Topic moved from General by dthead on 10 Oct 2016 21:40
  eddyb Chief Train Controller

Unlike Japan the Chinese have big distances so they are working on doing 1000kph Magtube now so there is no need for them to loan us anything

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  billybaxter Deputy Commissioner

Location: Bosnia Park, Fairfield
How do you know the Chinese are working on it now? Please provide a link. Don't expect us to believe you have inside information.
  eddyb Chief Train Controller

How do you know the Chinese are working on it now? Please provide a link. Don't expect us to believe you have inside information.
billybaxter
https://techxplore.com/news/2014-05-enclosed-tube-maglev-capable-mph.html
  billybaxter Deputy Commissioner

Location: Bosnia Park, Fairfield
That article is three years old and sources a tabloid newspaper, the sort that publishes stories about alien landings, ESP, Elvis sightings etc. Anything better?

Had a look for something more recent but only found stuff referring to the same Daily Mail story, for example... http://english.swjtu.edu.cn/public/viewNews.aspx?ID=154
Still three years old and not looking serious. Your 1000km/h is 'on paper'. His little fairground ride has managed 50. You seriously don't imagine business people riding this dodgem car in a clear plastic tube thingy at 50 km/h all the way to Melbourne do you? Capacity looks rather limited.

Today's quality transport story from the Daily Mail
http://www.dailymail.co.uk/sciencetech/article-4425160/Game-Thrones-ship-designed-Panama-Papers-criminals.html
See the quality of your source?
  eddyb Chief Train Controller

That article is three years old and sources a tabloid newspaper, the sort that publishes stories about alien landings, ESP, Elvis sightings etc. Anything better?

Had a look for something more recent but only found stuff referring to the same Daily Mail story, for example... http://english.swjtu.edu.cn/public/viewNews.aspx?ID=154
Still three years old and not looking serious. Your 1000km/h is 'on paper'. His little fairground ride has managed 50. You seriously don't imagine business people riding this dodgem car in a clear plastic tube thingy at 50 km/h all the way to Melbourne do you? Capacity looks rather limited.

Today's quality transport story from the Daily Mail
http://www.dailymail.co.uk/sciencetech/article-4425160/Game-Thrones-ship-designed-Panama-Papers-criminals.html
See the quality of your source?
billybaxter
Once again you are right Billy it was 2010 when that story broke and nothing much seems to have happened even though he is still working on it.

The problem is that to go 1,000kph you need tunnels and they are still thinking twin tunnels with vacuum pumps where at those speeds a single tunnel will suffice with passing loops at big distance stations and exhaust valves either end of each tunnel.

It really needs a big rethink on existing practice and perhaps they are doing that now as even though China makes most TBM in the world already they are designed in other countries.

Already there are only two companies that do not have Chinese investment now and they are only interested in obtaining the expertise. http://tunneltalk.com/Company-News-Apr2017-Lovsuns-sets-international-strategy.php
  Valvegear The Ghost of George Stephenson

Location: Norda Fittazroy
The problem is that to go 1,000kph you need tunnels and they are still thinking twin tunnels with vacuum pumps where at those speeds a single tunnel will suffice with passing loops at big distance stations and exhaust valves either end of each tunnel.
"eddyb"
Explain to me how these exhaust valves will work. The tunnel is at considerably lower pressure than the atmosphere, so any opening will cause air to enter, and there will be no exhaust function at all. Nothing will flow automatically from a low pressure area to an area of higher pressure - elementary physics.
  eddyb Chief Train Controller

The problem is that to go 1,000kph you need tunnels and they are still thinking twin tunnels with vacuum pumps where at those speeds a single tunnel will suffice with passing loops at big distance stations and exhaust valves either end of each tunnel.
Explain to me how these exhaust valves will work. The tunnel is at considerably lower pressure than the atmosphere, so any opening will cause air to enter, and there will be no exhaust function at all. Nothing will flow automatically from a low pressure area to an area of higher pressure - elementary physics.
Valvegear

We all have been in a subway station when a train is entering the station and felt the air being pushed by the train and as the Magtube train would be 5.6m diameter in a 6m diameter tunnel at 1,000kph the piston effect would be so much greater that most air would be pushed through the exhaust valve and that could just be a vertical 1m diameter pipe with a flap on top that is opened by any air escaping and closed by gravity.


There is some very heavy reading here https://www.recreationalflying.com/tutorials/groundschool/umodule2.html#pressure and the bit about the Pitot tube which we are all familiar with from “aircrash investigations” may explain more.


