Official SpaceX Hyperloop Pod Competition

[Memphis]

It's actually not all that difficult to maintain a pressure that low. Hospitals, Banks and Credit Unions do it all the time and it's not anything terribly trying on equipment or manpower to pull off. Scale it up and presto. It's actually pretty sound, mechanically speaking. We've been doing it for almost a century and we've got it down pat.  

Hoapitals banks and credit unions maintain large near complete vacums? What are you referencing? Its certainly not the tubing system we use as the whole tube is not a vacuum. Pneumatic tube systems pull air like a vacuum but the pressure in the whole tube never decreases to 99.9% of a vacuum. The hyperloop works by decompressing the entirety of the tube to cut down on drag etc. Clearly you know little about pneumatic tube design.

[Unobscured Vision]

Easy, now. I never said anything about a near-complete vacuum at all with those applications. I'm talking about the hardware used in those applications not being all that dissimilar from what the Hyperloop will be using -- just scaled up massively and running at far lower pressures. No reason to get your dander in a fluff. I don't claim to be an expert in pneumatics, and I'm not, but I know a lot more than you'd give me credit for. Sheesh ...

[DocM]

Hyperloop One's full diameter test track in Nevada has been completed, and they plan for tests in a few months.

 

https://techcrunch.com/2017/04/06/hyperloop-one-completes-vegas-test-track-tube-reveals-11-proposed-u-s-routes/

 

 

[Memphis]

Hyperloop One's full diameter test track in Nevada has been completed, and they plan for tests in a few months.
 
https://techcrunch.com/2017/04/06/hyperloop-one-completes-vegas-test-track-tube-reveals-11-proposed-u-s-routes/
 

 

It will never be built mark my words, it will never be approved.

[SALSN]

And landing rockets is also impossible!

[Memphis]

And landing rockets is also impossible!

 

Plausible, not impossible. This for many reasons is not even plausible. Did you not notice that the tubes they were using needed crossbar before they where put together? They can't even support themselves well what makes you think these will hold up for much more than the test.

 

[SALSN]

2 hours ago, sidroc said:

 

Plausible, not impossible. This for many reasons is not even plausible. Did you not notice that the tubes they were using needed crossbar before they where put together? They can't even support themselves well what makes you think these will hold up for much more than the test.

 

This is a test tube, it is only supposed to hold up for the test...
Even so, it seems like a good idea to make these as thin as safely possible, to save on weight and cost, lots of structures are made of components that are not rigid until they are assembled.
I'm no structural engineer, but I have a suspicion that a structural engineer has actually looked this over before they started to build it. After all, SpaceX have a lot of experience with making metal tubes that can take a beating.

[Memphis]

This is a test tube, it is only supposed to hold up for the test...
Even so, it seems like a good idea to make these as thin as safely possible, to save on weight and cost, lots of structures are made of components that are not rigid until they are assembled.
I'm no structural engineer, but I have a suspicion that a structural engineer has actually looked this over before they started to build it. After all, SpaceX have a lot of experience with making metal tubes that can take a beating.

Again Thunderf00t made good points on this project and none of you have been able to sufficiently counter them except to say"I'm sure they know what they're doing"

[Emn1ty]

10 minutes ago, sidroc said:

Again Thunderf00t made good points on this project and none of you have been able to sufficiently counter them except to say"I'm sure they know what they're doing"

 

The biggest counter point is that he's speaking from his armchair and doesn't actually know what he's talking about. Why don't we wait and see where the tech goes before committing to condemning or praising it? 

[SALSN]

I've watched all thunderf00ts videos on the matter (and all his other videos as well) never saw a good point, he is usually pretty sharp, but when it comes to Elons projects he seems to have some weird bias. In one video he even criticised Elon for claiming that his rockets could reach Europa (or perhaps one of the other moons) saying that such a place could not sustain humans, and return would be too difficult, when, in the referenced tweet, Elon never talked about humans or return missions, only payload to the moon. That seems to be the level of research thunderf00t puts into his videos about the hyperloop as well.

