Hyperloop Bankrupt and Busted.

[HenrySalayne]

5 hours ago, Uttamattamakin said:

The SPAN (length) AND  Thickness matter.  Don't be mislead.  It matters.   There are many reasons we can't build a proton accelerator of arbitrary size.  Magnets and energy and funding being big ones.  The difficulty of making a very good long vacuum chamber is a real challenge.    

The span is not the length, but the length of the "free" and unsuspended part between two supports. And you could know that, if you wouldn't have left out the part saying "The buckling pressure can also be computed through analytical formulas, depending upon the geometrical parameters of the tube and the Young’s modulus of the material. The most conservative one is for an infinite length of the tube:".

 

You know what also kills a vacuum chamber on earth with a large span? Gravity.

 

[CarlBar]

2 hours ago, HenrySalayne said:

The span is not the length, but the length of the "free" and unsuspended part between two supports. And you could know that, if you wouldn't have left out the part saying "The buckling pressure can also be computed through analytical formulas, depending upon the geometrical parameters of the tube and the Young’s modulus of the material. The most conservative one is for an infinite length of the tube:".

 

You know what also kills a vacuum chamber on earth with a large span? Gravity.

 

 

Yeah my reading, (now i've got a minute), is it's referring to the distance across the pipe. In engineering terms that's still a length so L will somtimes be used.

 

it's why i prefer for unfamiliar formulae with example diagrams, i can be sure of these things by referencing the diagram.

[Uttamattamakin]

16 hours ago, leadeater said:

From what I see all of what you quoted is for a beam and not a tube, which is what I would assume a hyper loop internal would be with an outer that is not at low pressure or closer to atmosphere than the internal tube.

It's a long document.  They are talking about different ways to approximate the forces on a non circular tube. 

 

CERN --Design  Rules For R Vacuum Chambers

Quote

If approximated by a beam, the maximum deflection (wmax) and stress (σmax) (upper and lower bounds) are

 

One way they discuss is approximating it with a rectangular, hollow beam that would hold the vacuum in it.  

 

16 hours ago, leadeater said:

No length in the equation.

For some reason CERN seems to use the term "span" for the length.   

 

CERN --Design  Rules For R Vacuum Chambers

Quote

l and t being, respectively, the span and the thickness of the tube.

Though I guess he could possible also mean width or the radius of the tube.  Why not just say radius? (  @CarlBar He uses the term radius for the width of the tube elsewhere in the doccument see below.   Span has to mean length.  What else is left?)

16 hours ago, leadeater said:

 

I hope you can see from above the most appropriate discussion would be circular not non-circular and I would imagine any non-circular structures seen is most likely only the outer and there will be an inner circular tube that is the pressure vessel. 

Yeah I know I see the apparent shape of these prototypical hyperloops  Circular shapes, like spheres have a certain symmetry that allows for simple analysis.   In an idealized mathematical model with perfect uniform materials  these shapes can transmit stress and strain around and through themselves in a way that allows for the external forces to be withstood. 

 

 In which case the stress we are concerned with grows with radius.  (Assuming perfect circular tubes which is a problem.)

 

BUT there is one force we can't ignore which means those shapes while close to being cylindrical are not perfectly cylindrical. 

 

Gravity.

Constantly pulling down on them means that they will assume a shape that is shorter vertically and wider horizontally.  While this becomes more human perceptible over time.  Gravity does this to a degree that will matter for engineering purposes instantly.  

 

Remember the old physics joke.  Ask a physicist why did the chicken cross the road?   The physicist will say "Assume a spherical chicken ...."  Real life isn't like our equations  Which is why that document by CERN also discusses  when they talk about the Youngs Modulus (a measure of stiffness) of the material. 

 

 

16 hours ago, leadeater said:

So if we go off the stated rule of thumb a 2m diameter tube would need at least 20mm thickness.

Bing tells me that Virgins hyperloop track was 3.3 meters in diameter.  That is big enough for a pop that can carry two people across.  Say this is supposed to carry people in two rows of two seats with an aisle between them.  So that means the outer vaccum tube needs to be 9-10 meters of diameter.   

 

So a 100 mm thick steel tube for a mass transit sized vehicle.

100 mm is 10 cm or 3.9 USA freedom inches.  

Each km of tube would have 6,314 cubic meters of steel.  Found by calculating the volume of an outer cylinder 10.1m in diameter - volume of one 10 meters in diameter. 

 

This would weighing 49,569.6 kilograms per kilometer.   That would mean 49 million USD per km just for the steel for the tube.   Just for a tube with nothing in it.  NO rail, NO Maglev, not even a specially made air tight Tesla to drive in it.   

NOTE: The above was a mistaken calculation see this below. 

This tube would have to be perfectly manufactured, and welded or joined to remain air tight.  Any irregularity would result in a casualty causing event. 

 

Then things become very non-linear.  The chicken is not spherical. 

 

11 hours ago, CarlBar said:

I don't have time to dig through in more detail ATM, woke up to a boiler leak and got to move stuff so the repairman can get to it easily, typed this whilst coming round enough to function for that.

I agree that it is a lot to read and consider.     He uses the term "radius" and a capital R for what you are calling width.  Those formulas are for approximating a non circular tube with a hollowed out beam.     Why he calls length "span" or why he would suddenly call radius "span" I don't get.  

 

We must bear in mind the tubes would not remain circular due to gravity how much a steel tube would sag due to that is something I am going to look into.   Complications like this may cumulatively be why as I and others said Hyperloop was never going to happen.  It pushes the bounds of physics and matterials and when peoples lives are at stake in there you have to ask if it is worth it. 

