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TerryM

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Re: The Hyperloop
« Reply #350 on: February 10, 2018, 04:42:44 PM »
Wow!
Assuming they were at speed, they'd have been at 430 kph and 350 kph. Their closing speed would have been 780 kpm or 485 mph.


The slower HSR would run from Los Angeles California to Las Vegas Nevada in just over one hour. Back in 2011 this train was transporting 82,000 passengers per day.


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

and

https://en.wikipedia.org/wiki/Shanghai%E2%80%93Hangzhou_high-speed_railway

These are not the newest designs. This maglev train has been running since 2004, and this HSR since 2010. North America is simply falling further and further behind the rest of the world.

Are we waiting for a technical fix that will leapfrog us over our competition, or will we simply delay attempting something we have neither the expertise, nor the financing to build?
Terry

Rob Dekker

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Re: The Hyperloop
« Reply #351 on: February 12, 2018, 04:27:27 AM »
Top Ten Reasons why Elon Musk should use MagLev instead of, or as part of, Hyperloop

http://www.levicar.com/Hyperloop/

10) Hyperloop is inflexible

Hyperloop goes only from one specific point to another specific point and back, meaning that if you need to get from somewhere else to somehwere else, you need to spend extra time just getting to the first station, and also just getting from the destination station to your final destination.
♦MagLev, using the hexOgrid configuration, will have rails in an 18-mile hexagrammoid grid, with depots within ten miles, by road, from any point in a built-up (urban or suburban) area.

9) Maintaining even a partial vacuum at this scale is difficult and expensive.

Hyperloop uses a huge partially-evacuated transportation tube.  Maintaining even a partial vacuum would be difficult.  A catastrophic loss of air would shut down the whole thing.  If a slow air-leak occurs, and it is not right where the vacuum pumps are, it might take a while for the leaked-in air to diffuse to the pump.
♦MagLev systems generally run in the open air, resulting in a simpler, cheaper architecture, at the expense of increased air resistance.

8) Hyperloop uses large, noisy fans in front of each pod.

A Hyperloop pod has a large suction fan in front.  Its purpose is to reduce the air resistance, even though the pod is moving through a partial vacuum; and to provide air to lift the pod's “skis” off the bottom inner surface of the tube, forming an “air bearing”.  (The skis support the pods.)  This suction fan is sure to make a lot of noise, probably overwhelming any sound insulation.
♦MagLev uses traditional methods to minimize air resistance and noise, such as streamlining and platooning, the latter being when several vehicles travel in a closely-spaced convoy so that they “draft” off of each other, the lead vehicle bearing most of the wind resistance.

7) There is too little clearance between the pods and the tube's inner walls.

In Hyperloop, the pods are supported by “skis”, which receive air from the suction fan, and use this air to push against the inner walls of the transportation tube to levitate the pod.  The clearance between the skis and the inner wall of the tube is only 0.020" to 0.050" (about 0.5 mm to 1.3 mm), far too small.  Any slight irregularity in the inner walls of the tubes, or any sudden movements of the tubes due to accident or seismic activity, could result in a damaging high-speed collision between the skis and the tube’s walls.  In addition, the tubes are required to expand and contract, and the difference is taken up at the terminals, using some sort of telescoping expansion joints.  This would be very rough on the skis.
♦MagLev (of the Danby-Powell architecture) uses clearances of 4" to 6" (about 100 mm to 150 mm), and is well able to tolerate such displacement, including any expansion joints.

6) Switching between tubes is impractical.

Hyperloop relies on the curved lower surface of the tube to keep the pod aligned properly.  In order to have two tubes join, there has to be an irregularity and discontinuity if the curvature of the tubes where they meet.  It is impractical to expect the skis to adjust to this change instantaneously.  This reinforces item (10), and precludes the use of intermediate depots.
♦MagLev:  Most MagLev systems use either heavy monorails, or otherwise use troughs, and switching between rails is therefore very slow, or is so difficult as to be impossible for moving vehicles.  The Danby-Powell MagLev architecture is unique among MagLev systems in that it provides for instantaneous switching between rails.  This is shown in the illustration on the right.  Danby-Powell MagLev vehicles can ride either on a monorail, or in a “double-rail” configuration, the latter supporting easy, instantaneous switching between rails.  Click on the picture to learn more.  This allows individual vehicles to be switched off onto other rails, or onto sidings.  The same strong superconducting magnetic fields that levitate the vehicle, also stabilize it in the double-rail configuaration.      D-P Vehicles

5) Hyperloop pods tend to roll, which might also damage the motors.

Hyperloop lacks any system to provide stability on a continuing basis.  This means that the pods may roll (rotate about the axis of travel), and might travel upside-down.  This also means that the “rotors” on the pods may collide with the stators protruding from the inner was of the tube.  Please check out problems 6 through 9, below.
♦With Danby-Powell MagLev you don’t have to worry if banking will cause a collision with your propulsion system, or how you are going to detect and correct any banking.  The constant drive force makes for a smoother ride.

4) Hyperloop pods are cramped.

Hyperloop  The individual seating inside a Hyperloop pod is reminiscent of a Mercury space capsule.  You cannot get up and move around.  If someone falls ill and needs emergency assistance from another passenger, there might be little room in which to provide it, unless medical equipment (like a defibrillator) is built into each seat.  More medical assistance would have to wait until the end of the trip.  The trips, though, are mercifully short, so it is unlikely that you’d get Deep-Vein Thrombosis (DVT).
♦MagLev offers a variety of seating.  LeviCar offers the same seating as a private automobile.  The MagLev network could also carry vans and buses, which would have more spacious seating.  (It could, in theory, also carry full-length trains, although that would defeat a lot of the flexibility of having individually-targeted vehicles.)  In case of a medical emergency, the vehicle can be diverted to the nearest hospital without waiting to complete the trip.  MagLev portals directly beside a hospital emergency room would place the patient within a few feet of help.

3) Hyperloop cannot carry some of the larger standard freight containers.