For further analysis on his actual comments on the hyperloop, see my comment on one of the previous pages.

Sure the project could fail, but don't put too much emphasis on criticism coming from someone who used the length of the test track as a predictor for failure.

[Memphis]

The biggest counter point is that he's speaking from his armchair and doesn't actually know what he's talking about. Why don't we wait and see where the tech goes before committing to condemning or praising it? 

If this was not the elon musk cult following, people would be sceptical. They have to show it can work and actually present how they have solved the issues brought up. Also Thunderf00t is quite qualified to make videos on science topics. Certainly more than any of us. Again what do you make of what he said? Your writing it off automatically.

[Memphis]

I've watched all thunderf00ts videos on the matter (and all his other videos as well) never saw a good point, he is usually pretty sharp, but when it comes to Elons projects he seems to have some weird bias. In one video he even criticised Elon for claiming that his rockets could reach Europa (or perhaps one of the other moons) saying that such a place could not sustain humans, and return would be too difficult, when, in the referenced tweet, Elon never talked about humans or return missions, only payload to the moon. That seems to be the level of research thunderf00t puts into his videos about the hyperloop as well.

For further analysis on his actual comments on the hyperloop, see my comment on one of the previous pages.

Sure the project could fail, but don't put too much emphasis on criticism coming from someone who used the length of the test track as a predictor for failure.

What did you respond to exactly? Not seeing anything substantial.

[Emn1ty]

12 minutes ago, sidroc said:

If this was not the elon musk cult following, people would be sceptical. They have to show it can work and actually present how they have solved the issues brought up. Also Thunderf00t is quite qualified to make videos on science topics. Certainly more than any of us. Again what do you make of what he said? Your writing it off automatically.

 

Of course we're skeptical, it's an emerging technology. But being skeptical isn't mutually exclusive to being optimistic about it. People here are just enthusiastic about the possibility of something that can drastically cut down commute times (and therefore in a way extend everyone's lives because they're wasting less time sitting in traffic or on other transit methods). Faster transit is major to humanity.

I am not writing it off, but it's interesting how you've latched onto a single party and assumed they are correct without taking into account other sources to formulate an opinion of your own. He does have valid concerns, but that doesn't make the case to abandon the project and state it'll never happen. That's taking the step from asking sensible questions and voicing concerns to deconstructive criticism.

Let the technology be explored and see how it pans out. If we were to approach things like this all the time I doubt we'd have ever broken the sound barrier, or gotten as far as we have with fusion reactors, etc.

[DocM]

I think the matter of maintaining the Hyperloop vacuum isn't as large an issue as perceived. A low vacuum can be achieved with a Dyson. Hyperloop uses a medium vacuum at a not particularly difficult level to pull, middle of the range, and there are numerous pumps which can do it at very high flow rates and with high reliability; scroll pump, Roots blower etc.  Staging vacuum pumps is standard practice.

 

And as for this tube: it's made to run tests during a development period, not for continuous duty. Two different standards.

[Memphis]

Of course we're skeptical, it's an emerging technology. But being skeptical isn't mutually exclusive to being optimistic about it. People here are just enthusiastic about the possibility of something that can drastically cut down commute times (and therefore in a way extend everyone's lives because they're wasting less time sitting in traffic or on other transit methods). Faster transit is major to humanity.

I am not writing it off, but it's interesting how you've latched onto a single party and assumed they are correct without taking into account other sources to formulate an opinion of your own. He does have valid concerns, but that doesn't make the case to abandon the project and state it'll never happen. That's taking the step from asking sensible questions and voicing concerns to deconstructive criticism.

Let the technology be explored and see how it pans out. If we were to approach things like this all the time I doubt we'd have ever broken the sound barrier, or gotten as far as we have with fusion reactors, etc.

