Hyperloop Bankrupt and Busted.

[SorryBella]

6 hours ago, leadeater said:

Have a look at Brightline Railways in the US, what they are doing is relatively new and actually going well. Glacial tides seem to be changing, slooooowwwly

 

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

The biggest issue with Brightline (and really future private medium speed railway industry in US) is the fact that these are going to focus heavily on heavily populated metropolitan areas with huge local business or tourism presence, and barely any flights around it without it being coked out of their mind on FAA subsidies. This means that the more rural areas that would benefit with these medium speed trains even more than metropolitans that high chance already have a car or frequent flyer membership with the big 4 is going to take even longer to be covered.

 

Amtrak needs to own more rails and expand Acela. But with current political climate thats basically a pipe dream.

[williamcll]

7 hours ago, 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2) It's really old and outdated.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.

The odd thing is that China does have a Hyperloop sponsored low pressure railway project. A recent article remarks of an upgrade combing maglev to hit transonic speeds.

[Uttamattamakin]

59 minutes ago, williamcll said:

The odd thing is that China does have a Hyperloop sponsored low pressure railway project. A recent article remarks of an upgrade combing maglev to hit transonic speeds.

https://interestingengineering.com/transportation/china-hyperloop-train-completes-test-run

 

Quote

These consisted of three test runs at a superconducting maglev test line in Datong, Shanxi province that reached speeds of 31 miles/h (50 km per hour). The goal of the next-generation train is to eventually carry passengersi and cargo at a speed of 621 miles/h (1,000 km per hour) or faster in a near-vacuum tube.

Quote

However, the current tube available for trials measures only 1.24 miles (two km) in length. It is expected to be extended to 37 miles (60 km) over the next few years.  

God speed to them... this sounds about like what Hyperloop 1 accomplished.  Maybe a little more.   Hyperloop ones test track was already a mile long.  So  not much more.  

[Sauron]

It WAS always a stupid idea, and Musk knew it. He has admitted it was just a way to delay and sabotage california high speed rail.

[CarlBar]

This isn't a suprise to me either. Hyperloop One never had the investment required, a decent test track would needs to be many miles long, and building that has all the challanges of building a railway of that length and the extra costs of the development of the new systems. Thats a billion dollar project easily. A full run of high speed rail over the distances of the final goal project would be a tens of billions of dollar to low hundred billion dollar project at a minimum. Building an all new system over that run? Multiple hundreds of billions of dollars easily. They had maybe 1/1000th the money they needed to meet their goals.

 

From a physics and engineering standpoints it's not super difficult, we do somthing that, (from an engineering and physics perspective), is very similar on a constant basis with the inspection "pigs", (industry term), that are pushed along natural gas pipelines for inspection purposes via high pressure gas. They don't achieve the same kinds of raw speeds but they're not designed to as their goal is inspection not transport, (and the high pressure environment makes it harder anyway). But it shares most of the challanges and physics problems with the Hyperloop concept as both are sealed tubes with a significant pressure differential running over long distances that an object has to travel through.

 

Thats not to say a Hyperloop hs no new challanges, but the ones people bring up constantly, (Expansion and Sealing), are allready dealt with, and whilst scaling up in diameter has it's own issues it's heavily offset by the fact that natural gas pipelines have much higher pressure differentials, the low pressure does impart some unique challenges, but the vacuum being able to be much higher than a spacecraft test chamber eases it.

 

Most of the real challanges are in the cars that have to run in the tube, the safety features that have to be built into the tubes, and just standardising everything and tooling up new production lines to make it all. It's a money problem mainly, not an engineering one.

[Avocado Diaboli]

14 minutes ago, CarlBar said:

But it shares most of the challanges and physics problems with the Hyperloop concept as both are sealed tubes with a significant pressure differential running over long distances that an object has to travel through.

That's simplifying it a lot. The pressure differential or a high-pressure tube pushing outward is not the same structural problem as the pressure differential of an atmosphere pushing inward on a tube. A balloon can contain a higher pressure but it can't hold its shape with a vacuum. To pretend that these two problems are equivalent is willfully ignorant.

 

17 minutes ago, CarlBar said:

Thats not to say a Hyperloop hs no new challanges, but the ones people bring up constantly, (Expansion and Sealing), are allready dealt with,

Yes, with expansion loops. Have fun travelling down a tube that suddenly changes direction at the proposed speeds.