Hyperloop  is specified with two different pod sizes, and, correspondingly, two different transportation tube diameters.  (These were the passenger-only pod, and the passenger plus vehicle pod.  Each has its own diameter, and its own requirement for the diameter of the transportation tube.)  At first, it seemed to me that the intention was to have two different-sized pods traveling in the same tube, as long as both satisfy the Kantrowitz Limit.  However, further reading indicated that each size needs its own tube, and, given the cost constraints, only one size tube can be built.  In any case, the larger 10'10" diameter (3.3 m) tube is too small for some standard freight containers, based on the container’s diagonal measurement vs. the inner diameter of the tube.  It looks like only half-height containers would fit.  It is important to be able to carry freight, because that is where the money is.
♦MagLev, becasue it operates in open air, has a lot more flexibility as to the size of the freight containers it can accomodate.  In the event that the 300-mph MagLev system is supplemented by adding vactrain-like shortcut tubes, or wormholes, to the hexOgrid, then the wormholes could be for passenger vehicles only, while freight would travel only on the 300-mph network.

2) Escaping from a transportation tube can be a dicey experience.

Hyperloop  is supposed to use solid steel transportation tubes, but these are to be equiped with escape hatches.  These hatches could be a problematic source of leaks.  Also, the hatches must not be where the skis are in near-contact with the walls, because that would produce irregularities in the walls that can cause collisions with the skis.
♦MagLev, again becasue it operates in open air, does not have these problems.
… and the final reason why Elon Musk should use MagLev:

1) Tesla is the best company to manufacture LeviCars.

The LeviCar system, in addition to the MagLev rail component, also features modular cars.  There are many reasons to use such modular cars.  They make it so only car body, with passengers and luggage, need to ride the MagLev rails.  By not including the drivetrain, wheels, and batteries or fuel tanks, we can reduce the mass that is transported, and enhance safety by eliminating concentrated stores of energy.  They are also much easier to repair.  If something goes bad in either the front or rear chassis, simply swap the chassis with another equivalent rebuilt one, and later rebuild the swapped-out chassis and give it to another customer.
Of all the automobile manufacturers in America, the one best equipped to built LeviCars is (drumroll, please) Tesla, Elon Musk’s company.  So, backing the LeviCar / RoboTrail MagLev system can be a very smart business move for Mr. Musk.  Tesla owns the IP rights to many of the components that can be used in a LeviCar vehicle, and even if Tesla does not have the capacity to manufacture all of them, they certainly could license the technology to other companies, and make millions from the royalties.

----

May I add to this the issue of tube thermal expansion, which is a deal killer for any tube longer than 10 km, and the issue of terrorist attacks (blowing or denting the tube) leading to catastrophic failure of the entire system.
« Last Edit: February 12, 2018, 06:41:58 AM by Rob Dekker »

Sleepy

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Re: The Hyperloop
« Reply #352 on: February 12, 2018, 11:48:27 AM »
These are not the newest designs. This maglev train has been running since 2004, and this HSR since 2010. North America is simply falling further and further behind the rest of the world.[/size]

Are we waiting for a technical fix that will leapfrog us over our competition, or will we simply delay attempting something we have neither the expertise, nor the financing to build?
Terry
Lost you comment, sorry.
Maglev works and has a lot of advantages, still there are chinese engineers who calls the Shanghai Transrapid a white elephant, economy wise. With a slightly broader view, not so much.

NA do seem to be slipping further behind the rest of the world nowadays. There are (and have been for years) real world solutions out there. Both when it comes to mitigation and transport problems.

One huge real world issue that affects all large scale transport solutions, is that they always need support from governments and tax payers.
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Sigmetnow

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Re: The Hyperloop
« Reply #353 on: February 12, 2018, 06:30:47 PM »
Top One Reason for not using a LeviCar:  Because a hyperloop is faster. 

The article says LeviCar travels at 300mph.  The Hyperloop can go more than twice that on straight sections, significantly reducing the time required for long-distance travel.

Speed is what kept the Concorde flying for 27 years — being valued more than safety, convenience and expense.  Customers did not care about the technical details, they just wanted to get to their destination as quickly as possible.
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Sleepy

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Re: The Hyperloop
« Reply #354 on: February 12, 2018, 09:07:03 PM »
<snip, unproven commercials>
Speed is what kept the Concorde flying for 27 years — being valued more than safety, convenience and expense.  Customers did not care about the technical details, they just wanted to get to their destination as quickly as possible.
Exactly. Maybe customers should have cared?



Taking one of the mentioned issues from the video above and a trip down memory lane to 1995, why noone never really could afford the Concorde:

Abstract

Emission indices of reactive gases and particles were determined from measurements in the exhaust plume of a Concorde aircraft cruising at supersonic speeds in the stratosphere. Values for NOx (sum of NO and NO2) agree well with ground-based estimates. Measurements of NOx and HOx indicate a limited role for nitric acid in the plume. The large number of submicrometer particles measured implies efficient conversion of fuel sulfur to sulfuric acid in the engine or at emission. A new fleet of supersonic aircraft with similar particle emissions would significantly increase stratospheric aerosol surface areas and may increase ozone loss above that expected for NOx emissions alone.

Adding that paper.
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Sigmetnow

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Re: The Hyperloop
« Reply #355 on: February 12, 2018, 09:49:10 PM »
<snip, unproven commercials>
Speed is what kept the Concorde flying for 27 years — being valued more than safety, convenience and expense.  Customers did not care about the technical details, they just wanted to get to their destination as quickly as possible.
Exactly. Maybe customers should have cared?
...
Taking one of the mentioned issues from the video above and a trip down memory lane to 1995, why noone never really could afford the Concorde:
Abstract

Emission indices of reactive gases and particles were determined from measurements in the exhaust plume of a Concorde aircraft cruising at supersonic speeds in the stratosphere. Values for NOx (sum of NO and NO2) agree well with ground-based estimates. Measurements of NOx and HOx indicate a limited role for nitric acid in the plume. The large number of submicrometer particles measured implies efficient conversion of fuel sulfur to sulfuric acid in the engine or at emission. A new fleet of supersonic aircraft with similar particle emissions would significantly increase stratospheric aerosol surface areas and may increase ozone loss above that expected for NOx emissions alone.
...

