The first Hyperloop demo has been built in Nevada, ready for testing this year

William Gayde

TS Addict
Staff member

Roads are clogged, flying is a hassle, taxis are expensive, and public transit is rarely there when you need it. What if there was a better way to travel? According to Elon Musk, the future of transit is the Hyperloop. His idea involves a rigid tube held at a near vacuum. Passenger pods could then travel inside at almost the speed of sound. They also levitate inside, of course, reducing friction to a minimum. If Musk's math is correct, the system could take you from L.A. to San Francisco in just 36 minutes and cost 90% less than traditional public transit.

The idea has many entrepreneurs excited and it's now a race to see who is the first to build a working Hyperloop and bring it to market. There are currently two main players: Hyperloop One and Hyperloop Transportation Technologies. HTT was set to start construction back in 2016, but missing permits delayed their construction. In the meantime, Hyperloop One has been hard at work and they finally have a test track built. Speaking in Dubai, Hyperloop One CEO Rob Lloyd unveiled the first images and construction plans for their new test site.

The "DevLoop" facility is located about 30 minutes from Las Vegas and is set to begin public trials in the next few months. The 500 meter long tube isn't that impressive from a visual perspective, but it's a big milestone for the Hyperloop community. Future installations will be much longer though since their current test track is only long enough for a few seconds travel at the speeds they're planning.

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andrewdoyle88

TS Addict
It would be awesome if these tubes could be transparent. I assume they might place cameras outside the tube and have this displayed on screens inside the vehicle. I know I wouldn't want the feeling of being trapped in a dark pipeline moving at the speed of sound.
 

Uncle Al

TS Evangelist
Good point! I also wonder just how secure these might be? At high speeds it would not take much of a disruption to create a rather large accident.
 

Skidmarksdeluxe

TS Evangelist
It would be awesome if these tubes could be transparent. I assume they might place cameras outside the tube and have this displayed on screens inside the vehicle. I know I wouldn't want the feeling of being trapped in a dark pipeline moving at the speed of sound.
But you're doing precisely that when you're flying in a commercial airliner. As long as you're not sitting in complete darkness in this thingamajig, why would you want to see outside anyway?
 
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bandit8623

TS Addict
It would be awesome if these tubes could be transparent. I assume they might place cameras outside the tube and have this displayed on screens inside the vehicle. I know I wouldn't want the feeling of being trapped in a dark pipeline moving at the speed of sound.
But you're doing precisely that when you're flying in a commercial airliner. As long as you're not sitting in complete darkness in this thingamajig, why would you want to see outside anyway?
planes have windows...
 

mbrowne5061

TS Evangelist
It would be awesome if these tubes could be transparent. I assume they might place cameras outside the tube and have this displayed on screens inside the vehicle. I know I wouldn't want the feeling of being trapped in a dark pipeline moving at the speed of sound.
Ignoring the trolling,

I wonder if we even have a transparent material that is strong enough - while still being cost effective - to withstand the vacuum they plan to pull on this tube?
 

lipe123

TS Evangelist
It would be awesome if these tubes could be transparent. I assume they might place cameras outside the tube and have this displayed on screens inside the vehicle. I know I wouldn't want the feeling of being trapped in a dark pipeline moving at the speed of sound.
Ignoring the trolling,

I wonder if we even have a transparent material that is strong enough - while still being cost effective - to withstand the vacuum they plan to pull on this tube?
It's not going to be a complete vacuum just a low pressure system, even regular perspex/plastic can handle that easily. https://www.quora.com/What-is-the-Hyperloop-How-does-it-work
 

mbrowne5061

TS Evangelist
It's not going to be a complete vacuum just a low pressure system, even regular perspex/plastic can handle that easily. https://www.quora.com/What-is-the-Hyperloop-How-does-it-work
If we want to get technical, we can't make a complete vacuum on earth - we don't have the appropriate materials nor techniques.

Moving beyond nitpicking, even a 50% reduction in air pressure inside of the tube would be 7.5lbs applied to every in^2 (never mind the change in force from passing cars creating higher, and then lower, pressures than the ambient average). 7.5lbs doesn't sound like much until you need to resist that applied continuously over a surface that is only supported every 50-100 feet. Keep in mind that tubes are weakest across their axis, or exactly how this force would be applied. It would get worse the closer they got to 'pure' vacuum, which they likely are aiming for. My bet is they will aim for around 25% normal air pressure (3.75psi).