 

Sorry if I'm harsh, but you sound as blue eyed and gullible as Elon, when he pretended that the Hyperloop is really simple, like a tube with an air hockey table. The idea was stupid from the start and no sugarcoating is going to make it any more credible.

[CarlBar]

44 minutes ago, Avocado Diaboli said:

That's simplifying it a lot. The pressure differential or a high-pressure tube pushing outward is not the same structural problem as the pressure differential of an atmosphere pushing inward on a tube. A balloon can contain a higher pressure but it can't hold its shape with a vacuum. To pretend that these two problems are equivalent is willfully ignorant.

 

Yes, with expansion loops. Have fun travelling down a tube that suddenly changes direction at the proposed speeds.

 

Sorry if I'm harsh, but you sound as blue eyed and gullible as Elon, when he pretended that the Hyperloop is really simple, like a tube with an air hockey table. The idea was stupid from the start and no sugarcoating is going to make it any more credible.

 

Pressure pushing out vs pressure pushing in does have some differences on a structural level, (not a sealing level which is what i was focusing on), but structurally it's not a massive problem, we deal with external loads grater on all kind of structures constantly, not to mention various submerged items that are watertight that have to deal with the same problem from water pressure, (different sealing problem though).

 

Expansion loops are one populous way of dealing with the problem, but you can find images of actual pipeline online where there's clearly no such loops in use because then length of visible pipe is much too long, (usually a shot out to the horizon) to not need some sort of expansion compensation yet no such loops are visble. I can also think of at least one type of expansion joint that would work fine for the purpose. 

 

Here's an example of a bellows joint, (not what i was thinking of, and structurally more complex in a low internal pressure setup, but another viable option): 

 

This was the type i was thinking of, a slip joint:  

technically a variation on a bellows where the bellows is merely a spring rather than a structural and seelign component.

[Donut417]

17 hours ago, leadeater said:

Far as I can tell it's a perception issue, passenger rail transport in the US is view much the same as "Greyhound buses".

 

If passenger rail is to ever succeed in the US it need a dedicated network of its own. That is where the biggest issue is. The freight companies dont care about speed, so they dont maintain the rail for speed. Shit they can barely stop derailments at this point.

[Mark Kaine]

19 hours ago, Shimejii said:

Trains. Just use trains. Whole idea was to prevent High speed rail from getting funding so they had to "Show" something.

so complete and utter nonsense, got it! 

 

op, is way too long, just needed to say "Elon Musk"... that's all there is to it (so nothing as usual)

[Mark Kaine]

18 hours ago, leadeater said:

@LAwLz Have a look at Brightline Railways in the US, what they are doing is relatively new and actually going well. Glacial tides seem to be changing, slooooowwwly

 

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

 

Lots and lots of work needs to be done for intercity rail and inner city rail in the US, inner city the most though. All the track layouts and stations are very inefficient and were put in long ago for a very different type of service and envisioned passenger needs.

 

Also highspeed rail is very often faster than aircraft total end to end time even over moderately long distances. If you want to move a lot of people around and quickly air travel isn't it.

 

Far as I can tell it's a perception issue, passenger rail transport in the US is view much the same as "Greyhound buses".

i recently heard (from an expert, as he's Texan) that "Americans love their cars, because freedom", and that it's not going to change in the next 100 or so years...

 

but the point is its all about "freedom".... they think this is freedom, so they probably never going to change until someone makes them. 

 

 

im sorry,  to me freedom is being at a beach and go dive and play with sharks or octopus or something, or just enjoy the sun while watching a formula one race * (well, when formula one still had real cars, ironically lol) and not the way of transportation i use.

 

ALTHOUGH GIVE ME A 737 OVER A FRIGGIN CAR ANYDAY TBH

 

 

*all of these things are actual hobbies of mine, although i haven't watched an F1 race in ages... too boring now with those neutered cars and engine sounds ¯\_(ツ)_/¯ 

[Uttamattamakin]

4 hours ago, CarlBar said:

 

Pressure pushing out vs pressure pushing in does have some differences on a structural level, (not a sealing level which is what i was focusing on), but structurally it's not a massive problem, we deal with external loads grater on all kind of structures constantly, not to mention various submerged items that are watertight that have to deal with the same problem from water pressure, (different sealing problem though).

The hyperloop pods were meant to move at near airliner speeds.  The need for these joints every 10's or 100's of meters would make that very difficult. 