Non sequitur.  None of the hyperloop options under discussion will have such emissions.
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Sleepy

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Re: The Hyperloop
« Reply #356 on: February 12, 2018, 10:01:07 PM »
Non sequitur?  ;D
Don't you ever read? I't was pretty clear what I was commenting, your defence for speed and that customers did not care about the technical details. Or this planet.

Edit; ok, I'll add comments for what I snipped off above as commercials:
Top One Reason for not using a LeviCar:  Because a hyperloop is faster

The article says LeviCar travels at 300mph.  The Hyperloop can go more than twice that on straight sections, significantly reducing the time required for long-distance travel.
None of this has happened yet. And most likely never will, all things considered.
« Last Edit: February 12, 2018, 10:08:55 PM by Sleepy »
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Sleepy

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Re: The Hyperloop
« Reply #357 on: February 12, 2018, 10:55:14 PM »
I don't use twitter anymore but that's not really needed. This is spot on as usual by Kevin Anderson and exactly what I think when it comes to all of these non proven futuristic promises.
https://twitter.com/KevinClimate/status/962763202978250753
It would've been far easier had we started in 1990 (i.e. publication of first IPCC report). But 28yrs of technocratic scams substituting for real mitigation leaves us facing the huge challenge you rightly outline. So are we now going to continue with scams or actually mitigate?
Adding Pielkes image, which he was commenting. It starts in 1992.
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SteveMDFP

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Re: The Hyperloop
« Reply #358 on: February 13, 2018, 01:40:34 AM »
Maglev trains have been brought up here in contrast with Hyperloop.  Interestingly, plans are advancing for a Mag-lev route between Baltimore and Washington, DC (with possible later extension to NYC):

Enthusiasm for ‘maglev’ train between D.C., Baltimore mounts — as does opposition
https://www.washingtonpost.com/local/trafficandcommuting/enthusiasm-for-maglev-train-between-dc-baltimore-mounts--as-does-opposition/2018/01/06/ef490ee0-e112-11e7-89e8-edec16379010_story.html?utm_term=.3b17b43c8ae6

Also interestingly, the route is very close the Musk's plan for the Boring tunnel between these cities.  They'd both pass just a few miles from me.  I wonder if one or both will have a stop at BWI airport?  That would be nifty.  Not that I ever fly, it's also a public transit hub.

TerryM

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Re: The Hyperloop
« Reply #359 on: February 13, 2018, 03:08:10 AM »
Apparently the Russians were experimenting with electromagnetically levitated cars running in an evacuated tube a little over 100 years ago.
Unfortunately WWI broke out, then a revolution. The inventor eventually starved to death in the siege of Leningrad during WWII.


https://www.kramola.info/vesti/novosti/izobreteniya-dorevolyucionnoy-rossii-vagon-mchashchiysya-bez-treniya-v-magnitnom

translate seems to work to some extent
Terry

jai mitchell

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Re: The Hyperloop
« Reply #360 on: February 13, 2018, 03:55:55 AM »
I don't use twitter anymore but that's not really needed. This is spot on as usual by Kevin Anderson and exactly what I think when it comes to all of these non proven futuristic promises.
https://twitter.com/KevinClimate/status/962763202978250753
It would've been far easier had we started in 1990 (i.e. publication of first IPCC report). But 28yrs of technocratic scams substituting for real mitigation leaves us facing the huge challenge you rightly outline. So are we now going to continue with scams or actually mitigate?
Adding Pielkes image, which he was commenting. It starts in 1992.

This Pielke image is, as usual, deceptive.  His equivalent energy consumption comparisons with electricity do not take into account that electric vehicles are 90% more efficient than internal combustion ones.  Similarly, local power generation by solar combined with heat pump heating (compared with coal or natural gas systems that are 60% to 70% efficient with 7-10% line loss and using only standard resistance-heating systems that are 50% less efficient than heat pump heating) would require a significantly smaller fraction of total energy for the same end-use purposes.  Not to mention the 10% of total energy usage being spent on fossil fuel extraction, transport and refining. . .
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Rob Dekker

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Re: The Hyperloop
« Reply #361 on: February 13, 2018, 05:40:22 AM »
Top One Reason for not using a LeviCar:  Because a hyperloop is faster. 

The article says LeviCar travels at 300mph.  The Hyperloop can go more than twice that on straight sections, significantly reducing the time required for long-distance travel.

I think Sleepy already touched on this issue, but it is worth emphasizing :
There are several issues that will come to play when Hyperloop exceeds speeds of 300 mph.

The most important one is that it is going to need a vacuum pump (a compressor) in front of each pod. Otherwise, air will stall and air resistance (even though it is under near vacuum) will increase exponentially. This is point 8 above in the list of why Hyperloop is a bad compared to plain MagLev.

That vacuum pump needs to have a diameter close to the diameter of the pod (2-3 meters or more) to be effective. And at 0.001 bar pressure, it will need to spin about 10x faster than a jet engine.
No such vacuum pump has been invented yet, let alone tested.

Also, if you DO develop such large diameter vacuum pump, you need to have a safety ring around it to contain blade failure. For jet engines they use a Kevlar ring, but since the pump needs to spin 10x faster than a jet engine, Kevlar is probably not good enough.

Here is a test of that Kevlar ring upon a blade failure on a jet engine :



Now imagine the blades spinning 10x faster...

And remember that without a containing ring, if a blade of that pump fails, it will not only de-pressurize (or destroy) the pod, but it will also penetrate the tube, which will cause catastrophic system failure, probably destroying all pods in the tube at that time.

And once again, this is only one of the really difficult issues faced when Hyperloop will want to go faster than MagLev (at 300 mph), and right now they don't have a tube long enough to even test that.
« Last Edit: February 13, 2018, 06:22:18 AM by Rob Dekker »

Sleepy

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Re: The Hyperloop
« Reply #362 on: February 13, 2018, 10:00:07 AM »
I don't use twitter anymore but that's not really needed. This is spot on as usual by Kevin Anderson and exactly what I think when it comes to all of these non proven futuristic promises.
https://twitter.com/KevinClimate/status/962763202978250753
It would've been far easier had we started in 1990 (i.e. publication of first IPCC report). But 28yrs of technocratic scams substituting for real mitigation leaves us facing the huge challenge you rightly outline. So are we now going to continue with scams or actually mitigate?
Adding Pielkes image, which he was commenting. It starts in 1992.

