General > General Technical Chat

The Hyperloop: BUSTED

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Mark_Of_Sanity:
What if this was only used for transporting cargo until they felt like they absolutely nailed
the human safety issue? It would eliminate limits on deceleration and what not.

Also I want to post something very interesting that was mentioned by someone else on this project.
I don't know much about gasses so hoping someone who does know can check if it's right.

https://www.reddit.com/r/Futurology/comments/4udgd2/the_hyperloop_one_busted_by_the_youtube/

By Hwillis

"...
Decompression Shockwaves: He clearly did not do any math. The hyperloop is 300,000 times longer than it is wide. The flow into the tube is extremely limited over distance. 2km from the breach, flow will be slowed to 5%. Assuming air is indeed rushing in at the speed of sound, air will only be moving 80mph in the tube 2km from the breach. Perfectly safe.

Additionally, in order to get that fast flow, you need to destroy a section of tube entirely. A hole half a meter wide would cause 6% the flow of a fully open tube. You need an fully open tube, not a breach or leak, in order to cause a dangerous failure. A bullet, grenade or even a car crash would not be enough to do that. Since the sudden change in air pressure is gonna try to shut the tube as well, this circumstance is extremely unlikely. This shutting effect would only be at the end of the tube, since the crushing effect would only happen for a very brief time, and the tube is very strong. It's made of the same thickness of steel they use to cover large holes in the road."

He cites two equation websites for his reduced flow claim.

http://www.engineeringtoolbox.com/pressure-drop-compressed-air-pipes-d_852.html

http://www.tlv.com/global/TI/calculator/water-flow-rate-through-orifice.html#

Moving on, another interesting example of a long vacuum tube is the LIGO experiment built to detect gravity waves.

https://www.ligo.caltech.edu/page/vacuum

They state,

"LIGO’s vacuum tubes were constructed of spiral-welded 304L stainless steel a mere 3 mm thick."

"The 1.2 m diameter beam tubes were created in 19 to 20 m-long segments, rolled into a tube with a continuous spiral weld (far left photo). While a mathematically perfect cylinder will not collapse under pressure, any small imperfection in a real tube would allow it to buckle (a crushed vacuum tube would be catastrophic). To prevent collapse, LIGO's tubes are supported with stiffener rings that provide a significant layer of resistance to buckling under the extreme pressure of the atmosphere. The tubes must withstand these stresses for at least 20 years."



T3sl4co1l:
Certainly, it's not going to be vulnerable to, say, small arms fire.  The number of people in possession of AP or HE munitions is probably small.  But, still, a valid risk, given the kind of people we have here...

The greatest challenge is, even if all these problems are solved (which I believe they can be), the fact will remain that it's preposterously expensive (way more than the initial estimate, to solve all the initially-unforeseen challenges, and to solve other problems as they arise), and worst of all, just a big overly-important financial circle-jerk for the backers (who will win and who will lose? Take a spin on Hyperloop Of Fortune!).

As with all things: follow the money.  Who gets paid, who gets shafted?  That's a bit of research I'd like to see.

Tim

hayatepilot:
The california high speed rail from los angeles to san francisco will cost $68billion to construct. That is for a conventional train.
How on earth is Hyperloop going to build the whole thing for 1/10th the price of a conventional rail?? This is pure BS.
It would more likely cost in the region of $100billion...

http://www.investopedia.com/articles/investing/050815/elon-musks-hyperloop-economically-feasible.asp

ConKbot:

--- Quote from: EEVblog on July 26, 2016, 01:36:06 am ---
--- Quote from: Maxlor on July 25, 2016, 03:24:52 pm ---Unconvincing bust. He simplifies things quite a bit, takes several cheap shots, and doesn't allow for any obvious or less obvious solutions to the fatal problems he mentions.

--- End quote ---

Perhaps you like to explain those solutions in detail then?

--- End quote ---

Well for the joints,  rather than a sliding joint for expansion, a simple bellows connection between each pipe segment would be simple and effective. Works in real high vacuum systems and for oil pipelines.  An emergency shutter to block any uncontrolled venting if the next car isn't going to hit it, etc. 

I'm sure there isn't going to be just a vacuum pumping station at either end,  so why not combine the shutter, pumping station and an emergency exit/station into one unit.

I also found the turbine / turbomolecular pump comparisons a bit lacking in substance.   (Turbomolecular pumps go this fast, turbines only go this fast)   
Sure, they are going to need a pressure ratio of 750-1000:1,  and jet engines are usually 20-40:1,  and turbo pumps are much higher. But at uhv, the physics get a lot different, and turbopumps don't even operate at 1 mbar like they want to operate the hyperloop at.  Sure its an engineering task, but not insurmountable.  It would be interesting to know what someone with experience in the field would say about it.

Honestly, I find the idea of metal fatigue in the passengers compartment, and station area much more concerning than some of the issues pointed out.  Luckily it doesnt need to be  as light as airplanes.

System Error Message:

--- Quote from: EEVblog on July 26, 2016, 01:37:31 am ---
--- Quote from: System Error Message on July 26, 2016, 01:26:46 am ---Qantas 32 had lots of error messages :P

--- End quote ---

It was crazy!
I highly recommend the book:
http://amzn.to/2a9vfSm

--- End quote ---

You didnt get my joke in relation to my name lol.

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