The Hyperloop: BUSTED

[EEVblog]

He's right, it's never going to happen. It's another Solar Roadways.

I've been on a MagLev train at 430kmh, it works, it's practical, and a hell of a lot less can go wrong with it. No contest.
Hyperloop will never happen.

[donotdespisethesnake]

I've always been dubious about this. I think some of the problems could be solved technically, but the infrastructure costs would be horrendous. Maintaining even a low pressure inside a 600 km tube with the safety implications is not doable IMO.

[EEVblog]

I've always been dubious about this. I think some of the problems could be solved technically

But it only takes one showstopper.

[EEVblog]

Shanghai Maglev ticket is $8/single journey, compared to metro it is 12 times more expensive. Still, the government pays hundreds of millions CNY per year to maintain it.

Then that's a marketing and pricing issue, not an engineering issue.
The Hyperloop is all about the engineering, because there are so many potential showstopper.

It would be interesting to see a privately operated 800kph tube running and actually making money.

You will never see it running because the engineering of it will fail dismally, or even you can get the engineering to work, a failure due to some nutcase with a gun (it's America remember) is all but guaranteed . And the first time a deadly accident happens and people realise it's a fatal flaw in the entire concept, the whole thing will be sunk.
Thunderf00t is bang on when he talks about one plane (or train) failing doesn't bring down the entire system.

[Alex Eisenhut]

And the first time a deadly accident happens and people realise it's a fatal flaw in the entire concept, the whole thing will be sunk.

[TerraHertz]

I'm chuckling, at people who didn't spot this as an obvious scam/stupidity from the very first mention.
My only question is, why is Musk involved in this? His other projects are fairly sensible, but the Hyperloop is completely whacked.
Some kind of tax writeoff perhaps?

Or maybe he uses it to warehouse the idiots who joined Tesla or SpaceX, after his HR dept recognizes them as idiots but can't fire them? Solution: shift them all to one project ideally suited to their 'skills', then let it fail spectacularly. Preferably with all the worst idiots in the first demonstration run of the hyperloop capsule.
Perhaps he even uses it as an idiot-detector. Survey form for all employees, along the lines of "Hey, have you heard of my wonderful  Hyperloop project? (Brief outline of idea) Isn't that great? Would you like to work on it?" Anyone who is stupid and/or sycophantic enough to say yes, gets transferred. Do not want such people working in rocketry.

If he gets too many idiots for one sacrificial company, maybe he should start a Space Elevator company as well. That's another 'great idea' that would be completely insane in practice. (Hint: what's the voltage differential across the electrically insulating atmosphere, between the very conductive ionosphere and very conductive Earth? And what is the total capacitance? So what is going to happen if you run a wire between the two?)

Added:

The fallen one, if my memory serves me correctly, is an AirFrance one. The poor thing was hit by a debris coming from a poorly maintained PanAm.
The ultimate reason of Concorde being phased out, IMHO, is solely for cost reasons. By that time, new generation B767 and B777 have astonishing fuel efficiency and can also offer smooth traveling experience.

It was a bit of metal debris lying on the runway from a previous plane. Sucked into an engine of the Concorde on takeoff, turbine disintegration ruptured a wing fuel tank. Fire caused structural failure before it could make it to any landing site.
But yes, the accident was an excuse to quit Concorde flights, that were actually no longer profitable.

[LabSpokane]

The first four letters were all I needed to read.   

[mtdoc]

My only question is, why is Musk involved in this? His other projects are fairly sensible, but the Hyperloop is completely whacked.

To be fair, I don't think Musk is really involved trying to produce this, is he?  I think he just introduced the conceptual idea to the public and coined the term. It may never work but it is an interesting idea.

While I don't dispute that it may not be possible, I think comparing it to the Solar Roadways nonsense is unfair and just a cheap shot. After all, companies like Hyperloop One have a large team of actual engineers and they have actually developed a small scale prototype. They cannot be unaware of the issues raised in video. Of course that in no way implies they will ever find a way to overcome those  obstacles but I find it improbable that they are all just trying to run a con.

So while I don't disagree with the argument that it will never work,  it is much different than the Solar Roadways scam.

[EEVblog]

My only question is, why is Musk involved in this?

He's not, finacially.
http://www.spacex.com/hyperloop
"Neither SpaceX nor Elon Musk is affiliated with any Hyperloop companies"

[technogeeky]

Shanghai Maglev ticket is $8/single journey, compared to metro it is 12 times more expensive. Still, the government pays hundreds of millions CNY per year to maintain it.

Then that's a marketing and pricing issue, not an engineering issue.
The Hyperloop is all about the engineering, because there are so many potential showstopper.