This is interesting  “Incidentally Daniel Bernoulli's father Johann [born 1667] was the mathematician who first adopted the symbol 'g' for the acceleration due to gravity.”
  Valvegear The Ghost of George Stephenson

Location: Norda Fittazroy
We all have been in a subway station when a train is entering the station and felt the air being pushed by the train and as the Magtube train would be 5.6m diameter in a 6m diameter tunnel at 1,000kph the piston effect would be so much greater that most air would be pushed through the exhaust valve and that could just be a vertical 1m diameter pipe with a flap on top that is opened by any air escaping and closed by gravity.
eddyb
Well done; you have only overlooked one small point.
What causes the "piston effect"?
Answer; Air - you said so yourself.

The train is at 1000 km/h because it is in a vacuum tube where there is no air.
Where will your piston effect come from?
Answer; It won't.
  eddyb Chief Train Controller

We all have been in a subway station when a train is entering the station and felt the air being pushed by the train and as the Magtube train would be 5.6m diameter in a 6m diameter tunnel at 1,000kph the piston effect would be so much greater that most air would be pushed through the exhaust valve and that could just be a vertical 1m diameter pipe with a flap on top that is opened by any air escaping and closed by gravity.
Well done; you have only overlooked one small point.
What causes the "piston effect"?
Answer; Air - you said so yourself.

The train is at 1000 km/h because it is in a vacuum tube where there is no air.
Where will your piston effect come from?
Answer; It won't.
Valvegear

As the air pressure has only to be reduced to the same as aircraft at cruise level around 5psi http://www.mide.com/pages/air-pressure-at-altitude-calculator  there would still be some piston effect to rid the tunnel any air that has leaked through the air doors etc.


Just remember that even though it would be in that rarefied atmosphere it would have no wings to drag along using far less power than a plane.
  Valvegear The Ghost of George Stephenson

Location: Norda Fittazroy
As the air pressure has only to be reduced to the same as aircraft at cruise level around 5psi http://www.mide.com/pages/air-pressure-at-altitude-calculator there would still be some piston effect to rid the tunnel any air that has leaked through the air doors etc.

Just remember that even though it would be in that rarefied atmosphere it would have no wings to drag along using far less power than a plane.
eddyb

Absolute rubbish; now you really are grasping at straws. Either you're operating in a vacuum or you're not - make your mind up.
Just in case you're not familiar with the fact, atmospheric pressure is about 14.7 psig, and it's spending all its time trying to push your tunnel doors down because there's no pressure on the other side. As soon as the doors are even slightly opened there will be a hurricane strength wind howling into the tunnel. This will happen whether the tunnel pressure is zero or 5 psig. The idea that your train will still be doing 1000 km/h, and generating this mythical "piston effect" against the massive head wind caused by the inrush of air is just devoid of any scientific justification at all.

I think it's time you acknowledged the fact that you are completely out of your depth with this whole idea.
  eddyb Chief Train Controller

As the air pressure has only to be reduced to the same as aircraft at cruise level around 5psi http://www.mide.com/pages/air-pressure-at-altitude-calculator there would still be some piston effect to rid the tunnel any air that has leaked through the air doors etc.

Just remember that even though it would be in that rarefied atmosphere it would have no wings to drag along using far less power than a plane.

Absolute rubbish; now you really are grasping at straws. Either you're operating in a vacuum or you're not - make your mind up.
Just in case you're not familiar with the fact, atmospheric pressure is about 14.7 psig, and it's spending all its time trying to push your tunnel doors down because there's no pressure on the other side. As soon as the doors are even slightly opened there will be a hurricane strength wind howling into the tunnel. This will happen whether the tunnel pressure is zero or 5 psig. The idea that your train will still be doing 1000 km/h, and generating this mythical "piston effect" against the massive head wind caused by the inrush of air is just devoid of any scientific justification at all.

I think it's time you acknowledged the fact that you are completely out of your depth with this whole idea.
Valvegear

Never have I ever said it would be operating in a vacuum but only at the same atmospheric pressure as a plane which would easily allow 1,000kph with the use of little energy as it would have no wings to drag along.

In mines we had double doors so there was only a very slight amount of air went into the returns and if anyone foolishly left one open there is no way you could open the other one due to the air pressure difference.