This Pielke image is, as usual, deceptive.  His equivalent energy consumption comparisons with electricity do not take into account that electric vehicles are 90% more efficient than internal combustion ones.  Similarly, local power generation by solar combined with heat pump heating (compared with coal or natural gas systems that are 60% to 70% efficient with 7-10% line loss and using only standard resistance-heating systems that are 50% less efficient than heat pump heating) would require a significantly smaller fraction of total energy for the same end-use purposes.  Not to mention the 10% of total energy usage being spent on fossil fuel extraction, transport and refining. . .
Thanks Jai, that might be so but how accurate will your own assumptions be? I haven't followed Pielke and I emphasized on Kevins comment.

I'm in a hurry right now, so I'll just quote these two commment I made yesterday and today. I don't have clue on what to expect from the US but this is what I see:
https://forum.arctic-sea-ice.net/index.php/topic,2252.msg141863.html#msg141863
https://forum.arctic-sea-ice.net/index.php/topic,2252.msg141918.html#msg141918

I'll cross post the previous comment in the Paris thread since it better suited there.
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Sleepy

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Re: The Hyperloop
« Reply #363 on: February 13, 2018, 03:15:30 PM »
And once again, this is only one of the really difficult issues faced when Hyperloop will want to go faster than MagLev (at 300 mph), and right now they don't have a tube long enough to even test that.

Or a pod with a working compressor to counter the Kantrowitz limit. I've seen a pod that had a fan but that was built into the pod. Either a larger fan or they have to build a larger tunnel.

That video needs a slow mo? :)
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Sigmetnow

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Re: The Hyperloop
« Reply #364 on: February 13, 2018, 09:14:11 PM »
“A circular-trough MagLev has not yet been designed…”
“Again, speculating:  One possibility is to use a D-P MagLev system with a Linear Synchronous Motor (LSM) in a monorail within the transportation tube. ”
“Of course, all this is sheer speculation — I haven’t solved any problems, just posed them.”
“Once we have a MagLev rail in the transportation tube, we might as well use something like the pneumatic assist…”
“When we put a D-P MagLev rail inside a transportation tube, we have to determine if it is feasible to have switching points…”


Your LeviCar article is nothing but spitballing. 

Richard Branson’s Virgin Hyperloop One has a full-size, functioning hyperloop pod being tested in a section of vacuum tube.  It has already gone much faster than the LeviCar ever will.  People like faster more than spit.
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Rob Dekker

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Re: The Hyperloop
« Reply #365 on: February 14, 2018, 05:16:14 AM »
Richard Branson’s Virgin Hyperloop One has a full-size, functioning hyperloop pod being tested in a section of vacuum tube.  It has already gone much faster than the LeviCar ever will.  People like faster more than spit.

The Hyperloop pod in Virgin Hyperloop went 240 mph in the test tube.
That's not as fast as MagLev, which clocks in at 300 mph.

The issue is that the real problems with Hyperloop only START when they want to go much faster than 300 mph.

For such speeds, I outlined 10 engineering issues above. And I highlighted one issue : the issue of the need for a wide diameter compressor on the pod, a compressor that has not been invented yet, let alone tested.

Sigmetnow, I really like your enthusiasm for Hyperloop, but the engineering challenges of moving a spacecraft through a gun barrel at near speed of sound are enormous, and I don't see that they have even started to address them in real life tests.

[edit] And that is not even addressing the question of how Hyperloop (MagLev in a vacuum tube) can ever be cheaper than plain MagLev.
« Last Edit: February 14, 2018, 05:26:04 AM by Rob Dekker »

gerontocrat

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Re: The Hyperloop
« Reply #366 on: February 14, 2018, 11:06:59 AM »

Sigmetnow, I really like your enthusiasm for Hyperloop, but the engineering challenges of moving a spacecraft through a gun barrel at near speed of sound are enormous, and I don't see that they have even started to address them in real life tests.

I once read that the gun barrel on a large howitzer only had a life span on a few seconds of actual use (mind you - a good many rounds could be fired in that time). The hyperloop is an awfully big gun barrel and the pod is an awfully big shell. But what do I know?
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Sleepy

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Re: The Hyperloop
« Reply #367 on: February 14, 2018, 11:30:47 AM »
Sigmetnow, I really like your enthusiasm for Hyperloop, but the engineering challenges of moving a spacecraft through a gun barrel at near speed of sound are enormous, and I don't see that they have even started to address them in real life tests.
No, they haven't.
There's also another consideration when it comes to the compressor itself, they would probably need to use contra-rotating blades to avoid rotational forces on the pod itself.
In a gun you want the bullet to rotate for stability, but I don't think passengers in a pod would appreciate that. :)

There's a magic number popping up everywhere I read, just above mach 0.5...

First image is the Kantrowitz equation. The A* would be then the bypass area and A the tube area. It's from this paper: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100001729.pdf

The rLoop team provides an open source github repository and since I have python installed, I installed it and after a few updates to python, ran it with their default values.
http://www.rloop.org/
https://github.com/rLoopTeam/Kantrowitz
Image number two shows really straight and nice lines right? Marked the interesting area in red.

The last graph is from the MIT team:
Area ratio (pod-to-tube) versus Mach number. Mext is the maximum Mach number of the flow around the pod – if M = 1 the flow is exactly choked. The red line indicates the Kantrowitz limit...

Also adding this link from SoftInWay Inc. A global engineering company specializing in turbomachinery:
http://blog.softinway.com/en/axial-compressor-challenges-in-hyperloop-designs/
Musk proposed a compression ratio of about 20:1, which would require several compression stages for an axial compressor arrangement and an intercooler system. The temperature increases resulting from this high order compression require a complex cooling method or a traditional steam pressure vessel for the proper dumping of hot air. A final challenge on the compressor end would be the fact that it will be operating at a very low pressure. Only a handful of companies like Safran Aero Boosters have the necessary experience with low-pressure compression.