[Uttamattamakin]

7 hours ago, HenrySalayne said:

The span is not the length, but the length of the "free" and unsuspended part between two supports. And you could know that, if

I can't include all parts of the paper in one screen shot.   I included the paper by linking to the whole long PDF.  The term span as the "width" or radius doesn't really make sense since he uses radius for that elsewhere in the paper.  I guess it's possible but why the change in terms?

 

7 hours ago, HenrySalayne said:

 

You know what also kills a vacuum chamber on earth with a large span? Gravity.

 

I mentioned that in my reply above.  This thing will only remain perfectly circular if there is no gravity.    Also any bridge that carrys it would need  to not expand, sway, stretch or compress much lest disaster would occur rapidly.  

 

Equations like those in this paper are fine for a chamber up to a certain size.  Which is why it refers to computational tools they have for simulating these chambers that can account for every variable and condition.  As soon as we start putting things inside the tube, and those things are in motion there are more complications.  

[Uttamattamakin]

In short terms what the CERN doccument indicates IF he is using "span" to mean length is as I have been saying and this blog post says it in simpler terms. 

https://interestingengineering.com/transportation/biggest-challenges-stand-in-the-way-of-hyperloop

Quote

Pressure

Continuously lingering above the near perfect vacuum tubes of the proposed Hyperloop is thousands of kilograms of atmosphere.

Before the Hyperloop becomes operational, the transportation tubes that will stretch hundreds of kilometers across the US will have to support the entire weight of the atmosphere above it. Essentially, the weight will accumulate about 10,000 kg per meter squared. That is, for every square meter of tube, there will be over 10,000 kg crushing down on it.

Since the proposed Hyperloop will extend 600 km with a diameter of about two meters, it will maintain a surface area of about four million meters squared. Given one square meter will experience 10,000 kg of force, the Hyperloop will have to endure nearly 40 billion kilograms of force over its entire surface.

 

A small compromise in the structure of the tube would result in a catastrophic implosion. If the tube became punctured, external air would tear into the tube, shredding it apart as it violently rushes in to fill the void. The effects would be similar to the railroad tank car vacuum implosion displayed below - only many times more violent.

EVEN IF WE ignore length and consider a steel tube shaped container the size it would take for a mass transit vehicle. IF it does implode, if any part of it is at all imperfect or compromised by all the factors discussed in this thread. 

 

[HenrySalayne]

24 minutes ago, Uttamattamakin said:

Bing tells me that Virgins hyperloop track was 3.3 meters in diameter.  That is big enough for a pop that can carry two people across.  Say this is supposed to carry people in two rows of two seats with an aisle between them.  So that means the outer vaccum tube needs to be 9-10 meters of diameter.   

Sometimes I wonder what is going on in your head...

A commercial pressure vessel seating 6 people in a row with an aisle in between has an outer diameter of less than 4 meters - the A320. How you get to 9 to 10 meters is beyond me.

31 minutes ago, Uttamattamakin said:

So a 100 mm thick steel tube for a mass transit sized vehicle.

100 mm is 10 cm or 3.9 USA freedom inches.  

Each km of tube would have 6,314 cubic meters of steel.  Found by calculating the volume of an outer cylinder 10.1m in diameter - volume of one 10 meters in diameter. 

 

This would weighing 49,569.6 kilograms per kilometer.   That would mean 49 million USD per km just for the steel for the tube.   Just for a tube with nothing in it.  NO rail, NO Maglev, not even a specially made air tight Tesla to drive in it.   

This tube would have to be perfectly manufactured, and welded or joined to remain air tight.  Any irregularity would result in a casualty causing event. 

 

Then things become very non-linear.  The chicken is not spherical. 

It doesn't matter which numbers you get if your assumptions are completely wrong to begin with.

Since large vacuum networks don't magically float in the atmosphere without any support, they don't behave like an unsupported, infinitely long tube prone to buckling. You can simply take equation 1 from paragraph 3.3 and calculate a sensible wall thickness (not considering weight of the tube and gravity).

Let's say you have a tube with a 4 m diameter and the conservative estimated permissible tension of your average S235 steel is 50 N/mm². Please calculate the wall thickness t to resist the pressure of 0.1 MPa and share your solution with the rest of us.

 

[CarlBar]

@Uttamattamakin Not really got back to this in full but short version after some thinking on the matter:

 

The reason it uses l is that they're actually using a formulae normally used for calculating the stress on an actual beam and thats just how it's done in that type of formulae. It's a weird convention but not necessarily out of line with normal engineering. This is why you need training in a specific formulae and why if i'm dealing with an unfamiliar one i like this i like a diagram.

 

I also think your just not understanding how strong materials actually are.

 

Really basic variation on one of the earliest example is was ever given in class.

 

Metal Bar 5cm by 5cm a side of square cross section. Material low carbon steel with an absolut compressive yield strength of 130Mn/m^2 Calculate the load required to cause complete failure.

 

 

The answer is to calculate the cross section in meters of the bar and multiply the given strength value by it. Comes out to 325,000 newtons or about 33 tons. This is of course the absolute failure point, the allowable force if you want no permanent damage will be a decent bit less, (without looking up a specific value likely around 20 tons). 

 

40 billion Kg's sounds like a lot but you don't actually need that much material in reality, about 50 square metres over a 600km run or 0.0000833~ square meters per meter of length. Thats less than 1 square meter of cross section.