Hyperloop is one of the things I alluded to in my original post.  Some things are totally prohibited by the basic laws of physics.  Those things simply do not exist.  

 

Other things, like hyperloop, push those laws to their limits and ultimately basic physics wins.  Eventually the constant pressure of the atmosphere and thermal expansion and contraction wins, gravity which causes that pressure wins, thermodynamics wins.   These forces can be resisted for a time and / or at a small scale. 

 

Maybe if we discover some unobtanium carbide to make this all out of it can work.   Who knows.   

[CarlBar]

3 hours ago, Mark Kaine said:

i recently heard (from an expert, as he's Texan) that "Americans love their cars, because freedom", and that it's not going to change in the next 100 or so years...

 

but the point is its all about "freedom".... they think this is freedom, so they probably never going to change until someone makes them. 

 

 

im sorry,  to me freedom is being at a beach and go dive and play with sharks or octopus or something, or just enjoy the sun while watching a formula one race * (well, when formula one still had real cars, ironically lol) and not the way of transportation i use.

 

ALTHOUGH GIVE ME A 737 OVER A FRIGGIN CAR ANYDAY TBH

 

 

*all of these things are actual hobbies of mine, although i haven't watched an F1 race in ages... too boring now with those neutered cars and engine sounds ¯\_(ツ)_/¯ 

 

It's probably going to change inside the next few decades. Europe's and parts of asia are planning on bringing in bans on new ICE sales in that timeframe. Thats going to make developing new ICE private vehicles much more expensive for the car manufactures whilst making electrics cheaper to develop. Thats going to be reflected in customer pricing and thats going to price most americans out of ICE's. And thats going to force changes as your average american can't go as far without mass transit.

 

1 hour ago, Uttamattamakin said:

The hyperloop pods were meant to move at near airliner speeds.  The need for these joints every 10's or 100's of meters would make that very difficult. 

Hyperloop is one of the things I alluded to in my original post.  Some things are totally prohibited by the basic laws of physics.  Those things simply do not exist.  

 

Other things, like hyperloop, push those laws to their limits and ultimately basic physics wins.  Eventually the constant pressure of the atmosphere and thermal expansion and contraction wins, gravity which causes that pressure wins, thermodynamics wins.   These forces can be resisted for a time and / or at a small scale. 

 

Maybe if we discover some unobtanium carbide to make this all out of it can work.   Who knows.   

 

No physics does not push this out to the edge. As noted we run much harder to seal natural gas pipelines using this type of joint over vastly longer distances and we do not have major issues with those pipes being leaky. If Physics would somehow make the Hyperloop impossible to keep sealed we couldn't have natural gas pipelines. We do and they're highly routine, therefore it's not a significant issue. The Hard part is not the seals, or the structural aspects, 9they're non-trivial but again we've build many large objects with much larger problems), it's the safety and carriages that have to run in them.

 

The point about the difficulties the joints give a high speed object is fair. But i never expected if anyone every built one of these for real, (i had my doubts it could be funded from a fairly early point), they'd actually run the carriages with the tube as the track. From an engineering perspective it allways made more sense to have a seperate track within the tube, with the tube just being the pressure vessel. At that point your getting into territory that high speed trains, (especially maglev), have allready dealt with.

[starsmine]

12 minutes ago, CarlBar said:

 

It's probably going to change inside the next few decades. Europe's and parts of asia are planning on bringing in bans on new ICE sales in that timeframe. Thats going to make developing new ICE private vehicles much more expensive for the car manufactures whilst making electrics cheaper to develop. Thats going to be reflected in customer pricing and thats going to price most americans out of ICE's. And thats going to force changes as your average american can't go as far without mass transit.

 

There honestly will be no forseeable change in how far you can go with an EV vs ICE with the rapid charging station roll outs. the NA standard is now the same as tesla, all new cars in the US use the same cable and can use tesla chargers as well as the ones from electrify America and others. Yes the charging infrastructure is not fully rolled out, but look at how much changed in the last 5 years, ICE ban is a decade away.

 

[RejZoR]

Whoever thinks electricity is going to be cheaper in the future is more blind than Stevie Wonder and Ray Charles combined.