Glass would likely be too brittle, and still too expensive. You could do it with acrylic. Really thick acrylic, that would get scratched and be very expensive. We an manufacture artificial diamond windows and tubes, but again, expensive. Transparent aluminum isn't just Star Trek BS, it exists (ALON - Aluminum Oxynitride), and it is pretty tough stuff. You can also form it into tubes and windows, but it is also really expensive.

A more likely scenario is that - best case - you'll get a strip of windows on either side of the tube. The trouble with that will be at the junctions of each tube. But there is a problem with this too. At the 500-600mph this car will be traveling at, assuming 100ft lengths for each section of tubing and continuous windows for nearly the entire length of each section, we would be looking at 7.3-8.8Hz flickering of bright light. Safe bet that most people will find that uncomfortable, and possibly nauseating. Breaking the window into smaller sections might actually help if you could get it to around or above 40Hz. But I'm not sure it would actually be better. Also, don't forget that we would need to create the same kind of windows for the cars themselves, albeit smaller windows.

Or they can just install simple entertainment systems for the super short journey - that you'll be going too fast to even really appreciate - that covers things like top news stories.
 

lipe123

TS Evangelist
Dude, read the article and stop debating vacuums. We can make damn near vacuums in vacuum chambers here on earth and we do it all the time with see through doors thats plain flat not even concave or anything.
The hyperloop vehicle has a GIANT FAN on the front that sucks air in and creates an air cushion under the thing like a hovercraft, none of that works in vacuums.

NOT A VACUUUM, stop worry about something that isn't a thing.
 

mbrowne5061

TS Evangelist
Dude, read the article and stop debating vacuums. We can make damn near vacuums in vacuum chambers here on earth and we do it all the time with see through doors thats plain flat not even concave or anything.
The hyperloop vehicle has a GIANT FAN on the front that sucks air in and creates an air cushion under the thing like a hovercraft, none of that works in vacuums.

NOT A VACUUUM, stop worry about something that isn't a thing.
Here is the actual definition of a vacuum, just to establish some kind of definition so you can follow along:
http://www.engineeringtoolbox.com/vacuum-d_837.html

In your own Quora link, it talks about partially evacuating the tube to reduce air friction on the pod - the Quora link even calls it "vacuum" - but I wasn't the one who started debating this. You're the one who got upset when they misunderstood the whole underpinning concept of the hyperloop: reduced air density to allow to higher transportation velocities.

I assumed a reasonable 50% vacuum. It might be more, it might be less, but they certainly are not going to try to push any cars through this tube at an atmospheric standard of 15psi. Even if you could get the air out of the way fast enough to approach 500mph, the compression of the air going around the car through such a tight space would generate large amounts of heat that would need to be dealt with. It is air being compressed in front of returning space craft that creates the heating, not 'air friction'. So all that fan on the front of the car is going to do is help 'float' the car away from the walls of the tube and reduce the amount of electromagnetic energy from the periodic motors necessary to lift and move the car.
If you don't believe me about the air pressure, you can read more.
Air velocity in a vacuum, observe that all the charts are using logarithmic scales and not linear ones:
http://www.engineeringtoolbox.com/vacuum-pipes-air-velocity-d_1195.html
Basic compression of gases. Fun fact, diesel engines work by compressing air to the point where it is hot enough to ignite the fuel. Just compression, no spark. Adiabatic is what we care about in this topic:
http://www.engineeringtoolbox.com/compression-expansion-gases-d_605.html
Heating from atmospheric re-entry, which is really just an open-system, higher-velocity, lower-pressure example of the physics that would be at play here:
https://www.quora.com/Why-does-a-spacecraft-heat-up-during-reentry

Now, that we've established that pulling a vacuum is a key aspect of a hyperloop system, lets discuss the mechanical implications of said vacuum. If you pull ANY kind of vacuum on a sealed system, the weight of the air that is outside of the system exerts a force upon the entire system. In this particular case, you end up with a case that can simply be described by equations for uniform loading of a beam:
http://www.engineeringtoolbox.com/beam-stress-deflection-d_1312.html

But even uniform beam stress equations are simplistic explanations in this particular case. The entire hyperloop fits the definition of a thin-walled tube. If you want to calculate the strength of a thin wall tube under pressure, you use these equations:
http://www.engineeringtoolbox.com/stress-thin-walled-tube-d_948.html

You'll notice that the thin-wall equations have a coefficient of 4 multiplied by the wall thickness in the denominator, compared to a coefficient of 2 for the 'more simple' uniform beam loading equations. This means that, all thicknesses being the same (wall vs beam), any tube will have approximately half the strength of a beam made of the same material.