[Uttamattamakin]

25 minutes ago, CarlBar said:

@Uttamattamakin Not really got back to this in full but short version after some thinking on the matter:

 

The reason it uses l is that they're actually using a formulae normally used for calculating the stress on an actual beam and thats just how it's done in that type of formulae. It's a weird convention but not necessarily out of line with normal engineering. This is why you need training in a specific formulae and why if i'm dealing with an unfamiliar one i like this i like a diagram.

I agree.  A labeled diagram that says just what each variable means is not only desirable but a mark of a good paper. Given the CERN document is mostly for internal consumption I suppose they all know what they are talking about with eachother.   

 

The term "span" for length is confusing  but looking into it apparently that is used for lengths of pipe all the time. 
https://www.piping-designer.com/index.php/datasheets/piping-layout-information/1669-allowable-pipe-span

One could maybe extrapolate from the table there to figure out what it would be for a 10 meter pipe.  

 

There is a NASA paper that talks about some of this. 

https://ntrs.nasa.gov/api/citations/20170001624/downloads/20170001624.pdf

 

It also talks about putting the loop under water which if anything I'd think would make everything harder....but they conclude oh no it's good and feasible.  At least in the sense of this would be an interesting problem to tackle and try to solve.  I have searched for an updated paper about it by NASA. NASA tends to look deep into tech like this.  I wonder if they still think this will work. 

 

So far to me the solution for a high volume, vacuum sealed, high-speed transport for people and cargo is a Boeing 737. 

25 minutes ago, CarlBar said:

 

I also think your just not understanding how strong materials actually are.

I was working off the CERN papers "rule of thumb" which relates the radius of the tube to the thickness for a steel vacuum chamber.    The thickness of the chamber wall being 1/100'th of the radius.  Maybe they are being conservative but that is meant to build in safety margin. 

25 minutes ago, CarlBar said:

Really basic variation on one of the earliest example is was ever given in class.

 

Metal Bar 5cm by 5cm a side of square cross section. Material low carbon steel with an absolut compressive yield strength of 130Mn/m^2 Calculate the load required to cause complete failure.

 

25 minutes ago, CarlBar said:

40 billion Kg's sounds like a lot but you don't actually need that much material in reality, about 50 square metres over a 600km run or 0.0000833~ square meters per meter of length. Thats less than 1 square meter of cross section.

Actually, I did make a mistake with that earlier calculation!    I used an online calculator and entered 10 meter diameter when the calculator calls for radius.

 

It's early in the morning in Chicagoland pre-coffee.  Now post coffee and double checking to respond to you I have found it.  To be sure I have done it again TWICE in a spreadsheet showing all the fundamental physics formulas.  
Calculations for hyperloop.ods
The total crushing forces are 7218 million lbs per km.    Given an internal pressure of 100 pa in the loop and average sea level ATM pressure of 101.3 kPa. 

The cost of the tube is 12.47 million USD per km... for the tube alone with nothing in it.  Not taking account of needing a mag lev. 

[Uttamattamakin]

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On 1/20/2024 at 8:36 PM, HenrySalayne said:

A commercial pressure vessel seating 6 people in a row with an aisle in between has an outer diameter of less than 4 meters - the A320. How you get to 9 to 10 meters is beyond me.

Look at the test of the hyperloop 1 hyperloop.  Not just the pod the WHOLE TUBE.   It is 3.3 meters wide to carry two people.  

The tube we are talking about has to be big enough to fit the pod inside of it. 

 

Bringing up the A320 as the inner pressurized hull people would ride in is pretty good for a visualization of what that would look like.  It raises the question which is really easier.  Putting this inside a tube that has to be flawless or doing what we have for 100 years and putting wings on it, and flying it. 

 

On 1/20/2024 at 8:36 PM, HenrySalayne said:

It doesn't matter which numbers you get if your assumptions are completely wrong to begin with.

My assumptions weren't wrong. The camera angle from inside that test makes it look like the pod is snug to the walls of the "loop" but it is not.  It has some clearance on every side.   My calculations today are based on taking this model and scaling it up.  You have to scale the tunnel and the pod.  

 

It would be nice to see the internal reports from hyperloop one to see WHY they gave up on this.  This was their whole thing.  There are Saudi billionaires looking to throw their money into this kind of thing.  What do they know that they haven't told everyone else? 

 

 

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Edited January 24 by LogicalDrm
Fun Anime gifs to lighten the mood. << removed as OT

[HenrySalayne]

29 minutes ago, Uttamattamakin said:

It's early in the morning in Chicagoland pre-coffee.  Now post coffee and double checking to respond to you I have found it.  To be sure I have done it again TWICE in a spreadsheet showing all the fundamental physics formulas.  
Calculations for hyperloop.ods
The total crushing forces are 7218 million lbs per km.    Given an internal pressure of 100 pa in the loop and average sea level ATM pressure of 101.3 kPa. 

The cost of the tube is 12.47 million USD per km... for the tube alone with nothing in it.  Not taking account of needing a mag lev. 

I think it's time to stop. I have no idea why you would need a spreadsheet to calculate the volume of a hollow cylinder and you even managed to screw up a second time, reducing the wall thickness to 50 mm instead of the 100 mm you just arbitrarily chose previously.

3 hours ago, Uttamattamakin said:

So a 100 mm thick steel tube for a mass transit sized vehicle.

100 mm is 10 cm or 3.9 USA freedom inches. 

