PDA

View Full Version : The Hyperloop


Flapjack
August 26th, 2016, 10:47 PM
Heyy I was thinking VT is dead so over the next day or so I am going to be posting a few threads.

I am not sure this belongs here as it could turn into a debate so sorry mods if it does :)

I want to know, what do you guys think of the hyperloop? I think with the information released so far it won't work and even if they do get it to work, a gunshot that could pierce the tube would obviously be catastrophic.

The first video goes into the details of the science and the second just visualises what would happen if there was a tube failure :)

RNFesa01llk
YIVJvpNyjdc

Desynchronized
August 26th, 2016, 11:26 PM
I kinda agree with you... Its a pretty poor idea lol. Accidents can happen quite easily. Sorry can't go into much details.
Off topic: hey buddy i don't think vt is dead at all.

dxcxdzv
August 27th, 2016, 04:07 PM
Those videos are bullshit.
If you scale up the acceleration will not be greater, that's even the contrary actually.

I'll add that a brutal difference of pressure is not a problem as there are ways to stop the Hyperloop simply by using a tension force or equaling atmosphere pressure on the other side.
Passengers are in a pressurized shuttle by the way so unless the Hyperloop hurts another one in the tube chances to die are quite low.

Flapjack
August 27th, 2016, 10:07 PM
Those videos are bullshit.
If you scale up the acceleration will not be greater, that's even the contrary actually.

Well there will be more force applied to one side as the air rushes in but the train thing weighs a few tone so yeah it might actually be less acceleration xD

The guy is a crazy smart irl scientist though so I dunno?

Those videos are bullshit.
I'll add that a brutal difference of pressure is not a problem as there are ways to stop the Hyperloop simply by using a tension force or equaling atmosphere pressure on the other side.
Passengers are in a pressurized shuttle by the way so unless the Hyperloop hurts another one in the tube chances to die are quite low.

Yeah as the hyperloop is pressurised it won't be crushed by the 1atm on both sides!! Smart cookie Reisey;)

I still think the expansion joints are a massive problem though :(

dxcxdzv
August 28th, 2016, 05:03 AM
Well there will be more force applied to one side as the air rushes in but the train thing weighs a few tone so yeah it might actually be less acceleration xD

The guy is a crazy smart irl scientist though so I dunno?
Smart or not he is omitting the square-cube law, scaling up won't be a significant issue in case of a brutal difference in pressure.



I still think the expansion joints are a massive problem though :(
You can reduce materials dilatation by covering them with an insulation one, the Alpha version had also photovoltaic panels that can absorb thermic energy as well.
And even if a leak appears in the tunnel you can deal with the pressure difference. The shuttles are pressurized so unless you break them that should be alright.

One thing noticeable is for the passengers' boarding, the shuttle has to enter an airlock so the pressure of the part of the tunnel where passengers board can be increased, once passengers are installed the shuttle is sealed, the tunnel entrance is sealed and the airlock pressure is being lowered to the tunnel's. A dramatic event could occur in case of a problem here but once again you can counteract it by for example blocking the shuttle so it can't move during the process.

I do agree that putting apart the physical risks for the passengers any problem of that kind could have disastrous financial consequences though.

Flapjack
August 28th, 2016, 07:11 AM
Smart or not he is omitting the square-cube law, scaling up won't be a significant issue in case of a brutal difference in pressure.

Trueee although I will say that the acceleration in the youtube video was only over a few feet... imagine that over 10m or so and that is assuming they can repressurise the tunnel in that time.

You can reduce materials dilatation by covering them with an insulation one, the Alpha version had also photovoltaic panels that can absorb thermic energy as well.
And even if a leak appears in the tunnel you can deal with the pressure difference. The shuttles are pressurized so unless you break them that should be alright.

One thing noticeable is for the passengers' boarding, the shuttle has to enter an airlock so the pressure of the part of the tunnel where passengers board can be increased, once passengers are installed the shuttle is sealed, the tunnel entrance is sealed and the airlock pressure is being lowered to the tunnel's. A dramatic event could occur in case of a problem here but once again you can counteract it by for example blocking the shuttle so it can't move during the process.

I do agree that putting apart the physical risks for the passengers any problem of that kind could have disastrous financial consequences though.