It would be interesting to see a privately operated 800kph tube running and actually making money.

You will never see it running because the engineering of it will fail dismally, or even you can get the engineering to work, a failure due to some nutcase with a gun (it's America remember) is all but guaranteed . And the first time a deadly accident happens and people realise it's a fatal flaw in the entire concept, the whole thing will be sunk.
Thunderf00t is bang on when he talks about one plane (or train) failing doesn't bring down the entire system.

I think you may be wrong on this one, but time will certainly tell. It's certainly not as insane as solar power roadways. I've always wondered how they will protect something like the hyperloop from, say, terrorist attacks. Your timing would have to be quite good (otherwise the vehicle would have time to stop), but you could probably do some serious damage that way.

Then again, the US (and others') oil pipelines could just as easily be destroyed in a similar way. Granted, this would not result in loss of life, but clearly the oil pipelines have some way of dealing with this potential problem. You (well I, for one,) don't hear about daily oil pipeline attacks.

I think it's absurd to say it's busted already. It's true that the engineering challenge is unbelievable, but it doesn't mean it's not worth trying.

It's clear for things like solar roadways, it's not even worth trying.

[LabSpokane]

My only question is, why is Musk involved in this?

He's not, finacially.
http://www.spacex.com/hyperloop
"Neither SpaceX nor Elon Musk is affiliated with any Hyperloop companies"

Musk introduced the idea for the simple reason that it generated press buzz for him, Tesla, and SpaceX. The actual viability of the project was irrelevant.

[mtdoc]

My only question is, why is Musk involved in this?

He's not, finacially.
http://www.spacex.com/hyperloop
"Neither SpaceX nor Elon Musk is affiliated with any Hyperloop companies"

Musk introduced the idea for the simple reason that it generated press buzz for him, Tesla, and SpaceX. The actual viability of the project was irrelevant.

Or he recognizes that it is an interesting idea that deserves further research despite the obvious technical challenges.  An idea that inspires engineers and entrepreneurs (which it has) and could lead to useful new technology even if it never leads to a large scale LA to SF type transporter.  Musk is not really an engineer after all. He is a futurist (and an entrepreneur) whose role is to inspire others. It's up to the engineers to determine if his ideas can become reality.

[LabSpokane]

My only question is, why is Musk involved in this?

He's not, finacially.
http://www.spacex.com/hyperloop
"Neither SpaceX nor Elon Musk is affiliated with any Hyperloop companies"

Musk introduced the idea for the simple reason that it generated press buzz for him, Tesla, and SpaceX. The actual viability of the project was irrelevant.

Or he recognizes that it is an interesting idea that deserves further research despite the obvious technical challenges.  An idea that inspires engineers and entrepreneurs (which it has) and could lead to useful new technology even if it never leads to a large scale LA to SF type transporter.  Musk is not really an engineer after all. He is a futurist (and an entrepreneur) whose role is to inspire others. It's up to the engineers to determine if his ideas can become reality.

I am more cynical than most when it comes to this stuff.  I think if you actually talked to Musk at a cocktail party about four drinks in, you'd find out his real opinion on the viability of hyperhype.

[TerraHertz]

My only question is, why is Musk involved in this?

He's not, finacially.
http://www.spacex.com/hyperloop
"Neither SpaceX nor Elon Musk is affiliated with any Hyperloop companies"

Ah ha, interesting. And yet: "To support this competition, SpaceX will construct a one-mile test track..." So he does have dollars in it.
I was mostly joking about the 'idiot filter' idea, but given Musk's involvement in 'Hyperloop concept support', including his personally coining the name, maybe it's not such a crazy thought after all.
He may not be an engineer, but he is smart and employs a lot of good engineers. Surely some of them would have explained Hyperloop's fundamental flaws to him, if he didn't see them himself?

As a name, "Hyperloop(y)" is a pretty cool joke. It's almost a stand-alone sanity check in itself.

[LazyJack]

It was a bit of metal debris lying on the runway from a previous plane. Sucked into an engine of the Concorde on takeoff, turbine disintegration ruptured a wing fuel tank. Fire caused structural failure before it could make it to any landing site.
But yes, the accident was an excuse to quit Concorde flights, that were actually no longer profitable.

Small correction. Debris on the runway cut one of the tires, which sent debris flying into the wing. This caused shock waves in one of the fuel tanks that ruptured the tank. The fuel eventually ignited. This happened a the worst possible moment, as they were already traveling too fast to abort takeoff. They plane became airborne, but was doomed by the fire, did not have enough time to return or divert to an other airport.