So, we have companies selling dreams (and municpalities spending tax payers money), while not having solved real world issues. Buying an acre of the moon would be better, you could at least look at it though a telescope when the weather allows.
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Sigmetnow

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Re: The Hyperloop
« Reply #368 on: February 14, 2018, 06:56:44 PM »
Richard Branson’s Virgin Hyperloop One has a full-size, functioning hyperloop pod being tested in a section of vacuum tube.  It has already gone much faster than the LeviCar ever will.  People like faster more than spit.

The Hyperloop pod in Virgin Hyperloop went 240 mph in the test tube.
That's not as fast as MagLev, which clocks in at 300 mph.
...

But it’s 240mph faster than the LeviCar vaporware you touted.

Edit:  The Hyperloop prototype speed is also limited by the amount of acceleration possible during the short length of the current tube.
« Last Edit: February 14, 2018, 07:09:55 PM by Sigmetnow »
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ghoti

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Re: The Hyperloop
« Reply #369 on: February 15, 2018, 03:29:04 PM »
The Hyperloop One (Virgin) dev test tube track is only 500 meters long. That's pretty high speed to hit given it also has to brake before the end!

Sleepy

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Re: The Hyperloop
« Reply #370 on: February 15, 2018, 10:15:44 PM »
It wouldn't matter if they built that tube ten times around the planet, they will never get past the Kantrowitz limit without a compressor, which does not exist. Look at the MIT graph above. The problems will start just above mach 0.5.
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Rob Dekker

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Re: The Hyperloop
« Reply #371 on: February 16, 2018, 06:33:35 AM »
There's a magic number popping up everywhere I read, just above mach 0.5...

First image is the Kantrowitz equation. The A* would be then the bypass area and A the tube area.

Spot on Sleepy !
I just found a great article by an engineer who outlines the basic issues with Hyperloop :

https://mappingignorance.org/2018/02/07/the-limits-of-hyperloop/

This guy nails it. He points out the Kantrowitz limit, and that beyond that you really need a large diameter compressor. And that such compressor that is not available yet. And that Hyperloop One does not seem to be planning on one either. Sure, you can muscle your way through the Kantrowitz limit, but that would defy the purpose of having a vacuum tube in the first place.

Interesting is that he notes that during the latest tests (the 240 mph test) Hyperloop One had to reduce the pressure in the tube to 25 Pa, which is already four times less than envisaged by Musk.
Which suggests that Hyperloop is are already feeling the Kantrowitz limit....

Either way, this article is a must-read for anyone interested in Hyperloop design.

Note also that Hyperloop One starts to look less and less like Elon's Alpha proposal.
They already ditched the 'air cushion' and went to MagLev instead.
They also ditched the 'compressor' which now restricts them to < 0.5 mach speed.
Now in order to eliminate the Kantrowitz limit they should ditch the tube as well.
Solves a lot of other fundamental problems too (like the thermal expansion problem).

What we would have left over is a MagLev, which then would need to compete with HSR on price.
« Last Edit: February 16, 2018, 08:22:23 AM by Rob Dekker »

Rob Dekker

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Re: The Hyperloop
« Reply #372 on: February 16, 2018, 06:36:31 AM »
The Hyperloop One (Virgin) dev test tube track is only 500 meters long.

Which makes me wonder : If they want to go as fast as they claim they want to go (670 miles per hour or 1080 kilometers per hour), why don't they build a test tube that can test that kind of speeds ?

Rob Dekker

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Re: The Hyperloop
« Reply #373 on: February 16, 2018, 07:06:48 AM »
One final note, and this one is technical.

Elon's design proposed "air cushions" to levitate the pod (about 1 mm over the steel tube).
Virgin Hyperloop One ditched that idea, and went for passive MagLev instead.
That does make sense, since without a (so far non-existing) compressor you would not have any way to form air cushions.

So MagLev it is. There are still many ways to implement that, but it seems that passive MagLev is preferred by both the Hyperloop One team and the Hyperloop Transportation Technologies (HTT).
HTT licensed the Inductrack technology from Lawrence Livermore Labs :

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

Now Inductrack is really nice technology. It uses permanent magnets in the pod (arranged in Halbach arrays) and coils in the railing. It provides a low-energy and very stable levitation system for MagLev.

There is only one problem : The rails need to consist of coils. That means the rails are going to be very expensive, especially compared to Elon's Alpha concept.

Incidentally, if you are going to use coils in the rail, you might as well integrate a power connection in them, so you can use it as a propulsion system as well.
That would eliminate the need for a separate linear motor, and also would make the ride a lot more smoother than Hyperloop One's current idea to install linear motors that would 'boost' the pods speed every minute or so....
« Last Edit: February 16, 2018, 08:27:08 AM by Rob Dekker »

Sleepy

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Re: The Hyperloop
« Reply #374 on: February 16, 2018, 03:16:14 PM »
There's a magic number popping up everywhere I read, just above mach 0.5...

First image is the Kantrowitz equation. The A* would be then the bypass area and A the tube area.

Spot on Sleepy !
I just found a great article by an engineer who outlines the basic issues with Hyperloop :

https://mappingignorance.org/2018/02/07/the-limits-of-hyperloop/

This guy nails it. He points out the Kantrowitz limit, and that beyond that you really need a large diameter compressor. And that such compressor that is not available yet. And that Hyperloop One does not seem to be planning on one either. Sure, you can muscle your way through the Kantrowitz limit, but that would defy the purpose of having a vacuum tube in the first place.

Interesting is that he notes that during the latest tests (the 240 mph test) Hyperloop One had to reduce the pressure in the tube to 25 Pa, which is already four times less than envisaged by Musk.
Which suggests that Hyperloop is are already feeling the Kantrowitz limit....

Either way, this article is a must-read for anyone interested in Hyperloop design.

Note also that Hyperloop One starts to look less and less like Elon's Alpha proposal.
They already ditched the 'air cushion' and went to MagLev instead.
They also ditched the 'compressor' which now restricts them to < 0.5 mach speed.
Now in order to eliminate the Kantrowitz limit they should ditch the tube as well.
Solves a lot of other fundamental problems too (like the thermal expansion problem).

What we would have left over is a MagLev, which then would need to compete with HSR on price.
LOL!  ;D
Thanks, quoting that one:
The estimates previously considered over the XP-1 capsule dimensions allow computing a possible Kantrowitz limit speed for the Virgin Hyperloop One test rig: approximately Mach 0.55 (188 m/s² or 677 km/h, assuming an inner tube temperature of 20 °C).
The Magic Number.