 

Your argument is a complete train wreck. You have so far only shown a certain lack of very basic maths skills and no knowledge about engineering.

Quote

Any idiot can build a bridge that stands, but it takes an engineer to build a bridge that barely stands.

Nobody in their right mind would build a vacuum tube as a solid piece of steel. It will be a frame with ribs and some relatively thin sheet metal in the sub-centimetre region to form the tube. That's how you built U-boats, spaceships and aircraft. Building vacuum pipes is not cheap, but a non-issue.

 

[Uttamattamakin]

On 1/20/2024 at 11:07 PM, HenrySalayne said:

I think it's time to stop. I have no idea why you would need a spreadsheet to calculate the volume of a hollow cylinder and you even managed to screw up a second time, reducing the wall thickness to 50 mm instead of the 100 mm you just arbitrarily chose previously.

The formula uses radius 10 meters is the DIAMETER.  Radius is 1/2 diameter.  Hence 5 m and 5.05 meters instead of 10 meters inside and 10.1 outside.   The spreadsheet is to show the calculations. 

 

The mm you mention above come from the CERN paper. 

 

On 1/20/2024 at 11:07 PM, HenrySalayne said:

 

Your argument is a complete train wreck. You have so far only shown a certain lack of very basic maths skills and no knowledge about engineering.

Again.  10 meters is the diameter    radius is 1/2 of that.   What is 1/2 of 10 meters?  

 

Also @HenrySalayne note though you made a little error by confusing radius and diameter and didn't read the thread to know where the safety factor of 1/100's of the tunnels radius, and didn't realize that the loop tunnel needs to be bigger than the pods in it ... I never insulted your intelligence. 

< removed by moderation >

Such as it is. 

 

On 1/20/2024 at 11:07 PM, HenrySalayne said:

Nobody in their right mind would build a vacuum tube as a solid piece of steel. It will be a frame with ribs and some relatively thin sheet metal in the sub-centimetre region to form the tube. That's how you built U-boats, spaceships and aircraft. Building vacuum pipes is not cheap, but a non-issue.

 

Yes it is time to stop.  Read the CERN paper. To discuss things we need to make various simplifying assumptions.  All the structure you mention does not make this less expensive or simpler or less likely to fail.  In fact if it could all be one solid piece that would be the strongest. 

 

Read the CERN That's where the needed thickness of  the pipe for safety comes from for vacuum chambers in general.

 

Edited January 24 by LogicalDrm
Som people here need to relax. So more anime gifs. Same character as the one I use for any avatar BTW << removed by moderation

[HenrySalayne]

10 minutes ago, Uttamattamakin said:

Yes it is time to stop.  Read the CERN paper. To discuss things we need to make various simplifying assumptions.  All the structure you mention does not make this less expensive or simpler or less likely to fail.  In fact if it could all be one solid piece that would be the strongest. 

 

Read the CERN That's where the needed thickness of  the pipe for safety comes from for vacuum chambers in general.

You're a lost case. I asked you to calculate the required wall thickness using one of the equations provided in the paper you are talking about. It would have given you some insight into the matter. But no, it doesn't fit your narrative, so just ignore it...

Instead fixate on the free-floating, infinitely long unsupported tube while failing to attribute for the wall thickness successfully...

 

21 minutes ago, Uttamattamakin said:

The formula uses radius 10 meters is the DIAMETER.  Radius is 1/2 diameter.  Hence 5 m and 5.05 meters instead of 10 meters inside and 10.1 outside.   The spreadsheet is to show the calculations. 

 

The mm you mention above come from the CERN paper. 

No, 100 mm was your "calculation" of 1/100th the diameter of your (unecessarily) 10 m wide pipe.

And then you calculated the volume of a tube with a wall thickness of 50 mm.  Because somehow you think if you have to divide the diameter by 2 to get the radius, you would also need to divide the wall thickness by 2?!? No. Wall thickness is the difference of outer and inner radii.

[Uttamattamakin]

On 1/20/2024 at 11:52 PM, HenrySalayne said:

No, 100 mm was your "calculation" of 1/100th the diameter of your (unecessarily) 10 m wide pipe.

And then you calculated the volume of a tube with a wall thickness of 50 mm.  Because somehow you think if you have to divide the diameter by 2 to get the radius, you

Take the size of hyperloop 1's track and scale it up.  For that matter check out the size of the total tube in this test. 

 

On 1/20/2024 at 11:52 PM, HenrySalayne said:

would also need to divide the wall thickness by 2?!? No. Wall thickness is the difference of outer and inner radii.

No the wall thickness formula is diameter times 1/100  from the CERN paper.  https://cds.cern.ch/record/1046848/files/p31.pdf

That does not get divided by two.   When calculating the volume of steel needed.  You calculate the volume as if it was one cylinder inside the other and subtract the volumes to get the steel in the pipe. 

 

IT's ok.  You didn't read all of the thread and aren't current on what we are talking about

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There there.

Edited January 24 by LogicalDrm

[HenrySalayne]

7 minutes ago, Uttamattamakin said:

That does not get divided by two. 

So why did you do it then?

[leadeater]

5 hours ago, Uttamattamakin said:

So that means the outer vaccum tube needs to be 9-10 meters of diameter.   

No way, it does not, the photos easily show it isn't. There are various different design proposals but that ones actually built or based in plausibility are not greater than 5m. Most of the train carriages are either barely standing height or not even standing height, you can board in a station with the sides open allowing easy access compared in within the tube proper.