I ha e latched on to nothing, i can just clearly see that your are not addressing huge problems with the hyperloop and writing it off as just armchair criticism. That's the definition of a fanboy. At least DocM is sort of addressing them even if he continues to repeat untruthful claims about the vacuum and not respond to how high the actual pressure is or shoe other examples with numbers.

[SALSN]

2 hours ago, sidroc said:

What did you respond to exactly? Not seeing anything substantial.

Because there were never any substantial criticisms, just conjecture and dubious assumptions, and a lot of complaining that the very first prototypes did not preform as the finished product is supposed to.
I'm not saying this is a guaranteed success, personally I think there is a good (or bad) chance it could fail, but I don't see any obvious reasons for why it should not work, unlike something like solar roadways, that can be debunked with practical examples and electro- and other physics calculations.

There are definitely challenges, like how to deal with thermal material expansion and contraction, or how to handle a breach, but these are not deal breakers, but something that can likely be solved with engineering solutions.

[DocM]

Since he won't believe anyone here this quote is from Carl Brockmeyer of Oerlikon Leybold Vacuum in Germany, a major vacuum gear supplier worldwide. They're working with HTT. Speaking of pulling the vacuum.

 

http://spectrum.ieee.org/transportation/mass-transit/elon-musks-hyperloop-proposal-gains-momentum

 

Quote

“I’m tempted to say it’s easy, but better to just say it’s very achievable—this will not be the big technology difficulty,” says Brockmeyer. “We are most likely suggesting a displacement pump,” he adds. “I’m not entitled to tell you how much equipment we’re going to use, but it depends not only on what’s necessary to keep vacuum—we also need a redundant system,” he goes on. “Maybe we’ll install an extra pump in case we need to exchange pumps or to not have to run them all at full speed.”

 

A (positive) displacement pump would include a scroll pump, Roots blower (including staged), Wankel pump, rotary vane and several others.

 

 

Edited April 9, 2017 by DocM

[Memphis]

Since he won't believe anyone here this quote is from Carl Brockmeyer of Oerlikon Leybold Vacuum in Germany, a major vacuum gear supplier worldwide. They're working with HTT. Speaking of pulling the vacuum.
 
http://spectrum.ieee.org/transportation/mass-transit/elon-musks-hyperloop-proposal-gains-momentum
 

“I’m tempted to say it’s easy, but better to just say it’s very achievable—this will not be the big technology difficulty,” says Brockmeyer. “We are most likely suggesting a displacement pump,” he adds. “I’m not entitled to tell you how much equipment we’re going to use, but it depends not only on what’s necessary to keep vacuum—we also need a redundant system,” he goes on. “Maybe we’ll install an extra pump in case we need to exchange pumps or to not have to run them all at full speed.”

 
A (positive) displacement pump would include a scroll pump, Roots blower (including staged), Wankel pump, rotary vane and several others.
 
 



What a surprise, its possible to create such a vacuum with pumps. Straw man, that's not in dispute that such a vacuum can be created at all. Again, how do you propose it would handle a decompression event in any part of the tube? What stops it from wrecking the entire tube and killing the passengers? This is not addressed. And saying they know what they're doing does not cut it

Because there were never any substantial criticisms, just conjecture and dubious assumptions, and a lot of complaining that the very first prototypes did not preform as the finished product is supposed to.
I'm not saying this is a guaranteed success, personally I think there is a good (or bad) chance it could fail, but I don't see any obvious reasons for why it should not work, unlike something like solar roadways, that can be debunked with practical examples and electro- and other physics calculations.

There are definitely challenges, like how to deal with thermal material expansion and contraction, or how to handle a breach, but these are not deal breakers, but something that can likely be solved with engineering solutions.

Keep sidestepping addressing anything.

[Shiranui]

Is Musk still persisting with this?

[DocM]

1 hour ago, Shiranui said:

Is Musk still persisting with this?

He released it to the public domain, and currently corporations and major engineering schools worldwide are working on it with test tracks being built or finished (Hyperloop One.)  Several nations are interested including Russia, India, Sweden, Finland, Indonesia, the Emirates and several Asian nations including China.  SpaceX is hosting a contest between (mostly) university teams, with a subscale test track outside of their headquarters.