25 Pa? Good luck, imagine keeping that on a 600km tube...
I'm browsing through that MIT final report:
web.mit.edu/mopg/www/papers/MITHyperloop_FinalReport_2017_public.pdf
The image (Kantrowitz_MIT-HL.png) above is from that paper, but the only reference to tube pressure is this:
For the SpaceX Hyperloop competition, the tube pressure is 860 Pa , and
the pod will travel at 250 mph .
The link in the article you posted:
https://hyperloop-one.com/blog/new-chairman-new-funding-new-speed-records
States 200,000 feet which is equivalent to 22 Pa, so it's even less than 25 Pa.

A couple of other quotes from the MIT final report:
Neither option is perfect, it either means limiting the cross-sectional area of the pod, hence decreasing payload or increasing tube construction costs, or it means adding an expensive, high-maintenance compressor to each pod. Furthermore, transonic compressors at such low
Reynolds numbers would require a large research and development effort, because they are not in use in any aerospace application today.
Of course, if the power requirement for a compressor to avoid the Kantrowitz
limit is higher than the power loss due to the additional drag from exceeding the Kantrowitz limit, adding a compressor would be futile.

So, they do know.

Edit; Rob (regarding your last post about the initial design with air bearings) the MIT paper also mentions that in section 3.1 Feasibility of Air Bearings and Compressor.
As more competition rules and track specifications were developed and shared, namely the 1 mm plate steps between track sections, air bearings quickly became infeasible without a massive risk of making contact with the track and putting enormous shear loads on the air bearings and suspension. A sample of the required tank volume as a function of gap height and pad area with a tank pressure at 5000 psi in Fig. 3.1 shows that the tank quickly becomes unfeasibly large at gap heights approaching 1 mm or higher. However, the addition of the aluminum track in the SpaceX track allows for the possibility of maglev systems to be implemented.
« Last Edit: February 16, 2018, 03:26:29 PM by Sleepy »
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Sigmetnow

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Re: The Hyperloop
« Reply #375 on: February 17, 2018, 01:35:21 AM »
Mr. Harj Dhaliwal, Managing Director, Middle East & India, Hyperloop One
spoke briefly yesterday at a conference in India sponsored by the Mahindra group.
“Confluence 2018: Cities on the Horizon - The Oberoi, Delhi - 15th February, 2018”

Mr. Dhaliwal talks about the new paradigm of mass transportation that adjusts to individual customer demands, increasing efficiency and saving energy as compared to rail and bus schedules that run regardless of passenger needs.  He also discusses how high-speed transportation such as the hyperloop can effectively join distant Indian cities together, and allow ports and manufacturing centers to be located away from city centers.

There were audio problems at the start of his speech; the problem is fixed at about 2:49:30.



The talk immediately preceding his, beginning at about 2h 22min, has a few interesting moments regarding autonomous transportation.  Such as: when all cars can talk to each other, heavy traffic can flow seamlessly through big intersections without the need for traffic signals….
« Last Edit: February 17, 2018, 01:44:07 AM by Sigmetnow »
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Sleepy

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Re: The Hyperloop
« Reply #376 on: February 17, 2018, 06:32:08 AM »
I would call the following screen shot presented by Mr. Harj Dhaliwal a blatant lie.

The left part of the image, IT-evolution during those years was highly dependent on miniaturization, we simply can't achieve that with transports. Unless someone invents a transporter á la Star Trek.

The right part of the image shows trains, cars, aviation and then the hyperloop as the next (BAU) step into infinity.  ::)
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Sigmetnow

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Re: The Hyperloop
« Reply #377 on: February 17, 2018, 04:16:24 PM »
Fortunately for this planet and its people, hyperloop development will continue despite the incessant trolling on this thread. 
People who say it cannot be done should not interrupt those who are doing it.

Sigmetnow

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Re: The Hyperloop
« Reply #378 on: February 17, 2018, 06:19:55 PM »
Washington, D.C., Has Given the Boring Company a Permit for a Possible Hyperloop Station
Washington, D.C., has issued a permit allowing Elon Musk’s Boring Company to do preparatory and excavation work in what is now a parking lot north of the National Mall. The company says the site could become a Hyperloop station.

The permit, reported Friday by the Washington Post, was issued way back on November 29th of 2017. The permit is part of an exploratory push by the city’s Department of Transportation, which according to a spokesperson is examining the feasibility of digging a Hyperloop network under the city. The Hyperloop is an as-yet theoretical proposal to use depressurized tubes and magnet-levitated pods to move passengers at very high speeds.

A Boring Company spokesperson told the Post that “a New York Avenue location, if constructed, could become a station” in an underground transportation network. The Boring Company last year showcased the possibility of moving cars underground on mag-lev sleds, though that concept wasn’t quite a version of the Hyperloop proper.

The increasing prominence of Musk’s own Boring Company in pushing for Hyperloop construction is a notable reversal of the entrepreneur’s initial plans for the concept. When he unveiled a paper describing the idea in 2013, Musk said he wouldn’t be directly involved with building it. That led several independent startups, including Hyperloop One and Hyperloop Transportation Technologies, to take up the cause.

But last summer, Musk started touting tentative Hyperloop partnerships between the Boring Company and governments in the Northeast U.S. A few weeks before the D.C. permit was issued, Maryland issued a permit for the Boring Company to build a 10.3-mile tunnel on a route between Baltimore and D.C.

Other Hyperloop projects have made headway in Europe and the American midwest, presenting the possibility of multiple regional Hyperloop systems operated by different companies.

The Hyperloop concept as a whole, though, has come under renewed scrutiny lately. It’s unclear how such a huge project would be paid for — selling Boring Company flamethrowers is unlikely to cover the bill. More fundamentally, urban planners have argued that the Hyperloop, which would use small pods to carry a few riders at a time, can’t scale sufficiently to really address urban transportation needs. Musk, in an unusual fit of pique, recently replied to one such criticism by calling its author an ‘idiot.’
http://fortune.com/2018/02/17/washington-hyperloop-station/
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TerryM

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Re: The Hyperloop
« Reply #379 on: February 17, 2018, 07:37:42 PM »
Didn't Sleepy recently report on a Chinese Maglev that has been transporting 86.000 passengers per day, for over a decade?
As long as Hyperloop can handle a similar passenger load, it might prove viable, although the Maglev in question was found to be too expensive, and putting a Maglev in a tunnel has to up the cost.