 

5m and 50mm thickness is quite thick but since we have had actual hyperloop test for real, Virgin, we know we don't need 50mm thickness.

 

Quote

The total ‘DevLoop’ tube length is 500 metres and the tube’s diameter is 3.3 metres

https://www.virgin.com/branson-family/richard-branson-blog/introducing-virgin-hyperloop-one-worlds-most-revolutionary-train-service

 

Quote

The pod achieved 3,151 horsepower during the test inside the depressurized tube with conditions similar to the atmosphere at 200,000 feet (61 km) above sea level.

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

 

What I cannot however tell you the thickness Virgin used but I can estimate based on looking at it that it's not 1/100th the diameter or 33mm.

 

I don't' even think hyperloops are supposed to or intend to run a fully complete vacuum either otherwise the carriages wouldn't need a fan on them, so actual thickness based on true vacuum would be incorrect in this application.

 

We could all probably talk about this for the next year and get nowhere since we have to know the operating environment to get towards any meaningful discussion, if we don't know the operating pressure then we cannot  talk with any semblance of authority (and we shouldn't be at all anyway) about how thick the pressure loaded pipes need to be.

 

The pressure is also a factor on building cost due to pipe thickness and also the target/required carriage horsepower to move it and the targeted/required speed. That's a lot of variables to be taking in to account and we know none of them since everything so far has been development testing and technology viability trials. An actual commercial build that will carry passages won't be exactly the same as anything currently, and I'd hope that is true and I'm not proven wrong.

 

Personally I think a 300mph target speed for an initial service is sufficiently fast enough and would make it sufficiently practical and within acceptable cost. Nobody has to go 500mph or 1000mph or whatever the first time around. Only ardent critics will care that it's not at claimed speed the first go at this.

 

5 hours ago, Uttamattamakin said:

This tube would have to be perfectly manufactured, and welded or joined to remain air tight.  Any irregularity would result in a casualty causing event. 

 

Then things become very non-linear.  The chicken is not spherical. 

That's what stiffening bands are for 

 

The deformation is going to be incredibly low, will actual structural engineers use the basic formula no but it's more than sufficient for this discussion. The whole point of computer modeling is to find out 1) How thick you actually need, 2) Where stiffening bands are required, 3) Worst case if a stiffening band fails.

 

Deviation from perfectly circular will not cause a catastrophic failure since nothing is actually circular and how much deformation is happening is the key factor. If it's a change by 0.1% that could well be irrelevant and be within design safety tolerances.

 

It's not like we don't have multiple km long low pressure tubes operating just fine, it's all just a scale problem rather than possibility problem. It's clearly possible. How much do you want to spend to achieve it?

[leadeater]

2 hours ago, Uttamattamakin said:

The formula uses radius 10 meters is the DIAMETER.  Radius is 1/2 diameter.  Hence 5 m and 5.05 meters instead of 10 meters inside and 10.1 outside.   The spreadsheet is to show the calculations. 

Err no, thickness remains constant. If you want to find out the radius, inner or outer then calculate that. But if we have a tube of 10m OD the thickness would be 10mm and that is a constant, your pipe doesn't get thinner when you want to figure out ID radius for example, it's still 10mm.

 

If it did change then you'd have a magical pipe and you should probably patent it and ask for a Nobel prize.

[Uttamattamakin]

1 hour ago, leadeater said:

Err no, thickness remains constant. If you want to find out the radius, inner or outer then calculate that. But if we have a tube of 10m OD the thickness would be 10mm and that is a constant, your pipe doesn't get thinner when you want to figure out ID radius for example, it's still 10mm.

 

If it did change then you'd have a magical pipe and you should probably patent it and ask for a Nobel prize.

Yeah you're right.  So it'd be even worse than I figured out in the first place.  It would need even more steel and cost even more. 

 

It would be more like 25 million dollars for 25 metric tons of steel per km of tube.  (Not as others have pointed out even accounting for things like supporting rings, or pylons for it to rest on or bridging it across gaps and river or burring it.   Not for as I have pointed out putting a mag lev in it.  Just for a tube as if we could somehow make it out of one single welded piece of steel. 

 

CORRECTED. Calculations for hyperloop.ods

 

In the spirit of levity, pointing out a mistake but not being mean about it, deserves a reward.  You get to see what the rest of me looks like.   Nothing naughty. lol

Spoiler

Seriously credit to the photographer for actually owning all those figures these things aren't cheap. 

 

3 hours ago, HenrySalayne said:

So why did you do it then?

OOps   Because I am doing this for giggles and not being super careful.  A minor error in calculation by me does not bring Hyperloop back to life.    If anything the corrected calculation is not better for hyperloop. 

 

2 hours ago, leadeater said:

Err no, thickness remains constant. If you want to find out the radius, inner or outer then calculate that. But if we have a tube of 10m OD the thickness would be 10mm and that is a constant, your pipe doesn't get thinner when you want to figure out ID radius for example, it's still 10mm.

 

If it did change then you'd have a magical pipe and you should probably patent it and ask for a Nobel prize.

 

2 hours ago, leadeater said:

No way, it does not, the photos easily show it isn't. There are various different design proposals but that ones actually built or based in plausibility are not greater than 5m. Most of the train carriages are either barely standing height or not even standing height, you can board in a station with the sides open allowing easy access compared in within the tube proper.

There is the tube, then there is the pod inside the tube.   10 meters is in that sweet spot of being big enough, but also being a nice round number. 