But wait, let's not forget about stress concentrations. Every cut they make, every bend, weld, joint, or any kind of change in geometry creates a place for mechanical stress to collect in a system. So if they cut holes for windows, they would only be introducing weaknesses. Nothing fatal, as long as they pay attention to exact geometries used: did they use a large enough radius for the edge chamfers, should they use a larger radius for the corners of the window? If you're curious:
http://engineersedge.com/material_science/stress_concentration_fundamentals_9902.htm

I'm not even going to bring up the dynamic stresses of the car traveling through the system - simply because I don't feel like doing/explaining 2nd and 3rd order Diff EQs or any kind of Laplace transform if we get into any kind of feedback & control territory. But off the top of my head, the hyperloop system will need to be designed to cope with how the air pressure in front and behind each car will play out across the tube, vibration of the super structure from turbulent and laminar flows, and any kind of wave motion of the air in the entire system.

Now, never mind the math. There is still the issue of actually building a system like this: sealing the windows will introduce additional operating costs by way of additional workload on the vacuum pumps (imperfections in workmanship leading to leaks), and additional construction costs by complicating the design and assembly. In theory, practice and theory are exactly the same, in practice, they are nothing alike

Of course, lets assume they solve all the engineering and construction problems: cutting windows still doesn't solve the strobing effect that those windows would create for anyone traveling past them at 500mph, even when you do cut them so large that they might be impossible/un-economical to make. So this might stop people from ridding the hyperloop at all in the first place. Not good for a fledgling system. But looking out a window still assumes you can make anything out when it wizzes by at 500mph and at close range. So I suspect that when the designers, and financiers, are faced with the choice of "$200 infotainment system for each car" or "multi-million dollar development and install costs for windows that increase the chance of system/project failure", they are going to pick the infotainment system each and every time. Plus, they can sell ads on the infotainment system to help recoup construction and operation costs, and they can't on the windows.

I never once suggested having windows was impossible; I even provided suggestions of how it could be done. No, I suggested that it didn't make economic sense to do so. Seems that Hyperloop One agrees with me, judging by their prototype. If they were considering windows for their design, they would have probably built at least one section with them to test things like bleed rates and stress on the system as cars pass through it.


tl;dr: applying a force evenly over an entire surface adds up quickly and "added up force" is just fancy engineer talk for "added up cost"- and if you're going to throw a hissy fit online when someone contradicts you, you should really know what you're talking about first.



As an aside, the NASA Space Power Facility is home to the world's strongest vacuum chamber at 10^-6 Torr; otherwise known as "not pure vacuum". It is close enough for practical tests on earth's surface, but it doesn't approach the approximate "1 hydrogen atom/cubic meter" that we observe outside of planetary magnetospheres:
https://facilities.grc.nasa.gov/spf/
 

lipe123

TS Evangelist
So double tl;dr version,
Your math is better than those of the engineers/etc thats working on this project and you don't think they can make it work?

You keep harping on the stresses of vacuums or partial vacuums but the super basic fact is that to create any aerodynamics or air pockets for this thing to ride on you will need quite a bit of gas in that tube and it really wont be such a big deal to worry about the vacuum stress.

Here is the actual definition of a vacuum, just to establish some kind of definition so you can follow along:
http://www.engineeringtoolbox.com/vacuum-d_837.html

In your own Quora link, it talks about partially evacuating the tube to reduce air friction on the pod - the Quora link even calls it "vacuum" - but I wasn't the one who started debating this. You're the one who got upset when they misunderstood the whole underpinning concept of the hyperloop: reduced air density to allow to higher transportation velocities.

I assumed a reasonable 50% vacuum. It might be more, it might be less, but they certainly are not going to try to push any cars through this tube at an atmospheric standard of 15psi. Even if you could get the air out of the way fast enough to approach 500mph, the compression of the air going around the car through such a tight space would generate large amounts of heat that would need to be dealt with. It is air being compressed in front of returning space craft that creates the heating, not 'air friction'. So all that fan on the front of the car is going to do is help 'float' the car away from the walls of the tube and reduce the amount of electromagnetic energy from the periodic motors necessary to lift and move the car.
If you don't believe me about the air pressure, you can read more.
Air velocity in a vacuum, observe that all the charts are using logarithmic scales and not linear ones:
http://www.engineeringtoolbox.com/vacuum-pipes-air-velocity-d_1195.html
Basic compression of gases. Fun fact, diesel engines work by compressing air to the point where it is hot enough to ignite the fuel. Just compression, no spark. Adiabatic is what we care about in this topic:
http://www.engineeringtoolbox.com/compression-expansion-gases-d_605.html
Heating from atmospheric re-entry, which is really just an open-system, higher-velocity, lower-pressure example of the physics that would be at play here:
https://www.quora.com/Why-does-a-spacecraft-heat-up-during-reentry

