Science Elon Musk to build Hyperloop bullet train 'within weeks'.

[RGClark]

Elon Musk to build Hyperloop bullet train 'within weeks'
By Taku Dzimwasha
October 24, 2015 16:38 BST

Engineers in California are to build a transportation system that propels passengers through an airless tube at the speed of sound. Hyperloop Transportation Technologies (HTT) will build a five-mile "hyperloop" which will allow the bullet train to reach speeds of 760mph
http://www.ibtimes.co.uk/elon-musk-build-hyperloop-bullet-train-within-weeks-1525529

Bob Clark

 

[Urwumpe]

.... 5 mile track? That is way shorter than the former Transrapid track, that was only long enough for doing tests with 260 mph... ah, the track should get limited to 160 mph, when testing with passengers, and go up to 780 mph without... could get funny.

 

[Loru]

They should make it open top and convert it to roller coaster. 780mph roller coaster.

 

[TachyonDriver]

Apart from not being able to breathe...

 

[Col_Klonk]

5 mile airless tube ?? I'd like to see them maintain the vacuum of such a wide, long chamber..
The costs would be hectic, and the tickets - why rush $$$ when you can cruise cheaply

 

[RisingFury]

It doesn't need to be the kind of vacuum as you have in particle colliders.

 

[ISProgram]

What about that test track outside SpaceX's headquarters...?

 

[Urwumpe]

It doesn't need to be the kind of vacuum as you have in particle colliders.

Also, you can likely easier have a vacuum in a pipeline, that multiple bars of overpressure with a gas pipeline.

 

[RisingFury]

I disagree. I think vacuum is more difficult to maintain.

Keep in mind that pressure = energy. If you're bleeding pressure, you're bleeding energy. And that's easier to put back into the system using a pump.


But a vacuum isn't about energy, it's about removing material. That ends up being a bit more tricky.

The pipe leaking isn't the problem. The stations where you load and unload passengers is. There has to be a seal around a relatively large area, that holds well, that remains functional after a long time of frequent operation.



But let's keep in mind that this isn't the final development model, it's a research tube. It's here to answer some basic questions, not serve as a viable prototype for Hyperloop construction. The point is to learn how to maintain a vacuum and other parameters of operation.

 

[Urwumpe]

I disagree. I think vacuum is more difficult to maintain.

An absolute vacuum yes. But now, it is just about a partial vacuum.

And then, if you have a lower pressure inside a tube, it compresses the tube, while a higher pressure expands it. And again: 0.01 bar are easier contained in a pressure vessel than 1.99 bar.

 

[Andy44]

If the seals break and passengers get sucked into the tunnel you get this:

 

[Thunder Chicken]

If the seals break and passengers get sucked into the tunnel you get this:

It could get ugly:

Maybe Elon has watched too much James Bond:

[ame="http://www.youtube.com/watch?v=-AzJ5_8Cqdc"]The Living Daylights (1987) - Koskov`s Escape 2-2 - YouTube[/ame]

 

[RisingFury]

An absolute vacuum yes. But now, it is just about a partial vacuum.

And then, if you have a lower pressure inside a tube, it compresses the tube, while a higher pressure expands it. And again: 0.01 bar are easier contained in a pressure vessel than 1.99 bar.

The physical stress the tube is under is not problem. Seals are.

If there's air in the tube, the drag won't follow the F = c * Rho * v^2 equation, because the air will not efficiently flow around the transport vehicle, but will be pushed along the tube.

As it's pushed along, it'll get accelerated, but it'll also pick up more air. The vehicle will act as a piston in a cylinder.


I'm guessing they're prepared for that and might use the vehicle as a pump to remove excess air from the tube.

 

[Urwumpe]

I'm guessing they're prepared for that and might use the vehicle as a pump to remove excess air from the tube.

Yes, I would also say so. Likely they will not have a perfect seal there anyway, but some lot of distance (after all, the vehicle also has to travel through curves) between vehicle and walls.

Maybe they just lower it by pumps to an economic compromise pressure level and then use the vehicles as some sort of Prince Albert molecular pump.

Sealing the stations might not be too hard, you could do that like we already do for inserting "pigs" into gas pipelines (We call those "Molch"/newt in Germany)

Instead of using dead-end stops there, such a station could just be a small side track to the full system. But then, I can't even imagine how a switch would look like for a hyperloop. Switches for maglev trains are already pretty arcane.

 

[Urwumpe]

Some update from the hyperloop world:

The port authority of Hamburg (Hamburger Hafen und Logistik AG) is planning to build a short Hyperloop track soon for transporting 4100 standard containers per day from the container terminal to a truck terminal further inland to relieve the roads at the port from many trucks. Two MoUs have already been signed there, construction should start in 2-3 years.

http://www.spiegel.de/auto/aktuell/hamburg-hyperloop-von-elon-musk-im-hafen-geplant-a-1238545.html