 

Nice thing about having a spread sheet is that if I change the diameter to 6 from 10 the cost going from 25 million per km to 9 million per km comes out automatically.   That's why I wrote the spreadsheet. 

 

For Hyperloop 1 the tube is according to them 3.3 meters in diameter.  6 meters would give enogh room for people to sit 2 by 2 but with an aisle what 0.3 meters or less.  Take a long look at the average person in America or most places.  can you see people s q u e e z ing by in a 0.3 meter aisle.   

 

This is what it is like in an A320 

 

It's labeled in USA Freedom units 25 '' times 2.54 cm/in 63.5 cm.   Do you see people paying enough to make it make sense to build to get in something more cramped than an A320? 

 

2 hours ago, leadeater said:

 

5m and 50mm thickness is quite thick but since we have had actual hyperloop test for real, Virgin, we know we don't need 50mm thickness.

 

https://www.virgin.com/branson-family/richard-branson-blog/introducing-virgin-hyperloop-one-worlds-most-revolutionary-train-service

 

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

 

What I cannot however tell you the thickness Virgin used but I can estimate based on looking at it that it's not 1/100th the diameter or 33mm.

I'll take your word for that.  It can't be too much less I mean unless they didn't care about safety margin.  Then government agencies don't have to worry as much about profit and cost and such.  Consider this which was once the largest vacuum chamber on Earth. 

 

That looks like they did more than the 1/100 rule. 

2 hours ago, leadeater said:

 

I don't' even think hyperloops are supposed to or intend to run a fully complete vacuum either otherwise the carriages wouldn't need a fan on them, so actual thickness based on true vacuum would be incorrect in this application.

100 Pascals is the running pressure.  It is like 99% or 99.9% vacuum compared to sea levels 101,300 Pascals. 

 

2 hours ago, leadeater said:

 

We could all probably talk about this for the next year and get nowhere since we have to know the operating environment to get towards any meaningful discussion, if we don't know the operating pressure then we cannot  talk with any semblance of authority (and we shouldn't be at all anyway) about how thick the pressure loaded pipes need to be.

100 Pascals is the supposed operating pressure.  There are some interesting things in the literature about that.    How if some pocket of that was compressed into a more dense region... a pod hitting it would be like it hitting a brick wall. 

 

2 hours ago, leadeater said:

 

The pressure is also a factor on building cost due to pipe thickness and also the target/required carriage horsepower to move it and the targeted/required speed. That's a lot of variables to be taking in to account and we know none of them since everything so far has been development testing and technology viability trials. An actual commercial build that will carry passages won't be exactly the same as anything currently, and I'd hope that is true and I'm not proven wrong.

I do too.  It would be nice if we had something like hyperloop.  I think the thought going into this will be useful to us when we are building infrastrcture on the moon.  Without needing to maintain a vacuum and also not having an air atmosphere to rely on ... having train technology that will work without an internal combustion engine, and in vacuum will be crucial for our long term expansion into space.  

 

2 hours ago, leadeater said:

Personally I think a 300mph target speed for an initial service is sufficiently fast enough and would make it sufficiently practical and within acceptable cost. Nobody has to go 500mph or 1000mph or whatever the first time around. Only ardent critics will care that it's not at claimed speed the first go at this.

 

That's what stiffening bands are for 

 

The deformation is going to be incredibly low, will actual structural engineers use the basic formula no but it's more than sufficient for this discussion. The whole point of computer modeling is to find out 1) How thick you actually need, 2) Where stiffening bands are required, 3) Worst case if a stiffening band fails.

 

Deviation from perfectly circular will not cause a catastrophic failure since nothing is actually circular and how much deformation is happening is the key factor. If it's a change by 0.1% that could well be irrelevant and be within design safety tolerances.

Not by itself.  Failures in complex systems tend to be cumulative.  Oh this part is a little not circular, or that part is a little bit thermally expanded and that bridge over there is experiencing more settling in its foundation than predicted.  Then boom.    Hundreds of people pay the price if we, whoever builds this, isn't careful. 

 

2 hours ago, leadeater said:

 

It's not like we don't have multiple km long low pressure tubes operating just fine, it's all just a scale problem rather than possibility problem. It's clearly possible. How much do you want to spend to achieve it?

That and is it worth the danger and risk as EEEblog put into his video.  The failure modes of hyperloop are almost all either it works perfectly or it's an instant catastrophic loss of life.  

Like I said in the first place. "Laws which if pushed to the limit will crush that which pushes their boundaries into twisted metal if not a black hole"  That's hyperloop. It pushes the boundaries. 

[Lurking]

On 1/14/2024 at 2:47 PM, LAwLz said:

I always dislike when the US talks about "it doesn't work because we're too big", as if having a train network (or fiber, which is another area where it often gets brought up) is a binary thing where it either has 100% coverage or none at all.

All of these major infrastructure projects has to be done in stages, and it's most likely going to be a neverending project since cities change. New cities are built, parts of cities become more or less relevant, and so on. Same with fiber-optics-based Internet access networks. You can't view it as something you just build during a period and then it's done.

 

I am not even sure if it's true that the US is "too big". It's all about priorities.

China is slightly bigger than the US when looking at land area, and China is heavily investing in railways. If China, which is larger than the US, isn't "too big" then I don't see why the US is.

 

I am fairly sure the US has more railroads than China does at this point in time. Two of the big issues with the US railway network are:

1) It seems to mostly be used for just transporting goods, not people.