 

Not only governments will have to somehow hoard taxes they currently collect from fossil fuels, our infrastructure just isn't ready for any of it. Just look at the state of charging stations. So few of them, half of them don't even achieve anywhere near speeds car manufacturers are bragging about, other half is out of order most of the time, because charging takes so long we don't have enough spots to charge so many EV's for extended periods of time, our power grids are not capable of juicing so many EV's at all times and ultimately, we don't have enough power produced. If we wanted to be up to the demand we'll have in 10 or 20 years, we'd have to start building nuclear plants when first EV's started coming to market some 10 years ago. Instead dumbasses like Germany were instead closing the nuclear plants.

 

All the hype around solar panels and wind turbines fall flat on the face when you see how much surface area they need for their crappy efficiency and how much waste there is when all this crap will start degrading. Germany has such huge problem with waste wind turbine blades, no one is even recycling them. They are made of fiberglass composite and they are nowhere near as eas to recycle and they just end up laying out in the fields next to operational wind turbines. It's peak idiocy through and through because veryone is hyping and rushing this BS "eco" nonsense with only goal being profits, not anything remotely related to actual ecology.

[Uttamattamakin]

36 minutes ago, CarlBar said:

No physics does not push this out to the edge. As noted we run much harder to seal natural gas pipelines using this type of joint over vastly longer distances and we do not have major issues with those pipes being leaky.

Natural gas pipes holding in pressure VS tubes that need to keep pressure out. 

 

This can easily holds in pressure but gets totally crushed by 1 ATM of pressure. 

 

36 minutes ago, CarlBar said:

 

If Physics would somehow make the Hyperloop impossible to keep sealed we couldn't have natural gas pipelines.

It's not about keeping it sealed its about materials having strength in tension VS in compression.   The physics of these things are very different.    As demonstrated in the above experiment. 

 

But what do I know about anything? 

Haven't mastered time travel or managing to lose the gut and keep the butt yet. 

 

[Uttamattamakin]

11 minutes ago, RejZoR said:

Whoever thinks electricity is going to be cheaper in the future is more blind than Stevie Wonder and Ray Charles combined.

IF we go hard on nuclear power and space based solar power.  Something Space X and a rocket like Starship (if they can make it work.  Perhaps a redesign will ) will make that much easier.  Put solar in space where weather is not an issue and beam it back with microwaves.   It could even make electricity basically free.  

 

There are other problems with using electricity for vehicles as their only drive train. 

 

11 minutes ago, RejZoR said:

Not only governments will have to somehow hoard taxes they currently collect from fossil fuels, our infrastructure just isn't ready for any of it. Just look at the state of charging stations. So few of them, half of them don't even achieve anywhere near speeds car manufacturers are bragging about, other half is out of order most of the time, because charging takes so long we don't have enough spots to charge so many EV's for extended periods of time, our power grids are not capable of juicing so many EV's at all times and ultimately, we don't have enough power produced. If we wanted to be up to the demand we'll have in 10 or 20 years, we'd have to start building nuclear plants when first EV's started coming to market some 10 years ago. Instead dumbasses like Germany were instead closing the nuclear plants.

Chicago is having this problem a lot right now.  

It is so cold here that this morning icicles had formed INSIDE the window.    Even though the air temp in the house was not below freezing.  The window was that cold.  -30 F windchills -10 or -15 F real temps.    Teslas have been having a very hard time. 
 

[CarlBar]

6 minutes ago, Uttamattamakin said:

Natural gas pipes holding in pressure VS tubes that need to keep pressure out. 

 

This can easily holds in pressure but gets totally crushed by 1 ATM of pressure. 

 

It's not about keeping it sealed its about materials having strength in tension VS in compression.   The physics of these things are very different.    As demonstrated in the above experiment. 

 

But what do I know about anything? 

Haven't mastered time travel or managing to lose the gut and keep the butt yet. 

 

 

Yes tension vs compression is different. But your acting like -1 atmosphere, (actually a bit less as it's not supposed to go down that low), is some massive value thats unbelievably hards to deal with structurally. It's not. We've built countless things that have to handle vastly greater compression strain, (again notably various submerged items, including some underwater pipes that have to be able to not collapse under a loss of pressure situation). It is not a problem. if it was we couldn't build anything that goes deeper than 10 meters underwater.

[Kisai]

40 minutes ago, starsmine said:

There honestly will be no forseeable change in how far you can go with an EV vs ICE with the rapid charging station roll outs. the NA standard is now the same as tesla, all new cars in the US use the same cable and can use tesla chargers as well as the ones from electrify America and others. Yes the charging infrastructure is not fully rolled out, but look at how much changed in the last 5 years, ICE ban is a decade away.