You are correct in saying that it needs a greater pressure than 14.7psi to open the exhaust valve flap and this would easily be achieved with the piston effect of a 5.6m diameter train in a 6m diameter tunnel doing 1,000kph in a 5psi atmosphere.
  Valvegear The Ghost of George Stephenson

Location: Norda Fittazroy
Never have I ever said it would be operating in a vacuum
eddyb
Fair enough - it was mentioned in some of the additional reading I did. My post did, however, canvass the possibilities in 5 psig tunnel pressure, and you are still looking at a hurricane force wind when the door is only slightly opened.

only at the same atmospheric pressure as a plane which would easily allow 1,000kph with the use of little energy as it would have no wings to drag along.
eddyb
Evidence and calculations?

In mines we had double doors so there was only a very slight amount of air went into the returns and if anyone foolishly left one open there is no way you could open the other one due to the air pressure difference.
eddyb
Precisely the point of physics to which I am alluding.

You are correct in saying that it needs a greater pressure than 14.7psi to open the exhaust valve flap and this would easily be achieved with the piston effect of a 5.6m diameter train in a 6m diameter tunnel doing 1,000kph in a 5psi atmosphere.
eddyb
At no point did I say that it needed more than 14.7 psig to open the exhaust valve. As usual, you have completely failed to address my point that I did make about the huge head wind the train will get as air enters. Both billybaxter and I have been bashing for ages trying to get you to publish some engineering proof of what you claim. We still haven't seen any. Now you say your piston effect would easily be achieved..... Not one scrap of evidence to support such a claim - as usual.

No doubt you are also familiar with the fact that pressure is evenly distributed in a fluid, and your so-called piston effect is going to spread along the train and away from the exhaust valves and doors.

I repeat, eddy, you are completely out of your depth.
  eddyb Chief Train Controller

Never have I ever said it would be operating in a vacuum
Fair enough - it was mentioned in some of the additional reading I did. My post did, however, canvass the possibilities in 5 psig tunnel pressure, and you are still looking at a hurricane force wind when the door is only slightly opened.

only at the same atmospheric pressure as a plane which would easily allow 1,000kph with the use of little energy as it would have no wings to drag along.
Evidence and calculations?

In mines we had double doors so there was only a very slight amount of air went into the returns and if anyone foolishly left one open there is no way you could open the other one due to the air pressure difference.
Precisely the point of physics to which I am alluding.

You are correct in saying that it needs a greater pressure than 14.7psi to open the exhaust valve flap and this would easily be achieved with the piston effect of a 5.6m diameter train in a 6m diameter tunnel doing 1,000kph in a 5psi atmosphere.
At no point did I say that it needed more than 14.7 psig to open the exhaust valve. As usual, you have completely failed to address my point that I did make about the huge head wind the train will get as air enters. Both billybaxter and I have been bashing for ages trying to get you to publish some engineering proof of what you claim. We still haven't seen any. Now you say your piston effect would easily be achieved..... Not one scrap of evidence to support such a claim - as usual.

No doubt you are also familiar with the fact that pressure is evenly distributed in a fluid, and your so-called piston effect is going to spread along the train and away from the exhaust valves and doors.

I repeat, eddy, you are completely out of your depth.
Valvegear

Valvegear

Perhaps I misled you when I called the Japanese atmospheric Maglev instead of 14.7psi Maglev



The train would have double doors far enough for the train to fit between on either side of each station with the exhaust tubes even further from the stations so with only one door opened at any time only a small amount of air would enter the tunnel.



When the train approaches the station there would be a piston effect with any air exhausting until it slowed whereby the flap would fall down sealing the tunnel from the outside atmosphere.



Actually it may be best to just have conventional 10m wide centre platform stations rather than the complexity of running the segmental lining through the station.



You only have to look at the front of a plane to see that it would have less air resistance but it can be calculated here https://www.recreationalflying.com/tutorials/groundschool/umodule2.html#pressure  by people smarter than me as it depends on weight, altitude, angle of attack etc.



There is a lot of talk about air pressure in tunnels here http://www.tunneltalk.com/TunnelTECH-May2015-Aerodynamics-and-ventilation-in-rail-tunnels-civil-measures.php and if it is cheaper to do more tunnelling or just use more power or go slower.



You will notice that air actually travels back between the train and the tunnel so with the 5psi Magtube 5.6mdiameter in a 6m diameter tunnel most remaining air would be pushed forward and out.