 

3 hours ago, sidroc said:

 What a surprise, its possible to create such a vacuum with pumps. Straw man,

Totally ignoring what the guy said about ease of doing such a vacuum. 

 

Quote

Again, how do you propose it would handle a decompression event in any part of the tube?

What kind of decompression event?

 

Are we talking the Aliens: Resurrection creature sucked through a bullet hole scenario? 

 

A bullet hole would take about 7 hours to empty the ISS, which is about 1,000 cubic meters. Such a hole has happened on ISS due to orbital debris and it didn't bother the crew, though the alarms did, and the repair was of course made. No one was sucked out. 

 

The ISS volume would be a Hyperloop track segment about 380 meters long. Losing the vacuum in a 200 kilometer Hyperloop run would take proportionately longer, giving a proportionately longer time to scram the system. 

 

Tube segment suffers catastrophic failure?

 

Even with a full breach, filling such a large volume takes time as the inflow cannot go past supersonic, meaning it would take ~5 seconds for the wavefront to travel 1.608 km (1 mile), 50 seconds for it to reach 16+ kilometers etc.  

 

First, we need shutter gates at regular intervals to close off that segment on sudden vacuum loss, sealing the remaining Hyperloop volume.  Redundant sensors instantly raise the red flag, as in a spacecraft launch abort system. These could be as simple as what's used on rockets - trip wires. 

 

Given warning of such an anomaly via said sensors, a pod stopping from 1200 kph in 50 seconds exposes the passengers to about  .68 G. 10 seconds is about 3.4 G - roller coaster turf. Tower of Terror in Gold Reef City SA does 6.3 G.  Pick your G number.

 

Car spacing? Depends on the emergency braking system. 20 km?

 

The lead pod closing on the breach may be save-able or not depending on its proximity, but then airplanes crash, cars hit trees, people fall down basement stairs etc. Pods behind it, or ahead of the breach, could safely slow to a stop more gradually. Upside: fewer would die in a pod than a crashing A320 or Bombardier Q400 commuter plane.

 

 

Edited April 10, 2017 by DocM

[DocM]

On 4/5/2017 at 10:12 AM, sidroc said:

Hoapitals .... maintain large near complete vacums? What are you referencing?

Linear accelerators and cyclotrons for gamma or charged particle radiotherapy, maintaining the vacuum in an MRI systems cryostat, ultracentrifuges which spin at 20,000 rpm need to run in a vacuum to prevent friction heating etc.

[Memphis]

What kind of decompression event?
 
Are we talking the Aliens: Resurrection creature sucked through a bullet hole scenario? 
 
A bullet hole would take about 7 hours to empty the ISS, which is about 1,000 cubic meters. Such a hole has happened on ISS due to orbital debris and it didn't bother the crew, though the alarms did, and the repair was of course made. No one was sucked out. 
 
The ISS volume would be a Hyperloop track segment about 380 meters long. Losing the vacuum in a 200 kilometer Hyperloop run would take proportionately longer, giving a proportionately longer time to scram the system. 
 
Tube segment suffers catastrophic failure?
 
Even with a full breach, filling such a large volume takes time as the inflow cannot go past supersonic, meaning it would take ~5 seconds for the wavefront to travel 1.608 km (1 mile), 50 seconds for it to reach 16+ kilometers etc.  
 
First, we need shutter gates at regular intervals to close off that segment on sudden vacuum loss, sealing the remaining Hyperloop volume.  Redundant sensors instantly raise the red flag, as in a spacecraft launch abort system. These could be as simple as what's used on rockets - trip wires. 
 
Given warning of such an anomaly via said sensors, a pod stopping from 1200 kph in 50 seconds exposes the passengers to about  .68 G. 10 seconds is about 3.4 G - roller coaster turf. Tower of Terror in Gold Reef City SA does 6.3 G.  Pick your G number.
 