2) It's really old and outdated. Electric trains are unarguably far superior to coal and diesel trains. The US has about 2,000 kilometers of electrified railway. China has about 100,000. China's electric railroad network is about 50 times larger than the US's network. Even my country, Sweden, has over 8,000 kilometers of electrified railway. 

The US's railway network is massive and already covers (in my opinion) >90% of the important stuff. It's just that it's old and outdated because it hasn't been a priority to fix and upgrade it.

Whoever says train can't work in the US because of size.... I present to you the Soviet Union, the largest country in the World. Almost all land transport was by train since roads were few and in poor shape. 

 

Maybe there are reasons, but size itself isn't one. There used to be trains all over the US built with 19th century technology. The continent back then was the same size. 

[Donut417]

16 minutes ago, Lurking said:

Whoever says train can't work in the US because of size.... I present to you the Soviet Union, the largest country in the World. Almost all land transport was by train since roads were few and in poor shape. 

 

Maybe there are reasons, but size itself isn't one. There used to be trains all over the US built with 19th century technology. The continent back then was the same size. 

There still are trains in the US, 30% of all freight is handled by rail. The issue is passenger train service is not practical because it utilizes the same infrastructure as freight. I have used Amtrak, here is my review :

Even with the problems I would still use the service. But it takes just as long as driving to get to where your going.

 

Some issues we have

• Current infrastructure
  • With freight trains only getting longer, it makes many Amtrak trains late, so we need to build dedicated rail for passenger service. Amtrak doesn't have the funds, even though they are pretty much government owned to build out that kind of rail. However, Amtrak has partnered with several states and are expanding services.
• Money
  • They talked about it on the WAN show how our government paid hundreds of thousands for fucking trash cans. People see headlines like that and dont want to pay more in taxes because the dickheads in DC will just waste it.
• Then there's the ignorant people.
  • These are the people who feel that government provided transit means they will have to give up their cars. Cars in their minds = freedom. No where did any one bring up banning cars.
• The scale of the project and doing it
  • This is like building out the interstate. It would require a lot of careful planning and execution. Between a failing school system and anti immigration, I dont think we have the skills to pull it off. People are not getting in to skilled trades. Then you need someone smart enough to design a rail network that actually works and make sense.

I personally would support dedicated rail, much like I support the efforts of NASA as I  think those type of project benefit us all. But its never going to happen.

[wanderingfool2]

13 hours ago, Uttamattamakin said:

For some reason CERN seems to use the term "span" for the length.   

 

CERN --Design  Rules For R Vacuum Chambers

Quote

l and t being, respectively, the span and the thickness of the tube.

Though I guess he could possible also mean width or the radius of the tube.  Why not just say radius? (  @CarlBar He uses the term radius for the width of the tube elsewhere in the doccument see below.   Span has to mean length.  What else is left?)

Okay you know what, I'm calling you out.  You are arguing in bad faith...

 

Your whole quoting, with the rule of thumb thing while trying to state ideas of length being important (and providing what you claim to be a forumula)...and yet the SENTENCE BEFORE that you clipped

Quote

The most conservative
one is for an infinite length of the tube

So no, span should not be defining length...instead span means exactly what everyone except you seems to be implying, the radius.

 

 

13 hours ago, Uttamattamakin said:

Bing tells me that Virgins hyperloop track was 3.3 meters in diameter.  That is big enough for a pop that can carry two people across.  Say this is supposed to carry people in two rows of two seats with an aisle between them.  So that means the outer vaccum tube needs to be 9-10 meters of diameter.   

 

So a 100 mm thick steel tube for a mass transit sized vehicle.

100 mm is 10 cm or 3.9 USA freedom inches.  

See, this is the type of reasoning that I was talking about when talking about ThunderF00t.  Picking numbers that you pronounce as being something as though it's fact, while ignoring the elephant in the room that the numbers picked are unreasonable to the point of being asinine.

 

You have a vehicle that you have conceded to be operating in a 3.3 meter tube; you are lacking some serious logic by saying that a real life version of this would now be requiring a 10 meter tube.

 

You pack more people onto the trains by extending the carts to be longer lengths.  Do you know why I picked 2m, it's about the size of a person standing...and you wouldn't require full standing room to actually transport people.  It's about the size that I would say would be potentially utilized in a real world situation (not some fantasy version where you can fit 6 people size by side).

 

Just to show how ridiculous your 10 meter tube is, the Canada Line here is 3.6m tall and 3m wide...and it rides in a 5.3m tube.  That is a train that can fit 4 people sitting, and 2 people standing for each row (and just enough walking room for someone to get by).

 

So no, again 10 meters is an outlandish claim and even going by modern standards it would be maybe 5m...but really that's not going to happen either as you don't need 4 people side by side (or full standing room).

 

The 2m also happens to be a larger size than what SpaceX was considering...which btw SpaceX used a 1/100th and in this case used a high vacuum.

 

I still contend though that you would need even just 0.5atm or 0.25 atm to achieve a speed that would be even acceptable to most for long distance travel...where if you reduce the atm to 0.25 you can go double the speed on the same energy input into the vehicle.

 

8 hours ago, leadeater said:

What I cannot however tell you the thickness Virgin used but I can estimate based on looking at it that it's not 1/100th the diameter or 33mm.

 

I don't' even think hyperloops are supposed to or intend to run a fully complete vacuum either otherwise the carriages wouldn't need a fan on them, so actual thickness based on true vacuum would be incorrect in this application.

From the pictures I've seen, I think it would be at least a couple cm, but I could see it being ~3cm as well based on the pictures I've seem.