 

A standard needed to exist before one could do this. To Tesla's credit, they at least just "built some" chargers. However a quick look on the maps will tell you exactly where they exist and where "Destination chargers" exist (eg maybe 1 in a basement parking level of a hotel)

 

https://www.cbc.ca/news/politics/canada-electric-vehicles-2035-1.7063993

Quote

New rules will effectively end sales of vehicles powered only by gasoline or diesel by 2035

 

More or less, even if the government flips, I don't see this changing. The short-term problem is building generation capacity, cause this is also coming down the pipe too:

https://canada.constructconnect.com/dcn/news/government/2023/12/climate-and-construction-fossil-fuel-ban-resistance-in-north-america-leaves-developers-in-a-quandary#:~:text=In British Columbia%2C the municipalities,B.C. Zero Carbon Step Code.

Quote

In British Columbia, the municipalities of Nanaimo, Saanich and Victoria have adopted bans or restrictions on new natural gas connections, some as early as 2024, as part of their adoption of the B.C. Zero Carbon Step Code.

 

One of the reasons the government had to basically ram through Site C, cause all this stuff is coming, and you need to look no further than Alberta and Texas to see the consequences of not investing in sufficient electrical capacity and relying on spot prices when the weather exceeds what was planned for.

 

For those who maybe didn't catch the news:

https://www.cbc.ca/news/canada/calgary/alberta-electrical-grid-emergency-decarbonization-1.7083664

Quote

Saturday evening's emergency alert from the province of Alberta, warning of rotating power outages because of pressure on the electrical grid caused by the extreme cold, underlines just how difficult the energy transition is going to be in the Prairie provinces, according to economist Andrew Leach.

https://aeso.ca/aeso/media/aeso-thanks-albertans-for-quick-response-to-call-for-power-conservation/

 

Echos of https://en.wikipedia.org/wiki/2021_Texas_power_crisis

 

There's also all kinds of property damage that happens if the power grid has to resort to rolling blackouts.

 

BTW, BC Hydro/BC Government was pretty smug about it:

https://globalnews.ca/news/10225470/bc-experiences-record-breaking-electricity-demand-amid-cold-snap-says-bc-hydro/

Quote

“Extreme weather events like drought and cold snaps are putting people and communities at increased risk,” said Josie Osborne, Minister of Energy, Mines and Low Carbon Innovation. “Thanks to the resiliency of our energy system and exceptional planning by BC Hydro, we are able to meet the needs of British Columbians while also delivering clean, reliable hydro-electricity to our neighbours in Alberta when they needed it most.”

 

Anyway to avoid things getting political and off topic, let's just focus on the fact that even stupid projects aren't 100% unviable all the time. There were aspects of the Hyperloop that would work given certain perfect scenarios that would never come to pass. It was definitely not a "new" invention, and anyone who's been a trainfan for years could have seen the glaring flaws. 

 

What needs to happen is for high speed rail to be competitive with air travel, otherwise the other option is make better forms of (albeit slower) air travel that don't require the amount of security and annoyance to travel on. I'd metaphorically kill for a way to board a comfortable train or aircraft and not have to spend an hour checking in and out. Automated cars promise that, but they are limited by road space.

 

[Uttamattamakin]

6 minutes ago, CarlBar said:

Yes tension vs compression is different. But your acting like -1 atmosphere, (actually a bit less as it's not supposed to go down that low), is some massive value thats unbelievably hards to deal with structurally. It's not. We've built countless things that have to handle vastly greater compression strain, (again notably various submerged items, including some underwater pipes that have to be able to not collapse under a loss of pressure situation). It is not a problem. if it was we couldn't build anything that goes deeper than 10 meters underwater.

Pressure is measured in 

Force Per Unit Area. 

A container that might hold up under 1 ATM   101.3 KiloPascals  of external pressure and is the size of a garbage can  ... may not hold up under that same pressure applied on a larger area.  Since as the area grows the total force it has to resist does not grow linearly but as the square.  

Consider for example a spherical shell of material one meter in radius.  Suppose it can resist 1 ATM of external pressure while hold vacum inside.    Surface area of a sphere is 4 Pi radius^2.    So it can resist 4 Pi ATM of total force applied to it.   

