Vacuum transport: the key to long distance transport?

[chatelot16]

magnetic levitation: exactly what it takes to lose the energy that the vacuum saves!

the good old wheel is enough, alas can be a tire to avoid noise, although it is less energetically good than metal on metal

power supply by rigid bar under tension, fixed by insulator to the tunnel, between the 2 rails

[bernardd]

I was also talking about the possibility of a linear motor: permanent magnets on the vehicle, windings on the rail / stator.

[Obamot]

... I went to see, it looks like there is something of both ...! The train being placed on skates at rest.

A primary rail and a secondary rail on each side, associated with a linear motor in the train, coupled to a guide / lateral traction ...!

At the same time, it looks like the train is resting on "nothing" ...



[Edit: ok I found the page]
http://swissmetro.ch/fr/projet/%C3%A9ta ... 3%A9riques

The simulations carried out subsequently concerned aerodynamic aspects (including the resulting improvements in the shape of the vehicle and its magnetic suspension), temperature assessments and the relationships between tunnel diameter, atmospheric pressure and energy consumption.

[chatelot16]

all false ! they are doing big aerodynamic studies ... it's not under vacuum

since it is not under vacuum it is necessary that the tunnel is much larger than the vehicle: diameter 7m!

with the vacuum it is enough that it passes nothing more

aerodynamics under vacuum no longer matters: completely right front and rear

[bernardd]

Thank you for your interest in this subject: at first it seems exotic, but when you look closely, you see better ... the interest :-)

The notion of "vacuum" remains relative: there is always a residual pressure.

As the friction is proportional to the pressure, but to the cube of the speed, there is still an aerodynamic study to do: it is a bit the problem of the re-entry of a space shuttle into the atmosphere, it heats up before to reach 1 bar above the ground, and yet it is a vacuum for concord.

The passage of a vehicle represents a volume compression, which loses energy: this is why some propose to use this inevitable compression to continue to empty, which is possible when the residual air mass becomes negligible in relation to the mass of the vehicles.

Geometrically, if the diameter of the vehicle is the radius of the tube, the compression is negligible: it is no coincidence that this is roughly the proportion of the swissmetro diagram, in my opinion :-)

Increasing the diameter of the vehicle is a compression that is quickly stronger, but interesting if you vacuum at the same time.

[Christophe]

aerodynamics under vacuum no longer matters: completely right front and rear

And no windows, few windows and very thick vehicle walls ...
It will look more like a space station than a metro ...

I do not see how the mass of the vehicle can be acceptable ... at a competitive price

[bernardd]

The vehicle must withstand only 1 bar of pressure, hardly needs mechanical resistance to shocks if everything is taken care of by "air balloons" and real-time monitoring, with an external energy input.

It therefore remains only to carry 100kg of passenger and life support systems: not the sea to drink.

We should even be able to integrate vital monitoring, like the pilots, or even massage chair :-)

It's a recumbent bike, but just a little faster!

With emergency pedaling pedaling in a vacuum, what speed, by the way?

[Christophe]

Uh 1 bar of pressure "only" it is funny the Bernardd ...

It's still 10 kg / m² ...

[bernardd]

It is dimensioning on a large fuselage which has surface.

On a cylinder with a maximum diameter of 1m, this is not much. At worst, you put a little coiled kevlar as for the composite tanks, which hold 1000bar of test for the most solid.

Think of the blue tanks with tight lid: they hold 2 bars without problem at atmospheric pressure.

Except for the propulsion attachments, there may not even be a need for a chassis, a cylinder should be sufficient for the mechanical strength of the vehicle.

[Christophe]

We agree but even on 1m it is strength ... the metroswiss project is public transport, so 3 to 4 m in diameter at least ... am I wrong?