 

 

Which again brings me back to the point, at least material cost it seems to add maybe $2m/km which is overall is a small cost compared to the cost of digging the actual tunnel (which is where I think this kind of project will most likely fail always)...Musk's boring company is neat, but I don't think they have been able to show they can scale to make economical tunnels.

 

Overall though, Hyperloop went bankrupt because Virgin isn't doing too well as a company itself (So Branson is in financial hardship).  Once of his space companies as well is going belly up.  That's what happens when a project that will cost billions in R&D to make happens.  Unless you can weather the storm and get to the point of actually making some form of revenue you will be forever doomed to go bankrupt as a company.

 

To put it in perspective, Tesla was nearly at the point of being bankrupt, SpaceX was almost at a point of being bankrupt, Apple nearly went bankrupt...so overall the concept of bankruptcy doesn't mean a technology isn't viable.

[leadeater]

2 hours ago, wanderingfool2 said:

From the pictures I've seen, I think it would be at least a couple cm, but I could see it being ~3cm as well based on the pictures I've seem.

Looked a little thinner to me but I'm also not that good at estimating thickness all that well 

[HenrySalayne]

7 hours ago, Uttamattamakin said:

This is what it is like in an A320 

 

It's labeled in USA Freedom units 25 '' times 2.54 cm/in 63.5 cm.   Do you see people paying enough to make it make sense to build to get in something more cramped than an A320? 

It's very annoying that you are constantly misrepresenting facts. The A320's standard seating for economy class is a 3+3 arrangement most if not all airlines are using. Even the smaller 737 fuselages (-14 cm) generally use a 3+3 arrangement.

I checked the biggest 3 airlines in the USA (American Airlines, Delta and United) and all of them use a 3+3 arrangement for their A320s as well as their 737s (Max).

https://seatmaps.com/airlines/

Your average "bullet" or high-speed train not only has a pressure-resistant cabin (so you won't pop your eardrums every time you enter or leave a tunnel) but has also a width of less than 3.0 m (Europe) with a 2+2 seating arrangement (less than 3.5 m in Japan with a 3+2 seating arrangement).

[leadeater]

9 hours ago, Uttamattamakin said:

Like I said in the first place. "Laws which if pushed to the limit will crush that which pushes their boundaries into twisted metal if not a black hole"  That's hyperloop. It pushes the boundaries. 

But it doesn't push the boundaries of pipes under vacuum, that is not the boundary being pushed. Everything else sure but that specifically no.

 

9 hours ago, Uttamattamakin said:

 10 meters is in that sweet spot of being big enough, but also being a nice round number. 

Being a nice round number and being a plausible consideration are very different things 

 

The cost and complexity is non-linear which is why no current plans or future plans are looking at 10m diameter pipes under a vacuum, regardless of possible or not. That's like buying a Airbus A380 to do the job of a A320, financially and engineering wise insanity.

 

Like the width of an A380 main fuselage is only slightly more than 7m, so I think you might need to re-adjust your sense of scale.

[Sauron]

On 1/19/2024 at 8:37 PM, wanderingfool2 said:

Cars aren't viable then because the cost to use a horse is so much less.

I wouldn't be so sure once you consider the costs of a stable, a carriage and someone who takes care of the horse every day. Regardless, even at face value the cost of a car is generally low enough that people can afford to buy one (although that's been changing recently...) and the advantages compared to the horse are so many that even a 10x cost would be justifiable. Here on the other hand we're talking about potentially spending hundreds of times more for a single potential benefit in the form of higher maximum speed... and not even that much higher in relative terms. A higher speed wouldn't even necessarily translate into a proportionally higher throughput if the trains would need to be shorter and less spacious.

 

By the way I like the "logic" here... I guess if spending more for higher speed in one instance is worth it then it must always be worth it...? I imagine you'd also argue that having everyone fly on a private jet for their daily commute would also be well worth the price in exchange for going 900kph?

On 1/19/2024 at 8:37 PM, wanderingfool2 said:

Again, you are oversimplifying it down to a specific usecase and declaring it's not ever feasible.  Longer distance travelled by trains has been a thing for hundreds of years.  We have overall gone towards things like cheap airlines etc now though; prior to that though we would have trains that connect cities together over hundreds of km.

I'm considering the use case it was proposed for. I struggle to see any use case for which it would be an economically viable alternative to rail, but even if there is one I don't really care; it was supposed to be built to do one thing and I'll critique it based on its inadequacy for that.

On 1/19/2024 at 8:37 PM, wanderingfool2 said:

And you know what, the cost to build thousands of km is already insanely expensive.

 

If you want an example, Canada Line in Vancouver cost over $1 billion in total funding to make...it travels less than 20 km....literally costs $50,000/meter...and again the 2 cm was based on full vacuum, which again wouldn't be practical (but a low vacuum environment would be).

I already posted and sourced the cost of laying double track high speed rail to be 165k/km. This is just for the physical rail, not other things that are independent of the type of rail used and would be present in the hyperloop as well and should therefore not be counted in a comparison. It's a 100x to 1000x lower price than maglev rail, not even accounting for the tube/tunnel.

On 1/19/2024 at 8:37 PM, wanderingfool2 said:

That's only an additional $1.26 million per km...or if you were to associate it with the cost to build the Canada line, it would equate to 2.5% of the build cost of the Canada Line.

That's already 10x the price of a railway, just for the tube.

 

[SpaceGhostC2C]

13 hours ago, Uttamattamakin said:

(...)

It seems we got us a Debbie Downer here...