This does not mean that the same shell can resist the same 1 ATM of pressure if it is scaled up to 5 meters in radius.  Now it is resisting  4*Pi*25 ATM or 100 Pi ATM of total force applied to it.  These are VERY different propositions.   This relationship between area and pressure and force is the immutable law of physics that makes it hard to build large vacuum chambers.  When they fail they fail explosively (technically implosively) and catastrophically. 

  

 

[Sauron]

8 minutes ago, CarlBar said:

Yes tension vs compression is different. But your acting like -1 atmosphere, (actually a bit less as it's not supposed to go down that low), is some massive value thats unbelievably hards to deal with structurally. It's not. We've built countless things that have to handle vastly greater compression strain, (again notably various submerged items, including some underwater pipes that have to be able to not collapse under a loss of pressure situation). It is not a problem. if it was we couldn't build anything that goes deeper than 10 meters underwater.

The problem isn't just achieving the vacuum or maintaining it, although it would be expensive and largely a waste of energy and money. The problem is that any failure would be catastrophic. If any part of the tunnel structure fails and the tunnel is decompressed it's likely to implode, in which case you die. There can be no emergency exits because of the vacuum so in case of, say, a fire on the shuttle, you die. If the shuttle is damaged and is no longer air tight, you die - compare this with a plane where having air in your lungs during a decompression event would not result in them bursting, meaning you can still survive the flight by using the built in oxygen masks. Also with a plane you only need to maintain the plane itself for it to remain safe to use, not hundreds of kilometers of tunnels.

 

Of course submarines can withstand higher pressures, but submarines are not kilometers long. Even if it's physically possible, it would be prohibitively expensive to make a large, airtight structure as strong as a submarine body over hundreds of kilometers.

[leadeater]

4 hours ago, Mark Kaine said:

play with sharks

I don't want your freedom, you can keep that one lol

[leadeater]

1 hour ago, RejZoR said:

All the hype around solar panels and wind turbines fall flat on the face when you see how much surface area they need

A tiny section of one state in Australia is enough to power most of the entire South East Asia, even though Sun Cable project failed for numerous reasons the surveys and assessments around land area usage were not wrong and you can go look them up. There are a lot of places on this planet with no significant land use potential for people or food which makes them suited to solar or wind (depending on local climates etc).

 

It's more about spending money wisely and making good choices than solar and wind being a bad idea. My town as been 100% wind and hydro powered for I think 20 years now, 80% wind last time I checked from memory.

 

Transporting turbine blades is damn difficult though.

[Mark Kaine]

29 minutes ago, leadeater said:

I don't want your freedom, you can keep that one lol

its in italy, they're kinda small (1 meter), well most of them

 

 

[CarlBar]

16 minutes ago, Uttamattamakin said:

Pressure is measured in 

Force Per Unit Area. 

A container that might hold up under 1 ATM   101.3 KiloPascals  of external pressure and is the size of a garbage can  ... may not hold up under that same pressure applied on a larger area.  Since as the area grows the total force it has to resist does not grow linearly but as the square.  

Consider for example a spherical shell of material one meter in radius.  Suppose it can resist 1 ATM of external pressure while hold vacum inside.    Surface area of a sphere is 4 Pi radius^2.    So it can resist 4 Pi ATM of total force applied to it.   

This does not mean that the same shell can resist the same 1 ATM of pressure if it is scaled up to 5 meters in radius.  Now it is resisting  4*Pi*25 ATM or 100 Pi ATM of total force applied to it.  These are VERY different propositions.   This relationship between area and pressure and force is the immutable law of physics that makes it hard to build large vacuum chambers.  When they fail they fail explosively (technically implosively) and catastrophically. 

  

 

 

And when you scale up the area you just build it stronger, why is this hard to understand? 

 

6 minutes ago, Sauron said:

The problem isn't just achieving the vacuum or maintaining it, although it would be expensive and largely a waste of energy and money. The problem is that any failure would be catastrophic. If any part of the tunnel structure fails and the tunnel is decompressed it's likely to implode, in which case you die. There can be no emergency exits because of the vacuum so in case of, say, a fire on the shuttle, you die. If the shuttle is damaged and is no longer air tight, you die - compare this with a plane where having air in your lungs during a decompression event would not result in them bursting, meaning you can still survive the flight by using the built in oxygen masks. Also with a plane you only need to maintain the plane itself for it to remain safe to use, not hundreds of kilometers of tunnels.