Once the maximum number of passengers per pod is worked out, the minimum number of pods needed per hour should a trivial calculation. Of course that assumes that the traffic volume at midnight is equal to the volume at noon.


It sounds like a very expensive way to move from here to there.
Terry

Sigmetnow

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Re: The Hyperloop
« Reply #380 on: February 17, 2018, 07:53:30 PM »
...
It sounds like a very expensive way to move from here to there.
Terry

The efficiency of the system will provide the savings.  Small pods can carry people quickly and directly to their destination, then jump to some other route where the demand is, rather than several big train cars, carrying only a few people but traveling a full route, on a fixed schedule, regardless of need. 

Of course, all developers claim their rides will be very inexpensive. ;) We’ll see.  But The Boring Company is financing tunnels in the U.S. themselves, meaning cities are not paying up front (except perhaps for loans and tax breaks).  And as always, higher volumes mean less expense per system/ride.
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ghoti

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Re: The Hyperloop
« Reply #381 on: February 17, 2018, 08:22:39 PM »
Didn't Sleepy recently report on a Chinese Maglev that has been transporting 86.000 passengers per day, for over a decade?
As long as Hyperloop can handle a similar passenger load, it might prove viable, although the Maglev in question was found to be too expensive, and putting a Maglev in a tunnel has to up the cost.


Once the maximum number of passengers per pod is worked out, the minimum number of pods needed per hour should a trivial calculation. Of course that assumes that the traffic volume at midnight is equal to the volume at noon.


It sounds like a very expensive way to move from here to there.
Terry
You might note that the chinese maglev train has 2 stations and runs for about 30kms. These trains are exceedingly expensive and only built to try to prove they can work and by governments with massive amounts of money to spend.

Given the way things work in North America they will never ever be possible here. We can't get any high speed lines built for many reasons. Only a wild paradigm switch could (maybe) result in something getting built.

Sigmetnow

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Re: The Hyperloop
« Reply #382 on: February 17, 2018, 09:26:47 PM »
Investment summit in India on Feb. 18 to feature Hyperloop signing.

... The crowning glory is of course Richard Branson, chairman of Hyperloop One, the company in talks with the Maharashtra government to build the country’s first Hyperloop track between Mumbai and Pune. A pre-feasibility study has already been done, said officials, and a agreement for a feasibility study will be signed with Branson’s company during the summit. The MOU would be for about $5 million.

The Maharashtra government believes the feasibility study could be completed in a few months and they could issue tenders for the construction of the track before the year-end. Others who are coming for the event are Tonino Lamborghini of Lamborghini, Edward Monser, president of Emerson, Hande Diltemiz, country manager, Global production, India,H&M, Cho Hyun-Joon, chairman, Hyosung Group and Sultan Ahmed Bin Sulayem, group chairman and CEO, DP World. ...
https://economictimes.indiatimes.com/news/economy/policy/richard-branson-coming-as-maharashtra-summit-attracts-big-names/articleshow/62906446.cms

30-second video at the link:  https://mobile.twitter.com/hyperloopone/status/964907317673189376
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TerryM

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Re: The Hyperloop
« Reply #383 on: February 17, 2018, 09:57:16 PM »
ghoti
I'm in total agreement, but if we'll never build even a short Maglev, how will a Maglev in a tube find it's niche here?
I was frankly very impressed that the Chinese Maglev was moving 86,000 people per day. It's a small number compared to the 10 to 12.5 million per day that use the Beijing Subway System, but still no small feat.


Personally I think that long HSR sets are the answer. Sleepy showed how a 19 car set cut the percentage of front and rear drag to something like 8%, a 38 car set would bring this to below 5%, hardly enough to justify maintaining an evacuated tube.


Those that are serious have been experimenting, building, and reaping the advantages for decades. We'll either get started, or fall further behind.
Terry


Sleepy

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Re: The Hyperloop
« Reply #384 on: February 18, 2018, 05:59:59 AM »
Fortunately for this planet and its people, hyperloop development will continue despite the incessant trolling on this thread.
That comment is only possible if one ignores physics and history.
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Rob Dekker

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Re: The Hyperloop
« Reply #385 on: February 18, 2018, 06:52:23 AM »
Fortunately for this planet and its people, hyperloop development will continue despite the incessant trolling on this thread.

Sigmetnow, I love your posts, but this one is similar to the Solar Roadways scam.

I wish them the best of luck though.

I also hope that potential customers of Hype-r-loop read the engineering assessments, such as the one I posted before :

https://mappingignorance.org/2018/02/07/the-limits-of-hyperloop/

and use some common sense before they invest.
« Last Edit: February 18, 2018, 08:42:09 AM by Rob Dekker »

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Re: The Hyperloop
« Reply #386 on: February 18, 2018, 07:00:07 AM »
Some more considerations which are consistent with the assessment that Hyperloop will be more expensive than plain MagLev, which is already more expensive than HSR :

"The Hyperloop will take a lot more money to build than Elon Musk anticipated"

https://www.recode.net/2016/10/26/13425592/hyperloop-one-elon-musk-cost-leaked-documents

and

"The Hyperloop is turning out to be much more expensive than Hyperloop One expected"

https://www.businessinsider.nl/hyperloop-one-raising-250-million-2016-10/


Sleepy

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Re: The Hyperloop
« Reply #387 on: February 18, 2018, 09:39:27 AM »
Didn't Sleepy recently report on a Chinese Maglev that has been transporting 86.000 passengers per day, for over a decade?
As long as Hyperloop can handle a similar passenger load, it might prove viable, although the Maglev in question was found to be too expensive, and putting a Maglev in a tunnel has to up the cost.


Once the maximum number of passengers per pod is worked out, the minimum number of pods needed per hour should a trivial calculation. Of course that assumes that the traffic volume at midnight is equal to the volume at noon.