Now, that we've established that pulling a vacuum is a key aspect of a hyperloop system, lets discuss the mechanical implications of said vacuum. If you pull ANY kind of vacuum on a sealed system, the weight of the air that is outside of the system exerts a force upon the entire system. In this particular case, you end up with a case that can simply be described by equations for uniform loading of a beam:
http://www.engineeringtoolbox.com/beam-stress-deflection-d_1312.html

But even uniform beam stress equations are simplistic explanations in this particular case. The entire hyperloop fits the definition of a thin-walled tube. If you want to calculate the strength of a thin wall tube under pressure, you use these equations:
http://www.engineeringtoolbox.com/stress-thin-walled-tube-d_948.html

You'll notice that the thin-wall equations have a coefficient of 4 multiplied by the wall thickness in the denominator, compared to a coefficient of 2 for the 'more simple' uniform beam loading equations. This means that, all thicknesses being the same (wall vs beam), any tube will have approximately half the strength of a beam made of the same material.

But wait, let's not forget about stress concentrations. Every cut they make, every bend, weld, joint, or any kind of change in geometry creates a place for mechanical stress to collect in a system. So if they cut holes for windows, they would only be introducing weaknesses. Nothing fatal, as long as they pay attention to exact geometries used: did they use a large enough radius for the edge chamfers, should they use a larger radius for the corners of the window? If you're curious:
http://engineersedge.com/material_science/stress_concentration_fundamentals_9902.htm

I'm not even going to bring up the dynamic stresses of the car traveling through the system - simply because I don't feel like doing/explaining 2nd and 3rd order Diff EQs or any kind of Laplace transform if we get into any kind of feedback & control territory. But off the top of my head, the hyperloop system will need to be designed to cope with how the air pressure in front and behind each car will play out across the tube, vibration of the super structure from turbulent and laminar flows, and any kind of wave motion of the air in the entire system.

Now, never mind the math. There is still the issue of actually building a system like this: sealing the windows will introduce additional operating costs by way of additional workload on the vacuum pumps (imperfections in workmanship leading to leaks), and additional construction costs by complicating the design and assembly. In theory, practice and theory are exactly the same, in practice, they are nothing alike

Of course, lets assume they solve all the engineering and construction problems: cutting windows still doesn't solve the strobing effect that those windows would create for anyone traveling past them at 500mph, even when you do cut them so large that they might be impossible/un-economical to make. So this might stop people from ridding the hyperloop at all in the first place. Not good for a fledgling system. But looking out a window still assumes you can make anything out when it wizzes by at 500mph and at close range. So I suspect that when the designers, and financiers, are faced with the choice of "$200 infotainment system for each car" or "multi-million dollar development and install costs for windows that increase the chance of system/project failure", they are going to pick the infotainment system each and every time. Plus, they can sell ads on the infotainment system to help recoup construction and operation costs, and they can't on the windows.

I never once suggested having windows was impossible; I even provided suggestions of how it could be done. No, I suggested that it didn't make economic sense to do so. Seems that Hyperloop One agrees with me, judging by their prototype. If they were considering windows for their design, they would have probably built at least one section with them to test things like bleed rates and stress on the system as cars pass through it.


tl;dr: applying a force evenly over an entire surface adds up quickly and "added up force" is just fancy engineer talk for "added up cost"- and if you're going to throw a hissy fit online when someone contradicts you, you should really know what you're talking about first.



As an aside, the NASA Space Power Facility is home to the world's strongest vacuum chamber at 10^-6 Torr; otherwise known as "not pure vacuum". It is close enough for practical tests on earth's surface, but it doesn't approach the approximate "1 hydrogen atom/cubic meter" that we observe outside of planetary magnetospheres:
https://facilities.grc.nasa.gov/spf/
 

mbrowne5061

TS Evangelist
So double tl;dr version,
Your math is better than those of the engineers/etc thats working on this project and you don't think they can make it work?

You keep harping on the stresses of vacuums or partial vacuums but the super basic fact is that to create any aerodynamics or air pockets for this thing to ride on you will need quite a bit of gas in that tube and it really wont be such a big deal to worry about the vacuum stress.
Once again, I never said they couldn't make it work. I never even suggested it would be too expensive. I said that adding windows in the tube would unnecessarily raise the price, would potentially irritate riders, and no investor would go for it - especially when the alternative (infotainment system) generates ad revenue. We can build pretty much anything, if you throw enough money at the problem - but that doesn't mean you should throw money at every project.

