Hyperloop: BUSTED
« Reply #244 on: January 17, 2018, 07:13:00 am »
A first simple check is to see if a project is done by multiple companies (in parallel) or just one and where the funding is coming from.

Another first simple step is to stop and think why no one has done this old idea before:

Has there been some radical breakthrough in maglev technology? No.
Has there been some radical breakthrough in ridiculously large scale vacuum tunnel technology suitable for human carriage over hundreds of km? No.
Has there been some other radical breakthrough in the transport market space? No.
Has there been some other breakthrough in cost reduction in anything to do with this? No.

Has there been some huge hype from the most influential tech person on the planet? Yes.
Does this hype attract bandwagon chasing money? Yes.
 

Offline technix

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Re: The Hyperloop: BUSTED
« Reply #245 on: January 17, 2018, 07:57:52 am »
I would still prefer the hourly high speed trains that runs at 20% below its maximum test speed. A lot safer and likely a lot cheaper. Yes I am talking about the China Railway High-speed trains "Rejuvenation" that runs between Shanghai and Peking.
 

Offline HalFET

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Re: The Hyperloop: BUSTED
« Reply #246 on: January 17, 2018, 08:16:46 am »
Still it is not undoable.

Solar roads, uBeam and Energous are not "undoable" either.

Quote
My point is that all these 'debunking', 'busted', etc videos about big projects are just scaremongering, FUD and fake news (as it is called nowadays).

No, they are calling out obvious impractical bullshit.

Quote
so how hard can it be to run a pod through a vacuum tube? Try it at least!

You'll see...

I'm mostly curious about energy efficiency, what'd take less energy:
  • Vacuum pumps running 24/7 to keep an inherently leaky system at low air pressures.
  • Doubling the speed of high speed maglev-based "rail".
I would expect there's a point where they meet, and I'm not so sure the current speeds are there already. Especially over long distances it would most likely be more energy efficient to run the second option.
 

Offline Tepe

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Re: The Hyperloop: BUSTED
« Reply #247 on: January 17, 2018, 08:16:55 am »
NASA and France space agency (CNES) both were skeptical about reusable rocket booster. Wording was not "impractical bullshit", but close. Yet SpaceX prove them wrong, in surprisingly short time BTW.
That skepticism is not without merit. Think of the Tsiolkovsky rocket equation. You have to lift the fuel you are going to need for the landing, so presumably it basically boils down to saving more on not having to build a new booster versus the price of the extra fuel needed.
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Online ogden

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Re: The Hyperloop: BUSTED
« Reply #248 on: January 17, 2018, 08:42:23 am »
Another first simple step is to stop and think why no one has done this old idea before:
Has there been some radical breakthrough in maglev technology? No.

Maglev and linear motor technology itself shall be considered as breakthrough in this context. Then it did not exist - maybe that's why no one has done it.

Quote
Has there been some huge hype from the most influential tech person on the planet? Yes.
Does this hype attract bandwagon chasing money? Yes.

Has there been people who tend to use popular hype "buzzwords" to their advantage? Yes.
Does such approach attract more people to their audience? Yes :)
 

Online ogden

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Re: The Hyperloop: BUSTED
« Reply #249 on: January 17, 2018, 08:51:02 am »
Think of the Tsiolkovsky rocket equation. You have to lift the fuel you are going to need for the landing

Yes. Think of it. When landing comes, payload and 2nd stage is already lifted and fuel which were used to lift all that is already gone - meaning not that much fuel is needed to decelerate remaining mass for safe reentry speed. After all they are doing it now, so nothing much to discuss here.
 


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