[technogeeky]

My only question is, why is Musk involved in this?

He's not, finacially.
http://www.spacex.com/hyperloop
"Neither SpaceX nor Elon Musk is affiliated with any Hyperloop companies"

Ah ha, interesting. And yet: "To support this competition, SpaceX will construct a one-mile test track..." So he does have dollars in it.
I was mostly joking about the 'idiot filter' idea, but given Musk's involvement in 'Hyperloop concept support', including his personally coining the name, maybe it's not such a crazy thought after all.
He may not be an engineer, but he is smart and employs a lot of good engineers. Surely some of them would have explained Hyperloop's fundamental flaws to him, if he didn't see them himself?

As a name, "Hyperloop(y)" is a pretty cool joke. It's almost a stand-alone sanity check in itself.

He is an very good engineer, and he had some very good engineers on the design document that he released the document Hyperloop Alpha

[mtdoc]

He is an very good engineer, and he had some very good engineers on the design document that he released the document Hyperloop Alpha

Nah. That's just the paper he used to introduce the concept. It is not intended to be any sort of engineering or comprehensive design document.

Hyperloop is considered an open source transportation concept (emphasis mine).

[HP-ILnerd]

Clearly, I haven't thought about this as hard as you guys or Thunderf00t, so I have a couple questions:

1)If the air pressure from a catastrophic fail up-tube is a problem, why wouldn't you make the tube capable of sensing that it has failed up-tube?
2)If you have done so and it has sensed this, why wouldn't you deliberately start venting air into the tube in a controlled fashion all along the tube?  Air in the tube would help any transiting hyperloop cars stop, right?
3)Since you need expansion joints, why wouldn't you take advantage of the non-standard section to add a door that drops down to block the tube in the event of a catastrophic fail?  It need not even be air-tight, it just has to make the air passage a lot smaller.  Could be made of cement with a steel top held up by permanent magnets.  In case of emergency, just disrupt the magnetic field of the permanent magnet (just like fire doors) and gravity does the rest.  Maybe every 5 km or so?  However far the maximum stopping time of a car in the tube is.  These expansion joints also seem like a good spot to put the re pressurization valves noted  above?
4)I'm just a programmer, not a thermal guy, but since he pointed out the temperature differential of  the top of the tube in sunlight vs the bottom.  Is the top of tube being in shade (solar panels!) all along its length not going to make any difference?
5)How can "the power go out" if it is locally powered by all those solar panels?  Was the power all supposed to be sent back to some centralized bank 600km away?

Since Thunderf00t didn't even suggest any solutions of the sort, I assume they can't work?

[optoisolated]

1)If the air pressure from a catastrophic fail up-tube is a problem, why wouldn't you make the tube capable of sensing that it has failed up-tube?

To a limited extent, you could. The issue comes down to the practicality of such a safety mechanism. It would require a complex array of sensors and mechanisms in order to adequately seal and safely repressurise the system. The issue is there are too many single-points-of-failure.

2)If you have done so and it has sensed this, why wouldn't you deliberately start venting air into the tube in a controlled fashion all along the tube?  Air in the tube would help any transiting hyperloop cars stop, right?

The key here is 'controlled fashion'. It requires many complex systems all working correctly to acheive this. It's not impossible, but grossly impractical. Remember: these safety mechanisms would need to be replicated the entire length of the hyperloop.

3)Since you need expansion joints, why wouldn't you take advantage of the non-standard section to add a door that drops down to block the tube in the event of a catastrophic fail?  It need not even be air-tight, it just has to make the air passage a lot smaller.  Could be made of cement with a steel top held up by permanent magnets.  In case of emergency, just disrupt the magnetic field of the permanent magnet (just like fire doors) and gravity does the rest.  Maybe every 5 km or so?  However far the maximum stopping time of a car in the tube is.  These expansion joints also seem like a good spot to put the re pressurization valves noted  above?

Again, such safety mechanisms are possible, but impractical, and would be expensive. They would add to the cost of maintenance and upkeep of the system and should any part of the system be offline for maintenance or malfunctioning, the entire system would be potentially unsafe to a catastrophic failure. From what I've seen of the projected construction costs, it seems unlikely these sort of safety mechanisms have been taken into consideration.

I can't speak to points 4 and 5.

One thing worth noting (and where I foresee a massive obstacle to such a system) is what would happen in the event of a turbine blade failure. It seems from the animations that there isn't much margin for movement within the carriage within the tunnel. In a turbine failure, the outer containment shell will warp to absorb the impact of the massive amount of kinetic energy stored in those blades. If that distortion happened at speed, the carriage would likely disintegrate, and if it didn't it would likely deform to the point where it would make contact with the outer walls of the tunnel. The same outcome would likely occur in that scenario.