In regards to "create any aerodynamics": 50% atmosphere is still plenty of gas to compress into small cushions around the pod as it travels. To give you some idea, humans can breath 7.5psi (50% of the accepted standard 1 earth atmosphere at sea level) unassisted for short periods of time. It wouldn't be comfortable, but you could do it. The compressors would run, but it still means 7.5lbf-per-sq-inch applied to entire hyperloop tube, a problem they've already overcome. But 7.5lbf-per-sq-inch is not a simple problem to overcome on any material suitable to be a window - especially when that window needs to be 50-100 feet long.

Now if your reading comprehension and mathematics skills were more advanced than primary school, we could continue this conversation. But they are not, so I'm done wasting my time.
 

Adhmuz

TechSpot Paladin
It would be awesome if these tubes could be transparent. I assume they might place cameras outside the tube and have this displayed on screens inside the vehicle. I know I wouldn't want the feeling of being trapped in a dark pipeline moving at the speed of sound.
At the speed these things would be traveling (upwards of 600mph) you would see nothing more than a blur at ground level looking out, this may even cause some very serious motion sickness to some if not most people. As pretty as it would be to have a clear tube with vehicles traveling at near the speed of sound, it would just be pointless IMO.
 

Skidmarksdeluxe

TS Evangelist
That is true! Better get out your flashlights!
I'd rather not and the last thing I want to see is the cabin crew running around with flashlights trying to find the source of the smoke. Believe it or not, that once happened to me and to say I was concerned is a bit of an understatement. Thankfully it was nothing major... or so they said. I guess it had to be because I'm still around. :eek:
 

merikafyeah

TS Addict
No need for windows if they're impractical. High quality displays inside, real-time camera feed from outside, problem solved. Think outside the box, or in this case, tube.

But still pretty pointless at the speed of sound. Like in Star Trek, whenever you enter hyperdrive you see nothing but streaks. Visually, it's a moot point. And the total trip time is also very short. Better to just show some local news or weather for wherever you're headed. Offering free wifi could also keep pretty much everyone happy for a measly half hour or so easy.
 

B5S46M

TS Enthusiast
It's not going to be a complete vacuum just a low pressure system, even regular perspex/plastic can handle that easily. https://www.quora.com/What-is-the-Hyperloop-How-does-it-work
If we want to get technical, we can't make a complete vacuum on earth - we don't have the appropriate materials nor techniques.

Moving beyond nitpicking, even a 50% reduction in air pressure inside of the tube would be 7.5lbs applied to every in^2 (never mind the change in force from passing cars creating higher, and then lower, pressures than the ambient average). 7.5lbs doesn't sound like much until you need to resist that applied continuously over a surface that is only supported every 50-100 feet. Keep in mind that tubes are weakest across their axis, or exactly how this force would be applied. It would get worse the closer they got to 'pure' vacuum, which they likely are aiming for. My bet is they will aim for around 25% normal air pressure (3.75psi).
You've obviously never done any work with vacuum. I designed UHV systems for nearly a decade. Vacuum is not a big deal, even what you call "complete vacuum." The transition from viscous flow to molecular flow is something a simple turbo pump can easily achieve, without even baking the chamber. 10E-3 or 10E-14 Torr, it's all the same. 14.7 psig (101.35 kPa) pressure on axis isn't an issue for any structural material. Compressive yield strength is measured in MPa, not kPa. Tubular shapes also have very high hoop strength. So, again, no issues to overcome there either.
 

mbrowne5061

TS Evangelist
You've obviously never done any work with vacuum. I designed UHV systems for nearly a decade. Vacuum is not a big deal, even what you call "complete vacuum." The transition from viscous flow to molecular flow is something a simple turbo pump can easily achieve, without even baking the chamber. 10E-3 or 10E-14 Torr, it's all the same. 14.7 psig (101.35 kPa) pressure on axis isn't an issue for any structural material. Compressive yield strength is measured in MPa, not kPa. Tubular shapes also have very high hoop strength. So, again, no issues to overcome there either.
If you're going to necro a thread, at least read it all the way through.
  • I never suggested that vacuum was a big deal to achieve, only impractical to go for something extreme in this case
  • 14.7psig on an axis that is 50-100 feet long is a big deal for a material when that material is something that is like a plexiglass that is expected to handle a 1-2 ton vehicle traveling at 500mph, so it would need to be very thick - which is why I kept saying they won't make the tube clear or install windows, because it would be too expensive compared to plain old steel
  • I never said Yield strength was measure in kPa, I provided links that stated MPa.
  • Hoop strength was covered already under the thin-walled tube equations.