Please keep asking questions as I am not allowed to mention it anywhere else here.
  billybaxter Deputy Commissioner

Location: Bosnia Park, Fairfield
Maybe, if instead of building these expensive tunnels and the machines to get the pressure down, and developing the trains to run in them, we could just get the maglevs up to an altitude of 30 000 or 40 000 feet where the pressure is that low and get them to move around there? I wonder if that's possible? Would certainly be cheaper.
  Valvegear The Ghost of George Stephenson

Location: Norda Fittazroy
You will notice that air actually travels back between the train and the tunnel
eddyb
If there's one thing I love, it's having my own words said back to me as if I'd never thought of the point. To repeat; pressure is evenly distributed in a fluid. . . that's an immutable law of physics.


Maybe, if instead of building these expensive tunnels and the machines to get the pressure down, and developing the trains to run in them, we could just get the maglevs up to an altitude of 30 000 or 40 000 feet where the pressure is that low and get them to move around there? I wonder if that's possible? Would certainly be cheaper.
billybaxter
Great idea!
Then we could do away with the Maglev and tunnels and call them aeroplanes.
I wonder whether if that would stop eddyb's non-stop waffling. He has used a bit of time today to demonstrate that he has little or no knowledge about the mechanics of fluid flow. We can add that to all the other tripe we've been fed.
  eddyb Chief Train Controller

Maybe, if instead of building these expensive tunnels and the machines to get the pressure down, and developing the trains to run in them, we could just get the maglevs up to an altitude of 30 000 or 40 000 feet where the pressure is that low and get them to move around there? I wonder if that's possible? Would certainly be cheaper.
billybaxter

Assuming the Magtube is good for 200 years and plane replacement cost about $1b a year it would be about the same and that is if we do not run out of oil.
  eddyb Chief Train Controller

You will notice that air actually travels back between the train and the tunnel
If there's one thing I love, it's having my own words said back to me as if I'd never thought of the point. To repeat; pressure is evenly distributed in a fluid. . . that's an immutable law of physics.


Maybe, if instead of building these expensive tunnels and the machines to get the pressure down, and developing the trains to run in them, we could just get the maglevs up to an altitude of 30 000 or 40 000 feet where the pressure is that low and get them to move around there? I wonder if that's possible? Would certainly be cheaper.
Great idea!
Then we could do away with the Maglev and tunnels and call them aeroplanes.
I wonder whether if that would stop eddyb's non-stop waffling. He has used a bit of time today to demonstrate that he has little or no knowledge about the mechanics of fluid flow. We can add that to all the other tripe we've been fed.
Valvegear

Even though pressure tries to be distributed evenly in the extreme case of an internal combustion motor the closeness of the rings to the bore prevents that and all I am suggesting is that the bigger the train is in relation to the tunnel the less air flowing back past the train.
  Valvegear The Ghost of George Stephenson

Location: Norda Fittazroy
Even though pressure tries to be distributed evenly in the extreme case of an internal combustion motor the closeness of the rings to the bore prevents that
"eddyb"
Totally irrelevant analogy. That's what the rings are there for; to prevent pressure loss and form a closed system.
Pressure is evenly distributed through the combustion chamber, and the piston rings form part of the combustion chamber by sealing against the cylinder wall.

Your silly comment is like saying that pressure tries to be distributed but is prevented by your tunnel doors. You apparently have no knowledge about types of closed systems.
(And, an internal combustion power plant is not a motor; by definition it is an engine.)

I am suggesting is that the bigger the train is in relation to the tunnel the less air flowing back past the train.
eddyb"
Thank you, Captain Obvious. Nobody would suggest anything else, but since when have we been concerned with volume? The pressure will still be evenly distributed.
  eddyb Chief Train Controller

Even though pressure tries to be distributed evenly in the extreme case of an internal combustion motor the closeness of the rings to the bore prevents that
Totally irrelevant analogy. That's what the rings are there for; to prevent pressure loss and form a closed system.
Pressure is evenly distributed through the combustion chamber, and the piston rings form part of the combustion chamber by sealing against the cylinder wall.

Your silly comment is like saying that pressure tries to be distributed but is prevented by your tunnel doors. You apparently have no knowledge about types of closed systems.
(And, an internal combustion power plant is not a motor; by definition it is an engine.)