By comparison, turbine blade failures occur occasionally during an an aircraft flight, for instance, and often result in the loss of an engines power, but no significant impact to the safe operation of the aircraft. Even in the event of significant damage (See QF32: ) the aircraft isn't in a tube where it could potentially impact the fuselage. Multiple redundant control systems meant the aircraft was still flyable and able to be safely landed. The pilots had room to maneuver and react. The turbine blade containment failure in this incident resulted in the kinetic energy in the blades being directed away from the aircraft for the most part. In a tunnel, this would be bad news, likely resulting in localised tunnel failure and worse yet, ricochet of debris within the cabin.

While I love the innovative effort of this project, it's just a non starter from a safety and cost perspective. It's ultimately cheaper and safer, to use other proven technologies like Maglev trains and Aircraft.

[Brutte]

I am watching the linked YT.

I do not like the part that describes thermal expansion. The deduction is flawed. It assumes no longitudinal strain is acceptable in the design while we know the strain is not a problem today - take a look at continuous (welded) railroads.
Thermal expansion is a design parameter. Besides, there are other materials available, like concrete, composites, elastomers, etc. As for steel, the 50mm expansion of 100m tube over [0:40]DegC seems like impossible to overcome. Otoh, that is a strain of only 100MPa (G=210GPa) or +-50MPa if you weld it at 20DegC. Any steel is capable of 50MPa. The one used for industrial piping goes up to 500MPa. Mind this is only the expansion part and the construction is subjected to other factors (vacuum, rust, terrorists, thieves, etc).

I would NOT use steel for members at compression, especially where the mass plays no role. I believe the steel is a temporary solution and the precast reinforced concrete + elastomeric joints are more likely to be a viable solution because of the cost and durability.

The idea that if the tube gets ruptured at any place and people inside die instantly because of the vacuum is also flawed. The capsules are pressurized and if the tube is punctured and filled with atmospheric air (gradually, via size-limited hole) then the drag would increase gradually and the capsule would eventually slow down. For God's sake that is not 600km of single piece of pipe and some locks are needed 

You can die there when you derail or exceed G, but OTOH slowing down 900km/h (250m/s) at 5G (50m/s2, at emergency) takes lousy 5 seconds. Just let some air into a tube in a controllable manner. Ok, that is 625m to a standstill but dude, I would not exaggerate, at least you cannot hit the moose on the road.

Hitting a coke can with a ball  Where is the BUT?

As of the emergency exiting, I think it should be presented in relation to emergency exiting when KLM + Pan AM meet on one runway. How about then?

The weakest part of the project is its capital cost and technological challenges of the scale. It competes with airplanes so it is not hard to calculate the borderline cost of the trip of the hyperloop. Make it more expensive and people won't buy it.

[FreddyVictor]

Added:

The fallen one, if my memory serves me correctly, is an AirFrance one. The poor thing was hit by a debris coming from a poorly maintained PanAm.
The ultimate reason of Concorde being phased out, IMHO, is solely for cost reasons. By that time, new generation B767 and B777 have astonishing fuel efficiency and can also offer smooth traveling experience.

It was a bit of metal debris lying on the runway from a previous plane. Sucked into an engine of the Concorde on takeoff, turbine disintegration ruptured a wing fuel tank. Fire caused structural failure before it could make it to any landing site.
But yes, the accident was an excuse to quit Concorde flights, that were actually no longer profitable.

<edit>LazyJack has it already

I did read that 9/11 resulted in a drop off of business travellers which made the service un-economic 

on-topic, the only MAGLEV I've been on was the one at Birmingham International (gone now I think) and it left alot to be desired !

[HP-ILnerd]

To a limited extent, you could. The issue comes down to the practicality of such a safety mechanism. It would require a complex array of sensors and mechanisms in order to adequately seal and safely repressurise the system. The issue is there are too many single-points-of-failure.

Why would it have to be complex?   A leak sensor system (required one way or another) wouldn't have to measure pressure, just that there is pressure.  Not off-scale low, just anywhere on-scale means a leak.  You could even make it triply redundant if you like.  I just priced some pressure transducers at DigiKey, and even 10's of thousands of them wouldn't register as budget noise in a multi-billion dollar civil works project.

The key here is 'controlled fashion'. It requires many complex systems all working correctly to acheive this. It's not impossible, but grossly impractical. Remember: these safety mechanisms would need to be replicated the entire length of the hyperloop.