This is all true buddy!:)

One thing I just thought of and it is so obvious I am pretty sure there is a simple answer I am overlooking is wouldn't the tube be crushed by the pressure on the outside? Like in that science experiment with the can with low pressure that is rapidly cooled? (https://www.youtube.com/watch?v=vcsxB5dKJMg)

I know the simple answer would be the tubes would be strong enough but with tubes like this:
http://ichef-1.bbci.co.uk/news/624/cpsprodpb/B5EB/production/_87817564_87817563.jpg
I just can't visualise it! Especially with the tubes being 400 miles long!

dxcxdzv
August 28th, 2016, 12:25 PM
One thing I just thought of and it is so obvious I am pretty sure there is a simple answer I am overlooking is wouldn't the tube be crushed by the pressure on the outside? Like in that science experiment with the can with low pressure that is rapidly cooled? (https://www.youtube.com/watch?v=vcsxB5dKJMg)

I know the simple answer would be the tubes would be strong enough but with tubes like this:
image (http://ichef-1.bbci.co.uk/news/624/cpsprodpb/B5EB/production/_87817564_87817563.jpg)
I just can't visualise it! Especially with the tubes being 400 miles long!
Would you mind provide me the plans of the Hyperloop One? I didn't find them.

I'm alright with calculating the stress exercised on the cylinder by I'd need the thickness as models do vary in function of it.

Flapjack
August 28th, 2016, 12:31 PM
Would you mind provide me the plans of the Hyperloop One? I didn't find them.

I'm alright with calculating the stress exercised on the cylinder by I'd need the thickness as models do vary in function of it.
Here you are buddy!! :) (http://www.spacex.com/sites/spacex/files/hyperloop_alpha-20130812.pdf)

dxcxdzv
August 28th, 2016, 01:22 PM
Here you are buddy!! :) (http://www.spacex.com/sites/spacex/files/hyperloop_alpha-20130812.pdf)
Thickness: 23 mm
Inner diameter: 2.23m

Wow, this is a thin-walled cylinder.

Such a cylinder, subject to external pressure will experience a hoop stress.

The tube has a thickness of 2.3.10^-3 m.

I used The Engineering ToolBox (http://www.engineeringtoolbox.com/stress-thick-walled-tube-d_949.html) and found an effective hoop stress of -57.49 Mpa (N.mm^-2). Which constitutes a stress of 567 atmospheres.
(this is a calculation for thick-walled cylinders but I'm just too lazy, otherwise it is about 0.999*2.23/0.0046 normally)

I'm searching concerning steel resistance to this kind of pressure in function of its thickness.

This steel here (http://www.azom.com/properties.aspx?ArticleID=863) can for example handle a stress 3 times higher without problem.

EDIT: Elon musk also said that the tube structure will be reinforced:
a uniform thickness steel tube reinforced with stringers was selected as the material of choice for the inner diameter tube

Flapjack
August 28th, 2016, 01:23 PM
Thickness: 23 mm
Inner diameter: 2.23m

Wow, this is a thin-walled cylinder.

Such a cylinder, subject to external pressure will experience a hoop stress.

The tube has a thickness of 2.3.10^-3 m.

I used The Engineering ToolBox (http://www.engineeringtoolbox.com/stress-thin-walled-tube-d_948.html) and found an effective hoop stress of -57.49 Mpa (N.mm^-2). Which constitutes a stress of 567 atmospheres.

I'm searching concerning steel resistance to this kind of pressure in function of its thickness.

This steel here (http://www.azom.com/properties.aspx?ArticleID=863) can for example handle a stress 3 times higher without problem.

EDIT: Elon musk also said that the tube structure will be reinforced:a uniform thickness steel tube reinforced with stringers was selected as the material of choice for the inner diameter tube
My gosh I continue to be amazed by your smarts!! Thanks buddy that clears so much up :)

dxcxdzv
August 28th, 2016, 01:31 PM
My gosh I continue to be amazed by your smarts!! Thanks buddy that clears so much up :)
I believe also that the Hyperloop One has some differences compared to the Alpha version so we can't be sure.
But I guess people whose this kind of things is the job (engineering) did better calculations, so considering that, I would tend to trust them.

jamie_n5
August 31st, 2016, 03:54 PM
The concept is maybe good but I don't know how practical it would be. They surely would have to make it safer. With all the terrorism in the world right now it would be a big target too.

Flapjack
September 3rd, 2016, 04:41 AM
The concept is maybe good but I don't know how practical it would be. They surely would have to make it safer. With all the terrorism in the world right now it would be a big target too.Sameeee especially with it going through a desert, someone could shoot at it and never be caught. With how dangerous a vacuum failure is and how many crazy gunmen there is in the US I can see it happening a lot :(