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The Hyperloop: BUSTED
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rs20:
The thing I don't get about this whole thing is that the logic seems to be: if you break the seal, everyone dies --> BUSTED!.

Well, by that metric, airplanes, trains, cars are all BUSTED as well because one can contrive (and see demonstrations of) deaths due to failures of components of all these things.

It's obviously a very very ambitious idea, and I have strong doubts whether it will ever succeed. But to call it "BUSTED", frankly, dilutes the brand of the word BUSTED which should be restricted to things that are impossible, not just dangerous.
EEVblog:

--- Quote from: Maxlor on July 26, 2016, 07:24:48 pm ---I'm not saying the Hyperloop can work, and I certainly don't have the skills do design the whole system, but I also don't make absolute claims, like Thunderf00t does.

--- End quote ---

He's doing back of the envelop calcs to show how impractical and fragile the system is going to be.
You only need one of those showstoppers to be true to the entire project to be a guaranteed bust.


--- Quote ---If you make claims, back them up with solid evidence. I don't know why you're calling me out here

--- End quote ---

Because you said this:

--- Quote ---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 ---

That implies that you think he's wrong and you have "obvious" solution to his argument.
Please present those obvious and less obvious solutions.


--- Quote ---, since this is exactly what you did in your various busting videos: let them have every detail that you can't 100% show isn't possible, and still show it doesn't work. Or is it just that because Thunderf00t can make a fancy video that he's more right? Hyperloop's videos are even fancier, you know...

--- End quote ---

It's about back of the envelope practicality calcs.


--- Quote ---Expansion of tubes, station shifting by hundreds of meters: as mentioned earlier in this thread, wouldn't rail tracks have the same problem? You don't see those shifting around all the time. Steel on this scale has quite a bit of elasticity to it, it can be compressed. Or if that's not an option, you can use sliding seals. Shock absorbers use those, and they hold up to a lot more than just 100kPa. I'm sure there are other solutions as well.

--- End quote ---

Shock absorbers are much smaller in diameter, not a good analogy.
And you need thousands of these large diameter seals to work perffectly 24/7 to keep this system working. It's a fundamentally stupid idea from a practical engineering standpoint, when you can eliminate all that problem with existing proven tech at half the speed (MagLev)


--- Quote ---Lot's of vacuum seals, and implication that it's impossible to get them all to seal properly: probably true

--- End quote ---

Now your getting it.


--- Quote ---but Hyperloop claim the distributed nature of the vacuum pumps will handle leaks, which even they acknowlege are unavoidable. So is it possible to make the seals reliable enough? I don't know, Thunderf00t certainly doesn't show any evidence that it isn't.

--- End quote ---

The argument is that it seems pretty stupid to even try to manage such a system.


--- Quote ---The video segments showing those interior designers: what are they doing in the video, they're supposed to show that Hyperloop consists of idea people with little background in engineering?

--- End quote ---

Solar Roadways have engineers.
UBeam have some of the finest ultrasonic PhD's in the world.
Both of these ideas will never ever work.


--- Quote ---Massive buckling problems due to temperature differentials: Couldn't you just make the pipes strong enough to handle it? Maybe that'd make it economically unviable, but that's not what Thunderf00t says - he says it's technically impossible. But it's clearly not, otherwise gas pipelines would buckle all the time. There's really very little in the way of technical limits as to how strong you can make something, as evidenced by submarines (military ones handle thousands of kPa, research ones tens of thousands even) or, say, dams and tunnels. And if the steel pipe on it's own really is too weak, welding in some rings as shown in th picture above should do it? Or does that make it too expensive already? I don't know, but I do know that there isn't a technical problem here.

--- End quote ---

It's technically possible if you throw money at it, but any practical engineer should be able to see all the big potential showstopper issues here. Unless you have a cool job at Hyperloop and then you have blinkers on, just like those at uBeam.


--- Quote ---A catastrophic accident of a single car causing destruction of every other car in the system: Yeah, no. First, even if you open the pipe to its full diameter and let air rush in, that shockwave is going to die down, question is, how quickly. Now I'm not sure how to calculate this situation (but I have a COMSOL simulation running over night) but we could get a very rough idea by using the formula for calculating pressure drop from a compressor in a pneumatic system with constant flow. The numbers say, after about 66km there's about a 100kPa drop, after 37km (average car distance according to Hyperloop) there's a roughly 60kPa drop. Now clearly, that isn't the definitive answer since the actual situation isn't static, but it's enough to make me think that friction plays a role here and the pressure wave is not going to travel through the whole system at full strength, destroying everything, as Thunderf00t claims.

--- End quote ---

I agree you are likely right here. But one incident will take down the entire system and likely costs lives. It's an inherent fragile engineering system. In fact it's probably the most fragile system you could come up with. Good engineering does not base itself around an inherently fragile system.


--- Quote ---Second, why would the whole system have to be one open, connected tube? You could add a pressure lock every 1km that opens for cars and closes behind them, which would thus contain a catastrophe.

--- End quote ---

A door (and seals) that need to automatically open and close every 1km, at 1000kmh, do the math. This idea simply takes you further down the rabbit hole of impracticality.
You are trying to come up with a solution to fix an idea that is inherently flawed.


--- Quote ---The engine: actually, that turbine is not meant for propulsion. Hyperloop say that the cars are powered by external linear actuators, the turbine is there to avoid the cars pushing a column of air in front of them, which even at 0.1kPa, will add up. So it doesn't have to produce any noticeable thrust. Of course, it might still be possible that even just moving the amount of air involved is impossible, I don't know. The parts of the video are based on a misunderstanding and aren't really helpful.

--- End quote ---

Probably right.
EEVblog:

--- Quote from: Maxlor on July 27, 2016, 12:39:10 pm ---What we can clearly see is that the pressure behind the wave front drops as the wave runs through the tube, and that the wave front itself becomes more spread out. If we take that factor of 0.75/5km, after 35km (average distance to next car) we'll have a factor of 0.13, which doesn't seem so catastrophic anymore.

--- End quote ---

You can go ride it first then, good luck. I'll take the infinitely more robust and safe MagLev at half the speed thanks.
EEVblog:

--- Quote from: rs20 on July 28, 2016, 01:35:06 am ---It's obviously a very very ambitious idea, and I have strong doubts whether it will ever succeed. But to call it "BUSTED", frankly, dilutes the brand of the word BUSTED which should be restricted to things that are impossible, not just dangerous.

--- End quote ---

BUSTED means it isn't a practical solution.
EEVblog:

--- Quote from: System Error Message on July 26, 2016, 02:49:25 pm ---
--- 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.

--- End quote ---

I didn't get the joke because it wasn't a joke!
If you read the QF32 book, it's all about constant endless error messages being kicked up by the ECAM system and how they spent hours working through them.
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