Again not seeing the complicated?  They don't even have to talk to each other, but you'd want them too because they could react faster if they did.  A backup "we can't communicate" mode where they all reacted passively should be possible.  Any one segment letting air in because it smelled a leak would trigger adjacent ones in a cascade fashion whether they could talk or not.  Again, the expansion sections seem ideal locations to put them.  You need to have pumps at each one to evacuate it in the first place, right?  Nobody would design it with one pump for the whole system at each end, right?  It'd take eons to pump down.  So you already have valves at each pump.  If they failed, you could simply have an explosive bolt fire (purportedly one of the most reliable gadgets in the world) and leave a hole of prescribed size through which air could flow.  There's your precisely controlled repressurization.  The new air in the tube would act as a buffer against the uncontrolled air from the catastrophic breach.  Considering the wiring/plumbing/HVAC,etc. in the average American Skyscraper, I don't see this as being orders more complex.

Again, such safety mechanisms are possible, but impractical, and would be expensive. They would add to the cost of maintenance and upkeep of the system and should any part of the system be offline for maintenance or malfunctioning, the entire system would be potentially unsafe to a catastrophic failure. From what I've seen of the projected construction costs, it seems unlikely these sort of safety mechanisms have been taken into consideration.

Every building of any size in the US is required to have a fire suppression system and automatic fire-doors that trigger automatically if one of the sensors pops (usually from measuring a pressure drop) or the alarms go off.  This seems virtually identical, and differs only in being spread out.  The system would require maintenance under normal circumstances, so it would need to be able to re pressurize in a controlled fashion anyway, right?

Thunderf00t is a pretty smart guy, and he may have had lots of experience working with vacuum, but (and I don't know the answer to this) has he ever worked on a large device that had to defend itself in the event of failure?  He seemed to be implying his apparatus was an actual fair representation of a working system.

[optoisolated]

The idea that if the tube gets ruptured at any place and people inside die instantly because of the vacuum is also flawed. The capsules are pressurized and if the tube is punctured and filled with atmospheric air (gradually, via size-limited hole) then the drag would increase gradually and the capsule would eventually slow down. For God's sake that is not 600km of single piece of pipe and some locks are needed 

This would be dependent on the location of the rupture, and where the carriage was in relation to that rupture. While a small rupture, as long as it didn't lead to some form of cascading failure of tube, could be handled, where I see concern is the rotational energy of the turbine being designed for the extreme low pressure of the tube suddenly (within a few seconds) of denser air. That would result in not insignificant anti-torque on the engine. That rotational energy would be transferred to the structure of the carriage, potentially deforming it. This could be tolerated within limits, but any significant sudden re-pressurisation would potentially be catastrophic for a turbine.

As of the emergency exiting, I think it should be presented in relation to emergency exiting when KLM + Pan AM meet on one runway. How about then?

No-one is saying airline travel is completely devoid of risk. Incidentally that article also references all of the safety improvements that have been implemented as a result of that accident.The airline industry has a proven track record of improving its safety over time. Perhaps after 100 years of development, we may be technologically in a position where the hyperloop could be feasible. None of this rules out the concept, but does illustrate how impractical it is.

[LazyJack]

Before we all go ahead and solve all possible engineering challenges of Hyperloop in this topic. Do not forget, that the set of engineering problems that may be solved is much much larger that the set of problems financially feasible to solve. Since eventually someone has to pay the bill, that is a very big limiting factor. Would a government (or crowd funding, or investors somehow convinced) commit unlimited money, I bet Hyperloop would come very quickly into existence, just as the Moon landing happened.
Look at for example microelectronics. The astronomical cost of a new generation fab is now much more limiting in getting more transistors squeezed on a chip than physics itself.

Of course, there is an other aspect of getting investors with false claims, then grab the money and run. But that is not engineering, but simple fraud, dressed into a nice engineering dress. I'm not saying that Hyperloop is this, but this is definitely a high profile case of creating the "we can solve anything, just give me money" type image.

[EEVblog]

Can someone please explain to me the requirement for the Hyperloop (apart from being cool), with all it's inherent engineering problems, over a MegLev train?
Sure it's potentially twice the speed (so they claim), but what else? Nothing, just downsides. MagLev exists, works, is fairly robust, and has only had one(?) fatal accident, and that was a collision cause by human error.
Heck, what's that passenger capacity vs the two? MagLev might actually have greater throughput. The Shanghai one is 574 passenger capacity.

With all the ridiculous engineering requirements and potential failure points worth twice the speed? (even if it was possible)
Again, it's like Solar Roadways, solar panels aren't nearly as sexy an idea, but infinitely more practical.