Car spacing? Depends on the emergency braking system. 20 km?
 
The lead pod closing on the breach may be save-able or not depending on its proximity, but then airplanes crash, cars hit trees, people fall down basement stairs etc. Pods behind it, or ahead of the breach, could safely slow to a stop more gradually. Upside: fewer would die in a pod than a crashing A320 or Bombardier Q400 commuter plane.
 
 

You misunderstand (or straw man?) Again. These tubes they are testing with needed supports to keep from warping under their own weight as can be clearly seen in the pictures. What keeps suddenly desensitization and implosion from occurring? If you say the steel will be reinforced, then how thick do you imagine it has to be to keep from imploding? And how do you think a 2.5 meter several inches thick reinforced steel tube that is 700 miles long would cost? And you think it will be more economical? Again obviously small leak could be patched as I have said in previous posts so long as the structure could withstand damage to its integrity. how would you reinforce it and make it even slightly affordable or more efficient than rail? You keep dodging the points thunderf00t brought up and answering questions no one is asking. Again your making a straw man and I think you know it

Linear accelerators and cyclotrons for gamma or charged particle radiotherapy, maintaining the vacuum in an MRI systems cryostat, ultracentrifuges which spin at 20,000 rpm need to run in a vacuum to prevent friction heating etc.

These systems are heavily reinforced and are quite small really.

[Shiranui]

Just go with MagLev.

[DocM]

1 hour ago, sidroc said:

You misunderstand (or straw man?) Again.

 

You asked

 

Quote

Again, how do you propose it would handle a decompression event in any part of the tube?

And I proposed how I see decompression management being handled. I'm sure I missed something, but that question doesn't mention structure.

 

Now you ask about structure.

 

Quote

These tubes they are testing with needed supports to keep from warping under their own weight as can be clearly seen in the pictures. What keeps suddenly desensitization and implosion from occurring? If you say the steel will be reinforced, then how thick do you imagine it has to be to keep from imploding? 

Science 101: atmospheric pressure is about 14.7 psi, which is what the tubes will be exposed to even with a vacuum inside. It's the differential plus deformation that kills you.

 

Key to the full application will be stiffener rings since the tube getting out of round an inch or so can increase radial loads by 30%+, but engineers have known this for a very long time. No need to turn it into armor plate.

 

For a short proof of principle test track stiffeners are not so essential, but there are some around the finished test track. Disconnected tubes on pallets don't count wrt visible warpage. 

Edited April 10, 2017 by DocM

[Memphis]

2 hours ago, DocM said:

You asked

 

And I proposed how I see decompression management being handled. I'm sure I missed something, but that question doesn't mention structure.

 

Now you ask about structure.

 

Science 101: atmospheric pressure is about 14.7 psi, which is what the tubes will be exposed to even with a vacuum inside. It's the differential plus deformation that kills you.

 

Key to the full application will be stiffener rings since the tube getting out of round an inch or so can increase radial loads by 30%+, but engineers have known this for a very long time. No need to turn it into armor plate.

 

For a short proof of principle test track stiffeners are not so essential, but there are some around the finished test track. Disconnected tubes on pallets don't count wrt visible warpage. 

I stiffner rings eh? Care to source where hyperloop one says that will work? Care to show what evidence they have proposed or cite their explanation for how they will do this and how it will withstand the pressures with these rings you speak of? Bear in mind, those horribly thin tubes on their test track have what you describe aleady and clearly they sag even so. Bear in mind stiffner rings add little support to the section between them they mainly help to limit deformation at given points and stop further deformation. You still have a high chance of a depressurization event in the tube with a fairly huge hole reauiring not only a repair, but re vacuming the entire space that lost air before any type of lock kicked in. Speaking of such construction issues, how do you expect to deal with expansion adequately? How many feet of expansion do you think a 700 long vacuum will be? How will you deal with expansion and not have serious structural weakness that on the slightest deformation does not implode?

Edited April 10, 2017 by sidroc