 

Of course submarines can withstand higher pressures, but submarines are not kilometers long. Even if it's physically possible, it would be prohibitively expensive to make a large, airtight structure as strong as a submarine body over hundreds of kilometers.

 

There's no reason a failure of one part of the tunnel would cause the whole thing to implode, thats not how the structural loads in this scenario work, (there are scenarios where it applies, but not somthing like a hyperloop tube).

 

Most of the other issues are a matter of safety systems. The two biggest problems are a catastrophic structural failure of the tube whilst the carriage is passing through that section, and a fire.

 

The first is equivalent of a severe derailment in a traditional train as the consequences in basic terms are the same. A sudden and uncontrolled deceleration in a very short length of time. And the difficulties of making it survivable are the same as with a high speed train, only further amplified by the higher speed. But it's also a problem for trains, high speed catastrophic derailments are almost impossible to make fully survivable with the constraints of a normal passenger experience, more so as the speed rises. The answer is allways to take ever greater measures to detect the varied circumstances that would lead to such a scenario before they cause a disaster and shut things down for maintenance when those warning signs are spotted.

 

A fire again has a bunch of issues in common with train and car tunnel fires, and the risks, problems, and mitigations are similar once you factor in the safety factors to deal with the lesser problems, (i'll touch on those below). It's a pain and a huge danger, but it's well understood problem, which doesn't mean it's not a big problem, much like the catastrophic derailment cenario it's one of the most likely, (in both a hyperloop and the equiveillances with cars and trains i mentioned), to lead to mass casualties because fires in tunnels are inherently highly lethal and avoiding them via intensive risk mitigation is vital. 

 

 

Almost every other problem has a simple solution. Rigorous detection and monitoring plus valve work, and braking systems so you can safely repressurise the tunnel and halt the carriage in a timely fashion. You can actually do so fairly quickly with good designs of both, (in fact a hyperloop carriage might be able to stop faster than a slower train carriage, depending on what deceleration limit you apply).

 

 

The one other exception to this is a catastrophic breech far enough downstream from the carriage it won't be immediately effected, but large enough to allow a significant rate of ingress, (the maximum flow into the pipe is constrained by the cross section of the breech, hence why valve work can safely repressurise without that issue, you can keep the flow rate below dangerously fast whilst still filling the tube in a fairly short timespan, exact speeds would depend on particulars of the system). However the very presence  of a repressurisation system allready provides a mitigation against it as the maximum flow rate, (and therefore destructiveness of the pressure wave), is dependent on two factors. The pressure difference between the area immediately behind the wave and the area immediately in front of the wave, and how laminer the flow is. The act of repressurising the tube inherently decreases the differential and that forces the pressure wave to begin to slow down. In the real world flow is never 100% laminar and a natural safety feature would be to design the interior of the tube with features (baffles is i believe the correct technical term), that disrupt laminar flow above a certain flow velocity. It effectively a problem you can solve with a mixture of passive measures and stuff your allready doing for other reasons.

 

Assuming a top speed around half the speed of sound and a maximum allowable deceleration force of half a G or so it takes around 4.5km and 30 seconds to stop. I'm less sure on exactly how fast you could repressurrise, (a lot depends on the specifics of that system, potentially at the upper end you could hit a very high speed without dangerous pressure waves, but it requires a very carefully engineered solution).

 

 

 

As for the Sub comparison, Sub have to handle much higher pressures, the claimed maximum diving depth of a Los Angeles Attack Sub equates to a pressure differential of approximately 20 atmospheres and it's pressure hull is far larger in diameter than a Hyperloop could ever need to be. I used Subs as an example of something that is over an order of magnitude more capable than would be required to emphasise how easy of a problem it is to solve engineering wise. We routinely build structures that exceed it by a wide margin. As i already noted we actually have seafloor gas pipelines and AFAIK in some places they have to be able to survive a complete loss of pressure and not implode, and those run for 100's of km at depths where the pressure can reach >10 atmospheres. if it was super expensive to build we wouldn;t have them.

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20 hours ago, leadeater said:

Freedom trains? 2nd Amendment trains?

 

Is embracing the term bullet the answer to the perception change? lol

I'd personally like a Nuke Train.

Carbon neutral, pray we don't lose containment!