It sounds like a very expensive way to move from here to there.
Terry
Terry, in case you didn't notice the last part of Sig's post above yours about Elon's trolling on twitter, here's that link Elon got upset about:
http://humantransit.org/2017/07/the-dangers-of-elite-projection.html
Elite projection is the belief, among relatively fortunate and influential people, that what those people find convenient or attractive is good for the society as a whole.  Once you learn to recognize this simple mistake, you see it everywhere.  It is perhaps the single most comprehensive barrier to prosperous, just, and liberating cities.

This is not a call to bash elites.  I am making no claim about the proper distribution of wealth and opportunity, or about anyone’s entitlement to influence. But I am pointing out a mistake that elites are constantly at risk of making.  The mistake is to forget that elites are always a minority, and that planning a city or transport network around the preferences of a minority routinely yields an outcome that doesn’t work for the majority. Even the elite minority won’t like the result in the end.

...

Again, we can’t challenge elite projection in others until we forgive it in ourselves.  Almost everyone reading this is part of some kind of elite.  But the more powerful you are, the more urgent this work is.  We must all ask ourselves: “Would this idea work for me if I were in a typical citizen’s situation, instead of my fortunate situation?”  Because if not, it won’t work for the city, and in the end that means it won’t even work for you.

I've never heard of Jarett Walker, but this is from his "about" page:
As an expert on public transit, let me warn you that the job of developing great transit must never be left entirely to experts.  Once a community has expressed its transit goals, experts have a role in designing systems to meet them.  But experts shouldn’t be the source of the goals themselves.  Citizens and their elected officials are entitled to a clear explanation of the underlying choices they face, and a chance to express their views on them. I believe every citizen has a right to debate about their public services in terms that they can understand.  Much of my work has been about creating that debate, and I’ll try to continue that process here.

Sounds highly reasonable, without the trolling...
« Last Edit: February 18, 2018, 09:45:04 AM by Sleepy »
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Sigmetnow

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Re: The Hyperloop
« Reply #388 on: February 18, 2018, 06:29:29 PM »
Virgin Hyperloop One comes to India
The Indian State of Maharashtra has announced their intent to build a Virgin Hyperloop between Pune and Mumbai, beginning with an operational demonstration track.

It was an honour to have Indian Prime Minister Narendra Modi and the Chief Minister of Maharashtra, Devendra Fadnavis, alongside us as we signed a Framework Agreement for the project. The hyperloop route would link central Pune, Navi Mumbai International Airport, and Mumbai in 25-minutes and connect 26 million people. Supporting 150 million passenger trips per year, it would help create a thriving, competitive megaregion.

As Virgin Hyperloop One Chairman, I’m incredibly excited about the potential to truly transform not just transportation, but wider society. Virgin Hyperloop One can help India become a global transportation pioneer and forge a new world-changing industry. As our team’s studies have found, the Pune-Mumbai route could result in USD $55 billion (INR ₹350,000 crores) in socio-economic benefits, time savings, accident reduction and operational cost savings, over 30 years of operation.

We expect the high-capacity passenger and cargo hyperloop system to create tens of thousands of jobs, helping to attract new business and investment in the region. The 100 per cent electric, efficient system will also ease severe expressway congestion and could reduce greenhouse gas emissions up to 86,000 tons over 30 years.

I believe Virgin Hyperloop One could have the same impact upon India in the 21st century as trains did in the 20th century. The Pune-Mumbai route is an ideal first corridor as part of a national hyperloop network that will dramatically reduce travel times between most of India’s major cities to under two hours. ...
https://www.virgin.com/richard-branson/virgin-hyperloop-one-comes-india


Cue the trolls in three... two... one...
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Sleepy

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Re: The Hyperloop
« Reply #389 on: February 18, 2018, 10:17:29 PM »
You seem to be stuck?
Discussing facts and physics, is not trolling. You are as free to ignore, or discuss, as everyone in here. You opted to ignore the MIT paper above and most of the other technical issues.

Be careful with who you call a troll, for us over here trolls are generally considered as something cute and also have a very long history, thanks to this (and John Bauer):
https://en.wikipedia.org/wiki/Among_Gnomes_and_Trolls
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gerontocrat

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Re: The Hyperloop
« Reply #390 on: Today at 12:33:28 AM »
Trolls are good guys? You never read "The three billy goats Gruff" ?
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DrTskoul

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Re: The Hyperloop
« Reply #391 on: Today at 12:40:37 AM »
Virgin Hyperloop One comes to India
The Indian State of Maharashtra has announced their intent to build a Virgin Hyperloop between Pune and Mumbai, beginning with an operational demonstration track.

It was an honour to have Indian Prime Minister Narendra Modi and the Chief Minister of Maharashtra, Devendra Fadnavis, alongside us as we signed a Framework Agreement for the project. The hyperloop route would link central Pune, Navi Mumbai International Airport, and Mumbai in 25-minutes and connect 26 million people. Supporting 150 million passenger trips per year, it would help create a thriving, competitive megaregion.

As Virgin Hyperloop One Chairman, I’m incredibly excited about the potential to truly transform not just transportation, but wider society. Virgin Hyperloop One can help India become a global transportation pioneer and forge a new world-changing industry. As our team’s studies have found, the Pune-Mumbai route could result in USD $55 billion (INR ₹350,000 crores) in socio-economic benefits, time savings, accident reduction and operational cost savings, over 30 years of operation.

We expect the high-capacity passenger and cargo hyperloop system to create tens of thousands of jobs, helping to attract new business and investment in the region. The 100 per cent electric, efficient system will also ease severe expressway congestion and could reduce greenhouse gas emissions up to 86,000 tons over 30 years.

I believe Virgin Hyperloop One could have the same impact upon India in the 21st century as trains did in the 20th century. The Pune-Mumbai route is an ideal first corridor as part of a national hyperloop network that will dramatically reduce travel times between most of India’s major cities to under two hours. ...
https://www.virgin.com/richard-branson/virgin-hyperloop-one-comes-india


Cue the trolls in three... two... one...

I hope he builds the solar power along with the hyper unicorn... Indian electrivity is mostly coal....
“You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's look at the bird and see what it's doing -- that's what counts.”
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