I am suggesting is that the bigger the train is in relation to the tunnel the less air flowing back past the train.
Thank you, Captain Obvious. Nobody would suggest anything else, but since when have we been concerned with volume? The pressure will still be evenly distributed.
Valvegear

As I hold a third class certificate of competency in NSW coal mines I know what I am talking about regarding ventilation even if you do not understand me.
  Valvegear The Ghost of George Stephenson

Location: Norda Fittazroy
As I hold a third class certificate of competency in NSW coal mines I know what I am talking about regarding ventilation even if you do not understand me.
"eddyb"
I understand you perfectly. You are competent at ventilation. However, your answers to the points I keep raising show conclusively that you know nothing whatsoever about physics and the mechanics of fluid flow. Such knowledge is vital to your tunnel pipe dream.
I hold a degree in Chemical Engineering and have five decades of experience working with fluid flow, and I'm telling you that you haven't got a clue about it.
  eddyb Chief Train Controller

As I hold a third class certificate of competency in NSW coal mines I know what I am talking about regarding ventilation even if you do not understand me.
I understand you perfectly. You are competent at ventilation. However, your answers to the points I keep raising show conclusively that you know nothing whatsoever about physics and the mechanics of fluid flow. Such knowledge is vital to your tunnel pipe dream.
I hold a degree in Chemical Engineering and have five decades of experience working with fluid flow, and I'm telling you that you haven't got a clue about it.
Valvegear

Itemise the points you keep raising and I will answer them as I have not got a clue what you do not understand.
  Valvegear The Ghost of George Stephenson

Location: Norda Fittazroy
Itemise the points you keep raising and I will answer them as I have not got a clue what you do not understand.
"eddyb"
Time for straight talking:-
There is nothing you have said that I don't understand.
There is a lot you have said that you obviously don't understand.
For months, both billybaxter and I have been itemising dozens of queries, and asking for good accurate, scientifically correct answers and you have steadfastly refused to provide them. Now you say you will, and I, for one, do not believe it, because you are not capable of it.
You do not have enough knowledge of the subject; it's as simple as that. What you are proposing is a massive amount more complicated than Ventilation.
I would need to be very careful in using all of my experience if I was involved with part of the engineering on such a project, in amongst the Civil, Mechanical, Electrical Engineers,etc, and other people with expertise in Geology, Aquifers, Tunnel Boring, Drainage, Safety and so on who would be essential to any successful design.


There is an old proverb that says "A little knowledge is a dangerous thing", and you are proving that this is true.
  eddyb Chief Train Controller

Itemise the points you keep raising and I will answer them as I have not got a clue what you do not understand.
Time for straight talking:-
There is nothing you have said that I don't understand.
There is a lot you have said that you obviously don't understand.
For months, both billybaxter and I have been itemising dozens of queries, and asking for good accurate, scientifically correct answers and you have steadfastly refused to provide them. Now you say you will, and I, for one, do not believe it, because you are not capable of it.
You do not have enough knowledge of the subject; it's as simple as that. What you are proposing is a massive amount more complicated than Ventilation.
I would need to be very careful in using all of my experience if I was involved with part of the engineering on such a project, in amongst the Civil, Mechanical, Electrical Engineers,etc, and other people with expertise in Geology, Aquifers, Tunnel Boring, Drainage, Safety and so on who would be essential to any successful design.


There is an old proverb that says "A little knowledge is a dangerous thing", and you are proving that this is true.
Valvegear

I recently saw a show on how they made the Ford V8 motor and Henry only used guys who had a can do attitude and in the mine if I ever felt something was a bit difficult my workmate would say ”you gotta wanna do it Edd”



Now if you get people with all the knowledge and experience with a can do attitude it may work but if not they would be beaten before they start.



Although I have 25 years experience in underground coal mines and 25 years sitting in traffic jams driving trucks that only gives me a very overall picture and if they found open minded people to do a study then why not.



Nobody wants the Japanese Maglev as wheels can do almost the same job at a fraction of the cost and China has a university that knows how to build Maglev but doesn't know yet how to build tunnels.



Australia has the expertise with our own Terratec and has a golden opportunity to build, in my opinion, an economically viable 1,000kph Magtube and develop TBM that can penetrate all types ground for long tunnels with robotic innovations or maybe pumping muck out.



As nothing like this has ever been done before it would be impossible to give you links where it has so it would be a learning curve for everybody but what we learned we could then export for top dollar.
  Valvegear The Ghost of George Stephenson

Location: Norda Fittazroy
Nothing you have just written alters the picture one little bit. My comments stand.
  eddyb Chief Train Controller

Nothing you have just written alters the picture one little bit. My comments stand.
Valvegear

So do you think it is worth a study by open minded people or not

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